摘要:

238 RICHARDS AND LOWRY THE ROTATORY DISPERSIVE XL. - The Rotatory Dispersive Power of Organic Compoundg. Part X I V . Simple Dispersion in l-Methylc yclohexylidene-4-acetic Acid. By EVAN MATTHEW RICHARDS and THOMAS M~ELTIN LOWRY. SPECIAL interest attaches to the rotatory dispersion of centro-asymmetric compounds which (according to the ordinary definition) contain no asymmetric atom. Through the kindness of Professor Pope we have recently had the opportunity of studying from this point of view his own specimens (compare J. 1909,95,1789) of the d- and 2-forms of the well-known acid, On Professor Pope's recommendation the measurements were made with solutions in methylal. The volatility of this solvent made it necessary to express the results in the form of dispersion-ratios, instead of by means of specific or molecular rotations since the solutions were originally cloudy and their concentrations were altered appreciably by filtration ; but we had the very great advan-tage of being able (except in the photographic region) to read a dextro against a l ~ v o solution under precisely similar conditions, without being compelled to make use of zero-readings.In these circumstances a very satisfactory agreement was obtained between the results recorded in two complete series of independent readings. The data are set out in Table I together wifh the corresponding dispersion-ratios calculated from the equation "/a5461 = 0.2422/ (A2 - 0.056). Since the value of 45461 was about 20" for the visual and 10" for the photographic observations an error of 0.001 in the dispersion-ratios corresponds with an error of 0.02" in the visual readings and of 0-01" in the photographic readings.The largest visual error was therefore about 0.2" (for a dBcult dark-blue line) and the largest photographic error about 0-3". The average error in the visual ratios is 0.003 and in the photographic ratios 0.02; the negative and positive errors are moreover dis-tributed in small groups and afford no evidence of systematic deviations from the formula such as were observed in the case of octyl oxalate. The data can be expressed over the range of wave-lengths covered by our observations and up to the existing limits of experi-mental accuracy by one term of Drude's equation. Moreover, since an exposure of more than an hour was required to give the last photographic reading it is clear that the measurements had been carried right up to the limit of the region of transparency withi POWER OF ORGANIC COMPOUNDS.PART XIV 239 TABLE I. Dispersion-ratios of 1 -MethylcycZohexylidene-4-acetic Acid in Methylal (about 6 gms. per 100 c.c.) at 20°.* Mol. wt. 154.17. a/a5461 = 0*2422/(h2 - 0.056). Sum of d and I w d First Secind -, Dispersion-ratios rotations. a la54 61' Line. series. series. series. series. Mean. Calc. Diff. Li 6708 12.81 11.00 0.611 0.602 0.607 0.615 -0.008 Zn 6362 14.53 12.56 0.694 0.688 0.691 0.694 -0.003 CU 5782 18.24 15.91 0.870 0.871 0.871 0.870 +O-001 Cd 6438 14-20 12-31 0.678 0.674 0.676 0.676 rt Na 5893 17.41 15.20 0.531 0.832 0.832 0.832 i Hg 5780 18.23 15-85 0.870 0.870 0.870 0.871 -0.001 CU 5700 18.82 16.45 0.898 0.901 0.900 0.901 -0.001 Hg 5461 20.95 18-26 1.000 1.000 1.000 1.000 * Cu 5218 23.48 20.47 1.121 1.121 1.121 1.120 +O-OOl CU 5153 24-29 21-19 1.160 1-160 1.160 1-156 +0-004 Cu 5106 24.89 21.64 1.188 1.185 1.187 1.183 +0.004 Cd 5086 25.19 21.85 1.202 1.196 1.199 1.195 +0*004 Zn 4811 28.87 - 1.378 - 1.378 1.381 -0.003 Cd 4800 29.14 25-32 1.391 1.386 1.389 1.389 3I Zn 4722 30.48 26.60 1.455 1.456 1.456 1.450 +0*006 Zn 4680 31.05 27.18 1.482 1.488 1.485 1.486 -0.001 Cd 4678 31.49 27.23 1.503 1.491 1.497 1.487 +O.OlO Hg 4368 37.92 32.96 1.810 1.805 1.808 1.808 & Photographic Series (a5461 = 9-54').Dispersion ratio. Line. Rotation. Obs. Cali. Diff. Fe 4376 17.11 1.79 1.79 f Fe 4337 17.36 1.82 1-83 -0.01 Fe 4308 17.61 1-85 1.87 - 0.02 Fe 4271 18.11 1.90 1.92 - 0.02 Fe 4261 18.36 1.92 1.93 -0.01 Fe 4236 18-61 1.95 1.96 - 0.01 Fe 4199 18.98 1.99 2.01 - 0.02 Fe 4187 19.23 2.02 2-03 - 0.01 Fe 4144 20.23 2.12 2.09 + 0.03 Fe 4132 20.36 2-13 2-1 1 + 0.02 Fe 4119 20.61 2.16 2.13 + 0.03 Fe 4072 21-50 2.23 2.21 + 0.02 * The temperature 20° was accidentally omitted from the corresponding tables for octyl alcohol and octyl oxalate in Part XI1 of this series (J.1924, 125 1595 1596). The opportunity may also be taken of correcting an error in Part XI (ibid. p. 1466 two lines from the bottom) where a shallow minimum " at 5 per cent." should be " a t 50 per cent." of ethyl tartrate. which alone Drude's formula is valid. As any deviations disclosed by pushing the observations beyond this limit would be irrelevant to the present discussion it appears that the simplicity of the dis-persion is not likely to be disproved by direct experimental measure-ments.Complexity could therefore be established only by the use of indirect tests such as that described in the previous pape 240 BRISCOE ROBINSON AND STEPHENSON : (p. 2511). In the present instance however as in the analogous case of octyl alcohol this test gives no clear answer to our question since the characteristic frequency of the dispersion-equation falls in a region in which absorption-bands are very difficult to detect. Thus the dispersion-constant A2 = 0.056 of Pope's acid corresponds to a wave-length X = 2364 A.U. only a little longer than that of the last strong line in the iron arc spectrum.Direct measurements of the molecular extinction coefficient of the acid in this region (Table 11) show however that the " general absorption '' (log Q = 3.9) of the acid at this wave-length is already more than 100 times greater than the maximum selective absorption (log C= 1.5) of ctimphor and of camphorquinone at the head of their absorption bands. It was therefore quite impossible to establish the existence of a band of selective absorption a t the wave-length indicated. In our opinion, however a negative result of this character does not provide valid evidence that the dispersion is complex; and until some positive evidence to the contrary is available we propose to dispersion of the compound as simple.TABLE 11. Molecular Extinction Coefficients. A = 2470 2440 2411 2375 2348 2338 log E = 3.31 3.61 3.78 3.91 4.01 4.09 describe the 2327 4.15 The acid contains only one unsaturated group namely the con-jugated system >C=CH-CqOH 0 . The characteristic frequency of this is perhaps given by the dispersion-constant of our equation. We desire to express our thanks to the Department of Scientific and Industrial Research for a maintenance grant to one of the authors (E. M. R.). UNIVERSITY CHEMICAL LABORATORY, CAMBRIDGE . [Received September 20th 1924. 238 RICHARDS AND LOWRY THE ROTATORY DISPERSIVE XL. - The Rotatory Dispersive Power of Organic Compoundg. Part X I V . Simple Dispersion in l-Methylc yclohexylidene-4-acetic Acid. By EVAN MATTHEW RICHARDS and THOMAS M~ELTIN LOWRY.SPECIAL interest attaches to the rotatory dispersion of centro-asymmetric compounds which (according to the ordinary definition) contain no asymmetric atom. Through the kindness of Professor Pope we have recently had the opportunity of studying from this point of view his own specimens (compare J. 1909,95,1789) of the d- and 2-forms of the well-known acid, On Professor Pope's recommendation the measurements were made with solutions in methylal. The volatility of this solvent made it necessary to express the results in the form of dispersion-ratios, instead of by means of specific or molecular rotations since the solutions were originally cloudy and their concentrations were altered appreciably by filtration ; but we had the very great advan-tage of being able (except in the photographic region) to read a dextro against a l ~ v o solution under precisely similar conditions, without being compelled to make use of zero-readings.In these circumstances a very satisfactory agreement was obtained between the results recorded in two complete series of independent readings. The data are set out in Table I together wifh the corresponding dispersion-ratios calculated from the equation "/a5461 = 0.2422/ (A2 - 0.056). Since the value of 45461 was about 20" for the visual and 10" for the photographic observations an error of 0.001 in the dispersion-ratios corresponds with an error of 0.02" in the visual readings and of 0-01" in the photographic readings. The largest visual error was therefore about 0.2" (for a dBcult dark-blue line) and the largest photographic error about 0-3".The average error in the visual ratios is 0.003 and in the photographic ratios 0.02; the negative and positive errors are moreover dis-tributed in small groups and afford no evidence of systematic deviations from the formula such as were observed in the case of octyl oxalate. The data can be expressed over the range of wave-lengths covered by our observations and up to the existing limits of experi-mental accuracy by one term of Drude's equation. Moreover, since an exposure of more than an hour was required to give the last photographic reading it is clear that the measurements had been carried right up to the limit of the region of transparency withi POWER OF ORGANIC COMPOUNDS.PART XIV 239 TABLE I. Dispersion-ratios of 1 -MethylcycZohexylidene-4-acetic Acid in Methylal (about 6 gms. per 100 c.c.) at 20°.* Mol. wt. 154.17. a/a5461 = 0*2422/(h2 - 0.056). Sum of d and I w d First Secind -, Dispersion-ratios rotations. a la54 61' Line. series. series. series. series. Mean. Calc. Diff. Li 6708 12.81 11.00 0.611 0.602 0.607 0.615 -0.008 Zn 6362 14.53 12.56 0.694 0.688 0.691 0.694 -0.003 CU 5782 18.24 15.91 0.870 0.871 0.871 0.870 +O-001 Cd 6438 14-20 12-31 0.678 0.674 0.676 0.676 rt Na 5893 17.41 15.20 0.531 0.832 0.832 0.832 i Hg 5780 18.23 15-85 0.870 0.870 0.870 0.871 -0.001 CU 5700 18.82 16.45 0.898 0.901 0.900 0.901 -0.001 Hg 5461 20.95 18-26 1.000 1.000 1.000 1.000 * Cu 5218 23.48 20.47 1.121 1.121 1.121 1.120 +O-OOl CU 5153 24-29 21-19 1.160 1-160 1.160 1-156 +0-004 Cu 5106 24.89 21.64 1.188 1.185 1.187 1.183 +0.004 Cd 5086 25.19 21.85 1.202 1.196 1.199 1.195 +0*004 Zn 4811 28.87 - 1.378 - 1.378 1.381 -0.003 Cd 4800 29.14 25-32 1.391 1.386 1.389 1.389 3I Zn 4722 30.48 26.60 1.455 1.456 1.456 1.450 +0*006 Zn 4680 31.05 27.18 1.482 1.488 1.485 1.486 -0.001 Cd 4678 31.49 27.23 1.503 1.491 1.497 1.487 +O.OlO Hg 4368 37.92 32.96 1.810 1.805 1.808 1.808 & Photographic Series (a5461 = 9-54').Dispersion ratio. Line. Rotation. Obs. Cali. Diff. Fe 4376 17.11 1.79 1.79 f Fe 4337 17.36 1.82 1-83 -0.01 Fe 4308 17.61 1-85 1.87 - 0.02 Fe 4271 18.11 1.90 1.92 - 0.02 Fe 4261 18.36 1.92 1.93 -0.01 Fe 4236 18-61 1.95 1.96 - 0.01 Fe 4199 18.98 1.99 2.01 - 0.02 Fe 4187 19.23 2.02 2-03 - 0.01 Fe 4144 20.23 2.12 2.09 + 0.03 Fe 4132 20.36 2-13 2-1 1 + 0.02 Fe 4119 20.61 2.16 2.13 + 0.03 Fe 4072 21-50 2.23 2.21 + 0.02 * The temperature 20° was accidentally omitted from the corresponding tables for octyl alcohol and octyl oxalate in Part XI1 of this series (J.1924, 125 1595 1596). The opportunity may also be taken of correcting an error in Part XI (ibid. p. 1466 two lines from the bottom) where a shallow minimum " at 5 per cent." should be " a t 50 per cent." of ethyl tartrate. which alone Drude's formula is valid. As any deviations disclosed by pushing the observations beyond this limit would be irrelevant to the present discussion it appears that the simplicity of the dis-persion is not likely to be disproved by direct experimental measure-ments.Complexity could therefore be established only by the use of indirect tests such as that described in the previous pape 240 BRISCOE ROBINSON AND STEPHENSON : (p. 2511). In the present instance however as in the analogous case of octyl alcohol this test gives no clear answer to our question since the characteristic frequency of the dispersion-equation falls in a region in which absorption-bands are very difficult to detect. Thus the dispersion-constant A2 = 0.056 of Pope's acid corresponds to a wave-length X = 2364 A.U. only a little longer than that of the last strong line in the iron arc spectrum. Direct measurements of the molecular extinction coefficient of the acid in this region (Table 11) show however that the " general absorption '' (log Q = 3.9) of the acid at this wave-length is already more than 100 times greater than the maximum selective absorption (log C= 1.5) of ctimphor and of camphorquinone at the head of their absorption bands.It was therefore quite impossible to establish the existence of a band of selective absorption a t the wave-length indicated. In our opinion, however a negative result of this character does not provide valid evidence that the dispersion is complex; and until some positive evidence to the contrary is available we propose to dispersion of the compound as simple. TABLE 11. Molecular Extinction Coefficients. A = 2470 2440 2411 2375 2348 2338 log E = 3.31 3.61 3.78 3.91 4.01 4.09 describe the 2327 4.15 The acid contains only one unsaturated group namely the con-jugated system >C=CH-CqOH 0 . The characteristic frequency of this is perhaps given by the dispersion-constant of our equation. We desire to express our thanks to the Department of Scientific and Industrial Research for a maintenance grant to one of the authors (E. M. R.). UNIVERSITY CHEMICAL LABORATORY, CAMBRIDGE . [Received September 20th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700238

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

240 BRISCOE ROBINSON AND STEPHENSON : XLI. -The Electrical Explosion of Tungsten Wires. By HENRY VINCENT AIRD BRISCOE PERCY LUCOCK ROBINSON, and GEORGE EDWARD STEPHENSON. THE phenomena accompanying heavy high-tension discharges in thin metallic wires were first studied by Anderson (Astrophys. J., 1920 51 37). Using a large glass plate and tin-foil condenser, he photographed the spectra of the light emitted by the electrical explosion of iron copper nickel and manganin wires and observe THE ELECTRICAL EXPLOSION O F TUNGSTEN WIRES. 241 very interesting eff'ects notably a reversal of many lines producing an absorption (Fraunhofer) spectrum instead of the bright-line spectrum usually observed. These phenomena are attributable to the momentary attainment of an exceptionally high temperature in the substance of the wire.Observations with a rotating mirror showed that the duration of the flash was less than 10-5 second, aid Anderson calculated that if the available energy of his condenser, equivalent to about 30 calories were wholly communicated to the 2 milligrams of wire in this time the temperature attained would be of the order of 300,000". The intrinsic brilliancy of the wire at the moment of explosion was found to correspond with a surface tem-peratnre of 20,000". Making liberal allowance for the inherent uncertainty of these estimates it seems evident that the temper-atures attained in such explosions are much higher than can be reached by any other means. I n 1922 Wendt and Irion ( J . Amer. Chem. Xoc. 44 1587) reported the results of experiments on the explosion of fine tungsten wires by Anderson's method.When the explosions were carried out in a vacuum some gas was formed and this subjected to an ordinary high-tension discharge gave a spectrum in which the yellow helium line D, was consistently observed. When the wires were exploded in an atmosphere of carbon dioxide a t ordinary pressure and the carbon dioxide afterwards absorbed in caustic potash solution, residual gas averaging 1.42 C.C. per milligram of tungsten remained. This gas was lost before its spectrum had been investigated. If it consisted wholly or mainly of helium it was on the average some 25% of the weight of tungsten taken. These results were so startling and if correct of such profound significance that the expcriments here described were undertaken to confirm them.The essential idea of these experiments is of course extremely simple. A fine tungsten wire is supported between heavy electrodes sealed into a glass vessel; this vessel is evacuated and a heavy discharge is passed from a condenser of large capacity. Thereafter an ordinary high tension-discharge is passed through a capillary side-tube on the bulb and the emitted light spectroscopically examined. I n practice the experimental difficulties are considerable and arise chiefly in securing the necessary conditions of very high vacuum and very good contact between the wire and the electrodes. Unless both these conditions Stre fulfilled the discharge does not pass through the wire but passes between the electrodes (possibly through the slight conductivity of gas remaining in the bulbs or produced by local heating of the wire) in such a way that the material of the wire is unaffected 242 BRISCOE ROBINSON AND STEPHENSON : E x P E R I M E N T A L.Preparation of Bulbs.-Three containers of the form shown in Fig. 1 were first constructed from 300 C.C. spherical Durosil bulbs A provided with main electrodes EE and a supplementary electrode F in a small bulb connected with A by a capillary tube C. While A was still open a t the line D the wire W was sprung into place between EE by means of suitable forceps thereafter the system of tubes B G H was sealed on a t D. The electrodes EE, were of heavy molybdenum wire approximately 0.1 inch in diameter : one end of each was drilled and countersunk with fine drills to receive the filament and they were then coated with glass nearly to the ends and sealed into the bulbs as shown in Fig.3. FIG. 1. FIG. 2. Serious difficulties were encountered in making this apparatus : unless the bulbs were of heavy glass they cracked a t the electrode seals and when the seals stood they frequently leaked a t pinholes so minute that they could only be detected by a pressure test under water. A T-shaped bulb of about 70 C.C. capacity constructed as in Fig. 2 from Durosil tubing 1” in diameter proved much more satisfactory . All attempts to seal heavy tungsten wires into Pyrex glass as described by Wendt and Irion failed completely but fortunately, it was found that molybdenum sealed fairly well into Durosil glass and could unlike tungsten be obtained as drawn wire of the heavy section required to carry the discharge without material loss THE ELECTRICAL EXPLOSION OF TUNGSTGN WIRES.243 We are indebted to Messrs. Duram Ltd. and to their chemist, Mr. S. C. Radford who very kindly supplied us with several samples of fine tungsten wire both hard-drawn and annealed. The annealed wire proved much less springy and easier to handle than the hard-drawn wire and was used throughout pieces about 4 cm. long were cut from a soft wire 0-035 mm. in diameter. It was quite impossible to spring these wires unsupported between the electrodes as Wendt and Irion stated they had done. With much patience and luck crystalline filaments from an old dran-n-wire lamp could be fitted in this way but they were so fragile as to be useless in practice.Therefore the wire was threaded through a very fine and light capillary glass tube bent back outside the tube a t both ends and then the tube and wire were sprung between the electrodes as shown in Figs. 3 and 3. Bulbs made as described were connected by the mercury-sealed ground glass joint H (Fig. 1) to a large all-glass Topler pump and McLeod gauge and after a preliminary evacuation by a water-pump connected to G, which was then sealed OR at the constriction were further evacu-ated with the Tiipler pump. The first bulb was kept a t 300" in an electrically heated air-bath, evacuated to 0.005 mm. and left a t 300" over-night. Next morning the pressure in the bulb was 0.02 mm.This difference appeared to be too large to be accounted for by the release of gases from the glass. The bulb was allowed to cool and each electrode seal T:-U tested in turn by coating it with sealing wax and carrying out a series of evacuations. By this means i t was established that leakage was occurring in the neighbourhood of the seals. After treating a large surface of the glass with a collodion varnish a vacuum of 0-001 mm. was maintained over-night. As a further test of this vacuum an induction coil discharge was passed between the sup-plementary electrode and one of the main electrodes there was a t first no visible discharge but after a time possibly through the release of gas from the wires or accidental breakage of the wax FIG.3. FIG. 4. I 244 BRISCOE ROBINSON AND STEPHENSON : seals a noisy visible discharge occurred and set up vibration which dislodged the mire and capillary and so rendered the bulb useless. The details given above for one case will serve to indicate the difhulties attendant on the use of molybdenum-glass seals As a result of a series of experiments another metal-glass seal was tried which promised to be more satisfactory because inter aEia, it permitted the proper support of a naked wire inside the bulb. The essential features of this seal are shown in Fig. 4. The glass tube was constricted to allow the tinned copper electrode to pass through neatly without play. The upper part of the glass was heated nearly to redness and molten lead poured into the tube; the lead chilled so quickly a t the constriction that it solidified there and prevented passage of lead into the bulb.The preliminary tests were carried out on single joints which were sealed to the pump and evacuated. It is interesting to observe that where the glass had been hot lead which had overflowed on the outside of the tube adhered strongly to the glass and a t the colder portions of the tube the lead peeled off quite easily. After some practice a satisfactory seal was obtainable and a T-shaped bulb was constructed using this type of joint for the elec-trode seals. In this bulb the tungsten wire was stretched between the two electrodes and a supporting capillary tube was unnecessary. One end of each copper electrode was hammered flat and folded into a small trough; then the end of the wire was laid along the trough and secured by hammering the sides together.Good electrical contact and a secure hold for the wire were thus obtained. The electrode and wire were passed through one side tube of the bulb; the upper electrode was then sealed in with molten lead, and finally the bulb was reversed and the second electrode similarly sealed in. This bulb was connected to the pump and evacuated; the following figures show the efficiency of the seals. 28\12/23 4 p.m. Pressure = 0-0003 mm. of mercury. 8/1/24 10 a.m. Pressure = 0.0080 , , 9 , Thus these seals while useful for many purposes did not appear tight enough for the present experiments. At this stage it was decided to conduct several explosions using the highest vacuum attainable with a number of bulbs having molybdenum-glass seals which had been prepared.The electrode seals were coated externally with sealing wax in such a manner as to give an even well melted coating of wax such coatings had been found to enable the bulbs to hold very high vacua and were really excellent except that they precluded strong heating of the bulb during evacuation. A bulb was evacuated to the limit of the pump THE ELECTRICAL EXPLOSION OF TUNGSTEN WIRES. 245 being heated meanwhile to about 100" by means of a soft luminous gas flame. The evacuated bulb was allowed to stand over-night on the pump and the state of the vacuum noted. I n each case a single stroke of the pump removed a minute bubble so small that it could not be driven down the capillary fall-tube of the pump.The bulb was again heated and another stroke of the pump showed that no gas had been released from the glass it was then sealed off a t the vertical capillary. The Explosions. Nessrs. A. Reyrolle & Co. Ltd. electrical engineers of Hebburn-upon-Tyne very courteously placed their high-tension testing plant a t our disposal and we desire to record here our thanks to Mr. H. ?V. Clothier and Mr. Rarle for their interest and active co-operation in carrying out the experiments a t their works. FIG. 5. Fig. 5 is a diagram of the circuit used. The two condensers, C C, each consisted of 100 glass plates 24 inches square having on each face tinfoil coatings 18 inches by 17 inches the plates were carried on porcelain insulators in a wooden frame heavy brass leads connected alternate coatings with two copper busbars on opposite sides of the condenser.The condensers were not oil-immersed. Each had a capacity of 0.3 microfarad the normal working pressure was 30,000 volts and the highest permissible pressure was 45,000 volts. The connexions permitted the use of either condenser singly or of both in parallel. Current a t 500 volts and 50 cycles A.C. from the supply mains fed to the transformer T was stepped up to any desired voltage (up to a maximum of 100,000 volts) and the output was rectified by a two-electrode thermionic valve R the filament current for which was supplied by the accumulator S. The knife switches, K being closed this rectified output charged the condensers.When the potential difference acruss the condensers reached a certai 246 THE ELECTRICAL EXPLOSION OF TUNGSTEN WIRES. value dependent on the width of the adjustable air-gap G between two large polished brass spheres the condensers discharged across the gap and through the bulb B. The whole of this apparatus was contained in a large cage of expanded steel well earthed and the necessary switches were actuated from the outside of the cage. A kilovoltmeter V across a tertiary winding of the transformer gave an approximate indication of the discharge potential. Through-out the experiments the spark-gap was kept constant and a t the coii-clusion of the tests a precise measurement showed that the potential difference required for discharge across the gap was 29,000 volts.In one case contact between the leads and the electrodes of the bulb was made through mercury contained in rubber tubing slipped over the latter. This bulb fractured on discharge probably because this method of securing contact was defective and the other bulbs were connected up in turn by twisting the leads tightly round the external parts of the electrodes. The phenomena associated with the explosions may best be described by giving the details with reference to one of the several bulbs exploded. Bulb No. 4 was spherical had molybdenum electrodes sealed in through the glass and a filament fitted in a capillary tube as already described. Both condensers were used connected in parallel giving a total capacity of 0.6 microfarad. At discharge the kilovoltmeter K indicated 30,000 volts.The air-gap was screened from sight and the explosion was well seen by four observers it was attended by a dull thud in the bulb, and by a bright flash in which the whole of the filament was seen to be involved. Both the noise and the brightness of the flash were much less than we had anticipated. On examining the bulb it was found that the filament had com-pletely disappeared the capillary now loose in the bulb was intact showed a mere trace of a metallic mirror at one end and was slightly bent at both ends having evidently been softened there by heat. It will be remarked that these effects differ substantially from those described by Wendt and Irion we nevertheless regarded this explosion as complete and satisfactory.Within a few hours after explosion the contents of the bulbs were investigated. An induction coil discharge was passed between the supplementary electrode F and one of the main electrodes, and the light emitted in the capillary tube C was examined visually with a Hilger constant deviation spectrometer. I n each of the bulbs there was a small amount of gas which permitted a discharge to pass and gave a faint banded spectrum on which were superposed a few bright lines the wave-lengths of which were read directl PHYSOSTIGMINE (ESERTNE). PART III. 247 on the spectrometer drum. The lines observed were the green lines of mercury and the red and blue hydrogen lines; none of the bulbs a t any time gave any yellow line whatever although the spectro-meter showed the two sodium lines bright and well defined in the light from an ordinary Bunsen flame.We conclude therefore that our experiments afford no evidence that tungsten can be made to yield helium when exploded by an electrical discharge. At the same time it is clear that extreme difficulties attend any attempt at a crucial experiment on these lines and we attach much more importance to experiments now in progress OP the electrical explosion of tungsten wires in relatively dense and non-conducting atmospheres of absorbable gas. Our conclusion is supported by the results published since our tests were completed of a similar series of experiments conducted in Dr. Anderson's laboratory (Sinclair Smith Proc. Nut. Acud. Science 1924 10 4). This investigator encountered difficulties in the construction of gas-tight containers and in attaining satis-factory vacua precisely similar to those we have described but he finds no evidence of any formation of helium by the electrical explosion of tungsten.,4 still more recent publication (Harkins and Allison J . Arner. C'hem. SOC. 1924 46 814) describes experiments in which heavy electrical discharges were passed (a) between fine wire electrodes and (b) through fine metallic wires and the gases (if any) were examined for helium by absorption in heated metallic calcium by Soddy's method. I n most cases the gas was completely absorbed slid in no case was there any evidence of helium. Hence it seems clear that the statements made by Wendt and Irion must be attributed to erroneous observations and have no foundation in fact.Our thanks are due to the Chemical Society for a grant which has defrayed the major part of the expenses incurred in this investi-gation and to the Department of Scientific and Industrial Researcli for a grant enabling one of us (G. E. S.) to take part therein. UNIVERSITY OF DURHSM ARMSTRONG COLLEGE, NEWCASTLE UPON TYNE. [Received November 24th 1924. 240 BRISCOE ROBINSON AND STEPHENSON : XLI. -The Electrical Explosion of Tungsten Wires. By HENRY VINCENT AIRD BRISCOE PERCY LUCOCK ROBINSON, and GEORGE EDWARD STEPHENSON. THE phenomena accompanying heavy high-tension discharges in thin metallic wires were first studied by Anderson (Astrophys. J., 1920 51 37). Using a large glass plate and tin-foil condenser, he photographed the spectra of the light emitted by the electrical explosion of iron copper nickel and manganin wires and observe THE ELECTRICAL EXPLOSION O F TUNGSTEN WIRES.241 very interesting eff'ects notably a reversal of many lines producing an absorption (Fraunhofer) spectrum instead of the bright-line spectrum usually observed. These phenomena are attributable to the momentary attainment of an exceptionally high temperature in the substance of the wire. Observations with a rotating mirror showed that the duration of the flash was less than 10-5 second, aid Anderson calculated that if the available energy of his condenser, equivalent to about 30 calories were wholly communicated to the 2 milligrams of wire in this time the temperature attained would be of the order of 300,000".The intrinsic brilliancy of the wire at the moment of explosion was found to correspond with a surface tem-peratnre of 20,000". Making liberal allowance for the inherent uncertainty of these estimates it seems evident that the temper-atures attained in such explosions are much higher than can be reached by any other means. I n 1922 Wendt and Irion ( J . Amer. Chem. Xoc. 44 1587) reported the results of experiments on the explosion of fine tungsten wires by Anderson's method. When the explosions were carried out in a vacuum some gas was formed and this subjected to an ordinary high-tension discharge gave a spectrum in which the yellow helium line D, was consistently observed. When the wires were exploded in an atmosphere of carbon dioxide a t ordinary pressure and the carbon dioxide afterwards absorbed in caustic potash solution, residual gas averaging 1.42 C.C.per milligram of tungsten remained. This gas was lost before its spectrum had been investigated. If it consisted wholly or mainly of helium it was on the average some 25% of the weight of tungsten taken. These results were so startling and if correct of such profound significance that the expcriments here described were undertaken to confirm them. The essential idea of these experiments is of course extremely simple. A fine tungsten wire is supported between heavy electrodes sealed into a glass vessel; this vessel is evacuated and a heavy discharge is passed from a condenser of large capacity. Thereafter an ordinary high tension-discharge is passed through a capillary side-tube on the bulb and the emitted light spectroscopically examined.I n practice the experimental difficulties are considerable and arise chiefly in securing the necessary conditions of very high vacuum and very good contact between the wire and the electrodes. Unless both these conditions Stre fulfilled the discharge does not pass through the wire but passes between the electrodes (possibly through the slight conductivity of gas remaining in the bulbs or produced by local heating of the wire) in such a way that the material of the wire is unaffected 242 BRISCOE ROBINSON AND STEPHENSON : E x P E R I M E N T A L. Preparation of Bulbs.-Three containers of the form shown in Fig. 1 were first constructed from 300 C.C.spherical Durosil bulbs A provided with main electrodes EE and a supplementary electrode F in a small bulb connected with A by a capillary tube C. While A was still open a t the line D the wire W was sprung into place between EE by means of suitable forceps thereafter the system of tubes B G H was sealed on a t D. The electrodes EE, were of heavy molybdenum wire approximately 0.1 inch in diameter : one end of each was drilled and countersunk with fine drills to receive the filament and they were then coated with glass nearly to the ends and sealed into the bulbs as shown in Fig. 3. FIG. 1. FIG. 2. Serious difficulties were encountered in making this apparatus : unless the bulbs were of heavy glass they cracked a t the electrode seals and when the seals stood they frequently leaked a t pinholes so minute that they could only be detected by a pressure test under water.A T-shaped bulb of about 70 C.C. capacity constructed as in Fig. 2 from Durosil tubing 1” in diameter proved much more satisfactory . All attempts to seal heavy tungsten wires into Pyrex glass as described by Wendt and Irion failed completely but fortunately, it was found that molybdenum sealed fairly well into Durosil glass and could unlike tungsten be obtained as drawn wire of the heavy section required to carry the discharge without material loss THE ELECTRICAL EXPLOSION OF TUNGSTGN WIRES. 243 We are indebted to Messrs. Duram Ltd. and to their chemist, Mr. S. C. Radford who very kindly supplied us with several samples of fine tungsten wire both hard-drawn and annealed.The annealed wire proved much less springy and easier to handle than the hard-drawn wire and was used throughout pieces about 4 cm. long were cut from a soft wire 0-035 mm. in diameter. It was quite impossible to spring these wires unsupported between the electrodes as Wendt and Irion stated they had done. With much patience and luck crystalline filaments from an old dran-n-wire lamp could be fitted in this way but they were so fragile as to be useless in practice. Therefore the wire was threaded through a very fine and light capillary glass tube bent back outside the tube a t both ends and then the tube and wire were sprung between the electrodes as shown in Figs. 3 and 3. Bulbs made as described were connected by the mercury-sealed ground glass joint H (Fig.1) to a large all-glass Topler pump and McLeod gauge and after a preliminary evacuation by a water-pump connected to G, which was then sealed OR at the constriction were further evacu-ated with the Tiipler pump. The first bulb was kept a t 300" in an electrically heated air-bath, evacuated to 0.005 mm. and left a t 300" over-night. Next morning the pressure in the bulb was 0.02 mm. This difference appeared to be too large to be accounted for by the release of gases from the glass. The bulb was allowed to cool and each electrode seal T:-U tested in turn by coating it with sealing wax and carrying out a series of evacuations. By this means i t was established that leakage was occurring in the neighbourhood of the seals.After treating a large surface of the glass with a collodion varnish a vacuum of 0-001 mm. was maintained over-night. As a further test of this vacuum an induction coil discharge was passed between the sup-plementary electrode and one of the main electrodes there was a t first no visible discharge but after a time possibly through the release of gas from the wires or accidental breakage of the wax FIG. 3. FIG. 4. I 244 BRISCOE ROBINSON AND STEPHENSON : seals a noisy visible discharge occurred and set up vibration which dislodged the mire and capillary and so rendered the bulb useless. The details given above for one case will serve to indicate the difhulties attendant on the use of molybdenum-glass seals As a result of a series of experiments another metal-glass seal was tried which promised to be more satisfactory because inter aEia, it permitted the proper support of a naked wire inside the bulb.The essential features of this seal are shown in Fig. 4. The glass tube was constricted to allow the tinned copper electrode to pass through neatly without play. The upper part of the glass was heated nearly to redness and molten lead poured into the tube; the lead chilled so quickly a t the constriction that it solidified there and prevented passage of lead into the bulb. The preliminary tests were carried out on single joints which were sealed to the pump and evacuated. It is interesting to observe that where the glass had been hot lead which had overflowed on the outside of the tube adhered strongly to the glass and a t the colder portions of the tube the lead peeled off quite easily.After some practice a satisfactory seal was obtainable and a T-shaped bulb was constructed using this type of joint for the elec-trode seals. In this bulb the tungsten wire was stretched between the two electrodes and a supporting capillary tube was unnecessary. One end of each copper electrode was hammered flat and folded into a small trough; then the end of the wire was laid along the trough and secured by hammering the sides together. Good electrical contact and a secure hold for the wire were thus obtained. The electrode and wire were passed through one side tube of the bulb; the upper electrode was then sealed in with molten lead, and finally the bulb was reversed and the second electrode similarly sealed in.This bulb was connected to the pump and evacuated; the following figures show the efficiency of the seals. 28\12/23 4 p.m. Pressure = 0-0003 mm. of mercury. 8/1/24 10 a.m. Pressure = 0.0080 , , 9 , Thus these seals while useful for many purposes did not appear tight enough for the present experiments. At this stage it was decided to conduct several explosions using the highest vacuum attainable with a number of bulbs having molybdenum-glass seals which had been prepared. The electrode seals were coated externally with sealing wax in such a manner as to give an even well melted coating of wax such coatings had been found to enable the bulbs to hold very high vacua and were really excellent except that they precluded strong heating of the bulb during evacuation.A bulb was evacuated to the limit of the pump THE ELECTRICAL EXPLOSION OF TUNGSTEN WIRES. 245 being heated meanwhile to about 100" by means of a soft luminous gas flame. The evacuated bulb was allowed to stand over-night on the pump and the state of the vacuum noted. I n each case a single stroke of the pump removed a minute bubble so small that it could not be driven down the capillary fall-tube of the pump. The bulb was again heated and another stroke of the pump showed that no gas had been released from the glass it was then sealed off a t the vertical capillary. The Explosions. Nessrs. A. Reyrolle & Co. Ltd. electrical engineers of Hebburn-upon-Tyne very courteously placed their high-tension testing plant a t our disposal and we desire to record here our thanks to Mr.H. ?V. Clothier and Mr. Rarle for their interest and active co-operation in carrying out the experiments a t their works. FIG. 5. Fig. 5 is a diagram of the circuit used. The two condensers, C C, each consisted of 100 glass plates 24 inches square having on each face tinfoil coatings 18 inches by 17 inches the plates were carried on porcelain insulators in a wooden frame heavy brass leads connected alternate coatings with two copper busbars on opposite sides of the condenser. The condensers were not oil-immersed. Each had a capacity of 0.3 microfarad the normal working pressure was 30,000 volts and the highest permissible pressure was 45,000 volts. The connexions permitted the use of either condenser singly or of both in parallel.Current a t 500 volts and 50 cycles A.C. from the supply mains fed to the transformer T was stepped up to any desired voltage (up to a maximum of 100,000 volts) and the output was rectified by a two-electrode thermionic valve R the filament current for which was supplied by the accumulator S. The knife switches, K being closed this rectified output charged the condensers. When the potential difference acruss the condensers reached a certai 246 THE ELECTRICAL EXPLOSION OF TUNGSTEN WIRES. value dependent on the width of the adjustable air-gap G between two large polished brass spheres the condensers discharged across the gap and through the bulb B. The whole of this apparatus was contained in a large cage of expanded steel well earthed and the necessary switches were actuated from the outside of the cage.A kilovoltmeter V across a tertiary winding of the transformer gave an approximate indication of the discharge potential. Through-out the experiments the spark-gap was kept constant and a t the coii-clusion of the tests a precise measurement showed that the potential difference required for discharge across the gap was 29,000 volts. In one case contact between the leads and the electrodes of the bulb was made through mercury contained in rubber tubing slipped over the latter. This bulb fractured on discharge probably because this method of securing contact was defective and the other bulbs were connected up in turn by twisting the leads tightly round the external parts of the electrodes.The phenomena associated with the explosions may best be described by giving the details with reference to one of the several bulbs exploded. Bulb No. 4 was spherical had molybdenum electrodes sealed in through the glass and a filament fitted in a capillary tube as already described. Both condensers were used connected in parallel giving a total capacity of 0.6 microfarad. At discharge the kilovoltmeter K indicated 30,000 volts. The air-gap was screened from sight and the explosion was well seen by four observers it was attended by a dull thud in the bulb, and by a bright flash in which the whole of the filament was seen to be involved. Both the noise and the brightness of the flash were much less than we had anticipated. On examining the bulb it was found that the filament had com-pletely disappeared the capillary now loose in the bulb was intact showed a mere trace of a metallic mirror at one end and was slightly bent at both ends having evidently been softened there by heat.It will be remarked that these effects differ substantially from those described by Wendt and Irion we nevertheless regarded this explosion as complete and satisfactory. Within a few hours after explosion the contents of the bulbs were investigated. An induction coil discharge was passed between the supplementary electrode F and one of the main electrodes, and the light emitted in the capillary tube C was examined visually with a Hilger constant deviation spectrometer. I n each of the bulbs there was a small amount of gas which permitted a discharge to pass and gave a faint banded spectrum on which were superposed a few bright lines the wave-lengths of which were read directl PHYSOSTIGMINE (ESERTNE).PART III. 247 on the spectrometer drum. The lines observed were the green lines of mercury and the red and blue hydrogen lines; none of the bulbs a t any time gave any yellow line whatever although the spectro-meter showed the two sodium lines bright and well defined in the light from an ordinary Bunsen flame. We conclude therefore that our experiments afford no evidence that tungsten can be made to yield helium when exploded by an electrical discharge. At the same time it is clear that extreme difficulties attend any attempt at a crucial experiment on these lines and we attach much more importance to experiments now in progress OP the electrical explosion of tungsten wires in relatively dense and non-conducting atmospheres of absorbable gas.Our conclusion is supported by the results published since our tests were completed of a similar series of experiments conducted in Dr. Anderson's laboratory (Sinclair Smith Proc. Nut. Acud. Science 1924 10 4). This investigator encountered difficulties in the construction of gas-tight containers and in attaining satis-factory vacua precisely similar to those we have described but he finds no evidence of any formation of helium by the electrical explosion of tungsten. ,4 still more recent publication (Harkins and Allison J . Arner. C'hem. SOC. 1924 46 814) describes experiments in which heavy electrical discharges were passed (a) between fine wire electrodes and (b) through fine metallic wires and the gases (if any) were examined for helium by absorption in heated metallic calcium by Soddy's method. I n most cases the gas was completely absorbed slid in no case was there any evidence of helium. Hence it seems clear that the statements made by Wendt and Irion must be attributed to erroneous observations and have no foundation in fact. Our thanks are due to the Chemical Society for a grant which has defrayed the major part of the expenses incurred in this investi-gation and to the Department of Scientific and Industrial Researcli for a grant enabling one of us (G. E. S.) to take part therein. UNIVERSITY OF DURHSM ARMSTRONG COLLEGE, NEWCASTLE UPON TYNE. [Received November 24th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700240

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

PHYSOSTIGMINE (ESERTNE). PART m. 247 XLI1.-Ph ysostigmine (Eserine). Part I I I . By EDGAR STEDXAN and GEORGE BARGER. CERTAIN details of the structure of physostigmine have been elucidated (J. 1923 123 758; 1924 125 1373) but the evidence which was available was insufficient to permit the construction o 248 STEDMAN AND BBRGER: a formula which satisfactorily represented the known facts con-cerning the chemistry of this alkaloid. Further experimental evidence is now advanced and this combined with previously published work appears to leave no doubt as to the structure of eseret’hole and hence of physostigmine which are respectively the ethyl ether and methylcarbamido-derivative of eseroline. The presence in eseroline of the grouping I has been recognised since the work of Straus (AnnuZen 1913 401 350; 1914 406, 332) who obtained a phenolic indole compound (physostigmol) by degradation of eseroline methiodide.It was shown by one of us (E. S. ; Zoc. cit. 1373) that physostigmol is 5-hydroxy-1 3-dimethyl-indole (11) and further that its ethyl ether may be obtained in a yield of 66% by distillation of eserethole methiodide. This estab-lished the position of the hydroxyl group in eseroline and also confirmed Straus’s supposition that physostigmol contains a methyl group attached to position 3 of the indole ring. The formation of an indole compound by the somewhat violent decompositicn of an alkaloid does not in general permit the conclusion to be drawn that a preformed indole skeleton exists in the latter. Nevertheless, it appears justifiable in view of the comparat,ive completeness with which eserethole methiodide is degraded into physostigmol ethyl ether to assume even without further evidence the presence of the grouping I11 in eseroline.Additional evidence pointing to the presence of an indoline grouping in the molecule is not however, wanting. Thus the feebly basic properties of one of the nitrogen atoms in physostigmine (Straus Zoc. cit.) and the properties of etheserolene obtained by Max and Michel Polonovski (BUZZ. Xoc. chim. 1918 [iv] 23 335; 1923 [iv] 33 969) by the exhaustive methylation of eserethole point in this direction. The presence of the grouping I11 may thus be regarded as estab-lished and the problem resolves itself into determining the manner in which the remainder of the molecule (C,H,N) is linked to this grouping The nitrogen atom the position of which has still to be determined is the one with the stronger basic properties.Straus has shown that one methyl group is attached to this nitrogen atom whilst Salway (J. 1912 101 978) had previously demon-strated its tertiary character. Formula IV which was suggested to us by Professor R. Robinson F.R.S. conforms to these con-ditions and evidence will be adduced in the following discussio PHYSOSTIGMINE ( ESERINE). PART rn. 249 to show that this actually represents the structure of eseroline. The constitution of physostigmine itself will accordingly be repre-sented by formula V. Me CM Me CH, HOf>-?/\$!H I NHMe*CO*ON\ &/\?€I2 (v. ’ “-t!H -l<AIe \/\,,4H--NMe \/\/ (IV.1 NMe NMe The considerations which have led to the adoption of formula I V for eseroline are largely based on the behaviour of eserethole towards reducing agents and on the properties of eseretholemethine. Polo-novski (Bull. Xoc. chim. 1918 [iv] 23 357) has shown that esere-thole on reduction with zinc and hydrochloric acid takes up two atoms of hydrogen a result which has now been confirmed using a catalytic method of reduction. That this reduction is not due to the presence of a double bond follows from the fact first pointed out by Max and Rfichel Polonovski (Compt. rend. 1024 178 2078), that whereas eserethole is a tertiary base dihydroeserethole is a secondary base. Reduction evidently opens a ring between the more strongly basic nitrogen atom and one of its adjacent carbon atoms.On the basis of IVY dihydroeserethole may thus be repre-sented by 171 the point a t which tjhe ring is ruptured being deter-Me Me I -$XH,*CH,*N,\le, NMe (T;II.) \ /\,/CJH.OH Etoli Et 0’ \--~-CH,*CH,*NH?IIe I i II \ / \ p H 2 (171.) NXe mined from Polonovski’s observation that the substance obtained by reduction of etheserolcne is identical with the product of the exhaustive methylation of dihydroeserethole. Eseretholemethine was ubtained by Max and Michel Polonovski (Zoc. cit.) by treating eserethole methiodide with sodium hydroxide. Its pseudo-basic character was not recognised until in Part I cf this series attention was directed to the fact that it is reconvertcd into eserethole rnethiodide on treatment with hydriodic acid m d that its behaviour in this respect was analogous to that of certain indoline compounds prepared by Brunner.As a result of this observation Polonovski revised the molecular formula of eserethole-methine and denionstrated that it was produced from methyl-eseretholinium hydroxide by a tautomeric change and not by loss of water. Experimental results which are enumerated in the succeeding paragraph have now been obtained which demonstrate that eseretholemethine is in fact a substituted indoline nit1 250 STEDMAN AND BARGER: hydroxyl group in the a-position (VII); its formation may accord-ingly be represented by the following scheme : tautomeric -CMe.CH 2 2 -CH *NMe CH2 4 /\ NaOH /\ change I -?Me yH2 -+ -$!Me $!H2 -+ -CH*OH -CH-NMe21 -CH-NMe,*OH Eserethole methiodide Intermediate Eseretholemethine quaternary hydroxide The position assigned to the basic nitrogen atom in V thus corre-sponds with this behaviour.Assuming the correctness of this scheme it is evident that while the conversion of eseretholemethine into a quaternary salt by treatment with methyl iodide should prevent the closure of the pyrrolidine ring on treatment with acids the compound should nevertheless retain its properties as a pseudo-base in virtue of its indolinol structure. This consequence has been verified. Treat-ment of eseretholemethine methiodide with picric acid results in the elimination of the hydroxyl group with the formation of a diquaternary picrate : \G-~Me*CH,*CH,=NMe,l \G-~Me*CH,°CH2*NMe3*OoC6H,06~3 ,,C CH*OH ,C CH ’ \/ ++ \/ /N\ NMe Me O*C6H,06N3 Still more conclusive are the results obtained by oxidation of eseretholemethine.Brunner (Nonatsh. 1896 17 253) has shown that 1 3 3-trimethyl-2-indolinol is oxidised by ammoniacal silver nitrate in alcoholic solution to 1 3 3-trimethyl-2-indolinone. By subjecting eseretholemethine to the same treatment a compound the composition of which corresponds with VIII has been obtained. The same substance has also been prepared by oxidising eserethole-methine with potassium ferricyanide a method which Decker ( J . pr. Chem. 1893 47 28) has employed for the oxidation of pseudo-bases. When this compound is degraded by the method of Et 0’ \-~MeCH2=CH,*NMe2 Et ON\-FMe-CH:CH2 I II \ \ / \ P O < II NMe W.1 \ \ / \ P O (VIII.) NMe Etd()-?MeEt (X.1 NMe \ / \ P PHYSOSTIGMINE ( ESERINE). PART III. 251 exhaustive methylation trimethylamine is evolved and an un-saturated compound (IX) obtained which is practically devoid of basic properties and forms a deep crimson picrate. On reduction, this takes up two atoms of hydrogen with the formation of a substance which is considered to be 5-ethoxy-1 3-dimethyl-3-ethyl-2-indolinone (X). The chemical properties of eserethole-methine thus correspond entirely with those predicted on the assumption that V correctly represents the structure of physos-tiginine ; the constitution of this alkaloid may therefore be regarded as established. As an additional confirmation the synthesis of the substance represented by X has been undertaken and it is hoped that it will be possible to communicate the results shortly.An explanation of the mcchanism of the formation of eserethole-methine and of dihydroeserethole identical with that advanced above has recently been put forward by Max and Michel Polonovski (Compt. rend. 1924 178 2078). These authors therefore consider that the structures of eserethole and eseretholemethine are repre-sented by XI and XII respectively; the former differs from that proposed by Straus (Zoc. cit.) for eseroline only in the position of the nitrogen atom contained in the piperidine ring. Although the reactions described in this communication could be formulated with equal facility upon the basis of these structures it is evident that they do not explain the formation of physostigmol; the ease with which this substance is formed demands the presence of a preformed methyl group in the P-position of the pyrrolinc ring.CH, Consideration of the possible mechanism of the phytochemical synthesis of the ring system present in physostigmine speaks no less convincingly in favour of formula V. Perkin and Robinson (J. 1919 115 944) have shown how harmine may be elaborated in the plant from tryptophan. If the assumption is made that the methylation of an indole nucleus may proceed in the plant in the manner in which it is known to take place in the laboratory a relation between physostigmine and this amino-acid at once becomes evident. By decarbosylation and methylation followed by a, ring closure the ring system of physostigmine would be readily formed 252 STEDMAN AND BAROER: (NH,)*CO,H decarboxylation f)-G*CH2*CH2*NH, -5- -NH / NH Me \/\/CH-fiMe NMe The possible mechanism of the phytochemical synthesis of the ring system present in XI cannot be similarly represented in a simple manner from known naturally-occurring substances.During the course of this investigation a small quantity of etheserolene was prepared. Contrary to Polonovski’s statement, it readily formed a yellow crystalline picrate. If etheserolene is formed by a straightforward degradation of eseretholemethine in a manner similar to that of the indolinone compound now described, one would feel inclined to attribute to it the structure represented by XIII. On this basis however it should possess the properties of a pseudo-base.But analysis of the picrate shows that this is not the case. It therefore appears that some isomeric change has taken place during its formation. This would correspond with the results of Polonovski who has recently stated (Cmpt. rend. 1924, 179 178) that etheserolene on reduction absorbs only two atoms of hydrogen and at the same time loses an atom of oxygen. Whether his view that this oxygen atom is not present as a hydroxyl group but forms part of a ring is correct cannot be stated with certainty a t present, Trinitroeserethole (XIV) and an oxidation product of eserethole which have been prepared during the course of this investigation and the results of a reinvestigation of the degradation of one of th PHYSOSTIGMINE (ESERINE).PART III. 253 esoline compounds described in Part I of this series are described in the experimental portion. E x P E R I M E N T A L. Dihydroeserethole (VI) .-Attempts to reduce eserethole catalytic-ally with a palladium sol in either neutral or acid solution with or without the addition of gum arabic as protective colloid werc unsuccessful owing to flocculation of the sol. With platinum black prepared by Willstatter's method (Ber, 1921 54 113), reduction took place readily. Platinum black (0.1 g.) was washed into a hydrogenation apparatus similar to that described by Hess (Ber. 1913 46 3113) air was completely removed a solution of 1 g. of eserethole in glacial acetic acid introduced and the mixture shaken; 52 C.C. of hydrogen were absorbed during the first hour, and 92 C.C.in all (calculated for two atoms 91 c.c.). The solution was filtered made alkaline with sodium hydroxide and the oil thus thrown down extracted with ether. From the extract dried over potassium carbonate a yellow oil was obtained which became almost colourless when distilled under the vacuum of a rotatory oil pump (bath at about 200°). When treated with alcoholic oxalic acid it formed an oxalate (sheaves of fine needles m. p. 204" from aqueous alcohol) identical with that obtained from dihydro-eserethole prepared by Polonovski's method (Zoc. cit.). Dihydroeserethole (1 g.) was heated in a sealed tube with excess of methyl iodide for 1 hour a t loo" the excess of methyl iodide evaporated and an alcoholic solution of the product treated with alcoholic picric acid.The yellow picrate precipitated on addition of water crystallised from aqueous alcohol in prisms m. p. 204" (Found C = 47.0 ; H = 4.7. C2,H,,Q1,N8 requires C = 47.3 ; H = 4.6%). The substance was thus a dipicrate and two methyl groups had been introduced into the molecule during methylation, indicating that in contrast Go eserethole dihydroeserethole is a secondary base. Behaviour of' Eseretholemethine Methiodide as a $-Base.-The orange oil which separated on mixing the salt (0-2 g.) and picric acid in alcoholic solution changed on warming into a crystalline solid (0.27 g.) which was obtained from aqueous alcohol in yellow prisms m. p. 170" (Pound C = 47.7; H = 4.7. C,,H,2015N,s requires C = 47.5; H = 4.4%). In the formation of this di-quaternary picrate water has been eliminated from the molecule, t l t u s inclienting the pscudo-basic function of the oxygen atom.L)eh~/clroeserethoZernethilze (VIII) .-The methine (1 g.) was refluxed for 10 hours with an ammoniacal solution of 3 g. of silver nitrate in methyl alcohol. After filtration evaporation and dissolutio 254 STEDMAN AND BARGER: of the residue in water ether extracted an insignificant amount of an oil which formed a crystalline picrate but was not investigated further. The hot aqueous solution made faintly alkaline with ammonia, was treated with hydrogen sulphide to remove excess of silver atered boiled to expel ammonia and hydrogen sulphide, and treated with alcoholic picric acid. The viscous precipitate first formed became crystalline on warming and by fractional crystallisation from aqueous alcohol gave two picrates the more soluble one forming needles m.p. 211" (Found C = 47.0; H = 4.5. Cl6H2,ON2,2CBH,0,N requires C = 46.7; H = 4.4%) and the less soluble fraction consisting of plates contaminated with some needles. The latter crystallised from acetone in plates m. p. 199" (Found C = 52.8 ; H = 5.4. CI6H2,O2N2,C6H,0,N requires C = 52-3; H = 5.4%). A different result was obtained by the following procedure An alcoholic solution of eseretholemethine (5 g.) was added to 15 g. of silver nitrate in alcohol made strongly alkaline with ammonia (d 0.88), the total volume being brought to about 100 C.C. A silver mirror formed on the sides of the flask almost immediately.The mixture was heated on the water-bath for 5 hours filtered and excess of silver removed by addition of hydrochloric acid; from the filtrate, made alkaline with sodium hydroxide ether extracted 4.45 g. of an oil which treated with alcoholic picric acid yielded 5.35 g. of the picrate m. p. 199" described above. No trace of the picrate of higher melting point was obtained in this experiment. It seems evident that this substance was formed by reduction of an indolinone to an indoline compound the reducing agent being the hydrogen sulphide used to remove excess of silver. Oxidation was also effected by means of potassium ferricyanide. A solution of eseretholemethine (3 9.) in a small quantity of alcohol was boiled with a strongly alkaline solution of 7-2 g.of potassium ferricyanide in 100 C.C. of water for about 5 minutes and after cooling extracted with ether. From this extract 4 g . of the methiodide which had previously been prepared in the manner described below were obtained. The picrate (4.19 g.) m. p. 199" was treated with sodium hydroxide and the oily base which separated extracted with ether. The extract was dried over sodium sulphate filtered concentrated, and methyl iodide added. A crystalline methiodide slowly formed (3.3 g.). This separated from acetone in transparent prisms but the method was wasteful owing to its large solubility in this solvent. It was therefore crystallised by addition of dry ether to the acetone solution. With dry solvents the methiodide was obtained as a colourless substance m.p. about 131"; the fact that the meltin PHYSOETIGMINE ( ESERINE). PART III. 256 point was not absolutely sharp was no doubt due to the water of crystallisation which it contained (Found for air-dried material, H,O = 3.7 ; for material dried at 110" I = 30.0. C1,HZ70,N,I,H,O requires H,O = 4.1 ; C1,H,,O,N,I requires I = 30.1%). When, however the solvents were not perfectly dry the transitory form-ation of a blue iodine adsorption compound was consistently observed ; its disappearance no doubt coincided with the trans-formation of an a t first amorphous precipitate into crystalline form. Degradation of Deh ydroeseretholemethine i!fethiodide by Hof I)Z an n ' s Nethod to Compound IX.-An aqueous solution of 1.9 g. of the methiodide was shaken with a suspension of silver oxide prepared from 2 g.of silver nitrate. After filtration and removal of the water by evaporation under diminished pressure the residual oil was distilled a t 12 mm. After evident decomposition with the evolution of a gas a slightly brown oil distilled when the tem-perature of the bath was between 200" and 210". The distillate would not crystallise. It was therefore treated with an alcoholic solution of picric acid when a small quantity of a crystalline picrate m. p. 199" identical with that described above was obtained. The residue from the mother-liquors was treated with sodium hydroxide and extracted with ether and the extract washed with water until the sodium picrate was completely removed. After drying over sodium sulphate the ether was evaporated, when a colourless oil which crystallised spontaneously was obtained.Recrystallised from aqueous alcohol it formed colourless prisms, m. p. 62" (Found C = 72.3; H = 7.3. C14H1702N requires C = 72-7; H = 7-4:/,). This substance was practically devoid of basic properties; it was insoluble in dilute hydrochloric acid but formed a picrate which at first separated from alcohol in a yellow form and quickly changed into a deep crimson one; m. p. 103". Reduction of Compound I X to Compound X.-Hydrogenation was effected in the apparatus mentioned above using a solutim of colloidal palladium as catalyst and gum arabic as protective colloid; 0.16 g. of substance was used. Hydrogen was readily absorbed but as a result of a mishap the amount could not be measured.After filtration from the palladium and evaporation of the alcohol (aqueous alcohol was used as solvent) the solution, after addition of a small quantity of sodium hydroxide to ensure alkalinity was extracted with ether. After drying and evaporation, this yielded a crystalline product which when crystallised from aqueous alcohol formed cubes m. p. 68" (Fcund C = 71.8 H = 8-2. It is evideat from the analysis that two atoms of hydrogen were absorbed and C1,H1,O,N requires C = 72.1 ; H = S-2:/,) 256 STEDMU AND BARGER: that the oxygen atom present as a carbonyl group was retained in the molecule. Trinitroeserethote.-Among the diverse experiments which have been carried out with a view to effect the oxidation of eserethole, the action of nitric acid on this substance has been studied.Cold dilute nitric acid has little if any action but the concentrated acid (d 1-4) reacts vigorously. Eserethole (1 g.) was added drop by drop to 3 C.C. of concentrated nitric acid cooled in a freezing mixture and vigorously stirred. The product was warmed on the water-bath for 8 hour cooled diluted with waber and the yellow crystalline precipitate (0.3 g.) recrystallised from aqueous alcohol, trinitroeserethole separating in orange rectangular plates m. p. 152" (Found C = 47.1 ; H = 5.0; N = 18.7. C1,H1,O,N requires C = 47-2; H = 5.0; N = 18.4%). It is insoluble in alkalis and dilute acids but dissolves in concentrated acids. Oxidation of Eserethole with Potassium Permanganate in Acetone Solution.-" solution of eserethole (1 g.) in 100 C.C.of acetone was maintained at about -10" while finely powdered potassium per-manganate (representing 6 0 ) was added during 2 days. The solution was then warmed with methyl alcohol to remove excess of permanganate filtered and the solvent evaporated. The red s p p thus obtained would not crystallise even after distillation in a high vacuum but on treatment with alcoholic picric acid it readily yielded a picrate (0.9 g.) which crystallised from alcohol in rhomb-shaped prisms m. p. 166" (Found C = 51.8; H = 4-9. Cl,H2,0,N,,C8H30,N3 requires C = 51.5; H = 4.7%). The base was recovered from this picrate by dissolving the latter in glacial acetic acid pouring into water and extracting the picric acid with ether making alkaline with sodium hydroxide and again extracting with ether.The oily base obtained on evaporation of the ether was warmed with methyl iodide and the product dissolved in hot methyl alcohol. On cooling the methiodide crystallised in needles, m. p. 198-199" (Found C =48*1; H = 5.8; I = 31-6. C1,H2,0~2,CH,I requires C = 4743; H = 5.8; I = 3106%). This methiodide resembles eserethole methiodide in its behaviour towards alkalis. It is stable towards sodium carbonate but when treated with sodium hydroxide yields an ether-soluble base. The latter could not however be crystallised neither could its methiodide be obtained in a crystalline condition. Etheserolene picrate was prepared incidentally during an experi-ment designed to test whether the presence of ethyl alcohol or sodium ethoxide was an essential condition for the formation of the esoline compounds described in Part I of this series.Starting from eserethole methiodide the experimental conditions mer PHYSOSTIGMINE ( ESERINE). PART III. 257 exactly similar to those described in that paper for the preparation of esoline ethyl ether dimethiodide except that a solution of sodium in n-propyl alcohol was used in place of one in ethyl alcohol. No solid separated however from the solution. The propyl alcohol was therefore evaporated the oily residue dissolved in water made strongly alkaline with solid sodium hydroxide and the solution refluxed for several hours tetramethylammonium iodide and an oil volatile in steam separating. The latter isolated from the mother-liquors by extraction with ether crystallised in a few hours, The solid m.p. about 45" (etheserolene according to Polonovski, melts at 48") was dissolved in alcohol and treated with alcoholic picric acid when a yellow picrate separated which crystallised from alcohol in stout prisms m. p. 98" (Found C = 52.1 ; H = 4.9. Calc. for Cl,H1,02N C6H307N3 C = 52.0; H = 4-b%). From the melting point of the original substance and the analysis of the picrate it seems evident that this was etheserolene picrate. It is also evident that the oxygen atom has no pseudo-basic function in this compound. Degradation of Esoline Ethyl Ether Dimethiodide.-The preliminary results of the degradation of this substance by Hofmann's method reported in Part I of this series have been confirmed. Since iden-tical results have been obtained by distillation of the product of the action of silver oxide on the iodide and by treating it with potassium hydroxide only the latter method need be described.The oil obtained by treating 4 g. of the iodide with silver oxide was refluxed for $ hour with 10 C.C. of SOY; potassium hydroxide. The solution was then steam-distilled until the oil had been com-pletely carried over. The distillate was extracted with ether upon evaporation of which an oily residue was obtained. This was dissolved in alcohol and the solution treated with picric acid. A viscous picrate separated which slowly solidified on warming. After filtration this was suspended in a relatively large volume of alcohol boiled and filtered. On cooling the filtrate a picrate separated in short stout prisms m.p. 156" unchanged on recrystallisation from aqueous alcohol (Found C = 46.7 ; H = 4.7. C,6H2,0N2,2C6H30,N3 requires C = 46.5; H = 4.7. soluble picrate which was separated in the manner described above, crystallised from aqueous alcohol in rhomb-shaped prisms m. p. quires C = 47.1 ; H = 4.7. C18H2g02N,,2C6H307N requires C = 47-2 ; H = 4-57;>. Both picrates were converted into methiodides by the following treatlment. The picrate was dissolved in glacial acetic acid poured into water extracted with ether to remove C16H260N2,2C6H30,N3 requires c = 46.7 ; H = 4.4%). The less 199" (Found C = 46.9 ; H = 4.7. C1&3,O2N2,2C6H,O7N3 re-VOL. CXXVII. 258 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON picric acid made alkaline with ammonia and the base extracted with ether.Addition of methyl iodide to the ethereal solution (dried over sodium sulphate) caused the methiodide to separate. The picrate melting a t 156" thus yielded a methiodide which crystallised in plates melted a t 169-170" and was identical with a methiodide which had been obtained directly from the crude product of the distillation of the quaternary hydroxide without purification through the picrate (Found C = 50.2; H = 7.4. C1,H,lON,I requires C = 50.2; H = 7.6. C1,H,,ON,I requires C = 50-5; H = 7.2%). The picrate melting at 199" yielded a methiodide m. p. 141"; when this was heated a t 100" in a sealed tube for 4 hour with excess of methyl iodide a second methiodide, m. p. 188" was obtained but no esoline ethyl ether dimethiodide was formed.Apparentlly this base was not as was originally believed the ethyl ether of bhe hypothetical esoline base. The authors desire to express their thanks to the administ'rators of the Carnegie Trust for the Scottish Universities for a grant which has alone rendered this research possible. DEPARTMENT OF MEDICAL CHEMISTRY, UNIVERSITY OF ED IN BURG^. [Received Notiember 18th 1924. PHYSOSTIGMINE (ESERTNE). PART m. 247 XLI1.-Ph ysostigmine (Eserine). Part I I I . By EDGAR STEDXAN and GEORGE BARGER. CERTAIN details of the structure of physostigmine have been elucidated (J. 1923 123 758; 1924 125 1373) but the evidence which was available was insufficient to permit the construction o 248 STEDMAN AND BBRGER: a formula which satisfactorily represented the known facts con-cerning the chemistry of this alkaloid.Further experimental evidence is now advanced and this combined with previously published work appears to leave no doubt as to the structure of eseret’hole and hence of physostigmine which are respectively the ethyl ether and methylcarbamido-derivative of eseroline. The presence in eseroline of the grouping I has been recognised since the work of Straus (AnnuZen 1913 401 350; 1914 406, 332) who obtained a phenolic indole compound (physostigmol) by degradation of eseroline methiodide. It was shown by one of us (E. S. ; Zoc. cit. 1373) that physostigmol is 5-hydroxy-1 3-dimethyl-indole (11) and further that its ethyl ether may be obtained in a yield of 66% by distillation of eserethole methiodide.This estab-lished the position of the hydroxyl group in eseroline and also confirmed Straus’s supposition that physostigmol contains a methyl group attached to position 3 of the indole ring. The formation of an indole compound by the somewhat violent decompositicn of an alkaloid does not in general permit the conclusion to be drawn that a preformed indole skeleton exists in the latter. Nevertheless, it appears justifiable in view of the comparat,ive completeness with which eserethole methiodide is degraded into physostigmol ethyl ether to assume even without further evidence the presence of the grouping I11 in eseroline. Additional evidence pointing to the presence of an indoline grouping in the molecule is not however, wanting. Thus the feebly basic properties of one of the nitrogen atoms in physostigmine (Straus Zoc.cit.) and the properties of etheserolene obtained by Max and Michel Polonovski (BUZZ. Xoc. chim. 1918 [iv] 23 335; 1923 [iv] 33 969) by the exhaustive methylation of eserethole point in this direction. The presence of the grouping I11 may thus be regarded as estab-lished and the problem resolves itself into determining the manner in which the remainder of the molecule (C,H,N) is linked to this grouping The nitrogen atom the position of which has still to be determined is the one with the stronger basic properties. Straus has shown that one methyl group is attached to this nitrogen atom whilst Salway (J. 1912 101 978) had previously demon-strated its tertiary character. Formula IV which was suggested to us by Professor R.Robinson F.R.S. conforms to these con-ditions and evidence will be adduced in the following discussio PHYSOSTIGMINE ( ESERINE). PART rn. 249 to show that this actually represents the structure of eseroline. The constitution of physostigmine itself will accordingly be repre-sented by formula V. Me CM Me CH, HOf>-?/\$!H I NHMe*CO*ON\ &/\?€I2 (v. ’ “-t!H -l<AIe \/\,,4H--NMe \/\/ (IV. 1 NMe NMe The considerations which have led to the adoption of formula I V for eseroline are largely based on the behaviour of eserethole towards reducing agents and on the properties of eseretholemethine. Polo-novski (Bull. Xoc. chim. 1918 [iv] 23 357) has shown that esere-thole on reduction with zinc and hydrochloric acid takes up two atoms of hydrogen a result which has now been confirmed using a catalytic method of reduction.That this reduction is not due to the presence of a double bond follows from the fact first pointed out by Max and Rfichel Polonovski (Compt. rend. 1024 178 2078), that whereas eserethole is a tertiary base dihydroeserethole is a secondary base. Reduction evidently opens a ring between the more strongly basic nitrogen atom and one of its adjacent carbon atoms. On the basis of IVY dihydroeserethole may thus be repre-sented by 171 the point a t which tjhe ring is ruptured being deter-Me Me I -$XH,*CH,*N,\le, NMe (T;II.) \ /\,/CJH.OH Etoli Et 0’ \--~-CH,*CH,*NH?IIe I i II \ / \ p H 2 (171.) NXe mined from Polonovski’s observation that the substance obtained by reduction of etheserolcne is identical with the product of the exhaustive methylation of dihydroeserethole.Eseretholemethine was ubtained by Max and Michel Polonovski (Zoc. cit.) by treating eserethole methiodide with sodium hydroxide. Its pseudo-basic character was not recognised until in Part I cf this series attention was directed to the fact that it is reconvertcd into eserethole rnethiodide on treatment with hydriodic acid m d that its behaviour in this respect was analogous to that of certain indoline compounds prepared by Brunner. As a result of this observation Polonovski revised the molecular formula of eserethole-methine and denionstrated that it was produced from methyl-eseretholinium hydroxide by a tautomeric change and not by loss of water.Experimental results which are enumerated in the succeeding paragraph have now been obtained which demonstrate that eseretholemethine is in fact a substituted indoline nit1 250 STEDMAN AND BARGER: hydroxyl group in the a-position (VII); its formation may accord-ingly be represented by the following scheme : tautomeric -CMe.CH 2 2 -CH *NMe CH2 4 /\ NaOH /\ change I -?Me yH2 -+ -$!Me $!H2 -+ -CH*OH -CH-NMe21 -CH-NMe,*OH Eserethole methiodide Intermediate Eseretholemethine quaternary hydroxide The position assigned to the basic nitrogen atom in V thus corre-sponds with this behaviour. Assuming the correctness of this scheme it is evident that while the conversion of eseretholemethine into a quaternary salt by treatment with methyl iodide should prevent the closure of the pyrrolidine ring on treatment with acids the compound should nevertheless retain its properties as a pseudo-base in virtue of its indolinol structure.This consequence has been verified. Treat-ment of eseretholemethine methiodide with picric acid results in the elimination of the hydroxyl group with the formation of a diquaternary picrate : \G-~Me*CH,*CH,=NMe,l \G-~Me*CH,°CH2*NMe3*OoC6H,06~3 ,,C CH*OH ,C CH ’ \/ ++ \/ /N\ NMe Me O*C6H,06N3 Still more conclusive are the results obtained by oxidation of eseretholemethine. Brunner (Nonatsh. 1896 17 253) has shown that 1 3 3-trimethyl-2-indolinol is oxidised by ammoniacal silver nitrate in alcoholic solution to 1 3 3-trimethyl-2-indolinone. By subjecting eseretholemethine to the same treatment a compound the composition of which corresponds with VIII has been obtained.The same substance has also been prepared by oxidising eserethole-methine with potassium ferricyanide a method which Decker ( J . pr. Chem. 1893 47 28) has employed for the oxidation of pseudo-bases. When this compound is degraded by the method of Et 0’ \-~MeCH2=CH,*NMe2 Et ON\-FMe-CH:CH2 I II \ \ / \ P O < II NMe W.1 \ \ / \ P O (VIII.) NMe Etd()-?MeEt (X. 1 NMe \ / \ P PHYSOSTIGMINE ( ESERINE). PART III. 251 exhaustive methylation trimethylamine is evolved and an un-saturated compound (IX) obtained which is practically devoid of basic properties and forms a deep crimson picrate. On reduction, this takes up two atoms of hydrogen with the formation of a substance which is considered to be 5-ethoxy-1 3-dimethyl-3-ethyl-2-indolinone (X).The chemical properties of eserethole-methine thus correspond entirely with those predicted on the assumption that V correctly represents the structure of physos-tiginine ; the constitution of this alkaloid may therefore be regarded as established. As an additional confirmation the synthesis of the substance represented by X has been undertaken and it is hoped that it will be possible to communicate the results shortly. An explanation of the mcchanism of the formation of eserethole-methine and of dihydroeserethole identical with that advanced above has recently been put forward by Max and Michel Polonovski (Compt. rend. 1924 178 2078). These authors therefore consider that the structures of eserethole and eseretholemethine are repre-sented by XI and XII respectively; the former differs from that proposed by Straus (Zoc.cit.) for eseroline only in the position of the nitrogen atom contained in the piperidine ring. Although the reactions described in this communication could be formulated with equal facility upon the basis of these structures it is evident that they do not explain the formation of physostigmol; the ease with which this substance is formed demands the presence of a preformed methyl group in the P-position of the pyrrolinc ring. CH, Consideration of the possible mechanism of the phytochemical synthesis of the ring system present in physostigmine speaks no less convincingly in favour of formula V. Perkin and Robinson (J.1919 115 944) have shown how harmine may be elaborated in the plant from tryptophan. If the assumption is made that the methylation of an indole nucleus may proceed in the plant in the manner in which it is known to take place in the laboratory a relation between physostigmine and this amino-acid at once becomes evident. By decarbosylation and methylation followed by a, ring closure the ring system of physostigmine would be readily formed 252 STEDMAN AND BAROER: (NH,)*CO,H decarboxylation f)-G*CH2*CH2*NH, -5- -NH / NH Me \/\/CH-fiMe NMe The possible mechanism of the phytochemical synthesis of the ring system present in XI cannot be similarly represented in a simple manner from known naturally-occurring substances. During the course of this investigation a small quantity of etheserolene was prepared.Contrary to Polonovski’s statement, it readily formed a yellow crystalline picrate. If etheserolene is formed by a straightforward degradation of eseretholemethine in a manner similar to that of the indolinone compound now described, one would feel inclined to attribute to it the structure represented by XIII. On this basis however it should possess the properties of a pseudo-base. But analysis of the picrate shows that this is not the case. It therefore appears that some isomeric change has taken place during its formation. This would correspond with the results of Polonovski who has recently stated (Cmpt. rend. 1924, 179 178) that etheserolene on reduction absorbs only two atoms of hydrogen and at the same time loses an atom of oxygen.Whether his view that this oxygen atom is not present as a hydroxyl group but forms part of a ring is correct cannot be stated with certainty a t present, Trinitroeserethole (XIV) and an oxidation product of eserethole which have been prepared during the course of this investigation and the results of a reinvestigation of the degradation of one of th PHYSOSTIGMINE (ESERINE). PART III. 253 esoline compounds described in Part I of this series are described in the experimental portion. E x P E R I M E N T A L. Dihydroeserethole (VI) .-Attempts to reduce eserethole catalytic-ally with a palladium sol in either neutral or acid solution with or without the addition of gum arabic as protective colloid werc unsuccessful owing to flocculation of the sol.With platinum black prepared by Willstatter's method (Ber, 1921 54 113), reduction took place readily. Platinum black (0.1 g.) was washed into a hydrogenation apparatus similar to that described by Hess (Ber. 1913 46 3113) air was completely removed a solution of 1 g. of eserethole in glacial acetic acid introduced and the mixture shaken; 52 C.C. of hydrogen were absorbed during the first hour, and 92 C.C. in all (calculated for two atoms 91 c.c.). The solution was filtered made alkaline with sodium hydroxide and the oil thus thrown down extracted with ether. From the extract dried over potassium carbonate a yellow oil was obtained which became almost colourless when distilled under the vacuum of a rotatory oil pump (bath at about 200°).When treated with alcoholic oxalic acid it formed an oxalate (sheaves of fine needles m. p. 204" from aqueous alcohol) identical with that obtained from dihydro-eserethole prepared by Polonovski's method (Zoc. cit.). Dihydroeserethole (1 g.) was heated in a sealed tube with excess of methyl iodide for 1 hour a t loo" the excess of methyl iodide evaporated and an alcoholic solution of the product treated with alcoholic picric acid. The yellow picrate precipitated on addition of water crystallised from aqueous alcohol in prisms m. p. 204" (Found C = 47.0 ; H = 4.7. C2,H,,Q1,N8 requires C = 47.3 ; H = 4.6%). The substance was thus a dipicrate and two methyl groups had been introduced into the molecule during methylation, indicating that in contrast Go eserethole dihydroeserethole is a secondary base.Behaviour of' Eseretholemethine Methiodide as a $-Base.-The orange oil which separated on mixing the salt (0-2 g.) and picric acid in alcoholic solution changed on warming into a crystalline solid (0.27 g.) which was obtained from aqueous alcohol in yellow prisms m. p. 170" (Pound C = 47.7; H = 4.7. C,,H,2015N,s requires C = 47.5; H = 4.4%). In the formation of this di-quaternary picrate water has been eliminated from the molecule, t l t u s inclienting the pscudo-basic function of the oxygen atom. L)eh~/clroeserethoZernethilze (VIII) .-The methine (1 g.) was refluxed for 10 hours with an ammoniacal solution of 3 g. of silver nitrate in methyl alcohol. After filtration evaporation and dissolutio 254 STEDMAN AND BARGER: of the residue in water ether extracted an insignificant amount of an oil which formed a crystalline picrate but was not investigated further.The hot aqueous solution made faintly alkaline with ammonia, was treated with hydrogen sulphide to remove excess of silver atered boiled to expel ammonia and hydrogen sulphide, and treated with alcoholic picric acid. The viscous precipitate first formed became crystalline on warming and by fractional crystallisation from aqueous alcohol gave two picrates the more soluble one forming needles m. p. 211" (Found C = 47.0; H = 4.5. Cl6H2,ON2,2CBH,0,N requires C = 46.7; H = 4.4%) and the less soluble fraction consisting of plates contaminated with some needles. The latter crystallised from acetone in plates m.p. 199" (Found C = 52.8 ; H = 5.4. CI6H2,O2N2,C6H,0,N requires C = 52-3; H = 5.4%). A different result was obtained by the following procedure An alcoholic solution of eseretholemethine (5 g.) was added to 15 g. of silver nitrate in alcohol made strongly alkaline with ammonia (d 0.88), the total volume being brought to about 100 C.C. A silver mirror formed on the sides of the flask almost immediately. The mixture was heated on the water-bath for 5 hours filtered and excess of silver removed by addition of hydrochloric acid; from the filtrate, made alkaline with sodium hydroxide ether extracted 4.45 g. of an oil which treated with alcoholic picric acid yielded 5.35 g. of the picrate m. p. 199" described above. No trace of the picrate of higher melting point was obtained in this experiment.It seems evident that this substance was formed by reduction of an indolinone to an indoline compound the reducing agent being the hydrogen sulphide used to remove excess of silver. Oxidation was also effected by means of potassium ferricyanide. A solution of eseretholemethine (3 9.) in a small quantity of alcohol was boiled with a strongly alkaline solution of 7-2 g. of potassium ferricyanide in 100 C.C. of water for about 5 minutes and after cooling extracted with ether. From this extract 4 g . of the methiodide which had previously been prepared in the manner described below were obtained. The picrate (4.19 g.) m. p. 199" was treated with sodium hydroxide and the oily base which separated extracted with ether.The extract was dried over sodium sulphate filtered concentrated, and methyl iodide added. A crystalline methiodide slowly formed (3.3 g.). This separated from acetone in transparent prisms but the method was wasteful owing to its large solubility in this solvent. It was therefore crystallised by addition of dry ether to the acetone solution. With dry solvents the methiodide was obtained as a colourless substance m. p. about 131"; the fact that the meltin PHYSOETIGMINE ( ESERINE). PART III. 256 point was not absolutely sharp was no doubt due to the water of crystallisation which it contained (Found for air-dried material, H,O = 3.7 ; for material dried at 110" I = 30.0. C1,HZ70,N,I,H,O requires H,O = 4.1 ; C1,H,,O,N,I requires I = 30.1%). When, however the solvents were not perfectly dry the transitory form-ation of a blue iodine adsorption compound was consistently observed ; its disappearance no doubt coincided with the trans-formation of an a t first amorphous precipitate into crystalline form.Degradation of Deh ydroeseretholemethine i!fethiodide by Hof I)Z an n ' s Nethod to Compound IX.-An aqueous solution of 1.9 g. of the methiodide was shaken with a suspension of silver oxide prepared from 2 g. of silver nitrate. After filtration and removal of the water by evaporation under diminished pressure the residual oil was distilled a t 12 mm. After evident decomposition with the evolution of a gas a slightly brown oil distilled when the tem-perature of the bath was between 200" and 210". The distillate would not crystallise.It was therefore treated with an alcoholic solution of picric acid when a small quantity of a crystalline picrate m. p. 199" identical with that described above was obtained. The residue from the mother-liquors was treated with sodium hydroxide and extracted with ether and the extract washed with water until the sodium picrate was completely removed. After drying over sodium sulphate the ether was evaporated, when a colourless oil which crystallised spontaneously was obtained. Recrystallised from aqueous alcohol it formed colourless prisms, m. p. 62" (Found C = 72.3; H = 7.3. C14H1702N requires C = 72-7; H = 7-4:/,). This substance was practically devoid of basic properties; it was insoluble in dilute hydrochloric acid but formed a picrate which at first separated from alcohol in a yellow form and quickly changed into a deep crimson one; m.p. 103". Reduction of Compound I X to Compound X.-Hydrogenation was effected in the apparatus mentioned above using a solutim of colloidal palladium as catalyst and gum arabic as protective colloid; 0.16 g. of substance was used. Hydrogen was readily absorbed but as a result of a mishap the amount could not be measured. After filtration from the palladium and evaporation of the alcohol (aqueous alcohol was used as solvent) the solution, after addition of a small quantity of sodium hydroxide to ensure alkalinity was extracted with ether. After drying and evaporation, this yielded a crystalline product which when crystallised from aqueous alcohol formed cubes m.p. 68" (Fcund C = 71.8 H = 8-2. It is evideat from the analysis that two atoms of hydrogen were absorbed and C1,H1,O,N requires C = 72.1 ; H = S-2:/,) 256 STEDMU AND BARGER: that the oxygen atom present as a carbonyl group was retained in the molecule. Trinitroeserethote.-Among the diverse experiments which have been carried out with a view to effect the oxidation of eserethole, the action of nitric acid on this substance has been studied. Cold dilute nitric acid has little if any action but the concentrated acid (d 1-4) reacts vigorously. Eserethole (1 g.) was added drop by drop to 3 C.C. of concentrated nitric acid cooled in a freezing mixture and vigorously stirred. The product was warmed on the water-bath for 8 hour cooled diluted with waber and the yellow crystalline precipitate (0.3 g.) recrystallised from aqueous alcohol, trinitroeserethole separating in orange rectangular plates m.p. 152" (Found C = 47.1 ; H = 5.0; N = 18.7. C1,H1,O,N requires C = 47-2; H = 5.0; N = 18.4%). It is insoluble in alkalis and dilute acids but dissolves in concentrated acids. Oxidation of Eserethole with Potassium Permanganate in Acetone Solution.-" solution of eserethole (1 g.) in 100 C.C. of acetone was maintained at about -10" while finely powdered potassium per-manganate (representing 6 0 ) was added during 2 days. The solution was then warmed with methyl alcohol to remove excess of permanganate filtered and the solvent evaporated. The red s p p thus obtained would not crystallise even after distillation in a high vacuum but on treatment with alcoholic picric acid it readily yielded a picrate (0.9 g.) which crystallised from alcohol in rhomb-shaped prisms m.p. 166" (Found C = 51.8; H = 4-9. Cl,H2,0,N,,C8H30,N3 requires C = 51.5; H = 4.7%). The base was recovered from this picrate by dissolving the latter in glacial acetic acid pouring into water and extracting the picric acid with ether making alkaline with sodium hydroxide and again extracting with ether. The oily base obtained on evaporation of the ether was warmed with methyl iodide and the product dissolved in hot methyl alcohol. On cooling the methiodide crystallised in needles, m. p. 198-199" (Found C =48*1; H = 5.8; I = 31-6. C1,H2,0~2,CH,I requires C = 4743; H = 5.8; I = 3106%). This methiodide resembles eserethole methiodide in its behaviour towards alkalis.It is stable towards sodium carbonate but when treated with sodium hydroxide yields an ether-soluble base. The latter could not however be crystallised neither could its methiodide be obtained in a crystalline condition. Etheserolene picrate was prepared incidentally during an experi-ment designed to test whether the presence of ethyl alcohol or sodium ethoxide was an essential condition for the formation of the esoline compounds described in Part I of this series. Starting from eserethole methiodide the experimental conditions mer PHYSOSTIGMINE ( ESERINE). PART III. 257 exactly similar to those described in that paper for the preparation of esoline ethyl ether dimethiodide except that a solution of sodium in n-propyl alcohol was used in place of one in ethyl alcohol.No solid separated however from the solution. The propyl alcohol was therefore evaporated the oily residue dissolved in water made strongly alkaline with solid sodium hydroxide and the solution refluxed for several hours tetramethylammonium iodide and an oil volatile in steam separating. The latter isolated from the mother-liquors by extraction with ether crystallised in a few hours, The solid m. p. about 45" (etheserolene according to Polonovski, melts at 48") was dissolved in alcohol and treated with alcoholic picric acid when a yellow picrate separated which crystallised from alcohol in stout prisms m. p. 98" (Found C = 52.1 ; H = 4.9. Calc. for Cl,H1,02N C6H307N3 C = 52.0; H = 4-b%).From the melting point of the original substance and the analysis of the picrate it seems evident that this was etheserolene picrate. It is also evident that the oxygen atom has no pseudo-basic function in this compound. Degradation of Esoline Ethyl Ether Dimethiodide.-The preliminary results of the degradation of this substance by Hofmann's method reported in Part I of this series have been confirmed. Since iden-tical results have been obtained by distillation of the product of the action of silver oxide on the iodide and by treating it with potassium hydroxide only the latter method need be described. The oil obtained by treating 4 g. of the iodide with silver oxide was refluxed for $ hour with 10 C.C. of SOY; potassium hydroxide. The solution was then steam-distilled until the oil had been com-pletely carried over.The distillate was extracted with ether upon evaporation of which an oily residue was obtained. This was dissolved in alcohol and the solution treated with picric acid. A viscous picrate separated which slowly solidified on warming. After filtration this was suspended in a relatively large volume of alcohol boiled and filtered. On cooling the filtrate a picrate separated in short stout prisms m. p. 156" unchanged on recrystallisation from aqueous alcohol (Found C = 46.7 ; H = 4.7. C,6H2,0N2,2C6H30,N3 requires C = 46.5; H = 4.7. soluble picrate which was separated in the manner described above, crystallised from aqueous alcohol in rhomb-shaped prisms m. p. quires C = 47.1 ; H = 4.7. C18H2g02N,,2C6H307N requires C = 47-2 ; H = 4-57;>.Both picrates were converted into methiodides by the following treatlment. The picrate was dissolved in glacial acetic acid poured into water extracted with ether to remove C16H260N2,2C6H30,N3 requires c = 46.7 ; H = 4.4%). The less 199" (Found C = 46.9 ; H = 4.7. C1&3,O2N2,2C6H,O7N3 re-VOL. CXXVII. 258 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON picric acid made alkaline with ammonia and the base extracted with ether. Addition of methyl iodide to the ethereal solution (dried over sodium sulphate) caused the methiodide to separate. The picrate melting a t 156" thus yielded a methiodide which crystallised in plates melted a t 169-170" and was identical with a methiodide which had been obtained directly from the crude product of the distillation of the quaternary hydroxide without purification through the picrate (Found C = 50.2; H = 7.4. C1,H,lON,I requires C = 50.2; H = 7.6. C1,H,,ON,I requires C = 50-5; H = 7.2%). The picrate melting at 199" yielded a methiodide m. p. 141"; when this was heated a t 100" in a sealed tube for 4 hour with excess of methyl iodide a second methiodide, m. p. 188" was obtained but no esoline ethyl ether dimethiodide was formed. Apparentlly this base was not as was originally believed the ethyl ether of bhe hypothetical esoline base. The authors desire to express their thanks to the administ'rators of the Carnegie Trust for the Scottish Universities for a grant which has alone rendered this research possible. DEPARTMENT OF MEDICAL CHEMISTRY, UNIVERSITY OF ED IN BURG^. [Received Notiember 18th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700247

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

258 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON XLII1.-The Action of Light on the Ferrous Ferric Iodine Iodide Equilibrium. By ERIC KEIGHTLEY RIDEAL and EDWARD GARDNER WILLIAMS. THE exceptions to Einstein’s laws of pliotochemical equivalence may be divided into two classes according as the number of quanta absorbed is (1) greater than the number of molecules decomposed, the excess quanta being emitted as fluorescence or dissipated in heating the reacting system or (2) less than the number of molecules decomposed. In class (Z) chain reactions occur of the atom type as is exemplified in the reactions C1 + H = HC1+ H and H + CH = HCl + C1 (Nernst 2. Elektrochem. 1918 24 335), the product of the reaction with the original energy of excitation together with the energy liberated by the reaction may excite other molecules on impact (Christiansen and Kramers 2.phy8ikaZ. Chem., 1924,104,452) as e.g. in the chorina~on of toluene a t low temper-atures without a chlorine carrier (Book and Eggert 2. Elektrochem., 1923 34.0 521). It is to be anticipated that if a photosensitive system could be formed in which chain reactions of either of these ssort could be eliminated the Einstein law of photochemical equi THE FERROUS FERRIC IODINE IODIDE EQUILIBRIUM. 259 valence would be obeyed. Conditions for such evidently obtain in systems in which the energy may be rapidly dissipated no atom chains being formed and in which the energy of excitation is relatively smail. It has long been known that the interaction between ferric salts and iodides to produce ferrous ions and free iodine is revemible and that the reaction expressed by the equation dark light 2Fe"' + 21' T+ 2Fe" + I, is photpensitive.Sasaki (Mem. CoZZ. Sci. Kyoto 1922 5 5) has shown more recently that under conditions of uniform illumination with light from an electric lamp it photochemical equilibrium different from the dark equilibrium is attained. It was considered that this reaction might reasonably be expected to obey the Einstein law of photoequivalence. An investigation of the photodynamics of the system revealed the fact that this law was rigidly fulfilled the mechanism of the reaction being expressible in the form I' If\ /I' \I' It/ \It I' \Fe" 3- Fee*/ -t hv = If-Jj'e*'* + Jj'e***-I' + I' : I-1'-I I f / and that the minimum value of a photochemically active quantum corresponded to a wave-length X = 5790 A.or a potential of 2.14 volts. Further investigation indicated that the photosensitive consti-tuent was the iodine; both the iron salts and the iodine ion being inactive over the region of spectrum employed. The value of the quantum determined in this way X = 5790 8. E = 49,200 cals. per gm.-mol. or V = 2-14 volts agrees very closely with the resonance potential of the iodine molecule 2.34 & 0.2 volts as determined by Foote and Mohler (" The Origin of Spectra," p. 78), thus supporting the evidence obtained from this investigation that the photochemical action results from the optical excitation of the iodine and that the level of energy corresponding to the resonance potential of the iodine molecule is also a chemically active state of excitation.E x P E R I M E N T A L. (a) Isolation of the Photochemically Active Light of Minimum Quantum Value. Equal volumes of two solutions of the compositions (A) Ferric ammonium afurt 0.02 molar ammonium sulphate 0.02 molar, E 260 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON made up to N/10 by the addition of sulphuric acid and (B) potassium iodide 0.09 molar were mixed. The following reaction occurs: Fe,( SO,), (NH,),S04,24H,0 + ( NH,),S04 + 4*5KI + 5H,S04 yt 2FeS0 + 2(NH,),S04 + K,SO f- I + 2.5KI + 5H,SO,. The liberation of iodine proceeds rapidly a t the start in the dark, and equilibrium is almost attained a t the end of 24 hours but a slow reaction goes on for several weeks.As source of light a 1000 c. p. gas-filled lamp (110 volts 10 amps.) was employed in conjunct'ion with a series of " M " light filters (Wratten type) for isolating comparatively narrow regions of the spectrum. The cuts of these filters as published by the makers were confirmed by means of a direct-vision spectroscope and found to be accurate under the conditions of the experiment. Both the gelatin light filter and the flat-sided glass-stoppered reaction vessel were maintained a t a uniform temperature of 25" in glass-sided troughs by means of a water-circulating system from a controlled thermostat. I n order to obtain approximate equality of intensity in the transmitted light the distance of the lamp from the filter was changed for each combination of filters according to their transmission as published by the makers.To follow the change in equilibrium the amount of iodine in solution was estimated by titration of 5 C.C. of solution run into 100 C.C. of water a t 0" with approximately N/200-sodium thio-sulphate solution using starch as indicator. The usual precautions concerning the quantity of starch and standardisation of the weak thiosulphate solution were taken. The following results were obtained :-Wave-Iength in A. of light transmitted. 6500-7000 6000-7000 5000-6300 4000-5 100 5100-5500 4300-4700 4870-5040 Exposure in hours. 2 2 2 2 2 2 2 1 Titration value for the unilluminated solution in C.C. less that for illuminated. 0 0.60 0.80 0.15 0 0 0 8.75 The region of the spectrum responsible for the photochemical change appears from these data to lie between h = 5500 and 6500 A.The quartz mercury vapour lamp emits a group of strong yellow lines a t about X = 5790 8. which can be isolated conveniently by means of a colour filter prepared by the Kodak Co. Replacing the 1000 c. p. lamp by a quartz mercury vapour lamp the following data were obtained the time of exposure being in all cases 2 hours THE FERROUS FERRIC IODINE IODIDE EQUILIBRIUM. 261 Titration value in C.C. Filter. Light transmitted in A. NI2OO-thio. Nil Complete spectrum 6.6 E 5790 5769 5679 (and red lines) 1.05 c 4916-4078 4047 0 H 5461 4916 4359 4348 4339 0 Mercury groen 5461 0.20 These results confirm those obtained with the 1000 c.p. electric lamp and show that in addition to the ultra-violet light the lines 5700 5769 5679 are photochemically active (the red lines although absorbed by the solution being very faint contributed but little if any energy to the system). The line X = 5790 A. corresponds to an energy of excitation of 49,200 calories or a potential of V = 2.14 volts a value as we have seen almost identical with the resonance potential of the iodine molecule. 274 yellow (b) The Photochemically Actire Constituent. As has already been indicated it would appear from the above experiments that the iodine was the photochemically active constituent. Since we are dealing with a reversible system any alteration in the equilibrium constant would entail a relative alteration in the velocity coefficients of the two reactions : (1) I + 2Pe" -+ 2Fe"' + 21' (2) 21' + 2Fe"'+ 2Fe" -i- 1, k , ka It was accordingly important to find out whether this apparent relative alteration in the velocity coefficients under illumination was produced by the actual alteration in k1 and that k remained unaltered under illurnination.In order to establish this point a modification of the Harcourt and Esson experiment as used by Donnan and Le Rossignol (J., 1903 83 703) to determine the order of reaction between the ferricyanide and iodide of potassium was employed. Fifty C.C. of the iodide solution B to which 2 C.C. of a standard thiosulphate solution and two drops of starch solution had been added were placed in a vessel provided with a stirrer and maintained at 25" in a thermostat.An equal volume of the ferric iron solution A at 25" was added and the time of appearance of the blue colour noted. Immediately on its appearance a fresh quantity of thiosulphate solution was added and the time of reappearance of the starch iodine blue observed. With the precautions as to strength of solution and use of the delivery pipette given by Donnan and Le Rossignol the reaction was carried out at 25" in the dark and in the light of the 1000 c. p. electric lamp. The rates of reaction both in the dark and under illumination were found to be identical 262 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON In the above reaction the iodide-ion concentration was maintained constant during the conversion of the ferric into ferrous ion and the system is insensitive to illumination.Thus the alteration in the equilibrium of the system under illumination is due to an increase in the velocity of the reaction :-I + 2Fe" --+ 2Fe"' + 21'. If the increase in the velocity coefficient of this reaction nnder illumination were due 60 a photochemical increase in the chemical activity or thermodynamic concentration of the iodine molecules, should exhibit a definite elec-tromotive force. Such cells constructed with platinum electrodes a n d v a r i o u s strengths of iodine solutions in potassium iodide showed after removal of all traces of dissolved oxygen no electromotive force on illumination of one half of %he cell. It therefore seems probable that the production of excited iodine molecules by the photochemical action is small compareJ with the rate a t which the reaction 2~ + I p- 21' occurs a t the electrode.(c) The Application of the Einstein Law of Photoepicalenee. E'or the determination of the amount of radiation absorbed and the concomitant chemical action produced by the radiation the following apparatus was employed (Fig. 1) : A. Mercury vapour lamp. B. Screen. C. Cooling trough. D. Blackened metal plate carrying gelatin light filter E. 3'. Cooling trough containing glass-stoppered reaction vessel G. H. Moll thermopile. I. compensating leads and galvanometer. The Moll thermopile H was first calibrated by mmns of a Leslie cube precautions being taken to ensure " black body " radiation as nearly ideal as possible in the circumstances by screening the system of Leslie cube and thermopile with non-conducting material faced with reflecting surfaces in which accurate openings were cut.The radiant energy received by the thermopile from the Leslie cube was calculated by the formula of Lummer and Pringsheim (Ann. PhysiE 1897 63 395) and found to be 1-23 x lo5 ergs per sec. I THE FERROUS FERRIC IODINE IODIDE EQUILIBRIUM. 263 The readings of the galvanometer connected t o the thermopile during the radiation fluctuated slightly between 35.4 and 36.4 cm., yielding a mean value of 35-95 cm. Hence the energy per cm. deflection is 3.423 x lo3 ergs per second. Allowing for the fact that lamp-black surfaces emit and absorb but 00% of the true black-body radiation the thermopile constant is 2-77 x 103.The volume of the solution in G covered by the funnel of the thermopile was found both by measurement and by calculation to he 31 C.C. The mercury vapour lamp was started and allowed to attain a steady state the current being checked by means of an ammeter connected in the circuit. The thermopile suitably protected from draughts was allowed to come into equilibrium with its surroundings, precautions being taken to keep the room temperature as steady as possible. The bottle was first filled with water and a number of readings were taken of the deflection caused on the galvanometer scale when the screen B was raised. The bottle was then filled up to the mark with the dark equilibrium solution and a number of readings taken as before. Since even with the utmost precaution mercury vapour lamps are apt to vary in intensity of illumination a number of independent experiments were performed of which the two appended represent the extremes of variation.The curve of the rate of disappearance of iodine under the same conditions was also obtained by means of a large number of experiments which agreed fairly closely. Water. Deflection on galvanometer scale in cm. Initial. Final. in cm. / \ TotaI deflection 7.3 27.8 7.0 27.5 7.0 27.2 5.4 27.8 5.6 28.2 5.6 28.2 (I) 7.2 27.5 (11) Dark equilibrium mixture. 6.9 15.1 (I) 7.0 15.0 6.9 14-8 7.0 15.3 5.4 13.7 (I1) 5.6 14-2 5.4 14.0 Energy absorbed by solution in (I) = Energy absorbed by solution in (11) = Mean = 20.2 22.6 8.3 12.3 x 2.77 x los ergs per second.14.03 x 2.77 x 10s ergs per second. 13.2 x 2.77 x 108 ergs per second 264 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON The rate of disappearance of iodine under the same conditions was next investigated. At various times 5.15 C.C. were withdrawn run into 100 C.C. of cold water and titrated with approx. N/lOO-thiosulphate the following data being obtained from which the velocity ccefficient [k = l/t.log a/(a - x)] has been calculated a = 7-5 x 0.0012696 g. of 12. T N/lOO-Thio. (mins.). (c.c.). t . X. k. 0 7.50 15 0.0006345 0.00463 15 7.14 30 0.001 142 0.00430 52 6.20 60 0.002030 0*00404 120 5.40 90 0.003173 0.00455 192 4-97 422 4.91 Mean = 0.00438 The reaction appears to follow the unimolecular law as indicated by the values of Ic hence the initial rate of disappearance of iodine may be calculat8ed.dx/dt = kc = 0.00438 x 0.000005 x 7.5 x 6.06 x molecules I2 per minute for 5-15 C.C. = 0.996 x 1016 molecules I2 per see. for 31 C.C. We can now proceed t o calculate the number of quanta absorbed Wave-length = 5790-66 A. Magnitude of quantum = h v = 6.55 x per see. by the solution. Frequency v = 517G x 1014. x 5.176 x 1014 = 3.39 x erg. Energy absorbed by solution = 13.2 x 2-77 x 103 ergs per see. Hence number of quanta absorbed by solution = 1.078 x 1016 per sec. - _____ -There are thus 0.996 x 1016 molecules of iodine being decomposed per second by 1.078 x 1016 quanta. The reaction thus obeys the Einstein law of photochemical equivalence under the condit,ions of the experiment.(d) The Temperature Coefiicient of the Reactions. The influence of temperature on the dark equilibrium system 2Fe" + I r j 2Fe"' + 21' is negligibly small but the rate a t which equilibrium is attained is very dependent on the temperature; this rate was investigated at 25" and 33-25" and the equilibrium point was reached in each case though more rapidly in the warmer solutions. By estimation of the amount of iodine liberated after mixing the solutions A and THE YERROlTS FERRIC IODISE IODIDE EQUILIBRIURI. 265 a t the two temperatures the temperature coefficient was calculated from the velocity coefficients to be for a rise in temperature of lo", k35*/k250 = 2.713. The iiifucnce of temperature on the rate of attainment of the light equilibrium was investigated by a potentio-metric method.A photovoltaic cell coiisisting of bright platinum electrocks inserted in a constricted U-tube containing the dark equilibrium mixture was eniploycd. On illumination of one limb of the U-tube with i~ioiioc~lromat'ic yellow radiation at 25" the equilibrium concentration in the exposetl limb is altered arid the rate of alteration can 1;e dctcrniined froiii thc electromotive force of the ccll. On cxtting off the radiation. the return of the photo-chciuical equilibriuni niihture to tlie dark equilibrium can readily he followed from the electromotive force of the cell. As typical of the readings obtaiticrt 1::- this method the follon-ing values may be cited. Time iii I n j 11s. 0 20 40 GO 90 113 9 ,..- 43 liilli-volt,s.10.30 10.30 10.20 !b70 8.85 6.45 6.25 5.90 Time i n rnins. 0 10 20 3 0 40 i) Teniperut,nre 35". Jlilli- lime in volts. inins. 0.0 50 1.40 60 2.80 70 4.85 80 6.40 90 7.63 100 Nilli-volts. S.60 9.25 9.65 10.00 10.17 10-17 From tlie velocity coefficiciits of the rate of attainment of photo-cheinictL1 equilibriuni the t emperature coefficient k,,./k,,. (light) was fouiid to be 1-17. It is probable that the velocity of the true piic;tocheiiiicaI reaction is not iiiflueiiced by temperature and that the value 01 1.1T obtai!ied is due to the effect of the increase i n velocity of tlicl dark reaction 11 ith thc tenipcrature huperiinposed o i l the vcblocitjr of Piic light roac'tio!i.I t has already bwil iiotctl that altliough the liberation of iodine from the reactiirg system co~i~ineiicw rilpidly J e i the reaction comes 1 ) u C slon-1) to eqi~ilihriuni. At the ciid of 24 l~oim thc average airlount of iodine 1ik)crdtctl as tfcieriniiied 1);)~ titration with thio-sulphatc v-as fouiid cqcivalc~nt to 7-50 C.C. of S/lOO-thiosulphate €or 5.15 C.C. of the equilibrium mixture. Although the reaction is apparently completed n e ~ ertheless a ~ O T V reaction is still pro-ccecliig towards a true ecluilibriurn. This ec1ui;ibriurn was estab-l i s l i c d at the eiicl of 3 i~ic~ntiis and found cqual to 8-37 c.c. of S/lOCI-tliiosiili~~i~ttc. Sincc the equilibrium attained is the result of the attaininelit of cqual velocity for two reactions 2Fe *+ I 4 K 266 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON 2Fe"'+ 21' and 2E"e"'+ 21'- 2Fe"+ I, it is clear that if the active masses of equilibrium concentrations of the reactants could be raised in equal proportion the reaction velocities of each reaction would proceed more rapidly and equilibrium would be more rapidly attained.The active masses or thermodynamic concentrations of the active ions whether simple as indicated above or complex as imagined by Sasaki (2. angew. Chem. 1024,137,181) can readily be raised by the addition of a neutral salt such as potassium chloride (Bronsted 2. physikal. Chem. 1922 103 307). I n the following curves (Fig. 2) the rate of attainment of equilibrium in thc dark for three mixtures to which varying amoiints of potassinm chloricte have been added are given.Fra. 2. Time minutes. It is clear from the curves that the augmentation in thermo-dynamic concentration of the reacting ions by the addition of the potassium chloride has as anticipated augmented the rate a t which true equilibrium is attained. That the separate reaction velocities are in reality augmented by the addition of potassium chloride was confirmed by repeating the modified Harcoixrt and Esson experiment as already described in presence of 1437-potassium chloride and in the ordinary solution without the salt addition. The marked increase in the velocity of the forward reaction on the addition of potassium chloride is evident from the following data : Time in minutes for appearance of starch-iodide colour. Thioadded(c.c.) 1 2 3 4 5 G 7 8 9 No KCl added 0.5 0.8 1.5 2.8 4-7 8.15 13.7 25-0 In 1.6N-KCl ...0.4 0.6 1.0 1.6 2-4 3.6 5.6 8.9 16. THE FERROUS FERRTC IODINE IODIDE EQUILIBRITTM. 267 At equilibrium in the dark the rates of the forward photosensitive reactions acre given in absence and presence of potassium chloride by the equations dzldt = Ic .f(I,)f (Fe**)2 - a and dx'ldt = II:.f'(I,)f'(Fe")2 = b where f andf' are the activity coefficients in absence and presence of the neutral salt. On illumination of the solutions tlhe respective velocities become dx/dtfil. = II .f(Iz)f(Fe")2 + ](I,) = a + x, dz'ldtill. = II .f'(12)f(Fe")2 + I(&) = b + X, where I is the intensity of the photoactive radiation. wiOhout and in presence of salt will evidently be, The ratio of the velocities of the two dark and light reactions Without KCl present Vill./Vdark = (a + x)/a = 1 + z/a.With ICC1 present Viu,/Vdark = (b + x)/b = 1 + xjb. Thus the greater the absolute velocity of the forward reaction a t equilibrium the smaller will be the apparent effect of the light on the equilibrium. We should thus anticipate that the shift in the equilibrium obtained with the solution containing potassium chloride on exposure to light will be far less than the shift in the equilibrium of the solutlion in the absence of potassium chloride on exposure to identical radiation since the addition of salt has as has been indicated by the previous experiments raised the value off' considerably above f or b > a. These expectations were fully realised by determining the rate of change of the dark equilibrium mixture on illumination both by the potentiometric method and by titration.The following data were obtained for a dark equilibrium mixture containing 1 -5N-potassium chloride exposed to mono-chromatic radiation a t 25". Time (mins.). 0 1 s 10 26 30 Milli- N/lOO-Thio. Time Milli- N/lOO-Thio. volts. (C.C.). (mins.). volts. (c.c.). 0 7.86 41 2.40 -0.1 - 52 2.60 I 0.8 - 60 2.65 7.30 1-05 - 70 2.70 -1.90 - 170 2.70 7.30 2.15 7.75 The final value of 2.70 mv. as compared with a value of 10.3 mv. for the solution in the absence of potassium chloride (see Table, p. 265) and a shift in the equilibrium concentration of iodine equivalent to only 0.56 C.C. of N/lOO-thiosulphate solution as com-pared with the value 2.50 C.C.obtained without the potassium chloride indicated clearly the effect of augmenting the velocity of the two reactions proceeding in either direction at equilibrium by elevation of the thermodynamic concentrations of the reactants. K" 268 THE FERROUS FERRIC IODINE IODIDE EQUILIBRITJM. The value of the equilibrium constant for the reaction K = (Fe")(12)$/(Fe"')(I') has been determined by Maitland (2. Elektrochem. 1906 112 263) and by Bronsted and Pedersen (2. physikal. Chem. 1922,103 307). Maitland obtained the value K = lO2'005 whilst the data of Bronsted and Pedersen yielded a value of K 2 y = 212.1 ~t~ilising a value of L = (I')(12)/(I'J = 0.0061. = 0.00611 for the equilibrium constant The data obtained in the above experiments permit us to calculate the value of K .The original concentration of ferric ions = 0.02 gm.-atom per litre. The titre of the dark equilibrium solution is 8.37 C.C. of N/100-Y Y Y Y Y 9 of iodide ions = 0.045 gm.-atom per litre. thiosulphate for 5.15 C.C. Hence a t equilibrium we obtain : (Fe"') = (2.0 - 8-37/5-15)10-2 gm.-atom per litre. (Fee*) = 8.37/5.15.10-2 gm.-atom per litre. (1') = 8.37/5.15.10-2 gm.-atom per litre. we obtain Also if the original iodide concentration be x and the final .z - a, I,' = 3a I = x - 2a, = 2.875 x I' = x - a and (x - 2a)(x - a)/% = 0.00611 . . . . . (1) * where x = (4.5 - 8.37/5.15)10-2 gm.-atom per litre gm.-atom per litre. Inserting this value of x in (I) and solving for a we obtain a = 0.58 x gm.-atom per litre.Hence (1') = (2.575 - 0.58j x 10-2 = 2.30 x 10-2 gm.-atom per litre. (1.625 x 10-2)(1*625 x 10-2)a ~ 23.6, (0.380 x 10-2)(2-30 x Hence K25" = value in close agreement with that of Bronsted and Pedersen. The slight discrepancy between 23.6 and 21.1 for the values of K in the two investigations is probably accounted for by the fact that Bronsted and Pedersen utilised only chlorides and iodides of iron and potassium whilst in the present case ammonium sulphate was present in addition. Xummary. The reaction 2Fe"'+ I ~2 2Fe"+ 21' is photosensitlive to both ultra-violet and visible light. The region of visible photoactive radiation is within the range 5500-6500A. with an apparen SHORT THE CONDENS-4TION OF PHENYLETHPLAMINE ETC. 269 maximum a t 58008.The tri-iodide ion is the photoactive constituent and the energy of excitation corresponding to a wave-length 5800 A. is equivalent to 2.14 volts a value almost identical with the resonance potential of the iodine molecule. It is found that one quantum of absorbed radiant energy causes 1 mol. of iodine to react; the mechanism of the reaction can be expressed in the 1-for111 2Fe1 + I,' -/- hv 1 2FeT3 + 1'. The dark eyuilil:)r.ium coils1 ant of the reaction is K = 23-6 = (Fe"')(T2}~/(Fe"')(I') a t 23". The temperature coefficient of the liberation of iodine in the dark is k,; ,ikZ5 - 2.723 whilst that of the photochemical reaction is ,'Idz5 = 1.17. The addition of potassium chloride raises the theimodynaiuic concentrations of all the reactants and although the equilibrium point is unchanged the rate of attainment is very considerably increased.Proof is given that equilibrium is the result of attainment of equal velocities of the forward and the back reaction since the effect of radiation of constant intensity on the equilibrium attained is less when the thermodynamic concentrat ions of the reactants (and thus the reaction velocities of the two reactions} are raised by the addition of potassium chloride. Our thanks are due to the Department of Scientific and Industrial Research for a grant out of which a part of the cost of the apparatus was provided. IA A u OR -i TO RT o 17 P HITS I ( .A 1 C H F JI r s-rR\-, G'AMI3RTI)C~E. [ R P c P ~ u P ~ ' Ncrc~t-r~~bcr 1&h 1024. 258 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON XLII1.-The Action of Light on the Ferrous Ferric Iodine Iodide Equilibrium.By ERIC KEIGHTLEY RIDEAL and EDWARD GARDNER WILLIAMS. THE exceptions to Einstein’s laws of pliotochemical equivalence may be divided into two classes according as the number of quanta absorbed is (1) greater than the number of molecules decomposed, the excess quanta being emitted as fluorescence or dissipated in heating the reacting system or (2) less than the number of molecules decomposed. In class (Z) chain reactions occur of the atom type as is exemplified in the reactions C1 + H = HC1+ H and H + CH = HCl + C1 (Nernst 2. Elektrochem. 1918 24 335), the product of the reaction with the original energy of excitation together with the energy liberated by the reaction may excite other molecules on impact (Christiansen and Kramers 2.phy8ikaZ. Chem., 1924,104,452) as e.g. in the chorina~on of toluene a t low temper-atures without a chlorine carrier (Book and Eggert 2. Elektrochem., 1923 34.0 521). It is to be anticipated that if a photosensitive system could be formed in which chain reactions of either of these ssort could be eliminated the Einstein law of photochemical equi THE FERROUS FERRIC IODINE IODIDE EQUILIBRIUM. 259 valence would be obeyed. Conditions for such evidently obtain in systems in which the energy may be rapidly dissipated no atom chains being formed and in which the energy of excitation is relatively smail. It has long been known that the interaction between ferric salts and iodides to produce ferrous ions and free iodine is revemible and that the reaction expressed by the equation dark light 2Fe"' + 21' T+ 2Fe" + I, is photpensitive.Sasaki (Mem. CoZZ. Sci. Kyoto 1922 5 5) has shown more recently that under conditions of uniform illumination with light from an electric lamp it photochemical equilibrium different from the dark equilibrium is attained. It was considered that this reaction might reasonably be expected to obey the Einstein law of photoequivalence. An investigation of the photodynamics of the system revealed the fact that this law was rigidly fulfilled the mechanism of the reaction being expressible in the form I' If\ /I' \I' It/ \It I' \Fe" 3- Fee*/ -t hv = If-Jj'e*'* + Jj'e***-I' + I' : I-1'-I I f / and that the minimum value of a photochemically active quantum corresponded to a wave-length X = 5790 A.or a potential of 2.14 volts. Further investigation indicated that the photosensitive consti-tuent was the iodine; both the iron salts and the iodine ion being inactive over the region of spectrum employed. The value of the quantum determined in this way X = 5790 8. E = 49,200 cals. per gm.-mol. or V = 2-14 volts agrees very closely with the resonance potential of the iodine molecule 2.34 & 0.2 volts as determined by Foote and Mohler (" The Origin of Spectra," p. 78), thus supporting the evidence obtained from this investigation that the photochemical action results from the optical excitation of the iodine and that the level of energy corresponding to the resonance potential of the iodine molecule is also a chemically active state of excitation.E x P E R I M E N T A L. (a) Isolation of the Photochemically Active Light of Minimum Quantum Value. Equal volumes of two solutions of the compositions (A) Ferric ammonium afurt 0.02 molar ammonium sulphate 0.02 molar, E 260 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON made up to N/10 by the addition of sulphuric acid and (B) potassium iodide 0.09 molar were mixed. The following reaction occurs: Fe,( SO,), (NH,),S04,24H,0 + ( NH,),S04 + 4*5KI + 5H,S04 yt 2FeS0 + 2(NH,),S04 + K,SO f- I + 2.5KI + 5H,SO,. The liberation of iodine proceeds rapidly a t the start in the dark, and equilibrium is almost attained a t the end of 24 hours but a slow reaction goes on for several weeks. As source of light a 1000 c.p. gas-filled lamp (110 volts 10 amps.) was employed in conjunct'ion with a series of " M " light filters (Wratten type) for isolating comparatively narrow regions of the spectrum. The cuts of these filters as published by the makers were confirmed by means of a direct-vision spectroscope and found to be accurate under the conditions of the experiment. Both the gelatin light filter and the flat-sided glass-stoppered reaction vessel were maintained a t a uniform temperature of 25" in glass-sided troughs by means of a water-circulating system from a controlled thermostat. I n order to obtain approximate equality of intensity in the transmitted light the distance of the lamp from the filter was changed for each combination of filters according to their transmission as published by the makers.To follow the change in equilibrium the amount of iodine in solution was estimated by titration of 5 C.C. of solution run into 100 C.C. of water a t 0" with approximately N/200-sodium thio-sulphate solution using starch as indicator. The usual precautions concerning the quantity of starch and standardisation of the weak thiosulphate solution were taken. The following results were obtained :-Wave-Iength in A. of light transmitted. 6500-7000 6000-7000 5000-6300 4000-5 100 5100-5500 4300-4700 4870-5040 Exposure in hours. 2 2 2 2 2 2 2 1 Titration value for the unilluminated solution in C.C. less that for illuminated. 0 0.60 0.80 0.15 0 0 0 8.75 The region of the spectrum responsible for the photochemical change appears from these data to lie between h = 5500 and 6500 A.The quartz mercury vapour lamp emits a group of strong yellow lines a t about X = 5790 8. which can be isolated conveniently by means of a colour filter prepared by the Kodak Co. Replacing the 1000 c. p. lamp by a quartz mercury vapour lamp the following data were obtained the time of exposure being in all cases 2 hours THE FERROUS FERRIC IODINE IODIDE EQUILIBRIUM. 261 Titration value in C.C. Filter. Light transmitted in A. NI2OO-thio. Nil Complete spectrum 6.6 E 5790 5769 5679 (and red lines) 1.05 c 4916-4078 4047 0 H 5461 4916 4359 4348 4339 0 Mercury groen 5461 0.20 These results confirm those obtained with the 1000 c. p. electric lamp and show that in addition to the ultra-violet light the lines 5700 5769 5679 are photochemically active (the red lines although absorbed by the solution being very faint contributed but little if any energy to the system).The line X = 5790 A. corresponds to an energy of excitation of 49,200 calories or a potential of V = 2.14 volts a value as we have seen almost identical with the resonance potential of the iodine molecule. 274 yellow (b) The Photochemically Actire Constituent. As has already been indicated it would appear from the above experiments that the iodine was the photochemically active constituent. Since we are dealing with a reversible system any alteration in the equilibrium constant would entail a relative alteration in the velocity coefficients of the two reactions : (1) I + 2Pe" -+ 2Fe"' + 21' (2) 21' + 2Fe"'+ 2Fe" -i- 1, k , ka It was accordingly important to find out whether this apparent relative alteration in the velocity coefficients under illumination was produced by the actual alteration in k1 and that k remained unaltered under illurnination.In order to establish this point a modification of the Harcourt and Esson experiment as used by Donnan and Le Rossignol (J., 1903 83 703) to determine the order of reaction between the ferricyanide and iodide of potassium was employed. Fifty C.C. of the iodide solution B to which 2 C.C. of a standard thiosulphate solution and two drops of starch solution had been added were placed in a vessel provided with a stirrer and maintained at 25" in a thermostat.An equal volume of the ferric iron solution A at 25" was added and the time of appearance of the blue colour noted. Immediately on its appearance a fresh quantity of thiosulphate solution was added and the time of reappearance of the starch iodine blue observed. With the precautions as to strength of solution and use of the delivery pipette given by Donnan and Le Rossignol the reaction was carried out at 25" in the dark and in the light of the 1000 c. p. electric lamp. The rates of reaction both in the dark and under illumination were found to be identical 262 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON In the above reaction the iodide-ion concentration was maintained constant during the conversion of the ferric into ferrous ion and the system is insensitive to illumination.Thus the alteration in the equilibrium of the system under illumination is due to an increase in the velocity of the reaction :-I + 2Fe" --+ 2Fe"' + 21'. If the increase in the velocity coefficient of this reaction nnder illumination were due 60 a photochemical increase in the chemical activity or thermodynamic concentration of the iodine molecules, should exhibit a definite elec-tromotive force. Such cells constructed with platinum electrodes a n d v a r i o u s strengths of iodine solutions in potassium iodide showed after removal of all traces of dissolved oxygen no electromotive force on illumination of one half of %he cell. It therefore seems probable that the production of excited iodine molecules by the photochemical action is small compareJ with the rate a t which the reaction 2~ + I p- 21' occurs a t the electrode.(c) The Application of the Einstein Law of Photoepicalenee. E'or the determination of the amount of radiation absorbed and the concomitant chemical action produced by the radiation the following apparatus was employed (Fig. 1) : A. Mercury vapour lamp. B. Screen. C. Cooling trough. D. Blackened metal plate carrying gelatin light filter E. 3'. Cooling trough containing glass-stoppered reaction vessel G. H. Moll thermopile. I. compensating leads and galvanometer. The Moll thermopile H was first calibrated by mmns of a Leslie cube precautions being taken to ensure " black body " radiation as nearly ideal as possible in the circumstances by screening the system of Leslie cube and thermopile with non-conducting material faced with reflecting surfaces in which accurate openings were cut.The radiant energy received by the thermopile from the Leslie cube was calculated by the formula of Lummer and Pringsheim (Ann. PhysiE 1897 63 395) and found to be 1-23 x lo5 ergs per sec. I THE FERROUS FERRIC IODINE IODIDE EQUILIBRIUM. 263 The readings of the galvanometer connected t o the thermopile during the radiation fluctuated slightly between 35.4 and 36.4 cm., yielding a mean value of 35-95 cm. Hence the energy per cm. deflection is 3.423 x lo3 ergs per second. Allowing for the fact that lamp-black surfaces emit and absorb but 00% of the true black-body radiation the thermopile constant is 2-77 x 103. The volume of the solution in G covered by the funnel of the thermopile was found both by measurement and by calculation to he 31 C.C.The mercury vapour lamp was started and allowed to attain a steady state the current being checked by means of an ammeter connected in the circuit. The thermopile suitably protected from draughts was allowed to come into equilibrium with its surroundings, precautions being taken to keep the room temperature as steady as possible. The bottle was first filled with water and a number of readings were taken of the deflection caused on the galvanometer scale when the screen B was raised. The bottle was then filled up to the mark with the dark equilibrium solution and a number of readings taken as before. Since even with the utmost precaution mercury vapour lamps are apt to vary in intensity of illumination a number of independent experiments were performed of which the two appended represent the extremes of variation.The curve of the rate of disappearance of iodine under the same conditions was also obtained by means of a large number of experiments which agreed fairly closely. Water. Deflection on galvanometer scale in cm. Initial. Final. in cm. / \ TotaI deflection 7.3 27.8 7.0 27.5 7.0 27.2 5.4 27.8 5.6 28.2 5.6 28.2 (I) 7.2 27.5 (11) Dark equilibrium mixture. 6.9 15.1 (I) 7.0 15.0 6.9 14-8 7.0 15.3 5.4 13.7 (I1) 5.6 14-2 5.4 14.0 Energy absorbed by solution in (I) = Energy absorbed by solution in (11) = Mean = 20.2 22.6 8.3 12.3 x 2.77 x los ergs per second.14.03 x 2.77 x 10s ergs per second. 13.2 x 2.77 x 108 ergs per second 264 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON The rate of disappearance of iodine under the same conditions was next investigated. At various times 5.15 C.C. were withdrawn run into 100 C.C. of cold water and titrated with approx. N/lOO-thiosulphate the following data being obtained from which the velocity ccefficient [k = l/t.log a/(a - x)] has been calculated a = 7-5 x 0.0012696 g. of 12. T N/lOO-Thio. (mins.). (c.c.). t . X. k. 0 7.50 15 0.0006345 0.00463 15 7.14 30 0.001 142 0.00430 52 6.20 60 0.002030 0*00404 120 5.40 90 0.003173 0.00455 192 4-97 422 4.91 Mean = 0.00438 The reaction appears to follow the unimolecular law as indicated by the values of Ic hence the initial rate of disappearance of iodine may be calculat8ed.dx/dt = kc = 0.00438 x 0.000005 x 7.5 x 6.06 x molecules I2 per minute for 5-15 C.C. = 0.996 x 1016 molecules I2 per see. for 31 C.C. We can now proceed t o calculate the number of quanta absorbed Wave-length = 5790-66 A. Magnitude of quantum = h v = 6.55 x per see. by the solution. Frequency v = 517G x 1014. x 5.176 x 1014 = 3.39 x erg. Energy absorbed by solution = 13.2 x 2-77 x 103 ergs per see. Hence number of quanta absorbed by solution = 1.078 x 1016 per sec. - _____ -There are thus 0.996 x 1016 molecules of iodine being decomposed per second by 1.078 x 1016 quanta. The reaction thus obeys the Einstein law of photochemical equivalence under the condit,ions of the experiment. (d) The Temperature Coefiicient of the Reactions.The influence of temperature on the dark equilibrium system 2Fe" + I r j 2Fe"' + 21' is negligibly small but the rate a t which equilibrium is attained is very dependent on the temperature; this rate was investigated at 25" and 33-25" and the equilibrium point was reached in each case though more rapidly in the warmer solutions. By estimation of the amount of iodine liberated after mixing the solutions A and THE YERROlTS FERRIC IODISE IODIDE EQUILIBRIURI. 265 a t the two temperatures the temperature coefficient was calculated from the velocity coefficients to be for a rise in temperature of lo", k35*/k250 = 2.713. The iiifucnce of temperature on the rate of attainment of the light equilibrium was investigated by a potentio-metric method.A photovoltaic cell coiisisting of bright platinum electrocks inserted in a constricted U-tube containing the dark equilibrium mixture was eniploycd. On illumination of one limb of the U-tube with i~ioiioc~lromat'ic yellow radiation at 25" the equilibrium concentration in the exposetl limb is altered arid the rate of alteration can 1;e dctcrniined froiii thc electromotive force of the ccll. On cxtting off the radiation. the return of the photo-chciuical equilibriuni niihture to tlie dark equilibrium can readily he followed from the electromotive force of the cell. As typical of the readings obtaiticrt 1::- this method the follon-ing values may be cited. Time iii I n j 11s. 0 20 40 GO 90 113 9 ,..- 43 liilli-volt,s.10.30 10.30 10.20 !b70 8.85 6.45 6.25 5.90 Time i n rnins. 0 10 20 3 0 40 i) Teniperut,nre 35". Jlilli- lime in volts. inins. 0.0 50 1.40 60 2.80 70 4.85 80 6.40 90 7.63 100 Nilli-volts. S.60 9.25 9.65 10.00 10.17 10-17 From tlie velocity coefficiciits of the rate of attainment of photo-cheinictL1 equilibriuni the t emperature coefficient k,,./k,,. (light) was fouiid to be 1-17. It is probable that the velocity of the true piic;tocheiiiicaI reaction is not iiiflueiiced by temperature and that the value 01 1.1T obtai!ied is due to the effect of the increase i n velocity of tlicl dark reaction 11 ith thc tenipcrature huperiinposed o i l the vcblocitjr of Piic light roac'tio!i. I t has already bwil iiotctl that altliough the liberation of iodine from the reactiirg system co~i~ineiicw rilpidly J e i the reaction comes 1 ) u C slon-1) to eqi~ilihriuni.At the ciid of 24 l~oim thc average airlount of iodine 1ik)crdtctl as tfcieriniiied 1);)~ titration with thio-sulphatc v-as fouiid cqcivalc~nt to 7-50 C.C. of S/lOO-thiosulphate €or 5.15 C.C. of the equilibrium mixture. Although the reaction is apparently completed n e ~ ertheless a ~ O T V reaction is still pro-ccecliig towards a true ecluilibriurn. This ec1ui;ibriurn was estab-l i s l i c d at the eiicl of 3 i~ic~ntiis and found cqual to 8-37 c.c. of S/lOCI-tliiosiili~~i~ttc. Sincc the equilibrium attained is the result of the attaininelit of cqual velocity for two reactions 2Fe *+ I 4 K 266 RIDEAL AND WILLIAMS THE ACTION OF LIGHT ON 2Fe"'+ 21' and 2E"e"'+ 21'- 2Fe"+ I, it is clear that if the active masses of equilibrium concentrations of the reactants could be raised in equal proportion the reaction velocities of each reaction would proceed more rapidly and equilibrium would be more rapidly attained.The active masses or thermodynamic concentrations of the active ions whether simple as indicated above or complex as imagined by Sasaki (2. angew. Chem. 1024,137,181) can readily be raised by the addition of a neutral salt such as potassium chloride (Bronsted 2. physikal. Chem. 1922 103 307). I n the following curves (Fig. 2) the rate of attainment of equilibrium in thc dark for three mixtures to which varying amoiints of potassinm chloricte have been added are given.Fra. 2. Time minutes. It is clear from the curves that the augmentation in thermo-dynamic concentration of the reacting ions by the addition of the potassium chloride has as anticipated augmented the rate a t which true equilibrium is attained. That the separate reaction velocities are in reality augmented by the addition of potassium chloride was confirmed by repeating the modified Harcoixrt and Esson experiment as already described in presence of 1437-potassium chloride and in the ordinary solution without the salt addition. The marked increase in the velocity of the forward reaction on the addition of potassium chloride is evident from the following data : Time in minutes for appearance of starch-iodide colour. Thioadded(c.c.) 1 2 3 4 5 G 7 8 9 No KCl added 0.5 0.8 1.5 2.8 4-7 8.15 13.7 25-0 In 1.6N-KCl ...0.4 0.6 1.0 1.6 2-4 3.6 5.6 8.9 16. THE FERROUS FERRTC IODINE IODIDE EQUILIBRITTM. 267 At equilibrium in the dark the rates of the forward photosensitive reactions acre given in absence and presence of potassium chloride by the equations dzldt = Ic .f(I,)f (Fe**)2 - a and dx'ldt = II:.f'(I,)f'(Fe")2 = b where f andf' are the activity coefficients in absence and presence of the neutral salt. On illumination of the solutions tlhe respective velocities become dx/dtfil. = II .f(Iz)f(Fe")2 + ](I,) = a + x, dz'ldtill. = II .f'(12)f(Fe")2 + I(&) = b + X, where I is the intensity of the photoactive radiation. wiOhout and in presence of salt will evidently be, The ratio of the velocities of the two dark and light reactions Without KCl present Vill./Vdark = (a + x)/a = 1 + z/a.With ICC1 present Viu,/Vdark = (b + x)/b = 1 + xjb. Thus the greater the absolute velocity of the forward reaction a t equilibrium the smaller will be the apparent effect of the light on the equilibrium. We should thus anticipate that the shift in the equilibrium obtained with the solution containing potassium chloride on exposure to light will be far less than the shift in the equilibrium of the solutlion in the absence of potassium chloride on exposure to identical radiation since the addition of salt has as has been indicated by the previous experiments raised the value off' considerably above f or b > a. These expectations were fully realised by determining the rate of change of the dark equilibrium mixture on illumination both by the potentiometric method and by titration.The following data were obtained for a dark equilibrium mixture containing 1 -5N-potassium chloride exposed to mono-chromatic radiation a t 25". Time (mins.). 0 1 s 10 26 30 Milli- N/lOO-Thio. Time Milli- N/lOO-Thio. volts. (C.C.). (mins.). volts. (c.c.). 0 7.86 41 2.40 -0.1 - 52 2.60 I 0.8 - 60 2.65 7.30 1-05 - 70 2.70 -1.90 - 170 2.70 7.30 2.15 7.75 The final value of 2.70 mv. as compared with a value of 10.3 mv. for the solution in the absence of potassium chloride (see Table, p. 265) and a shift in the equilibrium concentration of iodine equivalent to only 0.56 C.C. of N/lOO-thiosulphate solution as com-pared with the value 2.50 C.C.obtained without the potassium chloride indicated clearly the effect of augmenting the velocity of the two reactions proceeding in either direction at equilibrium by elevation of the thermodynamic concentrations of the reactants. K" 268 THE FERROUS FERRIC IODINE IODIDE EQUILIBRITJM. The value of the equilibrium constant for the reaction K = (Fe")(12)$/(Fe"')(I') has been determined by Maitland (2. Elektrochem. 1906 112 263) and by Bronsted and Pedersen (2. physikal. Chem. 1922,103 307). Maitland obtained the value K = lO2'005 whilst the data of Bronsted and Pedersen yielded a value of K 2 y = 212.1 ~t~ilising a value of L = (I')(12)/(I'J = 0.0061. = 0.00611 for the equilibrium constant The data obtained in the above experiments permit us to calculate the value of K .The original concentration of ferric ions = 0.02 gm.-atom per litre. The titre of the dark equilibrium solution is 8.37 C.C. of N/100-Y Y Y Y Y 9 of iodide ions = 0.045 gm.-atom per litre. thiosulphate for 5.15 C.C. Hence a t equilibrium we obtain : (Fe"') = (2.0 - 8-37/5-15)10-2 gm.-atom per litre. (Fee*) = 8.37/5.15.10-2 gm.-atom per litre. (1') = 8.37/5.15.10-2 gm.-atom per litre. we obtain Also if the original iodide concentration be x and the final .z - a, I,' = 3a I = x - 2a, = 2.875 x I' = x - a and (x - 2a)(x - a)/% = 0.00611 . . . . . (1) * where x = (4.5 - 8.37/5.15)10-2 gm.-atom per litre gm.-atom per litre. Inserting this value of x in (I) and solving for a we obtain a = 0.58 x gm.-atom per litre. Hence (1') = (2.575 - 0.58j x 10-2 = 2.30 x 10-2 gm.-atom per litre.(1.625 x 10-2)(1*625 x 10-2)a ~ 23.6, (0.380 x 10-2)(2-30 x Hence K25" = value in close agreement with that of Bronsted and Pedersen. The slight discrepancy between 23.6 and 21.1 for the values of K in the two investigations is probably accounted for by the fact that Bronsted and Pedersen utilised only chlorides and iodides of iron and potassium whilst in the present case ammonium sulphate was present in addition. Xummary. The reaction 2Fe"'+ I ~2 2Fe"+ 21' is photosensitlive to both ultra-violet and visible light. The region of visible photoactive radiation is within the range 5500-6500A. with an apparen SHORT THE CONDENS-4TION OF PHENYLETHPLAMINE ETC. 269 maximum a t 58008. The tri-iodide ion is the photoactive constituent and the energy of excitation corresponding to a wave-length 5800 A. is equivalent to 2.14 volts a value almost identical with the resonance potential of the iodine molecule. It is found that one quantum of absorbed radiant energy causes 1 mol. of iodine to react; the mechanism of the reaction can be expressed in the 1-for111 2Fe1 + I,' -/- hv 1 2FeT3 + 1'. The dark eyuilil:)r.ium coils1 ant of the reaction is K = 23-6 = (Fe"')(T2}~/(Fe"')(I') a t 23". The temperature coefficient of the liberation of iodine in the dark is k,; ,ikZ5 - 2.723 whilst that of the photochemical reaction is ,'Idz5 = 1.17. The addition of potassium chloride raises the theimodynaiuic concentrations of all the reactants and although the equilibrium point is unchanged the rate of attainment is very considerably increased. Proof is given that equilibrium is the result of attainment of equal velocities of the forward and the back reaction since the effect of radiation of constant intensity on the equilibrium attained is less when the thermodynamic concentrat ions of the reactants (and thus the reaction velocities of the two reactions} are raised by the addition of potassium chloride. Our thanks are due to the Department of Scientific and Industrial Research for a grant out of which a part of the cost of the apparatus was provided. IA A u OR -i TO RT o 17 P HITS I ( .A 1 C H F JI r s-rR\-, G'AMI3RTI)C~E. [ R P c P ~ u P ~ ' Ncrc~t-r~~bcr 1&h 1024.

ISSN:0368-1645    

DOI:10.1039/CT9252700258

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

SHORT THE CONDENS-4TION OF PHENYLETHPLAMINE ETC. 269 XLIV.-7'1w Condensation of PhenylethylaminP zviih' s-Dichlorodimethyl Ether. By WALLACE FRANK SHORT. BY the action of p-phenylethylarnine on an excess of methylal in presence of concentrated hydrochloric acid a t loo" Pictet and Spengler (Ber. 191 1 44 2030) obtained tetrahydroisoquinoline in 3 6 % yield. By a similar method Pictet and Gams (Ber. 1911, 44 2629) prepared hydronorhydrastinine from homopiperonyl-amine but Decker and Beclier (Ber. 1912 45 3404) who repeated the experiments obtained a base of the type NHR*CH,*NHR. Phenylethylamine itself yielded p -phenylethyldirnethylamine when condensed with an excess of formalin a t 130-140". The sam 270 SHORT THE CONDENSATION OF PHENYLETHYLAMINE ETC. authors have shown (Annalen 1913 395 342) that homopiperonyl-amine and other derivatives of p-phenylethylamine react readily at room temperature with an equimolecular quantity of an aldehyde to form the alkylidene derivative which is converted into a tetra-hydroisoquinoline derivative by a suitable catalyst,.Rosenmund (Ber. Deut. pharm. Ges. 1919 29 200) condensed homopiperonylamine (2 mols.) with s-dichlorodimethyl ether (1 mol.) in ethereal solution and obtained homopiperonylaminomethanol as a very unstable oil which was converted almost quantitatively into hydronorhydrastinine by heating a t 100" with 10% hydrochloric acid. In view of the above results it appeared to be of interest to determine whether a good yield of tetrahydroisoquinoline could be obtained by the condensation of p-phenylethylamine with the so-called '' chloromethyl alcohol." The products of the reaction were tetrahydroisoquinoline (yield 59 %) di( p-~henyZethyZamino)-methane and bases of unknown constitution.E X P E R I M E N T A L. p-Phenylethylamine was obtained in 30% yield (Wohl and Berthold Ber. 1910 43 2183). s-Dichlorodimethyl ether was prepared by Stephen Short and Gladding's method (J. 1920, 117 513). A mixture of 31.5 g. (2 mols.) of p-phenylethylamine hydro-chloride 14.4 g. of s-dichlorodimethyl ether (12 mols. equivalent to 2& mols. of chloromethyl alcohol) 0.5 g. of anhydrous zinc chloride and 100 C.C. of dry ether was cooled to room temperature, stirred for 8 hour and heated for 4 hours on the water-bath. Dis-tillation in a vacuum left a brown syrup which was dissolved in water the solution made alkaline and extracted with ether.The oily residue from the ethereal extract on solution in dilute hydro-chloric acid and treatment with sodium nitrite gave a yellow oil, which on reduction with tin and concentrated hydrochloric acid, deposited p-phenylethyl chloride. The aqueous layer was extracted with ether made alkaline with caustic soda and again extracted with ether. The second extract was distilled up to 235" and the distillate converted into a picrate which crystallised thrice from alcohol melted a t 196" ; the base generated therefrom by additlion of ammonia had b. p. 234"/763 mm. (yield 15.7 g . ) (Found C = 81.10; H = 8-39. Calc. for C,H,,N C = 81-15; H = 8.33%). These constants are in good agreement with those given in the literature for tetrahydroisoquinoline and show that the product cannot be Becker and Decker's p-phenylethyldimethylamine.The residue in the distilling flask was dissolved in hydrochloric acid boiled with animal charcoal and recrystallised several time BURGESS AND LOWRY NEW HALOGEN DERIVATIVES ETC. 271 froni water. The colourless crystals so obtained did not melt at 300". The base liberated with caustic soda consisted of white needles of di( p-phenyZethyEamino)methane m. p. 153" and absorbed carbon dioxide from the air (Found C = 80.16; H = 8.73; N = 10.S2. C,,€I,,N requires C = 80.25; H = 8.72; N = 1142%). About 107; of the p-phenylethylamine is converted into this secondary diaminc. The diacetyl derivative forms silky needles m.p. 191". My thanks are due to Mr. F. H. V. Fielder B.Sc. for assistance UNIVERSITY COLLEGE, in preparing the p-phenylethylamine for this investigation. AUCXLAND NEW ZEALAND. [Received October 3let 1924. SHORT THE CONDENS-4TION OF PHENYLETHPLAMINE ETC. 269 XLIV.-7'1w Condensation of PhenylethylaminP zviih' s-Dichlorodimethyl Ether. By WALLACE FRANK SHORT. BY the action of p-phenylethylarnine on an excess of methylal in presence of concentrated hydrochloric acid a t loo" Pictet and Spengler (Ber. 191 1 44 2030) obtained tetrahydroisoquinoline in 3 6 % yield. By a similar method Pictet and Gams (Ber. 1911, 44 2629) prepared hydronorhydrastinine from homopiperonyl-amine but Decker and Beclier (Ber. 1912 45 3404) who repeated the experiments obtained a base of the type NHR*CH,*NHR.Phenylethylamine itself yielded p -phenylethyldirnethylamine when condensed with an excess of formalin a t 130-140". The sam 270 SHORT THE CONDENSATION OF PHENYLETHYLAMINE ETC. authors have shown (Annalen 1913 395 342) that homopiperonyl-amine and other derivatives of p-phenylethylamine react readily at room temperature with an equimolecular quantity of an aldehyde to form the alkylidene derivative which is converted into a tetra-hydroisoquinoline derivative by a suitable catalyst,. Rosenmund (Ber. Deut. pharm. Ges. 1919 29 200) condensed homopiperonylamine (2 mols.) with s-dichlorodimethyl ether (1 mol.) in ethereal solution and obtained homopiperonylaminomethanol as a very unstable oil which was converted almost quantitatively into hydronorhydrastinine by heating a t 100" with 10% hydrochloric acid.In view of the above results it appeared to be of interest to determine whether a good yield of tetrahydroisoquinoline could be obtained by the condensation of p-phenylethylamine with the so-called '' chloromethyl alcohol." The products of the reaction were tetrahydroisoquinoline (yield 59 %) di( p-~henyZethyZamino)-methane and bases of unknown constitution. E X P E R I M E N T A L. p-Phenylethylamine was obtained in 30% yield (Wohl and Berthold Ber. 1910 43 2183). s-Dichlorodimethyl ether was prepared by Stephen Short and Gladding's method (J. 1920, 117 513). A mixture of 31.5 g. (2 mols.) of p-phenylethylamine hydro-chloride 14.4 g. of s-dichlorodimethyl ether (12 mols.equivalent to 2& mols. of chloromethyl alcohol) 0.5 g. of anhydrous zinc chloride and 100 C.C. of dry ether was cooled to room temperature, stirred for 8 hour and heated for 4 hours on the water-bath. Dis-tillation in a vacuum left a brown syrup which was dissolved in water the solution made alkaline and extracted with ether. The oily residue from the ethereal extract on solution in dilute hydro-chloric acid and treatment with sodium nitrite gave a yellow oil, which on reduction with tin and concentrated hydrochloric acid, deposited p-phenylethyl chloride. The aqueous layer was extracted with ether made alkaline with caustic soda and again extracted with ether. The second extract was distilled up to 235" and the distillate converted into a picrate which crystallised thrice from alcohol melted a t 196" ; the base generated therefrom by additlion of ammonia had b.p. 234"/763 mm. (yield 15.7 g . ) (Found C = 81.10; H = 8-39. Calc. for C,H,,N C = 81-15; H = 8.33%). These constants are in good agreement with those given in the literature for tetrahydroisoquinoline and show that the product cannot be Becker and Decker's p-phenylethyldimethylamine. The residue in the distilling flask was dissolved in hydrochloric acid boiled with animal charcoal and recrystallised several time BURGESS AND LOWRY NEW HALOGEN DERIVATIVES ETC. 271 froni water. The colourless crystals so obtained did not melt at 300". The base liberated with caustic soda consisted of white needles of di( p-phenyZethyEamino)methane m. p. 153" and absorbed carbon dioxide from the air (Found C = 80.16; H = 8.73; N = 10.S2. C,,€I,,N requires C = 80.25; H = 8.72; N = 1142%). About 107; of the p-phenylethylamine is converted into this secondary diaminc. The diacetyl derivative forms silky needles m. p. 191". My thanks are due to Mr. F. H. V. Fielder B.Sc. for assistance UNIVERSITY COLLEGE, in preparing the p-phenylethylamine for this investigation. AUCXLAND NEW ZEALAND. [Received October 3let 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700269

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

BURGESS AND LOWRY NEW HALOGEN DERIVATIVES ETC. 271 XLV.-New Halogen Derivatives of Camphor. Part V I . P-Bromo~mphor-a-sulphonic Acid. Part VII. The Constitution of the Reychler Series of Camphor-sulphonic Acids. Experiments on Chbrosulph-oxides. By HENRY BURGESS and THOMAS MARTIN LOWRY. Part VI.-p-Bromocamphor-a-sulphonic Acid. THE present paper describes a new series of sulphonic derivatives of camphor in which the sulphonic group occupies the a-position. This result is of interest since sulphonation has hitherto always been found to result in an attack upon a methyl group whilst the very reactive a-carbon atom has escaped. Thus even the gentle method of sulphonation used by Reychler gives p-derivatives and not the a-sulphonic acid which he thought he had prepared; and it is only after blocking the p-position with a halogen that we have been able to induce the sulphonic radical to enter the a-position.Armstrong and Lowry (J. 1902 81 1445) had already attempted to sulphonate p-bromocamphor but had obtained only a negative result. Our experiments have shown that although most of the p-bromocamphor can be recovered unchanged about 15 to 20% of it is sulphonated a t each operation. The product was at fist thought to be a p-bromocamphor-p-sulphonic acid where p repre-sents the position of the sulphonic group in Reychler’s acid but doubts arose when it was found that the sulphonamide did not yield an anhydramide like a-bromocamphor-p-sulphonamide but gave an acetyl derivative like a-bromocamphor-a-sulphonamide. Still more striking was the fact that the sulphonyl bromide whe 272 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES decomposed by heat did not give a new pp-dibromocamphor but 5t mixture of Kachler and Spitzer’s aP-dibromocamphor with our new a’p-dibromocamphor (J.1923,123,1867). This suggested that the sulphonic group occupied the a-position; but as the whole research was based upon a suspicion that the pyrogenic decom-position of a p-sulphonyl bromide might give a p-bromo-compound of different orientation we did not regard it as safe t o accept the above observation as a final proof of the structure of the acid. Confirmation was however obtained when the sulphonamide on bromination again gave rise to the same aP-dibromocamphor by a remarkable action in which the halogen displaces a sulphonamide group instead of eliminating one of the reactive a-hydrogen atoms.This result was very difficult to explain unless the sulphonic group were already in the a-position. Moreover this broinination was free from the suspicions which attached t o the formation of Np-di-bromocamphor by the pyrogenic decomposition of the sulphonyl bromide. Final proof that the sulphonic group had entered the a-position leaving the camphor nucleus intact except for the presence of the p-bromine atom was obtained when the spon-taneous oxidation of a dibromosulphonamide derived from our acid gave rise t o the hitherto unknown p-bromocarnphorquinone, and thence by a direct further oxidation to p-bromocamphoric anhydride (not the free acid although the oxidation took place in aqueous solution).The whole series of actions may be set out as follows : p-Bromocamphor-a-sulphonic acid. p-Bromocamphor-a-sulphonamide. 15-Bromocamphor-a-sulphonyl bromide. Acetyl derivative. a’b-Dibromocamphor-a-sulphonamide. .1 c8H,3Br<xE PI. 1 0 t-p-Bromocamphoric anhydride. p-Bromocamphorquinone O F CAMPHOR. PL2RTS 1'1 ANT \TI. 273 In tliesc forinulx the acetyl derivative has been assumed to be enolic as in the case of the .x-isoniericle the solubility of which (unlike that of the amide from which it is derived) is not increased by the addition of alkali (Low? and Magson J. 1906 89 1044), so that the acetyl derii-atire appears not to contain an cc-hydrogen atom. I n tlic prc-ent case the fact that the acetyl group was lost on huminat icin si:ggestetl very strongly that we were again dealing with an cnolic.iicctate arid not the -SO,*NHAc compoiind. 'I'his invebt igation C C J I ~ ~ ~ ~ I I ~ S t lie lriew of Lipp and Lausberg ( A )inale?L 1024 436 274) that P-hrornocawiphor mid the Reychlet. .~erica of Crctrii~~~"".'"(~J'hoiil'c acids hare the sattie o?-ie?ztatioiL since the blocking of the $-pu~itioii I I J ? a halcgen coiiipels the sulphonic group to enter :i I I P ~ \ ~ imsitioii in the molecule. The question whether thc [d-substituenti are attarlied to a carbon atom in the ring or to a inethyl grcbiij) i5 (liwIqscd in Part IT1 below. E X P E R I 53 I3 N T A L. S II I y lz o 1 i a t io I L of fJ - Ur o i n oca n2 phot. . - p - B r o m o c a in pho r ( 5 0 g .) was added slowly to a mixturc of acetic anhydride (80 c.c.) and con-centrated sulphuric acid (25 c.c.) when the mixture became brown and most of the fJ-broinocamphor dissolved. After standing for a week a t 30-40" itl was heated for 2 hours and poured on to crushed ice and the precipitated p-bromocamphor (41 g.) washed with water. Further heating or varying the quantities of acetic. anhydride and sulphuric acid gave a smaller yield of sulphonate and a much larger quantity of brown charred material. The solution n-as boiled till free from acetic acid neutralised with a crc~ini of c;?lcium czrlionate filtered niicl ccncentrated. The sliidge of chalk z:cd calcium sulphate (which separates only slowly in the presence of the calcium sulphonste) was washed three times with boiling u-ater to remove all the sulphonate.After recrystallising three times from methylated spirit the calciuxu sulphonate ivas obtained in colourless rhombic plates. The mother-liquors Irere decoiorised by bone charcoal. The total yield was 12 g. (about 90';;)) after allowing for the recovery of iiiost of the bromocainphor. 0.1515 gave 0.1800 of CO, 0.0660 of H,O anti 0.0273 of CaXO,. 0.1773 lost 0.0172 of H,O and gave (1.0924 of R g h C == 3241 H = 4.87 Ca = 5.30 Br = 22-1 S H,O = 9.i0. (C,,H,,e)Br*S0,),Ca,4H2(~ requires C = 32-78, H = 4-95 Cia == 5 4 7 IZr = 21.83 H,O = 9.54%. Calcium p-broinocainphor- a-szrlphotzate is very soluble in hot water but crystallises readily from hot methylated spirit,. It does not melt below 230". It has [ s ~ ] ~ ~ ~ ~ = + 50° [a]5461 - + 59", = 4 116.5" in water ( 2 g.per 100 c.c.) 274 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES Potassium /3-bromocamphor-cc-sulphonate prepared by addition of potassium oxalate (calc. amt.) to a solution of the calcium salt, filtration and evaporation crystallised from hot methyl alcohol in fine colourless needles. 0.2045 gave 0.2565 of CO and 0.0730 of H,O. 0.2152 lost no water a t 150-160" in a vacuum C = 34.22 I€ = 4-00 C,,H,,OBr~SO,K requires C = 34.37 H = 4-040,/,. P-Bromocamphor- a-sulphonyl Chloride (Formula as II).-A mix-ture of powdered phosphorus pentacliloride (5.4 g.) and the dry, powdered potassium salt (7-5 9.) was shaken and warmed in a dry flask on the water-bath until liquid. After 15 minutes it was shaken vigorously with powdered ice.The light brown solid was filtered and washed with water and a little dilute potassium carbonate solution ; it crystallised from ether in large compact crystals (Fig. l) which softened a t 93" and melted a t 97". 0.2393 FIQ.' 1. FIG. 2. gave 0.0940 of AgCl C1= 9.7. C,,H,,OBr*SO,Cl requires C1= 10.76%. p-Bromocamphor-a-sulphonyl chloride is comparatively stable when pure but loses chlorine quickly if impure and especially in presence of a little hydrochloric acid. It is very soluble in benzene or ether less soluble in cold alcohol and sparingly soluble in light petroleum. The crystallographic properties are as follows (two crystals were measured) : System Orthorhombic. Axial Ratios a b c = 0.2994 1 0.3769. Habit Both crystals were flattened parallel to C(OOl) with m(110) fairly large.The crystals were not quite transparent and did not give good reflections. Pmms present C(OOl) b(010) m(110) and n(Ol1). One face only of y(021) OF CAMPHOR. PARTS VI AND VII. 275 No. of Angles measure- Mean observed. ments. Limits. observation. Calculation. bnz 010 110 8 69" 52'-GS0 59' 69" 21' I cn 001:011 8 17 12-16 30 16 40 cy 001 :021 1 30 25;-31 35$ 31 04 30" 55' tnn 1 1 O O l l 4 84 28 -84 2 s.2 11 84 12 -Optical Characters Since thc crysials could not be immersed in liquids the optical data are scanty and liable to be inaccurate. The optic axial plane is parallel to b(010) with the acute bisectrix perpendicular to C(OOl) and the double refraction positive. The refractive indices determined by the minimum deviation method are very approximately a = 1.55 p = 1.56 y -1 1.58.~-Bromocamphor-a-szilphonamide (Formula ITI).-A mixture of the potassium sulphonate (7.0 9.) and phosphorus pentachloride (4.2 g.) was covered wi5h dry chloroform (50 c.c.) and left over-night. The chloroform was washed twice with ice-cold water, dried for an hour over calcium chloride filtered and excess of dry ammonia was passed into it when much heat was developed. After 12 hours the chloroform was distilled off and the residue was washed with water and crystallised from ether (yield 65%). 0.2045 gave 0.2895 of CO and 0.0955 of H,O. 0-2268 gave 0.1382 of AgBr C = 38.62 H = 5.23 Br = 25.93. C,oH,,O,NBrS requires C = 38.71 H = 5.20 Br = 25.77%. p-Bromocamphor- a-sulphonamide is very soluble in chloroform, alcohol ether or hot benzene less soluble in cold benzene and sparingly soluble in light petroleum or water.It melts a t 100-102" with the evolution of small bubbles of gas and has + 3 9 ~ 3 " ~ [a]5461 + 46.1" + 99" in alcohol (5.62 g. per 100 c.c.). The crystals which separate from an ethereal solution are tough and fibrous when crushed they are a t first quite transparent but after about 2 hours the surface becomes opaque and then the whole of the crystal perhaps as a result of polymorphic change. When this change is complete the crystal is easily crushed the fibrous structure having been lost completely. Attempts to Prepare an Anhydramide.-Lowry's two methods (J. 1902 81 1441) were employed. (a) A mixture of the sulphonamide (0.5 g.) with 45 C.C.of con-centrated hydrochloric acid was kept for a fortnight the clear solution diluted with water (2 vols.) and neutralised with potassium carbonate. ( b ) The sulphonamide (2.5 g.) was heated with acetic anhydride (10 c.c.) on the water-bath for 4 hours,* crystals separating. After * If the mixture is boiled instead of being heated on a water-bath con-Chloroform extracted the sulphonamide unchanged. siderable charring occurs 276 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES cooling these were filtered off and a further small quantity was obtained by diluting the cold mother-liquor with water (yield 80:/,). Although this product resembled a-bromocamphor-p-sul-phonanhydramide in appearance and in its sparing solubility in all solvents it was an acetyl derivative for 0.2060 gave 0.3140 of CO and 0.0955 of H,O and 0.1900 gave 0.1033 of AgRr and 0.1280 of BaSO C = 41-55 H = 5-19 Br = 22.89 S = 9-25.C,,H,,O,NBrX requires C = 40.90 H = 5.15 Rr = 22.69 S = Acetyl-p-bromocana3-7hor-v.-.~ulll,honamide (IV) prepared as de-scribed above is slightly soluble in hot acetone and in hot acetic anhydride but is sparingly soluble in the cold solvents and in all the other common organic solvents. It crystallises from acetone in small compact crystals m. 13. 217" (rapid decomp.). It has [a]5,yo - 3 7 ~ 5 " ~ [CY]~,~~ - 42" in acetone (0.613 g. per 100 c.c.). 9.10 74. The crystallographic properties are as follows : System Orthorhombic. Axial Ratios a 3 c = 1.804 1 1-206. Forms present .- a(100) m(110) 1(210) q(101) d(201) ~ ( 0 1 1 ) .Habit .- The crystals were very small (Fig. 2) the longest dimen-The faces were frequently curved and not The face a(100) was only The prism faces were always very sion being about l". well suited to accurate measurement. observed on two crystals. small with the domes predominating to give a stumpy outline. No. of Angles measure -observed. ments. Limits. mm' = 110 i i o 5 57'29'- 59'51' 11' = 210:210 5 84 22- 86 16 ' = 011 :g11 6 99 58-102 24 ;z = 101 l o 1 G 67 54- 70 23 dd' = 201 201 G 73 0- 75 19 mq = 110 101 G 71 22- 73 49 mp = 110 :011 5 46 53- 48 31 Id = 210 201 10 53 61- 56 19 Ep = 210:Oll 10 56 34- 59 25 zq = 210 101 4 65 13- 65 41 md = 110 201 2 66 41- 68 44 Average.6s" 43' 85 32 101 0 68 50 74 9 73 13 47 52 54 18 57 43 65 26 67 24 Calculated. 58" 0' 84 6 100 40 67 32 73 34 74 22 47 41 53 30 58 58 65 37 67 0 CEeavuge None observed. Specific gracity .- 1.562 determined by floating in Thoulet's solution. Decomposition of p- Bromocamphor- a-sulphonyl Bromide (Formnla II).-The method of preparation was similar to that used in making the sulphonyl chloride. As the oil obtained on evaporating off the chloroform from the washed and dried solution did not crystallise in a desiccator in 2 days it was dissolved in dry xylene and refluxed for about + hour until the evolution of sulphur dioxide whic OB CAMPHOR. PARTS VI AND W. 277 was a t first very rapid had practically ceased. The liquid charred rather badly during the heating.After the xylene had been dis-tilled off in steam a colourless oil came over and slowly solidified. This was filtered off and melted a t 46-85". When crystallised from dilute alcohol it gave three successive crops of crystals. The first fraction which melted almost constantly a t 92-94' on three successive crystallisations was a t once converted into almost pure a@-dibromocamphor on crystallking in presence of a trace of piper-idine and therefore was a mixture of .@- and a'p-dibromocamphors (compare J. 1923 123 1872). The second fraction after one further crystallisation was identified as cr'p-dibromocamphor (m. p. 133-135" not lowered by mixing; [cr]5461 - 77" instead of - 85" in acetone 1 g. per 100 c.c.). The third fraction was identi-fied after one further crystallisation as crp-dibromocamphor (m.p. 113-114" not lowered by mixing with a$-dibromocamphor ; [a]5461 125" instead of 127" in acetone 3.92 g. per 100 c.c.). The above results proved quite conclusively that the sulphonyl bromide had decomposed to a mixture of M @ - and a'@-dibromocamphors. Broinination of p-Bromocamphor-a-su1phonamide.-Bromine (2.7 g.) was added to a solution of the sulphonamide (2.0 8.) in glacial acetic (50 c.c.) and the mixture refluxed for 4 hours becoming pale yellow. From the aqueous solution neutralised with sodium carbonate ether extracted an oil (about 2 c.c.) co-ntaining some lachrymatory substance probably bromoacetic acid from which was separated about 0.3 g. of ctp-dibrcmocamphor m.p. 112-114' (alone or mixed with this substance). a'@-Dibromocamphor-cr-sulphozamide (Formula V).-Bromine (2.5 g.) was added to the acetyl derivative of p-bromocamphor-cr-sul-phonamide (0.8 g.) in glacial acetic acid (20 c.c.) and the mixture refluxed for 5 hours the acetyl derivative dissolving completely, and the bromine disappearing. After cooling the acetic acid was neutralised with ammonia tho mixture being cooled meanwhile ; the white precipitate crystallised from benzene-ligroin in beautiful, colourless prisms m. p. 145" softening at 143" (yield 0.7 g. or 80%). 0.2015 gave 0.2310 of CO and 0.0710 of water. 0.1818 gave 0.1751 of AgBr and 0.1070 of BaSO C = 31.27 H = 3.94 Br = 40.99, S -.- 8.08. C,o€I150,NBr,S reruires C = 30.86 H = 3.89 Br = 41.08 S = 8.24%).cc'@-Dibroniocamphor-~-sulphonamide is insoluble in water spar-ingly soluble in light petroleum but very soluble in other organic solvents. It has - 26" [c(]j461 - 29" in benzene (2.64 g. per 100 c.c.). When warmed with aqueous sodium hydroxide it liberates ammonia. p .Bromocamphorquinone (Formula VI).-During a cr~~stallisatio 278 BURGESS AND L O ~ Y NEW HALOGEN DERIVATIVES of dibromocarnphorsulphonamide from dilute alcohol the solution slowly became yellow and deposited bright bellow crystals as well as the colourless ones of the initial compound. After a week a large proportion of the colourless crystals had disappeared whilst the yellow compound had increased in quantitly. The mixture was filtered off and sublimed in a vacuum when bright yellow prisms, m.p. 104-107" were obtained. These were recrystallised from dilute alcohol and melted at 132" after softening above 115". 0.04766 gave 0.03655 of AgBr (micro-Carius) Br = 32.63. CloH,,O,Br requires Br = 32.61%. Attempts to prepare it by hydrolysis with sodium ethoxide and with calcium hydroxide failed; both gave the intense colour of the quinone but very little could be separated. Oxidation with hydrogen peroxide in aqueous alcoholic solution first gave the intense yellow colour of the quinone; but further heating led to its decomposition with the formation of p-bromocamphoric an-hydride m. p. about 143" (alone or mixed with a genuine specimen) ; the rotatory power (+ 7") also was in harmony with that (+ 5") of a specimen of tlhe anhydride prepared from p-bromocamphoric acid.The yellow colour also disappears slowly by oxidat'ion when the quinone is left in contact with aqueous alcohol. P-Bromocamphorquinone is very soluble in benzene ether or chloroform less soluble in alcohol and insoluble in water. It h m a characteristic pleasant odour which is unlike that of camphor-quinone. The absorption spectrum in alcoholic solution of a specimen melting at 104-107" gave an absorption band a t the same wave-length as that of camphorquinone. The results are given in Table I. TABLE I. The A6sorption o j p-nromocamp,ho~quinone in Alcohol. Conc. of solution = 0-0993 g.-mol. per lit,re. A. 4300. 4400. 4500. 4550. 4600. 4650. 4700. 4750. Length of tube = 1 dcm. log €1 ...... 0.891 1.012 1.127 1.147 1.158 1.160 1.149 1.145 log € 2 ......1.15 1.32 1.41 1.458 1.460 1.462 1.460 1.457 A. 4800. 4850. 4900. 5000. 5100. 5200. 5300. log ...... 1,120 1.010 0.790 0.261 1.947 z.735 1.626 log c2 ...... 1.425 1.365 1.230 0.525 0.085 1.442 -c1 is the extinction coefficient for B-bromocsmphorquinone. e2 is the extinction coefficient for camphorquinone (Lowry and French, J. 1924 125 1921). We are indebted to Mr. R. Jeffery of Peterhouse for the crystallo-graphic measurements which he obtained under the direction of Mr. A. Hutchinson F.R.S OF CAMPHOR. PARTS VI AND VII. 279 Part V1I.-The Coizstitution of the Reychler Series of Camphor-sulphonic Acids. Experimeiats on Chlorosulphoxides. The position occupied by the sulplionic group in Iteychler’s camphorsulphoiiic acid and the related question of the position of the halogen in p-bromocamphor have recently come up for reconsideration siiice Wcdeliind Schenlr and Stusser (Ber.1823, 56 633) have discovered a series of reactions by which Reychler’s acid can be convcrted into lretopinic acid by the destruction of one of the methyl groups of the original molecule of camphor. The evidence thus supplied that the sulphonic radical has entered a methyl group is liowcver a t variance with the equally definite evidence that the halogen of P-bromocamphor (which can be pre-pared by the thermal decomposition of the sulphonyl bromide of Reychler’s acid) has entered a methyZc.lze group in the ring. Part of this evidence was reviewed by Armstrong and Lowry (J. 1902, 81 1469) who directed attention to thc oxidation of P-bromo-camphor to p-bromocamphoric acid but were unable to oxidise it further to a tricarboxylic acid and by M.0. Forster (J. 1902, 81,265) who directed attention to the ready conversion of p-bromo-camphor into campholenic acid (compare Part V J. 1924 125, 2376) but further results have since become available which point in the same direction. Thus not only is campholenonitrile (11) readily formed by the removal of water from camphoroxime (I), but a similar action takes place in the case of epicamphoroxime, where the methyl group has been transplanted bodily to the 4-position. It is therefore remarkable that this action does not occur in p-bromocamphoroxime if as is now suggested the p-bromine which inhibits the action is in the inactive methyl group, instead of in the methylene group from which the hydrogen of the eliminated molecule of water is taken.The two lines of evidence disagree so much that it appeared impossible to reconcile them unless (i) a migration of the bromine atom had occurred in the preparation of P-bromocamphor from the sulphonyl bromide of Reychler’s acid or (ii) some change of orientation had taken place during the conversion of the sulphonyl chloride of Reychler’s acid into ketopinic acid. The first hypo-thesis is negatived by the results recorded in Part VI above; the present part deals with the second hypothesis. As a first step in the conversion of Reychler’s camphorsulphony 280 BURGESS AND L O ~ Y NEW HALOGEN DERIVATIVES chloride to ketopinic acid Wedekind and his colleagues obtained by loss of water a chlorocamphorsulphoxide which they formulated as follows : CH2-qH-CH CH2-qH-CH, CH,-v--CO -Ha0 I w e I CH2*S02C1 c1c:s:o -+ CH2-$+-- CO I VMe2 I Reychler’s camphor- 1 0-Chlorocamphor-sulphonyl chloride.sulphoxide. Since they obtained a similar compound from camphor-r-sulphonyl chloride but not from aromatic sulphonylchlorides they concluded that chlorosulphoxides can be obtained only from acids in which a methyE group has been sulphonated. An alternative view which would explain the formation of 10-ketopinic acid from a 6-derivative of camphor postulates instead that a methyl group must be contiguous to the sulphonic radical thus : CH2-vH-CH CH,-qH-CH CH,-vH-CH, CH-C-CO -+ CII-C--CO _f CH,-C--CO I \ c1 I VMe I -H,O I VMe I I (we2 I I O=T=/O H,/CH I K,.,,--.., Camphor-6-sulphonyl #(Cl ‘i.-. . 3 o=v=c, H I o=s=cc1 _.. ‘-#’ Camphor-10-chloro-sulphoxide. chloride. ..-_2. This mechanism assumes that the dehydration of the sulphonyl-chloride involves the formation of an intermediate ring-compound, and the migration of a hydrogen atom from the 10 to the 6-position in addition to the migration of chlorine from sulphur to carbon which was postulated by Wedekind Schenk and Stusser. This mechanism appeared all tlhe more plausible because in camphor-n-sulphonyl chloride there is a methyl group in a precisely similar position relative to the sulphonic radical since both com-pounds contain the group I n the case of the r-compound > CCH, however it was possible to determine whether a change of orient-ation had occurred in the dehydration of the sulplionyl chloride, since a different methyl group would then be destroyed on con-verting into a carboxylic acid (i) the a-bromocamphor obtained by the pyrogenic decomposition of camphor-r-sulphonyl bromide (pre-sumably without change of orientation compare Part V I above) ; (ii) the 7r-chlorosulphoxide obtained by dehydration of the r-sul-phony1 chloride by Wedekind’s method.If this wandering took place therefore the tricstrboxylic acid obtained by oxidising Wedekind’s isoketopinic acid should be isomeric and not identica OF CAMPHOR. PARTS VI AND VII. 281 with the acid which Kipping and Pope obtained by hydrolysing and then osidising r-hromocamphor. Since Wedekiiid and his collaborators did not mention whether they had osidised their procluct to a tricarboxylic acid we decided to test the reaction by preparing and oxidising (instead of their compound) an E-bromocaiitphor-rr-chlorosulphoxide prepared from ammoiiium a-l.)romocanipl.or-7i-sulphonate.When this was oxidised with nitric acid a tricarboxylic acid and anhydride were obtained, which were identical and not isomeric with those prepared by Kipping and Pope. There was therefore no evidence here of a change of orientation. We also attempted t o prepare chlorotoluenesulphoxide from o-tolueiiesulphonyl chloride since this compound also contains a methyl group in the appropriate position; but me were again unsuccessful as most of the sulphonyl chloride was recovered unchanged.The e\-idence therefore undoubtedly proves that the suggested iiieehanisni which appeared to offer a feasible explanation of the production of 10-lietopinic acid from a camphor-6-suiphonjc acid is incorrect. We have then no alternative but to accept the conclusion that the halogen in 3-l~roiiiocaniphor 21s well as the sulphonic group in Rcychler's acid has entered a methyl group and occupies the 10-position in the camphor molecule. In doing so however it is desirable to point oat that there is no single reactiou in which P-brorno-cni,iphor hrhcrws as if it co,#tai?is the group -CH,Br. Thus it has ncver heeii coiivertctl into a primary alcohol -CH,Br -+ -CH,*O€€, and when attenipts are made to bring about this change (see Part V), the nioiecule emerges (as a derivative of cainpholenic acid) witch a1 1 its methyl groups intact hiit with a double bond in the ring.On the other liaiicl it is aimzing that a halogen in the side chain should s1)solutely inhiLit the formation of this double bond in the ring, when the attempt is made t o convert p-bromocamphoroxime into I~-bro~ocanlpliolc-iiitrile especially in view of the fact that the side chain can be eliiniiiatecl completely without affecting the action. The conclusion appears inevitable that there must be some liiik between the G- and 10-positions which is not indicated by the conventional formulz just as there must be some con-riexion between the ketonic and the gemdimethyl group (or some mechanism which involves both groups ; see Armstrong and Lowry, J.1902 81 1409) to account for the r-sulphonation of camphor. The nature of this connexion is not yet clear but it would be shirking the facts not to recognise that there is still a problem to solve even when the admission has been made that the p-series of compounds are all 10-derivatives of camphor 282 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES ETC. E x P E R I M E N T A L . u-Bromocamp~~or-.rr-chlorosulphoxide C9H,,BrO*CC1:K0 was pre pared by the method of Wedekind Schenk and Stusser (Zoc. cit.) from a- bromocamphor-7r-sulphonyl chloride using dry pyridine as the dehydrating agent; but twice as much pyridine was used because the reaction mixture went solid before the addition of the sulphonyl chloride was complete and the later portions did not then react, The brownish-red granular solid was washed and crystallised three times from acetone.0.2003 gave 0.2830 of CO and 0.0700 of H,O. 0.1930 gave 0.2044 of AgCl 3- AgBr C = 38.55 H = 3-91 Br = 25.56 Cl = 11-34. C,,H,,O,CIBrS requires C = 38-63, H = 3.88 Br = 25.65 C1 = 11.38%. a-Bromocamphor-7r-chlorosulphoxide is very soluble in benzene, hot acetone or chloroform less soluble in cold acetone and the alcohols slightly soluble in hot ligroin or ether and insoluble in water. It crystallises in thin plates which are usually pointed a t one end but are occasionally hexagonal in shape. Its colour varies from pale to deep reddish-brown according t o the state of aggre-gation. It melts a t 158-159" and has + 31" [cx!J54sl + 39" in benzene (5-5 g. per 100 c.c.).Oxidution of ci-Brornocamphor-~-chlorosulphoxide.-This compound (3.5 9.) was refluxed with 20 C.C. of nitric acid (d 1.4) for 14 hours; the mixture was then cooled and water was added. After ex-traction with benzene to remove an oily by-product the aqueous layer was evaporated until crystals began to separate and then cooled. The crystals m. p. 180-185" after filtration and washing with a little water crystallised twice from benzene-.chloroform and once from ether gave a product which softened slightly a t 193" and melted a t 194-195" (decomp.); on mixture with a specimen of trans-camphotricarboxylic acid supplied by Prof. I?. S. Kipping P.R.S. its m.p. was undepressed. The substance had solu-bilities similar to those given by Kipping and Pope (J. 1896 69, 951) for that acid and gave precipitates with barium chloride, copper acetate ferric chloride and lead acetate as recorded by these authors.It has [aID + 34" [cc]~,~ + 35" and [cx]5461 + 40" in alcohol (0.281 g . in 15 c.c.). The anhydride prepared by heating with acetic anhydride diluting with water and extracting with ether separated from the ether in beautiful plates m. p. 252-254O (Pope and Kipping's trans-camphotricarboxylic acid melts a t 195-196" [decomp.] has [a]= + 37.2" in alcohol and gives an anhydride, m. p. 253-254"). The benzene extract gave a crystalline by-product m. p. about 202" (decomp.) [a]54al + 19.4" in acetone (2.166 g. per 100 c.c.) CONVERSION or AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 283 This was expected to be a 7I-chlorodinitro-a-bromocamphor ; but, unlike the compound which Wedekind obtained under analogous conditions it was soluble in alkalis as if it contained a primary or secondary instead of only tertiary nitro-groups.Moreover it appeared to contain an additional molecule of water although there was not enough material available to confirm the analysis. Since the constitution of the compound is still unknown it is hoped to investigate it more fully later. Attempt to JlaEe ToZu eri e-o -chZorosuZyhoxide.-o-Toluenesulphonyl chloride (14 c.c.) was heated with dry piperidine (11 g.) for 16 hours, the liquid becoming of an intense dark red colour as in the case of a-bromocamphor-rr-sulphonyl chloride. After washing with acidified water extracting with ether and drying over calcium chloride the oil was distilled in a vacuum 85% of the o-toluenesulphonyl chloride being recovered unchanged.The charred residue was not investigated. UNIVERSITY CHEMICAL LABORATORY, C-111 ERID GE. [Received November 18th 1924. BURGESS AND LOWRY NEW HALOGEN DERIVATIVES ETC. 271 XLV.-New Halogen Derivatives of Camphor. Part V I . P-Bromo~mphor-a-sulphonic Acid. Part VII. The Constitution of the Reychler Series of Camphor-sulphonic Acids. Experiments on Chbrosulph-oxides. By HENRY BURGESS and THOMAS MARTIN LOWRY. Part VI.-p-Bromocamphor-a-sulphonic Acid. THE present paper describes a new series of sulphonic derivatives of camphor in which the sulphonic group occupies the a-position. This result is of interest since sulphonation has hitherto always been found to result in an attack upon a methyl group whilst the very reactive a-carbon atom has escaped.Thus even the gentle method of sulphonation used by Reychler gives p-derivatives and not the a-sulphonic acid which he thought he had prepared; and it is only after blocking the p-position with a halogen that we have been able to induce the sulphonic radical to enter the a-position. Armstrong and Lowry (J. 1902 81 1445) had already attempted to sulphonate p-bromocamphor but had obtained only a negative result. Our experiments have shown that although most of the p-bromocamphor can be recovered unchanged about 15 to 20% of it is sulphonated a t each operation. The product was at fist thought to be a p-bromocamphor-p-sulphonic acid where p repre-sents the position of the sulphonic group in Reychler’s acid but doubts arose when it was found that the sulphonamide did not yield an anhydramide like a-bromocamphor-p-sulphonamide but gave an acetyl derivative like a-bromocamphor-a-sulphonamide.Still more striking was the fact that the sulphonyl bromide whe 272 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES decomposed by heat did not give a new pp-dibromocamphor but 5t mixture of Kachler and Spitzer’s aP-dibromocamphor with our new a’p-dibromocamphor (J. 1923,123,1867). This suggested that the sulphonic group occupied the a-position; but as the whole research was based upon a suspicion that the pyrogenic decom-position of a p-sulphonyl bromide might give a p-bromo-compound of different orientation we did not regard it as safe t o accept the above observation as a final proof of the structure of the acid.Confirmation was however obtained when the sulphonamide on bromination again gave rise to the same aP-dibromocamphor by a remarkable action in which the halogen displaces a sulphonamide group instead of eliminating one of the reactive a-hydrogen atoms. This result was very difficult to explain unless the sulphonic group were already in the a-position. Moreover this broinination was free from the suspicions which attached t o the formation of Np-di-bromocamphor by the pyrogenic decomposition of the sulphonyl bromide. Final proof that the sulphonic group had entered the a-position leaving the camphor nucleus intact except for the presence of the p-bromine atom was obtained when the spon-taneous oxidation of a dibromosulphonamide derived from our acid gave rise t o the hitherto unknown p-bromocarnphorquinone, and thence by a direct further oxidation to p-bromocamphoric anhydride (not the free acid although the oxidation took place in aqueous solution).The whole series of actions may be set out as follows : p-Bromocamphor-a-sulphonic acid. p-Bromocamphor-a-sulphonamide. 15-Bromocamphor-a-sulphonyl bromide. Acetyl derivative. a’b-Dibromocamphor-a-sulphonamide. .1 c8H,3Br<xE PI. 1 0 t-p-Bromocamphoric anhydride. p-Bromocamphorquinone O F CAMPHOR. PL2RTS 1'1 ANT \TI. 273 In tliesc forinulx the acetyl derivative has been assumed to be enolic as in the case of the .x-isoniericle the solubility of which (unlike that of the amide from which it is derived) is not increased by the addition of alkali (Low? and Magson J.1906 89 1044), so that the acetyl derii-atire appears not to contain an cc-hydrogen atom. I n tlic prc-ent case the fact that the acetyl group was lost on huminat icin si:ggestetl very strongly that we were again dealing with an cnolic. iicctate arid not the -SO,*NHAc compoiind. 'I'his invebt igation C C J I ~ ~ ~ ~ I I ~ S t lie lriew of Lipp and Lausberg ( A )inale?L 1024 436 274) that P-hrornocawiphor mid the Reychlet. .~erica of Crctrii~~~"".'"(~J'hoiil'c acids hare the sattie o?-ie?ztatioiL since the blocking of the $-pu~itioii I I J ? a halcgen coiiipels the sulphonic group to enter :i I I P ~ \ ~ imsitioii in the molecule. The question whether thc [d-substituenti are attarlied to a carbon atom in the ring or to a inethyl grcbiij) i5 (liwIqscd in Part IT1 below.E X P E R I 53 I3 N T A L. S II I y lz o 1 i a t io I L of fJ - Ur o i n oca n2 phot. . - p - B r o m o c a in pho r ( 5 0 g . ) was added slowly to a mixturc of acetic anhydride (80 c.c.) and con-centrated sulphuric acid (25 c.c.) when the mixture became brown and most of the fJ-broinocamphor dissolved. After standing for a week a t 30-40" itl was heated for 2 hours and poured on to crushed ice and the precipitated p-bromocamphor (41 g.) washed with water. Further heating or varying the quantities of acetic. anhydride and sulphuric acid gave a smaller yield of sulphonate and a much larger quantity of brown charred material. The solution n-as boiled till free from acetic acid neutralised with a crc~ini of c;?lcium czrlionate filtered niicl ccncentrated.The sliidge of chalk z:cd calcium sulphate (which separates only slowly in the presence of the calcium sulphonste) was washed three times with boiling u-ater to remove all the sulphonate. After recrystallising three times from methylated spirit the calciuxu sulphonate ivas obtained in colourless rhombic plates. The mother-liquors Irere decoiorised by bone charcoal. The total yield was 12 g. (about 90';;)) after allowing for the recovery of iiiost of the bromocainphor. 0.1515 gave 0.1800 of CO, 0.0660 of H,O anti 0.0273 of CaXO,. 0.1773 lost 0.0172 of H,O and gave (1.0924 of R g h C == 3241 H = 4.87 Ca = 5.30 Br = 22-1 S H,O = 9.i0. (C,,H,,e)Br*S0,),Ca,4H2(~ requires C = 32-78, H = 4-95 Cia == 5 4 7 IZr = 21.83 H,O = 9.54%.Calcium p-broinocainphor- a-szrlphotzate is very soluble in hot water but crystallises readily from hot methylated spirit,. It does not melt below 230". It has [ s ~ ] ~ ~ ~ ~ = + 50° [a]5461 - + 59", = 4 116.5" in water ( 2 g. per 100 c.c.) 274 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES Potassium /3-bromocamphor-cc-sulphonate prepared by addition of potassium oxalate (calc. amt.) to a solution of the calcium salt, filtration and evaporation crystallised from hot methyl alcohol in fine colourless needles. 0.2045 gave 0.2565 of CO and 0.0730 of H,O. 0.2152 lost no water a t 150-160" in a vacuum C = 34.22 I€ = 4-00 C,,H,,OBr~SO,K requires C = 34.37 H = 4-040,/,. P-Bromocamphor- a-sulphonyl Chloride (Formula as II).-A mix-ture of powdered phosphorus pentacliloride (5.4 g.) and the dry, powdered potassium salt (7-5 9.) was shaken and warmed in a dry flask on the water-bath until liquid.After 15 minutes it was shaken vigorously with powdered ice. The light brown solid was filtered and washed with water and a little dilute potassium carbonate solution ; it crystallised from ether in large compact crystals (Fig. l) which softened a t 93" and melted a t 97". 0.2393 FIQ.' 1. FIG. 2. gave 0.0940 of AgCl C1= 9.7. C,,H,,OBr*SO,Cl requires C1= 10.76%. p-Bromocamphor-a-sulphonyl chloride is comparatively stable when pure but loses chlorine quickly if impure and especially in presence of a little hydrochloric acid. It is very soluble in benzene or ether less soluble in cold alcohol and sparingly soluble in light petroleum.The crystallographic properties are as follows (two crystals were measured) : System Orthorhombic. Axial Ratios a b c = 0.2994 1 0.3769. Habit Both crystals were flattened parallel to C(OOl) with m(110) fairly large. The crystals were not quite transparent and did not give good reflections. Pmms present C(OOl) b(010) m(110) and n(Ol1). One face only of y(021) OF CAMPHOR. PARTS VI AND VII. 275 No. of Angles measure- Mean observed. ments. Limits. observation. Calculation. bnz 010 110 8 69" 52'-GS0 59' 69" 21' I cn 001:011 8 17 12-16 30 16 40 cy 001 :021 1 30 25;-31 35$ 31 04 30" 55' tnn 1 1 O O l l 4 84 28 -84 2 s.2 11 84 12 -Optical Characters Since thc crysials could not be immersed in liquids the optical data are scanty and liable to be inaccurate.The optic axial plane is parallel to b(010) with the acute bisectrix perpendicular to C(OOl) and the double refraction positive. The refractive indices determined by the minimum deviation method are very approximately a = 1.55 p = 1.56 y -1 1.58. ~-Bromocamphor-a-szilphonamide (Formula ITI).-A mixture of the potassium sulphonate (7.0 9.) and phosphorus pentachloride (4.2 g.) was covered wi5h dry chloroform (50 c.c.) and left over-night. The chloroform was washed twice with ice-cold water, dried for an hour over calcium chloride filtered and excess of dry ammonia was passed into it when much heat was developed. After 12 hours the chloroform was distilled off and the residue was washed with water and crystallised from ether (yield 65%).0.2045 gave 0.2895 of CO and 0.0955 of H,O. 0-2268 gave 0.1382 of AgBr C = 38.62 H = 5.23 Br = 25.93. C,oH,,O,NBrS requires C = 38.71 H = 5.20 Br = 25.77%. p-Bromocamphor- a-sulphonamide is very soluble in chloroform, alcohol ether or hot benzene less soluble in cold benzene and sparingly soluble in light petroleum or water. It melts a t 100-102" with the evolution of small bubbles of gas and has + 3 9 ~ 3 " ~ [a]5461 + 46.1" + 99" in alcohol (5.62 g. per 100 c.c.). The crystals which separate from an ethereal solution are tough and fibrous when crushed they are a t first quite transparent but after about 2 hours the surface becomes opaque and then the whole of the crystal perhaps as a result of polymorphic change.When this change is complete the crystal is easily crushed the fibrous structure having been lost completely. Attempts to Prepare an Anhydramide.-Lowry's two methods (J. 1902 81 1441) were employed. (a) A mixture of the sulphonamide (0.5 g.) with 45 C.C. of con-centrated hydrochloric acid was kept for a fortnight the clear solution diluted with water (2 vols.) and neutralised with potassium carbonate. ( b ) The sulphonamide (2.5 g.) was heated with acetic anhydride (10 c.c.) on the water-bath for 4 hours,* crystals separating. After * If the mixture is boiled instead of being heated on a water-bath con-Chloroform extracted the sulphonamide unchanged. siderable charring occurs 276 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES cooling these were filtered off and a further small quantity was obtained by diluting the cold mother-liquor with water (yield 80:/,).Although this product resembled a-bromocamphor-p-sul-phonanhydramide in appearance and in its sparing solubility in all solvents it was an acetyl derivative for 0.2060 gave 0.3140 of CO and 0.0955 of H,O and 0.1900 gave 0.1033 of AgRr and 0.1280 of BaSO C = 41-55 H = 5-19 Br = 22.89 S = 9-25. C,,H,,O,NBrX requires C = 40.90 H = 5.15 Rr = 22.69 S = Acetyl-p-bromocana3-7hor-v.-.~ulll,honamide (IV) prepared as de-scribed above is slightly soluble in hot acetone and in hot acetic anhydride but is sparingly soluble in the cold solvents and in all the other common organic solvents. It crystallises from acetone in small compact crystals m.13. 217" (rapid decomp.). It has [a]5,yo - 3 7 ~ 5 " ~ [CY]~,~~ - 42" in acetone (0.613 g. per 100 c.c.). 9.10 74. The crystallographic properties are as follows : System Orthorhombic. Axial Ratios a 3 c = 1.804 1 1-206. Forms present .- a(100) m(110) 1(210) q(101) d(201) ~ ( 0 1 1 ) . Habit .- The crystals were very small (Fig. 2) the longest dimen-The faces were frequently curved and not The face a(100) was only The prism faces were always very sion being about l". well suited to accurate measurement. observed on two crystals. small with the domes predominating to give a stumpy outline. No. of Angles measure -observed. ments. Limits. mm' = 110 i i o 5 57'29'- 59'51' 11' = 210:210 5 84 22- 86 16 ' = 011 :g11 6 99 58-102 24 ;z = 101 l o 1 G 67 54- 70 23 dd' = 201 201 G 73 0- 75 19 mq = 110 101 G 71 22- 73 49 mp = 110 :011 5 46 53- 48 31 Id = 210 201 10 53 61- 56 19 Ep = 210:Oll 10 56 34- 59 25 zq = 210 101 4 65 13- 65 41 md = 110 201 2 66 41- 68 44 Average.6s" 43' 85 32 101 0 68 50 74 9 73 13 47 52 54 18 57 43 65 26 67 24 Calculated. 58" 0' 84 6 100 40 67 32 73 34 74 22 47 41 53 30 58 58 65 37 67 0 CEeavuge None observed. Specific gracity .- 1.562 determined by floating in Thoulet's solution. Decomposition of p- Bromocamphor- a-sulphonyl Bromide (Formnla II).-The method of preparation was similar to that used in making the sulphonyl chloride. As the oil obtained on evaporating off the chloroform from the washed and dried solution did not crystallise in a desiccator in 2 days it was dissolved in dry xylene and refluxed for about + hour until the evolution of sulphur dioxide whic OB CAMPHOR.PARTS VI AND W. 277 was a t first very rapid had practically ceased. The liquid charred rather badly during the heating. After the xylene had been dis-tilled off in steam a colourless oil came over and slowly solidified. This was filtered off and melted a t 46-85". When crystallised from dilute alcohol it gave three successive crops of crystals. The first fraction which melted almost constantly a t 92-94' on three successive crystallisations was a t once converted into almost pure a@-dibromocamphor on crystallking in presence of a trace of piper-idine and therefore was a mixture of .@- and a'p-dibromocamphors (compare J.1923 123 1872). The second fraction after one further crystallisation was identified as cr'p-dibromocamphor (m. p. 133-135" not lowered by mixing; [cr]5461 - 77" instead of - 85" in acetone 1 g. per 100 c.c.). The third fraction was identi-fied after one further crystallisation as crp-dibromocamphor (m. p. 113-114" not lowered by mixing with a$-dibromocamphor ; [a]5461 125" instead of 127" in acetone 3.92 g. per 100 c.c.). The above results proved quite conclusively that the sulphonyl bromide had decomposed to a mixture of M @ - and a'@-dibromocamphors. Broinination of p-Bromocamphor-a-su1phonamide.-Bromine (2.7 g.) was added to a solution of the sulphonamide (2.0 8.) in glacial acetic (50 c.c.) and the mixture refluxed for 4 hours becoming pale yellow.From the aqueous solution neutralised with sodium carbonate ether extracted an oil (about 2 c.c.) co-ntaining some lachrymatory substance probably bromoacetic acid from which was separated about 0.3 g. of ctp-dibrcmocamphor m. p. 112-114' (alone or mixed with this substance). a'@-Dibromocamphor-cr-sulphozamide (Formula V).-Bromine (2.5 g.) was added to the acetyl derivative of p-bromocamphor-cr-sul-phonamide (0.8 g.) in glacial acetic acid (20 c.c.) and the mixture refluxed for 5 hours the acetyl derivative dissolving completely, and the bromine disappearing. After cooling the acetic acid was neutralised with ammonia tho mixture being cooled meanwhile ; the white precipitate crystallised from benzene-ligroin in beautiful, colourless prisms m.p. 145" softening at 143" (yield 0.7 g. or 80%). 0.2015 gave 0.2310 of CO and 0.0710 of water. 0.1818 gave 0.1751 of AgBr and 0.1070 of BaSO C = 31.27 H = 3.94 Br = 40.99, S -.- 8.08. C,o€I150,NBr,S reruires C = 30.86 H = 3.89 Br = 41.08 S = 8.24%). cc'@-Dibroniocamphor-~-sulphonamide is insoluble in water spar-ingly soluble in light petroleum but very soluble in other organic solvents. It has - 26" [c(]j461 - 29" in benzene (2.64 g. per 100 c.c.). When warmed with aqueous sodium hydroxide it liberates ammonia. p .Bromocamphorquinone (Formula VI).-During a cr~~stallisatio 278 BURGESS AND L O ~ Y NEW HALOGEN DERIVATIVES of dibromocarnphorsulphonamide from dilute alcohol the solution slowly became yellow and deposited bright bellow crystals as well as the colourless ones of the initial compound.After a week a large proportion of the colourless crystals had disappeared whilst the yellow compound had increased in quantitly. The mixture was filtered off and sublimed in a vacuum when bright yellow prisms, m. p. 104-107" were obtained. These were recrystallised from dilute alcohol and melted at 132" after softening above 115". 0.04766 gave 0.03655 of AgBr (micro-Carius) Br = 32.63. CloH,,O,Br requires Br = 32.61%. Attempts to prepare it by hydrolysis with sodium ethoxide and with calcium hydroxide failed; both gave the intense colour of the quinone but very little could be separated. Oxidation with hydrogen peroxide in aqueous alcoholic solution first gave the intense yellow colour of the quinone; but further heating led to its decomposition with the formation of p-bromocamphoric an-hydride m.p. about 143" (alone or mixed with a genuine specimen) ; the rotatory power (+ 7") also was in harmony with that (+ 5") of a specimen of tlhe anhydride prepared from p-bromocamphoric acid. The yellow colour also disappears slowly by oxidat'ion when the quinone is left in contact with aqueous alcohol. P-Bromocamphorquinone is very soluble in benzene ether or chloroform less soluble in alcohol and insoluble in water. It h m a characteristic pleasant odour which is unlike that of camphor-quinone. The absorption spectrum in alcoholic solution of a specimen melting at 104-107" gave an absorption band a t the same wave-length as that of camphorquinone. The results are given in Table I.TABLE I. The A6sorption o j p-nromocamp,ho~quinone in Alcohol. Conc. of solution = 0-0993 g.-mol. per lit,re. A. 4300. 4400. 4500. 4550. 4600. 4650. 4700. 4750. Length of tube = 1 dcm. log €1 ...... 0.891 1.012 1.127 1.147 1.158 1.160 1.149 1.145 log € 2 ...... 1.15 1.32 1.41 1.458 1.460 1.462 1.460 1.457 A. 4800. 4850. 4900. 5000. 5100. 5200. 5300. log ...... 1,120 1.010 0.790 0.261 1.947 z.735 1.626 log c2 ...... 1.425 1.365 1.230 0.525 0.085 1.442 -c1 is the extinction coefficient for B-bromocsmphorquinone. e2 is the extinction coefficient for camphorquinone (Lowry and French, J. 1924 125 1921). We are indebted to Mr. R. Jeffery of Peterhouse for the crystallo-graphic measurements which he obtained under the direction of Mr. A.Hutchinson F.R.S OF CAMPHOR. PARTS VI AND VII. 279 Part V1I.-The Coizstitution of the Reychler Series of Camphor-sulphonic Acids. Experimeiats on Chlorosulphoxides. The position occupied by the sulplionic group in Iteychler’s camphorsulphoiiic acid and the related question of the position of the halogen in p-bromocamphor have recently come up for reconsideration siiice Wcdeliind Schenlr and Stusser (Ber. 1823, 56 633) have discovered a series of reactions by which Reychler’s acid can be convcrted into lretopinic acid by the destruction of one of the methyl groups of the original molecule of camphor. The evidence thus supplied that the sulphonic radical has entered a methyl group is liowcver a t variance with the equally definite evidence that the halogen of P-bromocamphor (which can be pre-pared by the thermal decomposition of the sulphonyl bromide of Reychler’s acid) has entered a methyZc.lze group in the ring.Part of this evidence was reviewed by Armstrong and Lowry (J. 1902, 81 1469) who directed attention to thc oxidation of P-bromo-camphor to p-bromocamphoric acid but were unable to oxidise it further to a tricarboxylic acid and by M. 0. Forster (J. 1902, 81,265) who directed attention to the ready conversion of p-bromo-camphor into campholenic acid (compare Part V J. 1924 125, 2376) but further results have since become available which point in the same direction. Thus not only is campholenonitrile (11) readily formed by the removal of water from camphoroxime (I), but a similar action takes place in the case of epicamphoroxime, where the methyl group has been transplanted bodily to the 4-position.It is therefore remarkable that this action does not occur in p-bromocamphoroxime if as is now suggested the p-bromine which inhibits the action is in the inactive methyl group, instead of in the methylene group from which the hydrogen of the eliminated molecule of water is taken. The two lines of evidence disagree so much that it appeared impossible to reconcile them unless (i) a migration of the bromine atom had occurred in the preparation of P-bromocamphor from the sulphonyl bromide of Reychler’s acid or (ii) some change of orientation had taken place during the conversion of the sulphonyl chloride of Reychler’s acid into ketopinic acid. The first hypo-thesis is negatived by the results recorded in Part VI above; the present part deals with the second hypothesis.As a first step in the conversion of Reychler’s camphorsulphony 280 BURGESS AND L O ~ Y NEW HALOGEN DERIVATIVES chloride to ketopinic acid Wedekind and his colleagues obtained by loss of water a chlorocamphorsulphoxide which they formulated as follows : CH2-qH-CH CH2-qH-CH, CH,-v--CO -Ha0 I w e I CH2*S02C1 c1c:s:o -+ CH2-$+-- CO I VMe2 I Reychler’s camphor- 1 0-Chlorocamphor-sulphonyl chloride. sulphoxide. Since they obtained a similar compound from camphor-r-sulphonyl chloride but not from aromatic sulphonylchlorides they concluded that chlorosulphoxides can be obtained only from acids in which a methyE group has been sulphonated. An alternative view which would explain the formation of 10-ketopinic acid from a 6-derivative of camphor postulates instead that a methyl group must be contiguous to the sulphonic radical thus : CH2-vH-CH CH,-qH-CH CH,-vH-CH, CH-C-CO -+ CII-C--CO _f CH,-C--CO I \ c1 I VMe I -H,O I VMe I I (we2 I I O=T=/O H,/CH I K,.,,--.., Camphor-6-sulphonyl #(Cl ‘i.-. . 3 o=v=c, H I o=s=cc1 _.. ‘-#’ Camphor-10-chloro-sulphoxide. chloride. ..-_2. This mechanism assumes that the dehydration of the sulphonyl-chloride involves the formation of an intermediate ring-compound, and the migration of a hydrogen atom from the 10 to the 6-position in addition to the migration of chlorine from sulphur to carbon which was postulated by Wedekind Schenk and Stusser. This mechanism appeared all tlhe more plausible because in camphor-n-sulphonyl chloride there is a methyl group in a precisely similar position relative to the sulphonic radical since both com-pounds contain the group I n the case of the r-compound > CCH, however it was possible to determine whether a change of orient-ation had occurred in the dehydration of the sulplionyl chloride, since a different methyl group would then be destroyed on con-verting into a carboxylic acid (i) the a-bromocamphor obtained by the pyrogenic decomposition of camphor-r-sulphonyl bromide (pre-sumably without change of orientation compare Part V I above) ; (ii) the 7r-chlorosulphoxide obtained by dehydration of the r-sul-phony1 chloride by Wedekind’s method.If this wandering took place therefore the tricstrboxylic acid obtained by oxidising Wedekind’s isoketopinic acid should be isomeric and not identica OF CAMPHOR.PARTS VI AND VII. 281 with the acid which Kipping and Pope obtained by hydrolysing and then osidising r-hromocamphor. Since Wedekiiid and his collaborators did not mention whether they had osidised their procluct to a tricarboxylic acid we decided to test the reaction by preparing and oxidising (instead of their compound) an E-bromocaiitphor-rr-chlorosulphoxide prepared from ammoiiium a-l.)romocanipl.or-7i-sulphonate. When this was oxidised with nitric acid a tricarboxylic acid and anhydride were obtained, which were identical and not isomeric with those prepared by Kipping and Pope. There was therefore no evidence here of a change of orientation.We also attempted t o prepare chlorotoluenesulphoxide from o-tolueiiesulphonyl chloride since this compound also contains a methyl group in the appropriate position; but me were again unsuccessful as most of the sulphonyl chloride was recovered unchanged. The e\-idence therefore undoubtedly proves that the suggested iiieehanisni which appeared to offer a feasible explanation of the production of 10-lietopinic acid from a camphor-6-suiphonjc acid is incorrect. We have then no alternative but to accept the conclusion that the halogen in 3-l~roiiiocaniphor 21s well as the sulphonic group in Rcychler's acid has entered a methyl group and occupies the 10-position in the camphor molecule. In doing so however it is desirable to point oat that there is no single reactiou in which P-brorno-cni,iphor hrhcrws as if it co,#tai?is the group -CH,Br.Thus it has ncver heeii coiivertctl into a primary alcohol -CH,Br -+ -CH,*O€€, and when attenipts are made to bring about this change (see Part V), the nioiecule emerges (as a derivative of cainpholenic acid) witch a1 1 its methyl groups intact hiit with a double bond in the ring. On the other liaiicl it is aimzing that a halogen in the side chain should s1)solutely inhiLit the formation of this double bond in the ring, when the attempt is made t o convert p-bromocamphoroxime into I~-bro~ocanlpliolc-iiitrile especially in view of the fact that the side chain can be eliiniiiatecl completely without affecting the action. The conclusion appears inevitable that there must be some liiik between the G- and 10-positions which is not indicated by the conventional formulz just as there must be some con-riexion between the ketonic and the gemdimethyl group (or some mechanism which involves both groups ; see Armstrong and Lowry, J.1902 81 1409) to account for the r-sulphonation of camphor. The nature of this connexion is not yet clear but it would be shirking the facts not to recognise that there is still a problem to solve even when the admission has been made that the p-series of compounds are all 10-derivatives of camphor 282 BURGESS AND LOWRY NEW HALOGEN DERIVATIVES ETC. E x P E R I M E N T A L . u-Bromocamp~~or-.rr-chlorosulphoxide C9H,,BrO*CC1:K0 was pre pared by the method of Wedekind Schenk and Stusser (Zoc. cit.) from a- bromocamphor-7r-sulphonyl chloride using dry pyridine as the dehydrating agent; but twice as much pyridine was used because the reaction mixture went solid before the addition of the sulphonyl chloride was complete and the later portions did not then react, The brownish-red granular solid was washed and crystallised three times from acetone.0.2003 gave 0.2830 of CO and 0.0700 of H,O. 0.1930 gave 0.2044 of AgCl 3- AgBr C = 38.55 H = 3-91 Br = 25.56 Cl = 11-34. C,,H,,O,CIBrS requires C = 38-63, H = 3.88 Br = 25.65 C1 = 11.38%. a-Bromocamphor-7r-chlorosulphoxide is very soluble in benzene, hot acetone or chloroform less soluble in cold acetone and the alcohols slightly soluble in hot ligroin or ether and insoluble in water. It crystallises in thin plates which are usually pointed a t one end but are occasionally hexagonal in shape.Its colour varies from pale to deep reddish-brown according t o the state of aggre-gation. It melts a t 158-159" and has + 31" [cx!J54sl + 39" in benzene (5-5 g. per 100 c.c.). Oxidution of ci-Brornocamphor-~-chlorosulphoxide.-This compound (3.5 9.) was refluxed with 20 C.C. of nitric acid (d 1.4) for 14 hours; the mixture was then cooled and water was added. After ex-traction with benzene to remove an oily by-product the aqueous layer was evaporated until crystals began to separate and then cooled. The crystals m. p. 180-185" after filtration and washing with a little water crystallised twice from benzene-.chloroform and once from ether gave a product which softened slightly a t 193" and melted a t 194-195" (decomp.); on mixture with a specimen of trans-camphotricarboxylic acid supplied by Prof.I?. S. Kipping P.R.S. its m.p. was undepressed. The substance had solu-bilities similar to those given by Kipping and Pope (J. 1896 69, 951) for that acid and gave precipitates with barium chloride, copper acetate ferric chloride and lead acetate as recorded by these authors. It has [aID + 34" [cc]~,~ + 35" and [cx]5461 + 40" in alcohol (0.281 g . in 15 c.c.). The anhydride prepared by heating with acetic anhydride diluting with water and extracting with ether separated from the ether in beautiful plates m. p. 252-254O (Pope and Kipping's trans-camphotricarboxylic acid melts a t 195-196" [decomp.] has [a]= + 37.2" in alcohol and gives an anhydride, m. p. 253-254"). The benzene extract gave a crystalline by-product m. p. about 202" (decomp.) [a]54al + 19.4" in acetone (2.166 g. per 100 c.c.) CONVERSION or AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 283 This was expected to be a 7I-chlorodinitro-a-bromocamphor ; but, unlike the compound which Wedekind obtained under analogous conditions it was soluble in alkalis as if it contained a primary or secondary instead of only tertiary nitro-groups. Moreover it appeared to contain an additional molecule of water although there was not enough material available to confirm the analysis. Since the constitution of the compound is still unknown it is hoped to investigate it more fully later. Attempt to JlaEe ToZu eri e-o -chZorosuZyhoxide.-o-Toluenesulphonyl chloride (14 c.c.) was heated with dry piperidine (11 g.) for 16 hours, the liquid becoming of an intense dark red colour as in the case of a-bromocamphor-rr-sulphonyl chloride. After washing with acidified water extracting with ether and drying over calcium chloride the oil was distilled in a vacuum 85% of the o-toluenesulphonyl chloride being recovered unchanged. The charred residue was not investigated. UNIVERSITY CHEMICAL LABORATORY, C-111 ERID GE. [Received November 18th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700271

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

CONVERSION or AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 283 XLVI:.-Conversion of Amino-acids into Tertiary Amino-alcohols. By ALEX. MCKENZIE and GEORGE OGILVIE WILLS. THE first application of Grignard reagents towards esters of amino-acids was made by Baeyer and Villiger (Ber. 1904 37 3191), who converted methyl anthraiiilate into o-aminotriphenylcarbinol by means of magnesium phenyl bromide. Paal and Weidenkaff (Ber. 1905 38 1686) obtained p-amino-ua-diphcnylethyl alcohol from ethyl glycine (compare also Paal and Weidenkaff Ber. 1906, 39 810 4344; Krassusky Cornpt. rend. 1908 146 236). The Grignard reaction has been also applied in this laboratory for preparing amino-alcohols in connexioii with the study of semi-pinacolinic deamination. Since other workers (Thomas and Bett-zieche 2.physiol. Chem. 1924 140 244 261 279; Bettzieche, ibid. 273) have entered the same field quite recently we think it desirable to describe our further results. The elimination of the amino-group in tertiary amino-alcohols has heen dealt with (BlcKenzie and Richardson J . 1923 123 79; McKeiizie and Roger J. 1924 125 844; McKenzie and Dennler, J. 1924 125 2105). The first instance described in the literature as a semipinacolinic deamination arose from the accidental discovery that the transformation OH*CPh,CHPh*NU 3 OH*CPli,*CHPh*O 284 MCKENZIE AND WILLS CONVERSION OF could not be effected by the agency of nitrous acid; the product of the action was phenyldeoxybenzoin and not triphenylethylene glycol. p-Amino-ctap-triphenylethyl alcohol was prepared by McKenzie and Barrow (J.1913 103 1331) by the action of mag-nesium phenyl bromide on r-desylamine hydrochloride and later on r-phenylaminoacetic acid by McKenzie and Richardson. Thomas and Bettzieche have repeated its preparation from phenylamino-acetic acid and confirmed the conversion into phenyldeoxybenzoin. The conversion of r-phenylalanine into r- p-amino-p-benzyl-acc-diphenylethyl alcohol was also carried out in this laboratory and it was shown that the amino-alcohol undergoes semipinacolinic deamination : 7 Fh H ph I (bv HNO,) CH,Ph*y-y=Ph - + CH,Ph*C-yPh + NH OH ":&-OH OH CH2Ph>CH*CO*Ph. 4 bh CH,Ph*QH-(!*Ph * Ph -0 The phenyl group migrates and the product is benzyldeoxybenzoin. Those results are also confirmed by Thomas and Bettzieche.According to Paal and Weidenkaff (Zoc. cit.) the action of nitrous acid on p-amino-am-diphenylethyl alcohol leads to the formation of as-diphenylethylene oxide : I n the light of our work on semipinacolinic deamination it seemed possible that this conclusion was erroneous and that the product was actually deoxybenzoin. By arrangement with us Professor Tiffeneau and M. Or6khov had kindly undertaken the investigation of this point which meanwhile has been solved by Bettzieche. The product is deoxybenzoin and we would interpret its formation on the following lines the phenyl group migrating thus AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 285 I n a former paper we mentioned that we were continuing our study of the action of nitrous acid on compounds containing the >‘-?< with the object of extending our experience group b H NH, ultimately to optically active amino-alcohols.Accordingly in the present paper we describe the action of magnesium phenyl bromide on r-alanine thus : The amino-alcohol on deaminntion gave met,hyldeoxybenzoin : and thus pfovided another instance of the striking regularity with which the phenyl group migrates in all the cases of semipinacolinic deamination which have been studied. The change may be contrasted with the vinyl dehydration of r-methylhydrobenzoin studied by Tiff eneau and Or6khov (Bull. SOC. chim. 1921 [iv] 29 422) and by McKenzie and Roger inci-dentally to their work on the dehydration of optically active methylhydrobenzoin by concentrated sulphuric acid : The above result has already been arrived at by Bettzieche, who carried out the action with a trace of the amino-alcohol.In the light of the work of McKenzie and Roger as applied to the optically active methyl- and ethyl-hydrobenzoins the extension of this action to the optically active amino-alcohol derived from d-alanine presents obvious points of interest and we are a t present engaged in the investigation of this topic. As already stated the action of nitrous acid on p-amino-asp-triphenylethyl alcohol had been examined with the object of obtaining triphenylethylene glycol. The optically active forms of the latter compound had already been described (McKenzie and Wren J. 1910 97 473; XcKenzie Drew and Martin J., 1915 107 26) and the change in question if carried out with the optically active amino-alcohols would have provided data in connexion with the Walden inversion.This scheme however 286 MCKENZIE AND WILLS CONVERSION OF cannot be effected in practice for the reasons already given. Never-theless we have thought it desirable that the optically active amino-alcohols should a t least be prepared. The description of their preparation is now given in the experimental part. The compounds in question are highly active giving [XI, & 243" in chloroform; they rotate the plane of polarisation in the opposite sense to the phenylaminoacetic acids from which they are prepared. There is no configurative change here however since there is no substitution of a group directly attached to the asymmetric carbon atom so that the compound which is derived from d-phenylamino-acetic acid is designated as d- (3-amino-actp-triphenylethyl alcohol, although it is lzvorotatory d-phenylaminoacetic acid being taken as the reference type.It is rather curious to note that a similar change of sign of rotat'ion also occurs when methyl I-mandelate is converted by magnesium phenyl bromide into triphenylethylene glycol (McKenzie and Wren 7oc. c i t . ) . The action of nitlrous acid on the ci-amino-alcohol gives an optic-ally inactive product owing t o semipinacolii? ic deamination the product being phenyldeoxybenzoin. The isomeric camphorsulphonates of the d- and I-amino-alcohols were prepared but the resolution of the 1.-alcohol by d-camphor-S-sulphonic acid gave a very slow and imperfect separation and the method was obviously unsatisfactory.We are a t present engaged in resolving by means of camphorsulphonic acids the r-amino-alcohols related to desylamine. The changes C<R -+ d- CH,Ph>C- and d- CH,Ph*CH(NH,)*CO,H NH HO are also described but the study of the action of nitrous acid on the amino-alcohols has not yet been completed. Arising from the present research the following points have been investigated. The ethyl ester hydrochloride of Z-phenyl-aminoacetic acid gives on hydrolysis with a slight excess of alcoholic potash a phenylaminoacetic acid with [.ID - 12.4" in hydrochloric acid solution whereas the pure Z-acid has [.ID - 157.8" in the same solvent. This result was anticipated since in phenylaminoacetic acid we have both a phenyl group and a migrational hydrogen atom in direct attachment to the asymmetric carbon atom.McKenzie and Walker (J. 1915 107 1685) have shown that catalytic racemisation occurs when I-phenylbromoacetic acid i AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 287 acted on by ammonia. When the action was conducted in benzene solution that portion of the bromo-acid which had survived the attack of the ammonia had become largely racemised. It was thought possible that soniething of the same kind might occur when Z-phenylaminoacetic acid is acted on by nitrous acid; such, however is not the case. There was one other rather important point in connexion with tlhe study of the Walden inversion in the mandelic acid series which clearly required elucidation. E.Fischer and Weichhold (Ber. 1908 41 1286) acted on ethyl d-phenylaminoacetate with nitrous acid and obtained a change of sign of rotation the resulting ethyl mandelate being highly racemised and lanorotatory . On the other hand Marvel and Noyes ( J . Amer. Chern. Xoc. 1920 42, 2259) by acting on a solution of thc hydrochloride of ethyl 1-plieiiylaminoacctate in dilute sulphuric acid with nitrous acid, obtained an ethyl maidelate of the same sign of rotation as that of the original ethyl I-phenylaminoacetatc. We have repented the work both of Fischer and Weichliolcl and of Marvel and Noyes, and have found that a change of sign of rotation occurs when ethyl Z-phenylaminoacetate is acted on by nitrous acid if the solution, before the ester is extracted is kept sufficiently long after the addition of the nitrite.is therefore correct. 777) have shown that the change occurs the behaviour both of the ester and of the free acid towards nitrous acid is similar. The product obtained by the method of the American workers was contaminated with a nitrogenous com-pound (probably a diazo-compound). It seems that they had proceeded to isolate their ethyl mandelate too quickly after the addition of the sodium nitrite. The work on the action of nitrous acid on compounds containing Fischer and Weichhold’s conclusion, d-CHPh(NH,)*CO,Et + Z-CHPh( OH)*CO,Et, Since fi1cKenzie and Clough (J. 1909 95, d-CHPh( NH,)*CO,H -+ Z-CI-IPh( OH)*CO,H the grouping >?-?< is being continued. OH NH, E x P E R I M E N T A L. Semipinacolinic Dearnination of p-Amino-aa-diphenyl-n-propyl Alcohol .-Ethyl r-alanine hydrochloride (compare Curtius and Koch J .pr. Chem. 1888 [ii] 38 472; Barker and Skinner J . Amer. Chem. Xoc. 1924 46 403) was conveniently prepared as follows A current of dry hydrogen chloride was passed into a suspension of r-alanine (10 g . ) in ethyl alcohol (200 c.c.) for 1 hour, and the mixture after boiling for 1 hour longer was evaporate 288 MCKENZIE AND WILLS CONVERSION OF to dryness a t the ordinary temperature under 15 mm. pressure. The resulting syrup solidified when kept over soda-lime in a vacuum. It crystallised from ethyl acetate in needles (15.5 g. ; 90% of the theoretical). Ethyl r-alanine hydrochloride (20 g.) was added gradually to the Grignard reagent prepared from bromobenzene (245 g.) and the mixture heated for 8 hours.The product was decomposed by ice ammonium chloride and ammonia. The residual solid was extracted with ether and added to the main ethereal solution. After removal of ether and diphenyl as usual, the product (20 g.) was dissolved in hydrochloric acid and pre-cipitated by ammonia This treatment was repeated and then the product was crystallised three times from aqueous alcohol. P- Amino- cccc-diphenyl -n-prop yl alcohol separates from aqueous alcohol in rhombohedra1 plates m. p. 101-5-102~5" is readily soluble in ethyl alcohol methyl alcohol benzene toluene carbon tetrachloride carbon disulphide acetone or ether and very spar-ingly soluble in water (Found C z 79.4; H = 7-7 ; N = 6.2. C1,HI,ON requires C = 79.3 ; H = 7.5 ; N = 6.2%).A trace added to concentrated sulphuric acid assumes a golden-yellow tint and the solution becomes a t first pink and quickly colourless. A solution of 4-5 g. of sodium nitrite in 20 C.C. of water was gradually added (9 hour) to a solution of 5 g. of the amino-alcohol in 150 C.C. of 25% acetic acid cooled at 0". A flocculent pre-cipitate was gradually deposited which was filtered off after 24 hours and crystallised from aqueous alcohol. The silky needles (m. p. 50-51") which separated amounted to 4 g. and were identified as methyldeoxybenzoin (Found C = 85.8 ; H = 7.0. Calc. C = 85.7; H = 6.7%). There was no depression of the melting point when this substance was mixed with a specimen of the methyldeoxybenzoin prepared by McKenzie and Roger (J., 1924 125 844) by the dehydration of methylhydrobenzoin with concentrated sulphuric acid.The coloration observed wit8h con-centrated sulphuric acid was identical with that described by McKenzie and Roger for their product. The identity of the sub-stance was also proved by its behaviour towards magnesium phenyl bromide when accp-triphenylpropyl alcohol m. p. 86-5-87-5" was isolated. The latter compound had already been prepared by Mlle LBvy (Bull. Xoc. chim. 1921 [iv] 29 878) and by McKenzie and Roger. Hydrochlorides of Ethyl d- and 1-Pheny1aminoncetntes.-The optic-ally active phenylaminoacetic acids were prepared by E. Fischer and Weichhold (Ber. 1908 41 1286) who resolved the formyl r-acid by cinchonine and quinine and then hg'drolysed the d-and I-formyl acids with hydrobromic acid.The resolution o AMINO-AC'TDS TSTO TERTTAR'I' AMINO-.iT,C'OHOT>S. 289 ./.-phen~-larninoacetic acid into its opt ic'ally nc t ivc components by means of Reychler's d-camphor- 3-sulphonic acid in aqueous solu-tion has been described by Betti and Xayer (Ber. 1808 41 2071) and by Marvel and Noyes ( J . il?n,eY. Clzem. Soc. 1920 42 2259), the acids being einploj-etl in equiivolecular quantities. I n the inoclification described 1)y Ingersoll a i d Adanis ( J . Arne?.. Phem. Soc. 1922 44 2930) an c s c c ~ of tlic cauil>liorsulphouic acid was used. Since the latter aciti contains Tvater of carystallisation (Pope and Gibson ,J. 19l0 97 2211 ) ? antl sincc this may possibly be ])resent in varying ciiiantitj- T\ c employed this ruethotl.The optically pure 7-acicl was obtainetl by adding the rqiiisite amount of aiiiiiionia to the solntion of the salt o1)tainccl after several c~rystallisations. Thc cl-acid maj- t e preprcd from the acid mixture obtninecl from the first inother-iiqixor of the preceding rcsolutioii either by nieaiis of rl-r.-~rc~~ocaml~lior-,'3-siil~~~i~~iic acid or by formylating and then converting into the quinine salt. For the purification of the d-acid however it is more convenient to com-bine the crude acid with I-camphor-p-sulphonic acid and then to crystsllise until the caiii~~horsulplioiiate is homogeneous. Wc were enabled to conduct the resolution in thc latter iiianiicr owing t o the generous gift of c2 supply of I-csniphor from Sir William Pope.The I-camphorsulplioiiic acid. obtained from E-camphor by snlphon-ation in presence of acetic anhj-clride was crystallised from ethxl acetate and gave in aqueoiis solution 1 = 2 c = 3.8703 c ( ~ - 1-61', I-Camphorsulphonic ac-id combines with I-phenylarninoacetic acid to form a salt which is readily soliible in water from which i t separates in prisms. Its rotation n-as cleterininecl in aqueous solution : The diastereoisonieric salt. prepared froin d-camphorsulphonic acic1 and Lphenylaininoac4c acid has [.ID - 444)'i' (c' = 2.0883, I = 2) in aqueous solution (Hctti and Jfayer loc. cit.). This value enabled us to estimate the progress of the resolution of r-phenyl-amiiioacetic acid by (1- a lit1 Z-cninphorsulplioiiic acids. The polari-metric values for the I - a i d rI-pl~eiiS'1,2minoac.eiic acids obtained agreed with those of Fischer and Weichho1:l.Ethyl 1- P h e ~ ylarniiioacPtntc Ilylroch lor idc .-Fisclier and Weich -hold describe the conversion of I-pheii?.laminoacetic acid into the hydrochloride of its ethyl ester TI liicli they describe as dextro-rotatory [~(]fy f- S8.93" in aqucouc; so1::tjoii (21 = 5.021 d = 1.0087). For example a current of dry hydrogen chloride n-as 1)assecl into a mixture of 3.3 g. of l-phenyl-aminoacetic acid ant1 40 C . C . of etl1j.I alcohol for 1 hours. The solution was then boiled for a few minutes and filtered from a VOL. CXXVIT. L [.ID - 20.8". 1 = 2 G = 4.630 xD - 6*G4" [.ID - 51.7". Our results were (1 iffcrent 290 MCEENZIE AND WILLS CONVERSION OF small amount of solid.The alcohol was removed from the filtrate by gentle warming under diminished pressure the resulting acid dissolved in 20 C.C. of water and an equal volume of benzene added. The addition of the requisite amount of ammonia caused the separ-ation of the ester which was extracted with benzene. A current of dry hydrogen chloride was passed into the benzene solution for 15 minutes when the crystalline ester h~drochloride (4.2 g.) separ-ated. It had the following rotation i n aqiieous sollition 7 =1, Marvel and Noyes also obtained a laworotatory ester hydro-chloride with [.]* - 84.6" (concentration not quoted) from the I-amino-acid. The dextrorotation recorded by Pischer and Weich-hold is possibly due to a typographical error. Ethyl d-phenylapninoacetate hydrochloride was prepared in a similar manner from d-phenylaminoacetic acid 6.1 g.being obtained from 5.8 g. of d-acid. It was dextrorotatory in aqueous solution: Action of Magnesium Phenyl Bromide on the Hydrochlorides of Ethyl d- and 1-Pheny1aminoacetate.-The d-ester hydrochloride (6 g. ; 1 mol.) was gradually added wit!hin 15 minutes to the Grignard reagent prepared from 52 g. of bromobenzene (12 mols.) 16.5 g. of magnesium and 350 C.C. of ether and the mixture heated for 49 hours. After decomposition of the product with ice and ammonium chloride and remaining over-night the ethereal layer was separated and the aqueous layer extracted with ether. The ether and the diphenyl were removed the latter by steam dis-tillation. The residual yellow solid (8 g.) was crystallised from ethyl alcohol until the product after drying over concentrated sulphuric acid in a vacuum until constant gave a value which remained unchanged on polarimetric examination after repeated cry stallisation.d- @-Amino- axp-triphenylethyE alcohol is somewhat sparingly s o h ble in ethyl alcohol and separates in colourless needles m. p. 129.5-130° whereas the r-isomeride (McKenzie and Barrow J. 1913, 103 1331) melts a t 154-5-155". A trace of it added to con-centrated sulphuric acid gives a pink coloration which quickly becomes orange-brown. It is readily soluble in chloroform ether, benzene or acetone (Found C = 83.1 ; H == 6.8. C,,HISON requires C = 83.0 ; H = 6.6%). The substance has the opposite sign of rotation to thc original ester hydrochloride bcing strongly lzevorotatory in chloroform : I = 2 c = 1.276 a:f - 6-19" [a]:? - 243".In benzene 1 = 2, The I-ester hydrochloride (5 g.) was acted on by magnesium c = 5.070 ED - 4-53' [RID - 89.3". 2 = 1 c = 5.070 ED $- 4-60' [.ID 90.7". c = 2.027 - 9-45" [CC]:" - 233" AMINO-AUIDS INTO TERTIARY AMINO-ALCOHOLS. 291 phenyl bromide under conditions similar to those just described. Yield of crude amino-alcohol = 6 g. It was purified by crystallis-ation from ethyl alcohol, 1-p-Amino-aap-triphenylethyl alcohol has m. p. 129.5-130" (Found : N = 4.9. C,,H1,ON requires N = 4.8%). The compound is strongly dextrorotatory in chloroform 1 = 2 c = 1,304 ug5' + 6*34" + 243". I = 2 c = 1.304 $- 7*63" [~]:4;~ + 293". In bcnzene 1 = 2 c = 2.017 a:' + 9.44" [ a ] r + 234".Action of Nitroes Acid on d- (3 -Amino- a a p -triphen ylethyl Alcohol .-A solution of the d-amino-alcohol (0.68 g.) in 50 C.C. of dilute acetic acid was cooled in a freezing mixture of ice and salt and a solution of 0.5 g. of sodium nitrite in 5 C.C. of water added during 20 minutes. The solid (0.6 g.) which separated was crystallised from ethyl alcohol and 0.42 g. of phenyldeoxybenzoin needles m. p. 134-135" was obtained. It gave the characteristic emerald-green coloration with concentrated sulphuric acid. Its solution in chloro-form was optically inactive. Isomeric Camphorsulphonates of the d- and 1-Amino-Alcohol.s.-I-p-Amino-aap-triphenylefhanol d-camphorsulphonate prepared by combining the 1-amino-alcohol (1 mol.) with d-camphor-p-sulphonio acid (1 mol.) in ethyl-alcoholic solution separates in needles, m.p. 200-201" (decomp.) (Found S = 6.3. C,,H,,O,S requires S = 6.1%). In ethyl alcohol I = 2 c = 0.8568 a g + 2.08", [a]':' + 121"; I = 2 c = 04568 a:::* + 2*41" [a]:!&' + 143". The enantiomorphously related d-p-amino-aap-triphenylethanol 1-camphorsulphonate separates from ethyl aicohol in needles m. p. 200-2001" (decomp.) (Found N = 2.9. C,,H,,?N requires N = 2.7%). I n ethyl alcohol 1 = 2 c = 0.80 a:," - 1.91" [a]:' -119"; 1 = 2 c = 0.80, 1- p-Amino-aap-triphenylethanol I-camphorsulphonate separates from ethyl alcohol in needles m. p. 213.5-214.5" (decomp,). In ethyl alcohol 1 = 2 c = 0,4448 ag5' + 0*68" [a]:G' + 76"; I = 2, c = 0.4448 a::; + 0*76" [a];$ + 85". The enantiomorphously related d-P-amino-aap-triphenylethanol d-camphorsdphonate separates from ethyl alcohol in needles m.p. 213.5-2146" (decomp.) (Found S = 6.2. C1,H,,O,S requires S = 6.1%). In ethyl alcohol 1 = 2 c = 0.40 ag' - 0*61", [a]:"' - 76"; 1 = 2 c = 040 a:& - 0*72" [a]::;1 - 90". It is insoluble in most organic solvents moderately soluble in hot ethyl alcohol or water and sparingly soluble in these solvents a t the ordinary temperature. The concentrations employed in the determination of specific rotatory power were necessarily low so that the values for the specific rotatory power have little significance. Attempts were made to resolve the r-amino-alcohol by d-camphor-- 2-31' [a]iSI - 144". L 292 MCKENZIE AND WILLS CONVERSION OF p-sulphonic acid both in aqueous and ethyl-alcoholic solution.The progress of the resolution was however too slow to enable the method to be used as a preparative one for the d- and 1-amino-alcohols. Action of Magnesium Phenyl Bromide on a-Aminohydratropic Acid.-The amino-acid (6 g.; 1 mol.) prepared according to McKenzie and Clough (J. 1912 101 390) was added in instal-ments (Q hour) to the Grignard reagent (12 11101s.) prepared from bromobenzene (71 g.) and the mixture was heated for lo+ hours. After decomposition with ice and ammonium chloride the remain-ing solid was extracted with ether and the solution added to the main ethereal solution. The ether and diphenyl were removed ; the resulting oil solidified. Yield 5 g. It was tlriturated with light petroleum and the solid then crystnllised from rectified spirit until pure.p- Amino- ma p -triphen yl- p-methyleth yl alcohol separates from re cti-fied spirit in rectangular plates is soluble in benzene and chloro-form and melts a t 113-114" (Pound C = 83.0; H = 7.2; N = 4.8. C2,H210N requires C = 83.1 ; H = 7.0; N = 4.6%). A trace of this compound added to concentrated sulphuric acid produces an orange coloration which changes quickly to a permanent crimson colour. Action of Magnesium Phenyl Bromide on r-Phenyla1anine.-No visible action took place when r-phenylalanine (3 g.; 1 mol.) was gradually added to the Grignard reagent (12 mols.) prepared from 34 g. of bromobenzene. The mixture was heated for 20 hours, and then the additive compound was decomposed with ice and am-monium chloride.The ethereal layer was withdrawn and then the ether and diphenyl were removed from it in the usual manner. The residual solid amounted to 4 g. which were crystallised from ethyl alcohol. The yield of pure amino-alcohol was 2-4 g. cor-responding in crystalline form and melting point with r-p-amino-aa-diphenyl- P-benzylethyl alcohol which was prepared by McKenzie and Richardson (J. 1923 123 79) from the ethyl ester hydro-chloride of phenylalanine by the action of magnesium phenyl bromide. Action of Magnesium Phenyl Bromide on d- Phenyla1anine.-r-Phenylalanine was resolved by the alkaloidal method of E. Fischer and Schoeller (Annalen 1907 357 2) and d-phenylalanine was isolated with a specific rotation in aqueous solution of + 35.0" ( I = 2 c = 2.043 aD + 1.43") this value being identical with that quoted by Fischer and Schoeller.Three g. of this amino-acid were treated in the manner recorded in the above experiment, with the exception that the mixture was heated for 24 instead of Yield 2 g AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 293 20 hours. 4.2 G. of crude omino-alcohol were obtained and were crystallised froin ethyl alcohol several times until a steady value for the specific rotation was obtained in chloroform I = 2 c = 4-06" [CI],;:~;~ + 99.2". In benzene Z = 2 c r= 2.0512 E:!:" + 4-32', This compound has the same sign of rotation as the original amino-acid and since 110 configurative change can take place in the transformation of the amino-acid into the amino-alcohol it is accordifigly designated as d- ~-cr?,iiiio-ax-diphe?~~~- P-be?zxylethyl alcohol.It crystallises from ethyl alcohol in flat glassy needles m. p. 143-1Uo is soluble in acetone h i z z n e chloroform ether or toluene, but is insoluble in T.\.-ater (Found N = 4.6. C',lH,lON requires N = 4-60/,). A trace of the compound added to concentrated sulphuric acid produces an orange-brown coloration which quickly changes to pale pink and then gradually fades. This coloration is also observed with the corresponding r-amino-alcohol. Hydrolysis of Ethfyl 1-Yl~eiz~lnmiiioacetate Hydrochloride.-The Lester hydrochloride (1 g.) in 30 C.C. of ethyl-alcoholic potassium hydroxide (0.4487L\') remained for 24 hours a t the ordinary tem-perature and was then heated on the water-bath for 30 minutes.The alcohol was removed under diminished pressure the residue dissolved in water and the solution extracted with benzene to remove any trace of unchaiiged ester. The aqueous solution was then neutralised with hydrochloric acid and the amino-acid (0.5 g.) was separated. Its specific rotation was determined as follows : 0.3719 g. was dissolved in 3.35 C.C. of X-hydrochloric acid and 1.5 C.C. of water I = 0.5 p = i-193 d = 1.0286 xD - 0*4G" - 12-4". 3'11 c ester Iiydrochloridc was completely hydrolysed . Pa ~t icr l Den in i iiu t ion of I - Phe ii yln nzi 11 oncet ic d c id .-A solution of sodium nitrite (0.41 g.) in water ( 2 c.c.) was added drop by drop (30 minutes) to a solution of the I-amino-acid ( 2 g.) in X-sulphuric acid (30 c.c.) t L t 0". After 5 hours at 0" and 18 hours a t the ordinary tomperaturc the amiiio-acid (1.33 g.) as precipitated by the addition of aniiiioiiia in slight excess.0.7438 G . was dissolved in 6.7 C.C. of n'-hydrochloric acid and 3 c.c. of vcater I = 1 p = 7.193 dJ' = 1.0286 x ~ - L1.36" '[RID - 133-5" whereas thc originzl I-acid had Thc ammoniacal solution from which the amino-acid had been scparated TT~C?S acidified n-ith dilute hydrochloric acid and extracted with cther. The I-esulting mmdelic acid (0.23 6.) was slightly tlestrorotatory in aqueous solution Z = 2 c = 1.055 clD + 0.13". Deuminalioiz. of Ethyl l-Pl~ciiylnmi.Iioacetate.-~~~ethocl of E. F'isclzer und TPeichhoZd. These authors acted on the d-ester with nitrous 2.0472 c(::'* + 3.48" [XI;:'* + 85.0" ; l = 2 c = 2.0472 a3:;' + [a]::' + 105-3"; Z = 2 c = 2.0312 MI,; + 5*03" [cx]~$ + 122.6".- 156' under similar conditions 294 CONVERSION OF AMINO-ACIDS INTO THRTIARY AMINO-ALCOHOLS. acid and obtained a lzevorotatory ethyl mandelate with about [.ID - 10" in acetone solution On following their directions, using ethyl Z-phenylaminoacetate (0.90 g . ) in place of the d-ester, the resulting mandelic ester (0.325 g.) was dextrorotatory. A 10% solution gave ccD + 0.45" in a 0.5 dcm.-tube so that the value for the specific rotation is approximately + 9". The result of Fischer and Weichhold was thus confirmed. It should be stated that after the addition of the nitrite the solution remained over-night a t the ordinary temperature. The large amount of racemisation which accompanied this change is apparent when it is recalled that ethyl E-mandelate has according to Walden (2.physikal. Chem. 1895 17 705) [.ID - 90.6" in acetone solution. The dextrorotatory ester obtained above gave a negative result when tested for nitrogen. It was hydrolysed by 4.5 C.C. of aqueous potassium hydroxide (0.5755N) at the ordinary temperature for 18 hours. The solution was extracted with ether to remove any unsaponified ester and the rnandelic acid isolated from the aqueous solution as usual. The resulting acid (0.14 g.) was dextrorotatory in aqueous solut'ion E = 2 c = 0.622 uD + 0.27". Method of Marvel and Noyes. A solution of sodium nitrite (1.6 g.) in water (2.5 c.c.) was added drop by drop with constant stirring for 30 minutes to a solution of ethyl E-phenylaminoacetate hydrochloride (5.4 g.) in N-sulphuric acid (33 c.c.) the temperature being kept a t 0" throughout.A yellow oil separated. After 1 hour a t 0" and 2 hours a t the ordinary temperature the solution was extracted with ether the ethereal solution dried with anhydrous sodium sulphate and the ether expelled. The resulting oil was distilled and the portion (1.5 g.) b. p. 127-132"/18 mm. collected. I n acetone E = 2 c = 10 uD - 0.35'. The product obtained by Marvel and Noyes was also laevo-rotatory . When this oil was tested for nitrogen it gave a positive result. On hydrolysis under conditions similar to those described in the previous experiment it gave a mandelic acid (0.8 g . ) which was slightly dextrorotatory in aqueous solution I = 2 c = 3.109, This shows that the lzevorotation observed by Marvel and Noyes was not due to ethyl Z-mandelate but rather to the presence of an intermediate lzvorotatory diazo-compound which gradually passes into ethyl d-mandelate with lapse of time.That this view is probable appears from the result of the second experiment quoted below. The unattacked ethyl phenylaminoacetate hydrochloride was recovered from the aqueous solution remaining after the extraotion C(D $- 0.10" NEWBERY THE ACTION OF CAUSTIC ALKALI ETC. 295 of the deamination product with ether. The solution was made alkaline with ammonia extracted with benzene the benzene solution dried and dry hydrogen chloride passed in to precipitate t'he ester hydrochloride Yield 2 g. In aqueous solution 1 = 1 c = 5.07 aD - 469" [ a ] D - 90.5".The regenerated hydrochloride had thus practically the same rotation as the original. In a second experiment where 7 g. of the Lester hydrochloride were employed the conditions of deamination were exactly similar to those just described except that the solution after being kept a t 0" was allowed to remain for 39 instead of 2 hours. The resulting oil (2 g.) which gave a positive test for nitrogen mas in this case dextrorotatory in acetone solution E = 1 c = 10 tcD + 0.30". On hydrolysis with aqueous alkali under similar conditions to those adopted in the other experiments the resulting mandelic acid was dextrorotatory in aqueous solution I = 2 c = 3.32, The amino-ester hydrochloride was recovered as before. In The latter was filtered off.a D + 0.19". aqueous solution 1 = 1 c = 5.07 mD - 4-57" [.ID - 90.1". M7e desire to express our best thanks to the Department of Scientific and Industrial Research and to the Carnegie Trust for their assistance. We are also indebted to Dr. H. J. Plenderleith for his assistance in the deamination of p-amino-act-diphenyl-n-propyl alcohol. UNIVERSITY COLLEGE D UNDEE. UNIVERSITY OF ST. ANDREWS. [Received December 5th 1924. CONVERSION or AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 283 XLVI:.-Conversion of Amino-acids into Tertiary Amino-alcohols. By ALEX. MCKENZIE and GEORGE OGILVIE WILLS. THE first application of Grignard reagents towards esters of amino-acids was made by Baeyer and Villiger (Ber. 1904 37 3191), who converted methyl anthraiiilate into o-aminotriphenylcarbinol by means of magnesium phenyl bromide.Paal and Weidenkaff (Ber. 1905 38 1686) obtained p-amino-ua-diphcnylethyl alcohol from ethyl glycine (compare also Paal and Weidenkaff Ber. 1906, 39 810 4344; Krassusky Cornpt. rend. 1908 146 236). The Grignard reaction has been also applied in this laboratory for preparing amino-alcohols in connexioii with the study of semi-pinacolinic deamination. Since other workers (Thomas and Bett-zieche 2. physiol. Chem. 1924 140 244 261 279; Bettzieche, ibid. 273) have entered the same field quite recently we think it desirable to describe our further results. The elimination of the amino-group in tertiary amino-alcohols has heen dealt with (BlcKenzie and Richardson J . 1923 123 79; McKeiizie and Roger J.1924 125 844; McKenzie and Dennler, J. 1924 125 2105). The first instance described in the literature as a semipinacolinic deamination arose from the accidental discovery that the transformation OH*CPh,CHPh*NU 3 OH*CPli,*CHPh*O 284 MCKENZIE AND WILLS CONVERSION OF could not be effected by the agency of nitrous acid; the product of the action was phenyldeoxybenzoin and not triphenylethylene glycol. p-Amino-ctap-triphenylethyl alcohol was prepared by McKenzie and Barrow (J. 1913 103 1331) by the action of mag-nesium phenyl bromide on r-desylamine hydrochloride and later on r-phenylaminoacetic acid by McKenzie and Richardson. Thomas and Bettzieche have repeated its preparation from phenylamino-acetic acid and confirmed the conversion into phenyldeoxybenzoin.The conversion of r-phenylalanine into r- p-amino-p-benzyl-acc-diphenylethyl alcohol was also carried out in this laboratory and it was shown that the amino-alcohol undergoes semipinacolinic deamination : 7 Fh H ph I (bv HNO,) CH,Ph*y-y=Ph - + CH,Ph*C-yPh + NH OH ":&-OH OH CH2Ph>CH*CO*Ph. 4 bh CH,Ph*QH-(!*Ph * Ph -0 The phenyl group migrates and the product is benzyldeoxybenzoin. Those results are also confirmed by Thomas and Bettzieche. According to Paal and Weidenkaff (Zoc. cit.) the action of nitrous acid on p-amino-am-diphenylethyl alcohol leads to the formation of as-diphenylethylene oxide : I n the light of our work on semipinacolinic deamination it seemed possible that this conclusion was erroneous and that the product was actually deoxybenzoin.By arrangement with us Professor Tiffeneau and M. Or6khov had kindly undertaken the investigation of this point which meanwhile has been solved by Bettzieche. The product is deoxybenzoin and we would interpret its formation on the following lines the phenyl group migrating thus AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 285 I n a former paper we mentioned that we were continuing our study of the action of nitrous acid on compounds containing the >‘-?< with the object of extending our experience group b H NH, ultimately to optically active amino-alcohols. Accordingly in the present paper we describe the action of magnesium phenyl bromide on r-alanine thus : The amino-alcohol on deaminntion gave met,hyldeoxybenzoin : and thus pfovided another instance of the striking regularity with which the phenyl group migrates in all the cases of semipinacolinic deamination which have been studied.The change may be contrasted with the vinyl dehydration of r-methylhydrobenzoin studied by Tiff eneau and Or6khov (Bull. SOC. chim. 1921 [iv] 29 422) and by McKenzie and Roger inci-dentally to their work on the dehydration of optically active methylhydrobenzoin by concentrated sulphuric acid : The above result has already been arrived at by Bettzieche, who carried out the action with a trace of the amino-alcohol. In the light of the work of McKenzie and Roger as applied to the optically active methyl- and ethyl-hydrobenzoins the extension of this action to the optically active amino-alcohol derived from d-alanine presents obvious points of interest and we are a t present engaged in the investigation of this topic.As already stated the action of nitrous acid on p-amino-asp-triphenylethyl alcohol had been examined with the object of obtaining triphenylethylene glycol. The optically active forms of the latter compound had already been described (McKenzie and Wren J. 1910 97 473; XcKenzie Drew and Martin J., 1915 107 26) and the change in question if carried out with the optically active amino-alcohols would have provided data in connexion with the Walden inversion. This scheme however 286 MCKENZIE AND WILLS CONVERSION OF cannot be effected in practice for the reasons already given. Never-theless we have thought it desirable that the optically active amino-alcohols should a t least be prepared.The description of their preparation is now given in the experimental part. The compounds in question are highly active giving [XI, & 243" in chloroform; they rotate the plane of polarisation in the opposite sense to the phenylaminoacetic acids from which they are prepared. There is no configurative change here however since there is no substitution of a group directly attached to the asymmetric carbon atom so that the compound which is derived from d-phenylamino-acetic acid is designated as d- (3-amino-actp-triphenylethyl alcohol, although it is lzvorotatory d-phenylaminoacetic acid being taken as the reference type. It is rather curious to note that a similar change of sign of rotat'ion also occurs when methyl I-mandelate is converted by magnesium phenyl bromide into triphenylethylene glycol (McKenzie and Wren 7oc.c i t . ) . The action of nitlrous acid on the ci-amino-alcohol gives an optic-ally inactive product owing t o semipinacolii? ic deamination the product being phenyldeoxybenzoin. The isomeric camphorsulphonates of the d- and I-amino-alcohols were prepared but the resolution of the 1.-alcohol by d-camphor-S-sulphonic acid gave a very slow and imperfect separation and the method was obviously unsatisfactory. We are a t present engaged in resolving by means of camphorsulphonic acids the r-amino-alcohols related to desylamine. The changes C<R -+ d- CH,Ph>C- and d- CH,Ph*CH(NH,)*CO,H NH HO are also described but the study of the action of nitrous acid on the amino-alcohols has not yet been completed.Arising from the present research the following points have been investigated. The ethyl ester hydrochloride of Z-phenyl-aminoacetic acid gives on hydrolysis with a slight excess of alcoholic potash a phenylaminoacetic acid with [.ID - 12.4" in hydrochloric acid solution whereas the pure Z-acid has [.ID - 157.8" in the same solvent. This result was anticipated since in phenylaminoacetic acid we have both a phenyl group and a migrational hydrogen atom in direct attachment to the asymmetric carbon atom. McKenzie and Walker (J. 1915 107 1685) have shown that catalytic racemisation occurs when I-phenylbromoacetic acid i AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS. 287 acted on by ammonia. When the action was conducted in benzene solution that portion of the bromo-acid which had survived the attack of the ammonia had become largely racemised.It was thought possible that soniething of the same kind might occur when Z-phenylaminoacetic acid is acted on by nitrous acid; such, however is not the case. There was one other rather important point in connexion with tlhe study of the Walden inversion in the mandelic acid series which clearly required elucidation. E. Fischer and Weichhold (Ber. 1908 41 1286) acted on ethyl d-phenylaminoacetate with nitrous acid and obtained a change of sign of rotation the resulting ethyl mandelate being highly racemised and lanorotatory . On the other hand Marvel and Noyes ( J . Amer. Chern. Xoc. 1920 42, 2259) by acting on a solution of thc hydrochloride of ethyl 1-plieiiylaminoacctate in dilute sulphuric acid with nitrous acid, obtained an ethyl maidelate of the same sign of rotation as that of the original ethyl I-phenylaminoacetatc.We have repented the work both of Fischer and Weichliolcl and of Marvel and Noyes, and have found that a change of sign of rotation occurs when ethyl Z-phenylaminoacetate is acted on by nitrous acid if the solution, before the ester is extracted is kept sufficiently long after the addition of the nitrite. is therefore correct. 777) have shown that the change occurs the behaviour both of the ester and of the free acid towards nitrous acid is similar. The product obtained by the method of the American workers was contaminated with a nitrogenous com-pound (probably a diazo-compound).It seems that they had proceeded to isolate their ethyl mandelate too quickly after the addition of the sodium nitrite. The work on the action of nitrous acid on compounds containing Fischer and Weichhold’s conclusion, d-CHPh(NH,)*CO,Et + Z-CHPh( OH)*CO,Et, Since fi1cKenzie and Clough (J. 1909 95, d-CHPh( NH,)*CO,H -+ Z-CI-IPh( OH)*CO,H the grouping >?-?< is being continued. OH NH, E x P E R I M E N T A L. Semipinacolinic Dearnination of p-Amino-aa-diphenyl-n-propyl Alcohol .-Ethyl r-alanine hydrochloride (compare Curtius and Koch J . pr. Chem. 1888 [ii] 38 472; Barker and Skinner J . Amer. Chem. Xoc. 1924 46 403) was conveniently prepared as follows A current of dry hydrogen chloride was passed into a suspension of r-alanine (10 g .) in ethyl alcohol (200 c.c.) for 1 hour, and the mixture after boiling for 1 hour longer was evaporate 288 MCKENZIE AND WILLS CONVERSION OF to dryness a t the ordinary temperature under 15 mm. pressure. The resulting syrup solidified when kept over soda-lime in a vacuum. It crystallised from ethyl acetate in needles (15.5 g. ; 90% of the theoretical). Ethyl r-alanine hydrochloride (20 g.) was added gradually to the Grignard reagent prepared from bromobenzene (245 g.) and the mixture heated for 8 hours. The product was decomposed by ice ammonium chloride and ammonia. The residual solid was extracted with ether and added to the main ethereal solution. After removal of ether and diphenyl as usual, the product (20 g.) was dissolved in hydrochloric acid and pre-cipitated by ammonia This treatment was repeated and then the product was crystallised three times from aqueous alcohol.P- Amino- cccc-diphenyl -n-prop yl alcohol separates from aqueous alcohol in rhombohedra1 plates m. p. 101-5-102~5" is readily soluble in ethyl alcohol methyl alcohol benzene toluene carbon tetrachloride carbon disulphide acetone or ether and very spar-ingly soluble in water (Found C z 79.4; H = 7-7 ; N = 6.2. C1,HI,ON requires C = 79.3 ; H = 7.5 ; N = 6.2%). A trace added to concentrated sulphuric acid assumes a golden-yellow tint and the solution becomes a t first pink and quickly colourless. A solution of 4-5 g. of sodium nitrite in 20 C.C. of water was gradually added (9 hour) to a solution of 5 g. of the amino-alcohol in 150 C.C.of 25% acetic acid cooled at 0". A flocculent pre-cipitate was gradually deposited which was filtered off after 24 hours and crystallised from aqueous alcohol. The silky needles (m. p. 50-51") which separated amounted to 4 g. and were identified as methyldeoxybenzoin (Found C = 85.8 ; H = 7.0. Calc. C = 85.7; H = 6.7%). There was no depression of the melting point when this substance was mixed with a specimen of the methyldeoxybenzoin prepared by McKenzie and Roger (J., 1924 125 844) by the dehydration of methylhydrobenzoin with concentrated sulphuric acid. The coloration observed wit8h con-centrated sulphuric acid was identical with that described by McKenzie and Roger for their product. The identity of the sub-stance was also proved by its behaviour towards magnesium phenyl bromide when accp-triphenylpropyl alcohol m.p. 86-5-87-5" was isolated. The latter compound had already been prepared by Mlle LBvy (Bull. Xoc. chim. 1921 [iv] 29 878) and by McKenzie and Roger. Hydrochlorides of Ethyl d- and 1-Pheny1aminoncetntes.-The optic-ally active phenylaminoacetic acids were prepared by E. Fischer and Weichhold (Ber. 1908 41 1286) who resolved the formyl r-acid by cinchonine and quinine and then hg'drolysed the d-and I-formyl acids with hydrobromic acid. The resolution o AMINO-AC'TDS TSTO TERTTAR'I' AMINO-.iT,C'OHOT>S. 289 ./.-phen~-larninoacetic acid into its opt ic'ally nc t ivc components by means of Reychler's d-camphor- 3-sulphonic acid in aqueous solu-tion has been described by Betti and Xayer (Ber.1808 41 2071) and by Marvel and Noyes ( J . il?n,eY. Clzem. Soc. 1920 42 2259), the acids being einploj-etl in equiivolecular quantities. I n the inoclification described 1)y Ingersoll a i d Adanis ( J . Arne?.. Phem. Soc. 1922 44 2930) an c s c c ~ of tlic cauil>liorsulphouic acid was used. Since the latter aciti contains Tvater of carystallisation (Pope and Gibson ,J. 19l0 97 2211 ) ? antl sincc this may possibly be ])resent in varying ciiiantitj- T\ c employed this ruethotl. The optically pure 7-acicl was obtainetl by adding the rqiiisite amount of aiiiiiionia to the solntion of the salt o1)tainccl after several c~rystallisations. Thc cl-acid maj- t e preprcd from the acid mixture obtninecl from the first inother-iiqixor of the preceding rcsolutioii either by nieaiis of rl-r.-~rc~~ocaml~lior-,'3-siil~~~i~~iic acid or by formylating and then converting into the quinine salt.For the purification of the d-acid however it is more convenient to com-bine the crude acid with I-camphor-p-sulphonic acid and then to crystsllise until the caiii~~horsulplioiiate is homogeneous. Wc were enabled to conduct the resolution in thc latter iiianiicr owing t o the generous gift of c2 supply of I-csniphor from Sir William Pope. The I-camphorsulplioiiic acid. obtained from E-camphor by snlphon-ation in presence of acetic anhj-clride was crystallised from ethxl acetate and gave in aqueoiis solution 1 = 2 c = 3.8703 c ( ~ - 1-61', I-Camphorsulphonic ac-id combines with I-phenylarninoacetic acid to form a salt which is readily soliible in water from which i t separates in prisms.Its rotation n-as cleterininecl in aqueous solution : The diastereoisonieric salt. prepared froin d-camphorsulphonic acic1 and Lphenylaininoac4c acid has [.ID - 444)'i' (c' = 2.0883, I = 2) in aqueous solution (Hctti and Jfayer loc. cit.). This value enabled us to estimate the progress of the resolution of r-phenyl-amiiioacetic acid by (1- a lit1 Z-cninphorsulplioiiic acids. The polari-metric values for the I - a i d rI-pl~eiiS'1,2minoac.eiic acids obtained agreed with those of Fischer and Weichho1:l. Ethyl 1- P h e ~ ylarniiioacPtntc Ilylroch lor idc .-Fisclier and Weich -hold describe the conversion of I-pheii?.laminoacetic acid into the hydrochloride of its ethyl ester TI liicli they describe as dextro-rotatory [~(]fy f- S8.93" in aqucouc; so1::tjoii (21 = 5.021 d = 1.0087).For example a current of dry hydrogen chloride n-as 1)assecl into a mixture of 3.3 g. of l-phenyl-aminoacetic acid ant1 40 C . C . of etl1j.I alcohol for 1 hours. The solution was then boiled for a few minutes and filtered from a VOL. CXXVIT. L [.ID - 20.8". 1 = 2 G = 4.630 xD - 6*G4" [.ID - 51.7". Our results were (1 iffcrent 290 MCEENZIE AND WILLS CONVERSION OF small amount of solid. The alcohol was removed from the filtrate by gentle warming under diminished pressure the resulting acid dissolved in 20 C.C. of water and an equal volume of benzene added. The addition of the requisite amount of ammonia caused the separ-ation of the ester which was extracted with benzene.A current of dry hydrogen chloride was passed into the benzene solution for 15 minutes when the crystalline ester h~drochloride (4.2 g.) separ-ated. It had the following rotation i n aqiieous sollition 7 =1, Marvel and Noyes also obtained a laworotatory ester hydro-chloride with [.]* - 84.6" (concentration not quoted) from the I-amino-acid. The dextrorotation recorded by Pischer and Weich-hold is possibly due to a typographical error. Ethyl d-phenylapninoacetate hydrochloride was prepared in a similar manner from d-phenylaminoacetic acid 6.1 g. being obtained from 5.8 g. of d-acid. It was dextrorotatory in aqueous solution: Action of Magnesium Phenyl Bromide on the Hydrochlorides of Ethyl d- and 1-Pheny1aminoacetate.-The d-ester hydrochloride (6 g.; 1 mol.) was gradually added wit!hin 15 minutes to the Grignard reagent prepared from 52 g. of bromobenzene (12 mols.) 16.5 g. of magnesium and 350 C.C. of ether and the mixture heated for 49 hours. After decomposition of the product with ice and ammonium chloride and remaining over-night the ethereal layer was separated and the aqueous layer extracted with ether. The ether and the diphenyl were removed the latter by steam dis-tillation. The residual yellow solid (8 g.) was crystallised from ethyl alcohol until the product after drying over concentrated sulphuric acid in a vacuum until constant gave a value which remained unchanged on polarimetric examination after repeated cry stallisation. d- @-Amino- axp-triphenylethyE alcohol is somewhat sparingly s o h ble in ethyl alcohol and separates in colourless needles m.p. 129.5-130° whereas the r-isomeride (McKenzie and Barrow J. 1913, 103 1331) melts a t 154-5-155". A trace of it added to con-centrated sulphuric acid gives a pink coloration which quickly becomes orange-brown. It is readily soluble in chloroform ether, benzene or acetone (Found C = 83.1 ; H == 6.8. C,,HISON requires C = 83.0 ; H = 6.6%). The substance has the opposite sign of rotation to thc original ester hydrochloride bcing strongly lzevorotatory in chloroform : I = 2 c = 1.276 a:f - 6-19" [a]:? - 243". In benzene 1 = 2, The I-ester hydrochloride (5 g.) was acted on by magnesium c = 5.070 ED - 4-53' [RID - 89.3". 2 = 1 c = 5.070 ED $- 4-60' [.ID 90.7". c = 2.027 - 9-45" [CC]:" - 233" AMINO-AUIDS INTO TERTIARY AMINO-ALCOHOLS.291 phenyl bromide under conditions similar to those just described. Yield of crude amino-alcohol = 6 g. It was purified by crystallis-ation from ethyl alcohol, 1-p-Amino-aap-triphenylethyl alcohol has m. p. 129.5-130" (Found : N = 4.9. C,,H1,ON requires N = 4.8%). The compound is strongly dextrorotatory in chloroform 1 = 2 c = 1,304 ug5' + 6*34" + 243". I = 2 c = 1.304 $- 7*63" [~]:4;~ + 293". In bcnzene 1 = 2 c = 2.017 a:' + 9.44" [ a ] r + 234". Action of Nitroes Acid on d- (3 -Amino- a a p -triphen ylethyl Alcohol .-A solution of the d-amino-alcohol (0.68 g.) in 50 C.C. of dilute acetic acid was cooled in a freezing mixture of ice and salt and a solution of 0.5 g. of sodium nitrite in 5 C.C. of water added during 20 minutes.The solid (0.6 g.) which separated was crystallised from ethyl alcohol and 0.42 g. of phenyldeoxybenzoin needles m. p. 134-135" was obtained. It gave the characteristic emerald-green coloration with concentrated sulphuric acid. Its solution in chloro-form was optically inactive. Isomeric Camphorsulphonates of the d- and 1-Amino-Alcohol.s.-I-p-Amino-aap-triphenylefhanol d-camphorsulphonate prepared by combining the 1-amino-alcohol (1 mol.) with d-camphor-p-sulphonio acid (1 mol.) in ethyl-alcoholic solution separates in needles, m. p. 200-201" (decomp.) (Found S = 6.3. C,,H,,O,S requires S = 6.1%). In ethyl alcohol I = 2 c = 0.8568 a g + 2.08", [a]':' + 121"; I = 2 c = 04568 a:::* + 2*41" [a]:!&' + 143". The enantiomorphously related d-p-amino-aap-triphenylethanol 1-camphorsulphonate separates from ethyl aicohol in needles m.p. 200-2001" (decomp.) (Found N = 2.9. C,,H,,?N requires N = 2.7%). I n ethyl alcohol 1 = 2 c = 0.80 a:," - 1.91" [a]:' -119"; 1 = 2 c = 0.80, 1- p-Amino-aap-triphenylethanol I-camphorsulphonate separates from ethyl alcohol in needles m. p. 213.5-214.5" (decomp,). In ethyl alcohol 1 = 2 c = 0,4448 ag5' + 0*68" [a]:G' + 76"; I = 2, c = 0.4448 a::; + 0*76" [a];$ + 85". The enantiomorphously related d-P-amino-aap-triphenylethanol d-camphorsdphonate separates from ethyl alcohol in needles m. p. 213.5-2146" (decomp.) (Found S = 6.2. C1,H,,O,S requires S = 6.1%). In ethyl alcohol 1 = 2 c = 0.40 ag' - 0*61", [a]:"' - 76"; 1 = 2 c = 040 a:& - 0*72" [a]::;1 - 90". It is insoluble in most organic solvents moderately soluble in hot ethyl alcohol or water and sparingly soluble in these solvents a t the ordinary temperature.The concentrations employed in the determination of specific rotatory power were necessarily low so that the values for the specific rotatory power have little significance. Attempts were made to resolve the r-amino-alcohol by d-camphor-- 2-31' [a]iSI - 144". L 292 MCKENZIE AND WILLS CONVERSION OF p-sulphonic acid both in aqueous and ethyl-alcoholic solution. The progress of the resolution was however too slow to enable the method to be used as a preparative one for the d- and 1-amino-alcohols. Action of Magnesium Phenyl Bromide on a-Aminohydratropic Acid.-The amino-acid (6 g.; 1 mol.) prepared according to McKenzie and Clough (J.1912 101 390) was added in instal-ments (Q hour) to the Grignard reagent (12 11101s.) prepared from bromobenzene (71 g.) and the mixture was heated for lo+ hours. After decomposition with ice and ammonium chloride the remain-ing solid was extracted with ether and the solution added to the main ethereal solution. The ether and diphenyl were removed ; the resulting oil solidified. Yield 5 g. It was tlriturated with light petroleum and the solid then crystnllised from rectified spirit until pure. p- Amino- ma p -triphen yl- p-methyleth yl alcohol separates from re cti-fied spirit in rectangular plates is soluble in benzene and chloro-form and melts a t 113-114" (Pound C = 83.0; H = 7.2; N = 4.8. C2,H210N requires C = 83.1 ; H = 7.0; N = 4.6%).A trace of this compound added to concentrated sulphuric acid produces an orange coloration which changes quickly to a permanent crimson colour. Action of Magnesium Phenyl Bromide on r-Phenyla1anine.-No visible action took place when r-phenylalanine (3 g.; 1 mol.) was gradually added to the Grignard reagent (12 mols.) prepared from 34 g. of bromobenzene. The mixture was heated for 20 hours, and then the additive compound was decomposed with ice and am-monium chloride. The ethereal layer was withdrawn and then the ether and diphenyl were removed from it in the usual manner. The residual solid amounted to 4 g. which were crystallised from ethyl alcohol. The yield of pure amino-alcohol was 2-4 g. cor-responding in crystalline form and melting point with r-p-amino-aa-diphenyl- P-benzylethyl alcohol which was prepared by McKenzie and Richardson (J.1923 123 79) from the ethyl ester hydro-chloride of phenylalanine by the action of magnesium phenyl bromide. Action of Magnesium Phenyl Bromide on d- Phenyla1anine.-r-Phenylalanine was resolved by the alkaloidal method of E. Fischer and Schoeller (Annalen 1907 357 2) and d-phenylalanine was isolated with a specific rotation in aqueous solution of + 35.0" ( I = 2 c = 2.043 aD + 1.43") this value being identical with that quoted by Fischer and Schoeller. Three g. of this amino-acid were treated in the manner recorded in the above experiment, with the exception that the mixture was heated for 24 instead of Yield 2 g AMINO-ACIDS INTO TERTIARY AMINO-ALCOHOLS.293 20 hours. 4.2 G. of crude omino-alcohol were obtained and were crystallised froin ethyl alcohol several times until a steady value for the specific rotation was obtained in chloroform I = 2 c = 4-06" [CI],;:~;~ + 99.2". In benzene Z = 2 c r= 2.0512 E:!:" + 4-32', This compound has the same sign of rotation as the original amino-acid and since 110 configurative change can take place in the transformation of the amino-acid into the amino-alcohol it is accordifigly designated as d- ~-cr?,iiiio-ax-diphe?~~~- P-be?zxylethyl alcohol. It crystallises from ethyl alcohol in flat glassy needles m. p. 143-1Uo is soluble in acetone h i z z n e chloroform ether or toluene, but is insoluble in T.\.-ater (Found N = 4.6. C',lH,lON requires N = 4-60/,). A trace of the compound added to concentrated sulphuric acid produces an orange-brown coloration which quickly changes to pale pink and then gradually fades.This coloration is also observed with the corresponding r-amino-alcohol. Hydrolysis of Ethfyl 1-Yl~eiz~lnmiiioacetate Hydrochloride.-The Lester hydrochloride (1 g.) in 30 C.C. of ethyl-alcoholic potassium hydroxide (0.4487L\') remained for 24 hours a t the ordinary tem-perature and was then heated on the water-bath for 30 minutes. The alcohol was removed under diminished pressure the residue dissolved in water and the solution extracted with benzene to remove any trace of unchaiiged ester. The aqueous solution was then neutralised with hydrochloric acid and the amino-acid (0.5 g.) was separated. Its specific rotation was determined as follows : 0.3719 g.was dissolved in 3.35 C.C. of X-hydrochloric acid and 1.5 C.C. of water I = 0.5 p = i-193 d = 1.0286 xD - 0*4G" - 12-4". 3'11 c ester Iiydrochloridc was completely hydrolysed . Pa ~t icr l Den in i iiu t ion of I - Phe ii yln nzi 11 oncet ic d c id .-A solution of sodium nitrite (0.41 g.) in water ( 2 c.c.) was added drop by drop (30 minutes) to a solution of the I-amino-acid ( 2 g.) in X-sulphuric acid (30 c.c.) t L t 0". After 5 hours at 0" and 18 hours a t the ordinary tomperaturc the amiiio-acid (1.33 g.) as precipitated by the addition of aniiiioiiia in slight excess. 0.7438 G . was dissolved in 6.7 C.C. of n'-hydrochloric acid and 3 c.c. of vcater I = 1 p = 7.193 dJ' = 1.0286 x ~ - L1.36" '[RID - 133-5" whereas thc originzl I-acid had Thc ammoniacal solution from which the amino-acid had been scparated TT~C?S acidified n-ith dilute hydrochloric acid and extracted with cther.The I-esulting mmdelic acid (0.23 6.) was slightly tlestrorotatory in aqueous solution Z = 2 c = 1.055 clD + 0.13". Deuminalioiz. of Ethyl l-Pl~ciiylnmi.Iioacetate.-~~~ethocl of E. F'isclzer und TPeichhoZd. These authors acted on the d-ester with nitrous 2.0472 c(::'* + 3.48" [XI;:'* + 85.0" ; l = 2 c = 2.0472 a3:;' + [a]::' + 105-3"; Z = 2 c = 2.0312 MI,; + 5*03" [cx]~$ + 122.6". - 156' under similar conditions 294 CONVERSION OF AMINO-ACIDS INTO THRTIARY AMINO-ALCOHOLS. acid and obtained a lzevorotatory ethyl mandelate with about [.ID - 10" in acetone solution On following their directions, using ethyl Z-phenylaminoacetate (0.90 g .) in place of the d-ester, the resulting mandelic ester (0.325 g.) was dextrorotatory. A 10% solution gave ccD + 0.45" in a 0.5 dcm.-tube so that the value for the specific rotation is approximately + 9". The result of Fischer and Weichhold was thus confirmed. It should be stated that after the addition of the nitrite the solution remained over-night a t the ordinary temperature. The large amount of racemisation which accompanied this change is apparent when it is recalled that ethyl E-mandelate has according to Walden (2. physikal. Chem. 1895 17 705) [.ID - 90.6" in acetone solution. The dextrorotatory ester obtained above gave a negative result when tested for nitrogen. It was hydrolysed by 4.5 C.C. of aqueous potassium hydroxide (0.5755N) at the ordinary temperature for 18 hours.The solution was extracted with ether to remove any unsaponified ester and the rnandelic acid isolated from the aqueous solution as usual. The resulting acid (0.14 g.) was dextrorotatory in aqueous solut'ion E = 2 c = 0.622 uD + 0.27". Method of Marvel and Noyes. A solution of sodium nitrite (1.6 g.) in water (2.5 c.c.) was added drop by drop with constant stirring for 30 minutes to a solution of ethyl E-phenylaminoacetate hydrochloride (5.4 g.) in N-sulphuric acid (33 c.c.) the temperature being kept a t 0" throughout. A yellow oil separated. After 1 hour a t 0" and 2 hours a t the ordinary temperature the solution was extracted with ether the ethereal solution dried with anhydrous sodium sulphate and the ether expelled.The resulting oil was distilled and the portion (1.5 g.) b. p. 127-132"/18 mm. collected. I n acetone E = 2 c = 10 uD - 0.35'. The product obtained by Marvel and Noyes was also laevo-rotatory . When this oil was tested for nitrogen it gave a positive result. On hydrolysis under conditions similar to those described in the previous experiment it gave a mandelic acid (0.8 g . ) which was slightly dextrorotatory in aqueous solution I = 2 c = 3.109, This shows that the lzevorotation observed by Marvel and Noyes was not due to ethyl Z-mandelate but rather to the presence of an intermediate lzvorotatory diazo-compound which gradually passes into ethyl d-mandelate with lapse of time. That this view is probable appears from the result of the second experiment quoted below.The unattacked ethyl phenylaminoacetate hydrochloride was recovered from the aqueous solution remaining after the extraotion C(D $- 0.10" NEWBERY THE ACTION OF CAUSTIC ALKALI ETC. 295 of the deamination product with ether. The solution was made alkaline with ammonia extracted with benzene the benzene solution dried and dry hydrogen chloride passed in to precipitate t'he ester hydrochloride Yield 2 g. In aqueous solution 1 = 1 c = 5.07 aD - 469" [ a ] D - 90.5". The regenerated hydrochloride had thus practically the same rotation as the original. In a second experiment where 7 g. of the Lester hydrochloride were employed the conditions of deamination were exactly similar to those just described except that the solution after being kept a t 0" was allowed to remain for 39 instead of 2 hours. The resulting oil (2 g.) which gave a positive test for nitrogen mas in this case dextrorotatory in acetone solution E = 1 c = 10 tcD + 0.30". On hydrolysis with aqueous alkali under similar conditions to those adopted in the other experiments the resulting mandelic acid was dextrorotatory in aqueous solution I = 2 c = 3.32, The amino-ester hydrochloride was recovered as before. In The latter was filtered off. a D + 0.19". aqueous solution 1 = 1 c = 5.07 mD - 4-57" [.ID - 90.1". M7e desire to express our best thanks to the Department of Scientific and Industrial Research and to the Carnegie Trust for their assistance. We are also indebted to Dr. H. J. Plenderleith for his assistance in the deamination of p-amino-act-diphenyl-n-propyl alcohol. UNIVERSITY COLLEGE D UNDEE. UNIVERSITY OF ST. ANDREWS. [Received December 5th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700283

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

NEWBERY THE ACTION OF CAUSTIC ALKALI ETC. 295 XLVI1.-The Action of Caustic Alkali on a-Bromo-a-ethylbutyrylca~ba~~de. By GEORGE NEWBERY. THE action of water caustic alkali and of pyridine on a-bromo-a-ethylbutyrylcarbamide (adalin) CBrEt,*CO-NH-CO*NH, was investigated by Rosenmund and Hermann (Ber. deut. phrm. Ges. 1912 22 SS) who considered the main product m. p. 185O, to be 5 5-diethylhydantoin. This substance prepared according to those authors melted when pure at 198" and was moreover, identical with a product invariably obtained in experiments in-volving the condensation of adalin in alkaline solution and also from the condensation if not adequately controlled of a-bromo-a-ethylbutyryl bromide and carbamide. 5 5-Diethylhydantoi 296 NEWBERY THE ACTION OF CAUSTIC ALKALI (Errara Gazxetta 1896 26 i 207; Ingold Sako and Thorpe, J.1922 121 1193) has m. p. 165" and is readily converted by dilute alkali into a salt of diethylhydantoic acid; under the same conditions the substance m. p. 198" remains unchanged. After the reaction between 2N-sodium hydroxide (rather more than 1 mol.) and a-bromo-a-ethylbutyrylcarbamide three main products were isolated the substance m. p. 198"; an unsa,turated acid oil b. p. 200-210"/760 mm. which was shown to be a mixture of the isomeric forms of a-ethylcrotonic acid; and a saturated acid b. p. 283-286"/760 mm. which corresponded in properties with the oil to which Rosenmund and Hermann ascribed the formula C,,H,,O,N,. No evidence of the formation of diethyl-hydantoin nor of the unsaturated substance m.p. 91" described by these authors as a-ethylcrotonylcarbamide could be obtained. Analysis of the substance m. p. 198" gave figures in satisfactory agreement with the formula C,H,,O,N and although it did not readily decolorise solutions of bromine (whilst in common with adalin it is readily oxidised by alkaline permanganate) its behaviour on hydrolysis showed clearly that it must be regarded as a ureide of a-ethylcrotonic acid (I). Hydrolysis by alcoholic potash led to the formation of an unsaturated neutral substance m. p. 118", and to a mixture of the two a-ethylcrotonic acids. Analysis and further hydrolysis by prolonged boiling with 20% caustic soda solution indicated that the neutral substance was an amide of or-ethylcrotonic acid (11).That this was actually the case was proved by its synthesis from a-ethylcrotonyl chloride and ammonia. The action of a-ethylcrotonyl chloride on carbamide or of phosphoryl chloride on a mixture of either of the forms of a-ethyl-crotonic acid and carbamide yielded an isomeric unsaturated ureide m. p. 158" which showed no readiness to decolorise bromine solutions and on hydrolysis gave the unsaturated amide m. p. 118" together with the solid form of a-ethylcrotonic acid. The ureides m. p. 198" and 158" respectively are therefore probably geometrical isomerides of the unsaturated ureide (I). Small amounts of the lower-melting isomeride and of an isomeric a-ethylcrotonamide m. p. 104" were also isolated from the treat-ment of a-bromo-a-ethylbutyrylcarbamide with alkali.This amide was also obtained in better yield by the action of excess (2 mols.) of caustic alkali and was remarkably stable when heated with moderately strong alkali but on prolonged hydrolysis with very concentrated aqueous caustic soda it gave only ammonia and a mixture of the isomeric a-ethylcrotonic acids. It is identical with the amide m. p. 09" obtained by Maniiich and Zernik (Arch. PhcGrm. 1908 246 183) by the action of water on a-bromo-a-ethyl OX (x-BROMO - CI-ETHYLBUTYRYLCARBAMIDE. 297 butyramide (neuronal) ; a preparation thus made also melted at 104" (corr.).* The behaviour of the amides and ureides on reduction was in harmony with the view taken of them as pairs of isomerides of unsatnr'iied character. The amides m. p. 118" and 104" respect-ively yielded on reduction with sodium amalgam and water, r-ethylbutyramide in.p. 11%" whilst the ureides m. p. 198" and 135" respectively reduced with sodium and alcohol gave cc-ethyl-butyrylcar~,arnide m. p. 205". The two ainides unlike the ureides readily decolorised solutions of broiiiiiie ; on treatment with bromine in carbon disulphide, that of in. 11. 104" yielded c2 dibromide m. p. 128" identical with t,hnt recorded by Mannicli and Zernik (Zoc. cit.) whilst the amide, in. p. 1 IS" gave an iwmcric ap-dibromo-r-ethylbutyramide, Cl-IMelBr.C'BrEt.CO*~H, m. 1). 59". I h e corresponding ureitles although brominated with difficulty, yielded under suitable conditions dibromides m. p. 143" and 112" respectively presu mab 1 y racemic forms of a p- dibromo - CI- et hyl-bu tyrylcarbamide C'H3leBr.CBrEt *CO*NH.CO*NH,.Although the unsaturated aniides react additively with bromine far more readily than the corresponding ureides the addition of the elements of hydrogen bromide t o the former has so far not been achieved. The trdnsformation of the more fusible to the less fusible amide is however brought about by treatment with hydrobromic acid, as it is also by concentrated alkali or by heat. On the other hand, the higher-melting ureide is apparently the labile form since it is converted into that of lo\ver melting point by boiling with hydro-Lromic acid. From either isomeride a small yield of p-bromo-a-ethylbutyrylcarbamide CiKPlle13r*C'MEt*C0."II, m. I>. 17!)" is obtained by the action of the same reagent.The product is of some interest as an isomeride of adalin. The relationships of the weidcs arid amides to one another and to the i.omeric a-ethylcrotonic acids are tabulated on p. 298. The stable forms of urcide amicie and acid alone are obtained froiri the acid chloride (compare Blaise and Bagard Arm. Chirn., 1907 [viii] 1.1 129) axid the labile forms of ureide and amide on hydrolysis with concentrated alkali yield the liquid form of cc-ethyl-crotonic acid slightly contaminated with the stable €orrn whereas the isomerides yield the stable form alone. r 7 * Recently Ann-t.rs (dnizulen 1023 432 77) has described the prepar-ation of an amicle of a-cthylcrotonic acid in. p. 114-115' from a-ethyl-crotoriyl cliloride a i d arninonin in ethereal solution. He was however, apparently uiiablo to isolato the lower-melting amido by the method of Mannich and Zernik the amide in.11. 114-115° being alone obtained 298 NEWBERY THE ACTION OF CAUSTIO ALKALI Labile forms. Stable forms. CHJl'e:CEL*CO.NHCO*NH, a-Ethj-lcrotonylcarbamide m r a-Ethylcrotonylcarbamide, (I.) CHJle CE t .CO*NHCO .NH, \ m. p. 1 9 8 O . __f m. p. 158'. S-EOH CHMe:CEtCO*NH2 (11.) CHMe:CEt.CO.NH, m. p. 104'. - m. p. 118". centretetl a-Ethylcrotonamide EBr h i t . a-Ethglarotonamide, alkali 20% NdUEI 20% CHMe:CEt*CO,H CHXe:C KII a-Ethyl-C- crotonyl chloride. &O,H Liquid a-ethyl. HBr or PCI Solid a-ethylcrotonic acid, crotonic acid - m. p. 42'. The acid oil b. p. 283-286' to which Rosenmund and Hermann ascribed the formula C,,H,,O,N, solidified on standing in the ice-chest and then had m.p. 24". Analysis gave no figures in satisfactory agreement with a simple formula but the substance, which behaved as a dibasic acid gave on hydrolysis diethyl-glycollamide OH*CEt,*CO*NH, m. p. 88" and diethylglycollic acid OH*CEt,.CO,H m. p. 79-80" and was thus recognised as the symmetrical bisdiethylglycollylcarbamide (OH*CEt,.CO*XH),CO, described by Clemmensen and Heitman (Amer. Chem. J. 1908, 40 287) ; when purified essentially by their method it had m. p. 29' and corresponded with the formula C1,H,,O,N,. Its silver salt reacted with ethyl iodide to produce bis-u-ethoxy-u-ethylbutyryl-carbamide (OEt*CEt,*CO*NH),CO b. p. 240" which gave on hydrolysis a-ethxy-u-ethylbutyramide m. p. 36". The presence of alkali cyanide in the reaction mixture from the action of caustic alkali on u-bromo-a-ethylbutyrylcarbamide noted by Rosenmund and Hermann and confirmed by the present author, is probably to be accounted for by the intermediate formation of a small amount of u-bromo-u-ethylbutyramide.The latter was shown by Mannich and Zernik (Zoc. cit.) to give on treatment with caustic soda diethyl ketone and hydrobromic and hydrocyanic acids (compare also Mossler Monatsk. 1908 29 69). The amount of diethyl ketone isolated as semicarbazone from the main reaction mixture was in approximate agreement with that required by the assumption that sodium cyanide had been formed in equimolecular quantity. Treatment of a-bromo-a-ethylbutyrylcarbamide and the u-ethyl-crotonylcarbamides with N - or 2N-alkali always led to the pro-b.p. 199' 0 V x -BROMO- a-ETHYLBUTY RY LCARBAMIDE. 299 duction of laiger quantities of the mixed a-ethylcrotonic acids than would be expected on the assumption that the correspondin amides are necessarily intermediate products of the hydrolysis. It seems probable therefore since under similar conditions of time concentration of alkali etc. the unsaturated amides are not appreciably hydrolysed t o the corresponding acids that the hydrolysis of the unsaturated ureides proceeds in two directions :-(a) CHMe:CEt.CO hTH.CO*NH + H,O + CHhle:CEt*CO,H + NH,.CO.NH,. ( 6 ) CHMe:CEt*CO-NH CO-XH + H,O -+ CHhle:CEt*CO.NH + NH + CO,. Under certain conditions the carbamide formed in the action (a) escapes complete hydrolysis to ammonia and carbon dioxide and can be isolated in part as the characteristic nitrate.Bisdiethylglycollylcarbamide on the other hand was hydrolysed by mild treatment with alkali to the stable amide and only further to diethylglycollic acid under the more drastic conditions necessary t o hydrolyse the amide. Finally the small amount of the stable form of E-ethylcrotonyl. carbamide isolated from the action of 2S-caustic soda solution on adalin appears to be derived directly from the latter by the elimin-ation of hydrogen bromide and not by the isomerisation of its labile isomeride since no conversion of the latter on treatment with alkali of this concentration could be detected. CEt,Br.CO*XH.CO.NH, a-Bromo-a-ethylbutyry?carbamide m. p.119". J. + J. CHMe:CEtCO*NH.CO.TU'H 1 2[OH4l!Et,CO.NHCONR,I [CEt,Br,CO.NH,] a-ethylcrotonylcarbamide Labile 1 (Nee j a-Bromi-a-eth butyramide. y 1-m. p. 198'. isolated) Stable a-Ethylcrotonylcarbamide, m. p. 158'. I & CHJIe:CEtCO.kH,+SH,fCO OHCEt,GO.NH Et,CO+ a-ethylcrotonamide m. p. 104'. OH'CEtz'CO'xH' + NH,CO.NH, Labile \CO HBr +HCN. Diethyl ketone, J. 8-Bisdiethylglycolly1-carbamide m. p. 29'. CHMe:CEt+CO,H + NH,*CO.PU'H,. Labile Stable a-ethylcrotonic acid --f a-ethylcrotonic acid m. p. 42'. b. p. 199'. E x P E R I 31 E N T A L. Action of Sodium Hydroxide (1 mol.) on a-Bromo-cc-etlaylbutyryl-cccrbcsmide.-Commercial a d a b of m. p. 119" (100 g.) was treate 300 NEWBERY THE ACTION OF CAUSTIU ALKALI with gently boiling 2N-sodium hydroxide (270 c.c.; rather more than 1 equiv.) in an apparatus through which a current of air could be aspirated and passed in sequence through sufficient of a hot 2N-solution of sulphuric acid to absorb the evolved ammonia, a strong solution of semicarbazide hydrochloride saturated with sodium acetate and finally a little dilute permanganate solution acidified with sulphuric acid.A semicarbazone (a) shortly began to separate and as long as there was sufficient excess of semicarbazide there was no appreciable decoloration of the permanganste. After being heated for an hour the mixture was cooled the crystalline solid (b) filtered off and the filtrate made up to 500 C.C. Fifty C.C. (c) were removed for the titration of cyanide and the remainder was extracted once with chloroPorm (d).The liquors were then saturated with sodium chloride exhaustively extracted with chloro-form (e) and acidified (congo-red) with concentrated hydrochloric acid there being considerable disengagement of carbon dioxide and the liberation of an oily layer which was completely extracted with ether (f) Finally the mixture was neutralised exactly with caustic soda (phenolphthalein) evaporated to dryness and the residual salt extracted in a Soxhlet apparatus successively with alcohol and acetone (9). The semicarbazone (a) after being washed with a little water, dried (0.2 g.; m. p. 135-136") and recrystallised from acetone, melted a t 139" alone or mixed with synthetic diethyl ketone semicarbazone. The solid ( b ) weighed 20 g. and after repeated crystallisation from alcohol and from acetone melted a t 198" (corr.) (Found C = 53.7; H = 7.7; N = 18.1.C,H,,O,N requires C = 53.8; H = 7.7; N = 18.0%). This a-ethylcrolonylcarbamide crystallises from much alcohol acetone or benzene in long colour-less needles is very slightly solublc in ether and is soluble in strong alkali or strong mineral acid from which it is thrown out unchanged on dilution or neutralisation. The cyanide content (estimated by the De1~igi.s method) of (c) indicated a total amount of 0-08 g. of sodium cyanide (molecular equivalence with 0.23 g. of diethyl ketone semicarbazone). The chloroform extract (d) dried over anhydrous sodium sulphate left on evaporation 311 oil (2.5 g.) wliich quickly solidified and after repeated crystallisation from alcohol gave colourless needles m.p. 158" of the low-melting a-ethylcrotonylcarbamide. The Purther chloroform extracts (e) also left an oil which quickly solidified and, after repeated crystallisation from ether furnished about 1 g. of a-ethylcrotonamide m. p. 104". The ethereal cxtract (f) dried over calcium chloride yielded an oil which on fractionation gave (i) ail unsaturated acid oil b. p. 200-220" (4.7 g.) and (ii ON U-BROMO-a(-ETHYLBUTYRYLCARBAMXDE. 301 saturated acid fraction b. p. 282-284" (28.2 g.). The former was identified as a mixture of the two forms of or-ethylcrotonic acid and was converted by a drop of concentrated hydrobromic acid or by the successive action of phosphorus trichloride and water into the solid form of the acid m. p.42" not depressed by admixture with a genuine specimen. The examination of the fraction (ii) is described below. The combined extracts (9) yielded on evaporation no apprecia1)le residue. The yields of the various products together accounted fc$r practically the whole of the adalin employed. Hydrolysis of High-meltijy a-Ethylcrotony1carbarnide.-(a) The ureide m. p. 198" (40 g.) and potassium hydroxide (40 g. dissolved in the minimum of water and diluted with alcoliol 200 c.c.) were heated under reflux for 24 hours. After removal of the excess of alcohol in a vacuum two layers formed; the upper quickly crystallised and yielded on being drained 2.7 g. of crude amide. The liquors yielded to ether 8-5 g. of yellow oil which gave a further crop of crude amide somewhat contaminated with the lower-melting isomeride.The aqueous liquors on acidification and ether extraction gave an unsaturated acid oil (15.5 g.) which on distillation gave a fraction b. p. 196-206" (6.4 g.) and a fraction, b. p. 205-220" (5.0 g.). Both showed marked unsaturation but neither solidified on cooling. Both however yielded or-ethyl-crotonic acid m. p. 42" on treatment with phosphorus trichloride and subsequently with water. ( b ) The ureide m. p. 198" (17 g.) was heated for 1 hour on the water-bath with X-potassium hydroxide (350 c.c.). The solution was saturated with sodium chloride filtered from a little unchanged material and repeatedly extracted with chloroform ; this removed an oil (7 g.) from which was isolated a-ethylcrotonamide white needles m.p. 104". Acidification of the aqueous liquors yielded an unsaturated acid oil (4.3 g.) which on distillation gave nearly pure liquid a-ethylcrotonic acid b. p. 190-200"; this was con-verted as before into the solid isomeride m. p. 42". The combined yields accounted for 95% of the unsaturated ureide employed. (c) I n a further experiment the hydrolysis was carried on for 30 minutes only. The final liquors after removal of the neutral and the acid fraction were evaporated t o dryness in a vacuum; from the residue boiling alcohol extracted carbamide (identified as the nitrate). High-melting a-Eth$crotonanzide.-The crude unsaturated amide from the above preparation (a) on repeated crystallisation from ether formed colourless needles or leaflets m. p.118" (corr.) (Found C = 63-8 ; H = 10.0; N = 12.4. C,H1,ON require 302 NEWBERY THE ACTION OF OAUSTIC ALKALI C = 63.7; H = 9.7; N = 12.4%). It is very soluble in alcohol, moderately soluble in benzene or water slightly soluble in cold ether and insoluble in light petroleum. Prepared synthetically from cz-etliylcrotonyl chloride and strong aqueous ammonia the same amide was obtained in 75y0 yield in glistening plates m. p. 118" (Pound N = 126%). Hydrolysis of High-m elt i ~ g u- Ethy1crotonamide.-The unsatur-ated amide (6.5 g.) was refluxed for 3 hours with 20% aqueous caustic soda (15 c.r.). Ammonia was evolved and after the ex-traction of some 3 g. of unchanged amide by chloroform acidification and ether extraction yielded an acid oil (3 g.) from which a-ethyl-crotonic acid was obtained; m.p. 40'. Action of Sodium Hydroxide (2 mols.) on a-Brorno-a-ethylbutyryl-curbamide.-Finely-powdered commercial adalin (100 g.) was heated under reflux with N-sodium hydroxide (1000 c.c.) for 90 minutes and when cold the liquid was saturated with sodium chloride, filtered from high-melting a-ethylcrotonylcarbamide (4 g.) and extracted with ether. From the extract dried over anhydrous sodium sulphate were obtained 4 g . of a substance which readily sublimed at about lOO" quickly solidified on cooling and after repeated crystallisation from ether melted a t 104" alone or mixed with a-ethylcrotonamide (m. p. 104" after several crystallisations), prepared according to Mannich and Zernik (loc. cit.). Low-melting a-ethylcrotonamide crystallises in colourless needles from ether in which it is more soluble than the high-melting isomer-ide is very soluble in alcohol or chloroform moderately soluble in benzene or water and insoluble in light petroleum (Found C = 63.6; H = 9.9; N = 12.5.Calc. for C,H,,ON C = 63.7; H = On acidification the reaction product also yielded a mixture of the two a-ethylcrotonic acids b. p. 190-220" (11 g.) and the saturated acid oil b. p. 284-287" (26 g . ) . Hydrolysis of Lotomelting a-Ethy1crotonamide.-(a) a-Ethyl-crotonamide m. p. 104" (6 9.) was heated on the steam-bath for 1 hour with N-caustic potash (125 c.c.). Saturation with sodium chloride and chloroform extraction yielded the unchanged amide (5.8 g.; 97% recovery). ( b ) The amide (4 g . ) boiled under reflux with 20% caustic soda (10 c.c.) for 3 hours yielded as before 3 g .of unsaturated amide m. p. 100" (indefinite) which was probably a mixture of the two isomeric amides since repeated crystallisation from ether yielded the less soluble form m. p. 118". The acid fraction yielded liquid a-ethylcrotonic acid (0-7 g.) b. p. ZOO". (c) The amide (3.5 g.) heated for 5 hours with boiling 40% 9.7; N = 12.4%). There was no appreciable acid fraction ON a-BROMO - a-ETHYLBUTYRYLOARB AMID E . 303 caustic soda (20 c.c.) yielded when worked up in a similar way, the high-melting form of the amide (0.25 g.) together with a mixture of the two cc-ethylcrotonic acids b. p. 195-205" (3 g.). Synthesis of Low-melting a-Ethylcrotony1carbamide.-a-Bromo-a-ethylbutyryl bromide (200 g.; b. p. 128"/30 mm.) was run slowly into a boiling solutio6 of potassium*hydroxide (400 g.) in water (250 c.c.) and alcohol (750 c.c.). Much heat was developed and the alcohol kept boiling vigorously. The mixture mas heated for 30 minutes on the steam-bath water added to dissolve the separ-ated potassium bromide and the excess of alcohol removed in a vacuum. Acidification with hydrochloric acid and ether extrac-tion yielded a mixture of the two forms of a-ethylcrotonic acid (75 g. ; b. p. 190-210; yield 90% of theory). (a) To the mixed acids (5 g.) was' added phosphoryl chloride (3 g,) followed almost immediately by 8 g. of carbamide. A vigorous reaction ensued which was not controlled and after 30 minutes' heating on the water-bath addition of water and a short period of further heating, the mixture was cooled and the crude carbamide (3.5 g.) filtered off.(a) a-Ethylcrotonyl chloride (2.2 g.; b. p. 58'114 mm.), prepared from the mixed acids and phosphorus trichloride was heated on the water-bath for 2 hours with carbamide (2.5 g.). The semi-liquid mass became more viscous and was finally nearly solid. Water was added and the crude carbamide (2 g.) filtered off. Low-melting cc-Ethylcrotonylcarbamide m. p. 158" (corr.) crystallised in colourless needles from alcohol; it was not readily soluble in cold alcohol benzene acetone or ether and did not readily de-colorise bromine water (Found C = 53.6; H = 7.8; N = 18.1. C,H,,0,N2 requires C = 53.8; H = 7.7; N = 18.0y0). Hydrolysis of Low-melting a-Ethylcrotony1carbamide.-The hydro-lysis of the ureide m.p. 158" (5 8.) was effected with hr-caustic potash (100 c.c.) under exactly similar conditions to those employed for the hydrolysis of the isomeric ureide m. p. 198". The chloro-form extract yielded an oil (2 8.) which quickly solidified and crystallised from ether in leaflets m. p. 118" alone or mixed with synthetic a-ethylcrotonamide. The aqueous liquors after acidific-ation yielded to ether an oil (1-8 g.) which quickly solidified and proved to be solid a-ethylcrotonic acid m. p. 42". Hydrolysis for 3 hours with concentrated alcoholic potash yielded the same products. Reduction of the Isomeric cc-Ethy1crotonamides.-A warm solution of cc-ethylcrotonamide m. p. 118" (1 g.) in water (50 c.c.) was reduced with 4% sodium amalgam (50 g,) and after filtration from mercury was extracted with chloroform.Desiccation and evaporation of the solvent yielded an oil which solidiiied on stand 304 NEWBERY THE ACTION OF CAUSTIC ALKALI. ing. Repeated crystallisation from ether yielded white needles, m. p. l l l " which did not reduce alkaline permanganate or de-colorise bromine water. a-Ethylcrotonamide m. p. 104" under the same conditions yielded the same product. a-Ethy1butyramide.-a-Ethylbutyryl chloride b. p. 65"/70 mm. (5 g.) was run slowly with continuous stirring into excess (10 c.c.) of concentrated ammonia solution cooled by ice. The solid which separated together with a further quantity obtained by chloroform extraction (3-5 g. in all; 82% of theory) crystallised from ether in colourless needles m.p. 112" (cow.) alone or mixed with the reduction product from either u-ethylcrotonamide (Found N = 12.3. Calc. for C,H,,ON N = 12.2Y0). The alkaline hydrolysis of synthetic a-ethylbutyrylcarbamide likewise led to the same saturated amide m. p. 112' (E. Fischer and Dilthey Ber. 1902, 35 853 give m. p. 107"). Reduction of the Isomeric a-Ethylcrotony1carbamides.-Either isomeride (1 g.) was reduced with boiling ethyl alcohol (20 c.c.) and sodium (1.5 g.). Chloroform (50 c.c.) was added to the mixture, followed by water (100 c.c.). The solid (0.4 g.) isolated from the chloroform extract crystallised from alcohol in colourless needles, m. p. 205-206" which did not reduce a cold alkaline permanganate solution nor depress the m.p. (206-207") of synthetic a-ethyl-butyrylcarbamide. Brornination of L ow-melting a-Ethglcroton amide .-a-Ethylcroton-amide m. p. 104" (2.5 g.) suspended in carbon disulphide (30-40 c.c.) at O" required the theoretical quantity of bromine in the same solvent to give a permanent coloration after an hour. The crystals which began to separate during tha addition were washed with carbon disulphide dried (3.5 g.; 5SY0 of theory) and re-crystallised from alcohol high-melting ap-dibromo-a-ethylbutyr-amide separating in colourless needles m. p. 127-128" slightly soluble in cold carbon disulphide ether or petroleum (Found : Br = 58.6. Bromination of High-melting a-Bthy1crotonamide.-a-Ethylcroton-amide m. p. 118" (2.5 g.) treated in a similar way gave a less sharp end-point absorption of bromine being less rapid and only towards the end of the addition was there any separation of the dibromide.The solvent was evaporated the residue which solidi-fied after some hours a t 0" was washed with ether-petroleum (b. p. 40-60") and crystallised from the same mixture yielding low-melting a@-dibromo-a-ethylbutyramide (2-5 g. ; 42% of theory) as a slightly yellow crystalline powder m. p. 77-78' ; by repeated crystallisation colourless plates m. p. 79-80' were obtained. This dibromide was more soluble in carbon disulphide alcohol or Calc. for C,H,,ONBr, Br = 58.6%) ON CL-BROMO-C~-ETHYLEUTYRYLCARBANIDE. 305 ether than the high-melting isomeride and was somewhat soluble in hot petroleum (b. p. 40-60") (Found Br = 58.5. C,H,,ONBr, requires Br = 58.6%).Brominat ion of Low melting -a-Et h ylcrotonylcarbamide .-a- Ethyl-crotonylcarbamide m. p. 158" (5 g.) was exposed for 48 hours over excess of bromine in a closed desiccator. Excess of bromine was removed in a current of air and the residue refluxed with ether (200 c.c.). After filtration the ethereal solution was con-centrated to 20 c.c. and the crystals (3 g.) which separated were recrystallised from alcohol when low-melting -ap-dibromo-a-ethyE-butyrylcnrbamide was obtained in colourless needles m. p. 112" (Found Br = 50.7. C,H,,0,N2Br2 requires Br = 50.6%). Brominatio?h of High-melting -a-Ethylcrotony1carbamide.-The ureide m. p. 198" (5 g.) brominated in a similar manner gave high-melting a p-dibromo- -a-ethylbutyrylcarbamide (3.2 g.) which crystallised from alcohol in colourless prisms m.p. 142-143". It is moderately soluble in ether (Found Br = 50.4. C7H1,02N2Br2 requires Br = 50.6 yo). Action of Hydrogen Bromide o n Low-melting a-Ethy1crotonamide.--a-Ethylcrotonamide m. p. 104" (2.5 g.) was heated on the water-bath for 2 hours with acetic acid saturated with hydrogen bromide a t 0" (25 c.c.). Excess of the acids was removed in a vacuum, the residue (10 c.c.) nearly neutralised with 2N-sodium hydroxide, and the mixture extracted with chloroform. The solid (0.6 g.) which remained after the removal of the solvent crystallised from ether in leaflets m. p. 117-118" not depressed by admixture with the synthetic amide m. p. 118". Bebwiour of Hydrogen Bromide with High-melting a-Eihylcroton-amide.-The amide m.p. 118" (0.3 g.) was heated for 6 hours in a sealed tube a t 100" with acetic acid saturated with hydrogen bromide a t 0" (2 c.c.). The mixture after dilution and neutral-isation gave on extraction only the unchanged amide m. p. 118". Actioiz of Hydrogen Bromide on Low-melting a-Ethylcrotonyl-carbanzide.-A mixture of the ureide m. p. 158" (4 g.) with acetic acid saturated with hydrogen bromide a t 0" (40 c.c.) was heated under reflux for 20 hours on the steam-batJh and when poured into cold water (500 c.c.) yielded a solid product (1 g.). p-Bromo- a-ethylbzrtyrylcarbamide was obtained in colonrless needles m. p. 179-180" by repeated crystallisation from alcohol. It is sparingly soluble in alcohol benzene or ether (Found N = 1 1 4 ; Br = 33-4.C,H,,O,N Br requires N = 11.8 ; Br = 33.75%). Action o$ Hydrogex. Bromide on Low-meltiiLg cc-Ethylcrotonyl-carbaniide.-The ureide m. p. 19s" (5 g.) together with saturated acetic-hydrobromic acid (30 c.c.) was hezted for 8 hours in a sealed \-oL. @SSVII. i 306 NEWBERY THE ACTION OF CAUSTI~ ALKAIJ ETC. bottle in a boiling-water bath. The mixture was filtered from a little ammonium bromide water added and the solution nearly neutralised with 20% caustic soda solution. On cooling a white solid (4 g.) separated which after repeated crystallisation from alcohol melted at 177" and was identical with the p-bromo-a-ethyl-butyrylcarbamide described above. Chloroform extraction of the still slightly acid mother-liquors yielded a small amount of oil, which solidified on standing and after repeated crystallisation from alcohol had m.p. 158" not depressed by admixture with the unsaturated ureide of that melting point. Examination of the Saturated Acid b. p . 283-286'.-Bisdiethylglycollylcarbamide was obtained in a pure condition from the acid oil b. p. 283-286" by a slight modification of the method proposed by Clemmensen and Heitman (Zoc. cit.) involving the preparation of the silver salt from the ammonium salt followed by the decomposition of the former by hydrogen sulphide. It then melted a t 29" and agreed in physical and chemical pro-perties with bisdiethylglycollylcarbamide prepared synthetically (Found C = 54.2 54.0; H = 8-1 8.3; N = 9.8 9.7. Calc. for Hydrolysis of Bisdiethylglycolly1carbamide.-(a) The oil b.p. 283-286' (21 g.) was refluxed for 48 hours on the steam-bath with alcoholic potash from potassium hydroxide (21 g.) dissolved in the minimum of water and 100 C.C. of alcohol. Ammonia was evolved during the whole period of heating. The mixture yielded on dilution and ether extraction an oil b. p. 164"/25 mm. (10 g.). This quickly solidified and on crystallisation from ether gave diethylglycollamide m. p. 88" in colourless hexagonal plates (Found N = 1043. C,Hl,O,N requires N = 10.7%). The aqueous liquors on acidification likewise yielded an acid fraction (10 g.) which on distillation boiled for the most part at 115-130°/10 mm. There was a small amount of unchanged material b. p. 152-155"/10 mm. The main fraction quickly solidified and crystallised from petroleum (b.p. 60-80") in colourless needles, m. p. 80" not depressed by admixture with synthetic diethyl-glycollic acid m. p. 81". (b) The same oil (40 g.) hydrolysed under the same conditions for 3 hours only yielded diethylglycollamide (15 g.) and unchanged material (10 g.). No diethylglycollic acid could be isolated. (c) The oil (13 g.) boiled on the sand-bath for 1 hour with 2N-caustic soda gave no diethylglycollamide and the acid fraction yielded only unchanged material (12.5 g.). Bis-a-ethxy-a-ethyZbutyryZcarbarmide.-The silver salt (19 g.) of bis-diethylglycollylcarbamide (Found Ag=40.1. C,,H,,O5N&g2,2H,O requires Ag = 40.1%) from the saturated acid oil b. p. 283-286", C13H2405N2 C = 54.1 ; H = 8.3; N = 907%) THE DIRECT COMBINATION OF ETHYLENIC HYDROCARBONS ETC.307 after being dried a t loo" was heated with ethyl iodide (25 c.c.) for 15 minutes silver iodide was removed by filtration and the oil (12 g.; 97% of theory) which was insoluble in caustic soda, distilled a t 160-170"/60 mm. The oil so obtained had a char-acteristic odour of garlic and b. p. 240" (Found C = 59.0 ; H = 9.3. C,,H,,O,N requires C = 59-3; H = 9.3%). A preparation in a similar way from synthetic bisdiethylgiycollylcarbamide yielded the same product. Hydrolysis of Bis-a-ethoxy-u-ethylbutyry1carbamide.-The ethoxy-carbamide (20 g.) was hydrolysed for 12 hours on the steam-bath with alcoholic potash from potassium hydroxide (20 g.) in the minimum of water and 200 C.C. of alcohol. After the removal of excess alcohol in a vacuum and dilution ether extraction gave an oil (10 g.) b.p. 141-144"/11 mm. which solidsed after remaining a few hours a t 0". cc-Ethoxy- a-ethylbutyramide when pure melts a t 38" and is very soluble in most organic solvents but practically insoluble in light petroleum. It could not be crystallised satisfactorily and was apparently best purified by repeated distillation in a vacuum (Found N = 8.7. The aqueous liquors from this preparation yielded practically no acid fraction, and ethoxyethylbutyramide was found to be extremely resistant to the hydrolytic action of alkali. C,H,,O,N requires N = S+3~0). The author desires to express his indebtedness to the Directors of Messrs May and Baker Ltd. for permission to publish the results embodied in the above paper to Dr.A. J. Emins for his interest in the investigation and to Mr. M. A. Phillips for assistance in much of the experimental work. MESSRS MAY AND BAKER LTD., WANDSWOHTH S.W. 18. RESEARCH LABORATORY, [Received. July 3rd 1924. NEWBERY THE ACTION OF CAUSTIC ALKALI ETC. 295 XLVI1.-The Action of Caustic Alkali on a-Bromo-a-ethylbutyrylca~ba~~de. By GEORGE NEWBERY. THE action of water caustic alkali and of pyridine on a-bromo-a-ethylbutyrylcarbamide (adalin) CBrEt,*CO-NH-CO*NH, was investigated by Rosenmund and Hermann (Ber. deut. phrm. Ges. 1912 22 SS) who considered the main product m. p. 185O, to be 5 5-diethylhydantoin. This substance prepared according to those authors melted when pure at 198" and was moreover, identical with a product invariably obtained in experiments in-volving the condensation of adalin in alkaline solution and also from the condensation if not adequately controlled of a-bromo-a-ethylbutyryl bromide and carbamide.5 5-Diethylhydantoi 296 NEWBERY THE ACTION OF CAUSTIC ALKALI (Errara Gazxetta 1896 26 i 207; Ingold Sako and Thorpe, J. 1922 121 1193) has m. p. 165" and is readily converted by dilute alkali into a salt of diethylhydantoic acid; under the same conditions the substance m. p. 198" remains unchanged. After the reaction between 2N-sodium hydroxide (rather more than 1 mol.) and a-bromo-a-ethylbutyrylcarbamide three main products were isolated the substance m. p. 198"; an unsa,turated acid oil b. p. 200-210"/760 mm. which was shown to be a mixture of the isomeric forms of a-ethylcrotonic acid; and a saturated acid b.p. 283-286"/760 mm. which corresponded in properties with the oil to which Rosenmund and Hermann ascribed the formula C,,H,,O,N,. No evidence of the formation of diethyl-hydantoin nor of the unsaturated substance m. p. 91" described by these authors as a-ethylcrotonylcarbamide could be obtained. Analysis of the substance m. p. 198" gave figures in satisfactory agreement with the formula C,H,,O,N and although it did not readily decolorise solutions of bromine (whilst in common with adalin it is readily oxidised by alkaline permanganate) its behaviour on hydrolysis showed clearly that it must be regarded as a ureide of a-ethylcrotonic acid (I). Hydrolysis by alcoholic potash led to the formation of an unsaturated neutral substance m.p. 118", and to a mixture of the two a-ethylcrotonic acids. Analysis and further hydrolysis by prolonged boiling with 20% caustic soda solution indicated that the neutral substance was an amide of or-ethylcrotonic acid (11). That this was actually the case was proved by its synthesis from a-ethylcrotonyl chloride and ammonia. The action of a-ethylcrotonyl chloride on carbamide or of phosphoryl chloride on a mixture of either of the forms of a-ethyl-crotonic acid and carbamide yielded an isomeric unsaturated ureide m. p. 158" which showed no readiness to decolorise bromine solutions and on hydrolysis gave the unsaturated amide m. p. 118" together with the solid form of a-ethylcrotonic acid. The ureides m. p. 198" and 158" respectively are therefore probably geometrical isomerides of the unsaturated ureide (I).Small amounts of the lower-melting isomeride and of an isomeric a-ethylcrotonamide m. p. 104" were also isolated from the treat-ment of a-bromo-a-ethylbutyrylcarbamide with alkali. This amide was also obtained in better yield by the action of excess (2 mols.) of caustic alkali and was remarkably stable when heated with moderately strong alkali but on prolonged hydrolysis with very concentrated aqueous caustic soda it gave only ammonia and a mixture of the isomeric a-ethylcrotonic acids. It is identical with the amide m. p. 09" obtained by Maniiich and Zernik (Arch. PhcGrm. 1908 246 183) by the action of water on a-bromo-a-ethyl OX (x-BROMO - CI-ETHYLBUTYRYLCARBAMIDE. 297 butyramide (neuronal) ; a preparation thus made also melted at 104" (corr.).* The behaviour of the amides and ureides on reduction was in harmony with the view taken of them as pairs of isomerides of unsatnr'iied character.The amides m. p. 118" and 104" respect-ively yielded on reduction with sodium amalgam and water, r-ethylbutyramide in. p. 11%" whilst the ureides m. p. 198" and 135" respectively reduced with sodium and alcohol gave cc-ethyl-butyrylcar~,arnide m. p. 205". The two ainides unlike the ureides readily decolorised solutions of broiiiiiie ; on treatment with bromine in carbon disulphide, that of in. 11. 104" yielded c2 dibromide m. p. 128" identical with t,hnt recorded by Mannicli and Zernik (Zoc. cit.) whilst the amide, in. p. 1 IS" gave an iwmcric ap-dibromo-r-ethylbutyramide, Cl-IMelBr.C'BrEt.CO*~H, m.1). 59". I h e corresponding ureitles although brominated with difficulty, yielded under suitable conditions dibromides m. p. 143" and 112" respectively presu mab 1 y racemic forms of a p- dibromo - CI- et hyl-bu tyrylcarbamide C'H3leBr.CBrEt *CO*NH.CO*NH,. Although the unsaturated aniides react additively with bromine far more readily than the corresponding ureides the addition of the elements of hydrogen bromide t o the former has so far not been achieved. The trdnsformation of the more fusible to the less fusible amide is however brought about by treatment with hydrobromic acid, as it is also by concentrated alkali or by heat. On the other hand, the higher-melting ureide is apparently the labile form since it is converted into that of lo\ver melting point by boiling with hydro-Lromic acid.From either isomeride a small yield of p-bromo-a-ethylbutyrylcarbamide CiKPlle13r*C'MEt*C0."II, m. I>. 17!)" is obtained by the action of the same reagent. The product is of some interest as an isomeride of adalin. The relationships of the weidcs arid amides to one another and to the i.omeric a-ethylcrotonic acids are tabulated on p. 298. The stable forms of urcide amicie and acid alone are obtained froiri the acid chloride (compare Blaise and Bagard Arm. Chirn., 1907 [viii] 1.1 129) axid the labile forms of ureide and amide on hydrolysis with concentrated alkali yield the liquid form of cc-ethyl-crotonic acid slightly contaminated with the stable €orrn whereas the isomerides yield the stable form alone.r 7 * Recently Ann-t.rs (dnizulen 1023 432 77) has described the prepar-ation of an amicle of a-cthylcrotonic acid in. p. 114-115' from a-ethyl-crotoriyl cliloride a i d arninonin in ethereal solution. He was however, apparently uiiablo to isolato the lower-melting amido by the method of Mannich and Zernik the amide in. 11. 114-115° being alone obtained 298 NEWBERY THE ACTION OF CAUSTIO ALKALI Labile forms. Stable forms. CHJl'e:CEL*CO.NHCO*NH, a-Ethj-lcrotonylcarbamide m r a-Ethylcrotonylcarbamide, (I.) CHJle CE t .CO*NHCO .NH, \ m. p. 1 9 8 O . __f m. p. 158'. S-EOH CHMe:CEtCO*NH2 (11.) CHMe:CEt.CO.NH, m. p. 104'. - m. p. 118". centretetl a-Ethylcrotonamide EBr h i t . a-Ethglarotonamide, alkali 20% NdUEI 20% CHMe:CEt*CO,H CHXe:C KII a-Ethyl-C- crotonyl chloride.&O,H Liquid a-ethyl. HBr or PCI Solid a-ethylcrotonic acid, crotonic acid - m. p. 42'. The acid oil b. p. 283-286' to which Rosenmund and Hermann ascribed the formula C,,H,,O,N, solidified on standing in the ice-chest and then had m. p. 24". Analysis gave no figures in satisfactory agreement with a simple formula but the substance, which behaved as a dibasic acid gave on hydrolysis diethyl-glycollamide OH*CEt,*CO*NH, m. p. 88" and diethylglycollic acid OH*CEt,.CO,H m. p. 79-80" and was thus recognised as the symmetrical bisdiethylglycollylcarbamide (OH*CEt,.CO*XH),CO, described by Clemmensen and Heitman (Amer. Chem. J. 1908, 40 287) ; when purified essentially by their method it had m.p. 29' and corresponded with the formula C1,H,,O,N,. Its silver salt reacted with ethyl iodide to produce bis-u-ethoxy-u-ethylbutyryl-carbamide (OEt*CEt,*CO*NH),CO b. p. 240" which gave on hydrolysis a-ethxy-u-ethylbutyramide m. p. 36". The presence of alkali cyanide in the reaction mixture from the action of caustic alkali on u-bromo-a-ethylbutyrylcarbamide noted by Rosenmund and Hermann and confirmed by the present author, is probably to be accounted for by the intermediate formation of a small amount of u-bromo-u-ethylbutyramide. The latter was shown by Mannich and Zernik (Zoc. cit.) to give on treatment with caustic soda diethyl ketone and hydrobromic and hydrocyanic acids (compare also Mossler Monatsk. 1908 29 69). The amount of diethyl ketone isolated as semicarbazone from the main reaction mixture was in approximate agreement with that required by the assumption that sodium cyanide had been formed in equimolecular quantity.Treatment of a-bromo-a-ethylbutyrylcarbamide and the u-ethyl-crotonylcarbamides with N - or 2N-alkali always led to the pro-b. p. 199' 0 V x -BROMO- a-ETHYLBUTY RY LCARBAMIDE. 299 duction of laiger quantities of the mixed a-ethylcrotonic acids than would be expected on the assumption that the correspondin amides are necessarily intermediate products of the hydrolysis. It seems probable therefore since under similar conditions of time concentration of alkali etc. the unsaturated amides are not appreciably hydrolysed t o the corresponding acids that the hydrolysis of the unsaturated ureides proceeds in two directions :-(a) CHMe:CEt.CO hTH.CO*NH + H,O + CHhle:CEt*CO,H + NH,.CO.NH,.( 6 ) CHMe:CEt*CO-NH CO-XH + H,O -+ CHhle:CEt*CO.NH + NH + CO,. Under certain conditions the carbamide formed in the action (a) escapes complete hydrolysis to ammonia and carbon dioxide and can be isolated in part as the characteristic nitrate. Bisdiethylglycollylcarbamide on the other hand was hydrolysed by mild treatment with alkali to the stable amide and only further to diethylglycollic acid under the more drastic conditions necessary t o hydrolyse the amide. Finally the small amount of the stable form of E-ethylcrotonyl. carbamide isolated from the action of 2S-caustic soda solution on adalin appears to be derived directly from the latter by the elimin-ation of hydrogen bromide and not by the isomerisation of its labile isomeride since no conversion of the latter on treatment with alkali of this concentration could be detected.CEt,Br.CO*XH.CO.NH, a-Bromo-a-ethylbutyry?carbamide m. p. 119". J. + J. CHMe:CEtCO*NH.CO.TU'H 1 2[OH4l!Et,CO.NHCONR,I [CEt,Br,CO.NH,] a-ethylcrotonylcarbamide Labile 1 (Nee j a-Bromi-a-eth butyramide. y 1-m. p. 198'. isolated) Stable a-Ethylcrotonylcarbamide, m. p. 158'. I & CHJIe:CEtCO.kH,+SH,fCO OHCEt,GO.NH Et,CO+ a-ethylcrotonamide m. p. 104'. OH'CEtz'CO'xH' + NH,CO.NH, Labile \CO HBr +HCN. Diethyl ketone, J. 8-Bisdiethylglycolly1-carbamide m. p. 29'. CHMe:CEt+CO,H + NH,*CO.PU'H,. Labile Stable a-ethylcrotonic acid --f a-ethylcrotonic acid m. p. 42'.b. p. 199'. E x P E R I 31 E N T A L. Action of Sodium Hydroxide (1 mol.) on a-Bromo-cc-etlaylbutyryl-cccrbcsmide.-Commercial a d a b of m. p. 119" (100 g.) was treate 300 NEWBERY THE ACTION OF CAUSTIU ALKALI with gently boiling 2N-sodium hydroxide (270 c.c.; rather more than 1 equiv.) in an apparatus through which a current of air could be aspirated and passed in sequence through sufficient of a hot 2N-solution of sulphuric acid to absorb the evolved ammonia, a strong solution of semicarbazide hydrochloride saturated with sodium acetate and finally a little dilute permanganate solution acidified with sulphuric acid. A semicarbazone (a) shortly began to separate and as long as there was sufficient excess of semicarbazide there was no appreciable decoloration of the permanganste.After being heated for an hour the mixture was cooled the crystalline solid (b) filtered off and the filtrate made up to 500 C.C. Fifty C.C. (c) were removed for the titration of cyanide and the remainder was extracted once with chloroPorm (d). The liquors were then saturated with sodium chloride exhaustively extracted with chloro-form (e) and acidified (congo-red) with concentrated hydrochloric acid there being considerable disengagement of carbon dioxide and the liberation of an oily layer which was completely extracted with ether (f) Finally the mixture was neutralised exactly with caustic soda (phenolphthalein) evaporated to dryness and the residual salt extracted in a Soxhlet apparatus successively with alcohol and acetone (9).The semicarbazone (a) after being washed with a little water, dried (0.2 g.; m. p. 135-136") and recrystallised from acetone, melted a t 139" alone or mixed with synthetic diethyl ketone semicarbazone. The solid ( b ) weighed 20 g. and after repeated crystallisation from alcohol and from acetone melted a t 198" (corr.) (Found C = 53.7; H = 7.7; N = 18.1. C,H,,O,N requires C = 53.8; H = 7.7; N = 18.0%). This a-ethylcrolonylcarbamide crystallises from much alcohol acetone or benzene in long colour-less needles is very slightly solublc in ether and is soluble in strong alkali or strong mineral acid from which it is thrown out unchanged on dilution or neutralisation. The cyanide content (estimated by the De1~igi.s method) of (c) indicated a total amount of 0-08 g.of sodium cyanide (molecular equivalence with 0.23 g. of diethyl ketone semicarbazone). The chloroform extract (d) dried over anhydrous sodium sulphate left on evaporation 311 oil (2.5 g.) wliich quickly solidified and after repeated crystallisation from alcohol gave colourless needles m. p. 158" of the low-melting a-ethylcrotonylcarbamide. The Purther chloroform extracts (e) also left an oil which quickly solidified and, after repeated crystallisation from ether furnished about 1 g. of a-ethylcrotonamide m. p. 104". The ethereal cxtract (f) dried over calcium chloride yielded an oil which on fractionation gave (i) ail unsaturated acid oil b. p. 200-220" (4.7 g.) and (ii ON U-BROMO-a(-ETHYLBUTYRYLCARBAMXDE. 301 saturated acid fraction b. p. 282-284" (28.2 g.).The former was identified as a mixture of the two forms of or-ethylcrotonic acid and was converted by a drop of concentrated hydrobromic acid or by the successive action of phosphorus trichloride and water into the solid form of the acid m. p. 42" not depressed by admixture with a genuine specimen. The examination of the fraction (ii) is described below. The combined extracts (9) yielded on evaporation no apprecia1)le residue. The yields of the various products together accounted fc$r practically the whole of the adalin employed. Hydrolysis of High-meltijy a-Ethylcrotony1carbarnide.-(a) The ureide m. p. 198" (40 g.) and potassium hydroxide (40 g. dissolved in the minimum of water and diluted with alcoliol 200 c.c.) were heated under reflux for 24 hours.After removal of the excess of alcohol in a vacuum two layers formed; the upper quickly crystallised and yielded on being drained 2.7 g. of crude amide. The liquors yielded to ether 8-5 g. of yellow oil which gave a further crop of crude amide somewhat contaminated with the lower-melting isomeride. The aqueous liquors on acidification and ether extraction gave an unsaturated acid oil (15.5 g.) which on distillation gave a fraction b. p. 196-206" (6.4 g.) and a fraction, b. p. 205-220" (5.0 g.). Both showed marked unsaturation but neither solidified on cooling. Both however yielded or-ethyl-crotonic acid m. p. 42" on treatment with phosphorus trichloride and subsequently with water. ( b ) The ureide m. p. 198" (17 g.) was heated for 1 hour on the water-bath with X-potassium hydroxide (350 c.c.).The solution was saturated with sodium chloride filtered from a little unchanged material and repeatedly extracted with chloroform ; this removed an oil (7 g.) from which was isolated a-ethylcrotonamide white needles m. p. 104". Acidification of the aqueous liquors yielded an unsaturated acid oil (4.3 g.) which on distillation gave nearly pure liquid a-ethylcrotonic acid b. p. 190-200"; this was con-verted as before into the solid isomeride m. p. 42". The combined yields accounted for 95% of the unsaturated ureide employed. (c) I n a further experiment the hydrolysis was carried on for 30 minutes only. The final liquors after removal of the neutral and the acid fraction were evaporated t o dryness in a vacuum; from the residue boiling alcohol extracted carbamide (identified as the nitrate).High-melting a-Eth$crotonanzide.-The crude unsaturated amide from the above preparation (a) on repeated crystallisation from ether formed colourless needles or leaflets m. p. 118" (corr.) (Found C = 63-8 ; H = 10.0; N = 12.4. C,H1,ON require 302 NEWBERY THE ACTION OF OAUSTIC ALKALI C = 63.7; H = 9.7; N = 12.4%). It is very soluble in alcohol, moderately soluble in benzene or water slightly soluble in cold ether and insoluble in light petroleum. Prepared synthetically from cz-etliylcrotonyl chloride and strong aqueous ammonia the same amide was obtained in 75y0 yield in glistening plates m. p. 118" (Pound N = 126%). Hydrolysis of High-m elt i ~ g u- Ethy1crotonamide.-The unsatur-ated amide (6.5 g.) was refluxed for 3 hours with 20% aqueous caustic soda (15 c.r.).Ammonia was evolved and after the ex-traction of some 3 g. of unchanged amide by chloroform acidification and ether extraction yielded an acid oil (3 g.) from which a-ethyl-crotonic acid was obtained; m. p. 40'. Action of Sodium Hydroxide (2 mols.) on a-Brorno-a-ethylbutyryl-curbamide.-Finely-powdered commercial adalin (100 g.) was heated under reflux with N-sodium hydroxide (1000 c.c.) for 90 minutes and when cold the liquid was saturated with sodium chloride, filtered from high-melting a-ethylcrotonylcarbamide (4 g.) and extracted with ether. From the extract dried over anhydrous sodium sulphate were obtained 4 g . of a substance which readily sublimed at about lOO" quickly solidified on cooling and after repeated crystallisation from ether melted a t 104" alone or mixed with a-ethylcrotonamide (m.p. 104" after several crystallisations), prepared according to Mannich and Zernik (loc. cit.). Low-melting a-ethylcrotonamide crystallises in colourless needles from ether in which it is more soluble than the high-melting isomer-ide is very soluble in alcohol or chloroform moderately soluble in benzene or water and insoluble in light petroleum (Found C = 63.6; H = 9.9; N = 12.5. Calc. for C,H,,ON C = 63.7; H = On acidification the reaction product also yielded a mixture of the two a-ethylcrotonic acids b. p. 190-220" (11 g.) and the saturated acid oil b. p. 284-287" (26 g . ) . Hydrolysis of Lotomelting a-Ethy1crotonamide.-(a) a-Ethyl-crotonamide m.p. 104" (6 9.) was heated on the steam-bath for 1 hour with N-caustic potash (125 c.c.). Saturation with sodium chloride and chloroform extraction yielded the unchanged amide (5.8 g.; 97% recovery). ( b ) The amide (4 g . ) boiled under reflux with 20% caustic soda (10 c.c.) for 3 hours yielded as before 3 g . of unsaturated amide m. p. 100" (indefinite) which was probably a mixture of the two isomeric amides since repeated crystallisation from ether yielded the less soluble form m. p. 118". The acid fraction yielded liquid a-ethylcrotonic acid (0-7 g.) b. p. ZOO". (c) The amide (3.5 g.) heated for 5 hours with boiling 40% 9.7; N = 12.4%). There was no appreciable acid fraction ON a-BROMO - a-ETHYLBUTYRYLOARB AMID E . 303 caustic soda (20 c.c.) yielded when worked up in a similar way, the high-melting form of the amide (0.25 g.) together with a mixture of the two cc-ethylcrotonic acids b.p. 195-205" (3 g.). Synthesis of Low-melting a-Ethylcrotony1carbamide.-a-Bromo-a-ethylbutyryl bromide (200 g. ; b. p. 128"/30 mm.) was run slowly into a boiling solutio6 of potassium*hydroxide (400 g.) in water (250 c.c.) and alcohol (750 c.c.). Much heat was developed and the alcohol kept boiling vigorously. The mixture mas heated for 30 minutes on the steam-bath water added to dissolve the separ-ated potassium bromide and the excess of alcohol removed in a vacuum. Acidification with hydrochloric acid and ether extrac-tion yielded a mixture of the two forms of a-ethylcrotonic acid (75 g. ; b. p. 190-210; yield 90% of theory).(a) To the mixed acids (5 g.) was' added phosphoryl chloride (3 g,) followed almost immediately by 8 g. of carbamide. A vigorous reaction ensued which was not controlled and after 30 minutes' heating on the water-bath addition of water and a short period of further heating, the mixture was cooled and the crude carbamide (3.5 g.) filtered off. (a) a-Ethylcrotonyl chloride (2.2 g.; b. p. 58'114 mm.), prepared from the mixed acids and phosphorus trichloride was heated on the water-bath for 2 hours with carbamide (2.5 g.). The semi-liquid mass became more viscous and was finally nearly solid. Water was added and the crude carbamide (2 g.) filtered off. Low-melting cc-Ethylcrotonylcarbamide m. p. 158" (corr.) crystallised in colourless needles from alcohol; it was not readily soluble in cold alcohol benzene acetone or ether and did not readily de-colorise bromine water (Found C = 53.6; H = 7.8; N = 18.1.C,H,,0,N2 requires C = 53.8; H = 7.7; N = 18.0y0). Hydrolysis of Low-melting a-Ethylcrotony1carbamide.-The hydro-lysis of the ureide m. p. 158" (5 8.) was effected with hr-caustic potash (100 c.c.) under exactly similar conditions to those employed for the hydrolysis of the isomeric ureide m. p. 198". The chloro-form extract yielded an oil (2 8.) which quickly solidified and crystallised from ether in leaflets m. p. 118" alone or mixed with synthetic a-ethylcrotonamide. The aqueous liquors after acidific-ation yielded to ether an oil (1-8 g.) which quickly solidified and proved to be solid a-ethylcrotonic acid m.p. 42". Hydrolysis for 3 hours with concentrated alcoholic potash yielded the same products. Reduction of the Isomeric cc-Ethy1crotonamides.-A warm solution of cc-ethylcrotonamide m. p. 118" (1 g.) in water (50 c.c.) was reduced with 4% sodium amalgam (50 g,) and after filtration from mercury was extracted with chloroform. Desiccation and evaporation of the solvent yielded an oil which solidiiied on stand 304 NEWBERY THE ACTION OF CAUSTIC ALKALI. ing. Repeated crystallisation from ether yielded white needles, m. p. l l l " which did not reduce alkaline permanganate or de-colorise bromine water. a-Ethylcrotonamide m. p. 104" under the same conditions yielded the same product. a-Ethy1butyramide.-a-Ethylbutyryl chloride b. p. 65"/70 mm.(5 g.) was run slowly with continuous stirring into excess (10 c.c.) of concentrated ammonia solution cooled by ice. The solid which separated together with a further quantity obtained by chloroform extraction (3-5 g. in all; 82% of theory) crystallised from ether in colourless needles m. p. 112" (cow.) alone or mixed with the reduction product from either u-ethylcrotonamide (Found N = 12.3. Calc. for C,H,,ON N = 12.2Y0). The alkaline hydrolysis of synthetic a-ethylbutyrylcarbamide likewise led to the same saturated amide m. p. 112' (E. Fischer and Dilthey Ber. 1902, 35 853 give m. p. 107"). Reduction of the Isomeric a-Ethylcrotony1carbamides.-Either isomeride (1 g.) was reduced with boiling ethyl alcohol (20 c.c.) and sodium (1.5 g.). Chloroform (50 c.c.) was added to the mixture, followed by water (100 c.c.).The solid (0.4 g.) isolated from the chloroform extract crystallised from alcohol in colourless needles, m. p. 205-206" which did not reduce a cold alkaline permanganate solution nor depress the m. p. (206-207") of synthetic a-ethyl-butyrylcarbamide. Brornination of L ow-melting a-Ethglcroton amide .-a-Ethylcroton-amide m. p. 104" (2.5 g.) suspended in carbon disulphide (30-40 c.c.) at O" required the theoretical quantity of bromine in the same solvent to give a permanent coloration after an hour. The crystals which began to separate during tha addition were washed with carbon disulphide dried (3.5 g.; 5SY0 of theory) and re-crystallised from alcohol high-melting ap-dibromo-a-ethylbutyr-amide separating in colourless needles m.p. 127-128" slightly soluble in cold carbon disulphide ether or petroleum (Found : Br = 58.6. Bromination of High-melting a-Bthy1crotonamide.-a-Ethylcroton-amide m. p. 118" (2.5 g.) treated in a similar way gave a less sharp end-point absorption of bromine being less rapid and only towards the end of the addition was there any separation of the dibromide. The solvent was evaporated the residue which solidi-fied after some hours a t 0" was washed with ether-petroleum (b. p. 40-60") and crystallised from the same mixture yielding low-melting a@-dibromo-a-ethylbutyramide (2-5 g. ; 42% of theory) as a slightly yellow crystalline powder m. p. 77-78' ; by repeated crystallisation colourless plates m. p. 79-80' were obtained. This dibromide was more soluble in carbon disulphide alcohol or Calc.for C,H,,ONBr, Br = 58.6%) ON CL-BROMO-C~-ETHYLEUTYRYLCARBANIDE. 305 ether than the high-melting isomeride and was somewhat soluble in hot petroleum (b. p. 40-60") (Found Br = 58.5. C,H,,ONBr, requires Br = 58.6%). Brominat ion of Low melting -a-Et h ylcrotonylcarbamide .-a- Ethyl-crotonylcarbamide m. p. 158" (5 g.) was exposed for 48 hours over excess of bromine in a closed desiccator. Excess of bromine was removed in a current of air and the residue refluxed with ether (200 c.c.). After filtration the ethereal solution was con-centrated to 20 c.c. and the crystals (3 g.) which separated were recrystallised from alcohol when low-melting -ap-dibromo-a-ethyE-butyrylcnrbamide was obtained in colourless needles m.p. 112" (Found Br = 50.7. C,H,,0,N2Br2 requires Br = 50.6%). Brominatio?h of High-melting -a-Ethylcrotony1carbamide.-The ureide m. p. 198" (5 g.) brominated in a similar manner gave high-melting a p-dibromo- -a-ethylbutyrylcarbamide (3.2 g.) which crystallised from alcohol in colourless prisms m. p. 142-143". It is moderately soluble in ether (Found Br = 50.4. C7H1,02N2Br2 requires Br = 50.6 yo). Action of Hydrogen Bromide o n Low-melting a-Ethy1crotonamide.--a-Ethylcrotonamide m. p. 104" (2.5 g.) was heated on the water-bath for 2 hours with acetic acid saturated with hydrogen bromide a t 0" (25 c.c.). Excess of the acids was removed in a vacuum, the residue (10 c.c.) nearly neutralised with 2N-sodium hydroxide, and the mixture extracted with chloroform.The solid (0.6 g.) which remained after the removal of the solvent crystallised from ether in leaflets m. p. 117-118" not depressed by admixture with the synthetic amide m. p. 118". Bebwiour of Hydrogen Bromide with High-melting a-Eihylcroton-amide.-The amide m. p. 118" (0.3 g.) was heated for 6 hours in a sealed tube a t 100" with acetic acid saturated with hydrogen bromide a t 0" (2 c.c.). The mixture after dilution and neutral-isation gave on extraction only the unchanged amide m. p. 118". Actioiz of Hydrogen Bromide on Low-melting a-Ethylcrotonyl-carbanzide.-A mixture of the ureide m. p. 158" (4 g.) with acetic acid saturated with hydrogen bromide a t 0" (40 c.c.) was heated under reflux for 20 hours on the steam-batJh and when poured into cold water (500 c.c.) yielded a solid product (1 g.).p-Bromo- a-ethylbzrtyrylcarbamide was obtained in colonrless needles m. p. 179-180" by repeated crystallisation from alcohol. It is sparingly soluble in alcohol benzene or ether (Found N = 1 1 4 ; Br = 33-4. C,H,,O,N Br requires N = 11.8 ; Br = 33.75%). Action o$ Hydrogex. Bromide on Low-meltiiLg cc-Ethylcrotonyl-carbaniide.-The ureide m. p. 19s" (5 g.) together with saturated acetic-hydrobromic acid (30 c.c.) was hezted for 8 hours in a sealed \-oL. @SSVII. i 306 NEWBERY THE ACTION OF CAUSTI~ ALKAIJ ETC. bottle in a boiling-water bath. The mixture was filtered from a little ammonium bromide water added and the solution nearly neutralised with 20% caustic soda solution. On cooling a white solid (4 g.) separated which after repeated crystallisation from alcohol melted at 177" and was identical with the p-bromo-a-ethyl-butyrylcarbamide described above.Chloroform extraction of the still slightly acid mother-liquors yielded a small amount of oil, which solidified on standing and after repeated crystallisation from alcohol had m. p. 158" not depressed by admixture with the unsaturated ureide of that melting point. Examination of the Saturated Acid b. p . 283-286'.-Bisdiethylglycollylcarbamide was obtained in a pure condition from the acid oil b. p. 283-286" by a slight modification of the method proposed by Clemmensen and Heitman (Zoc. cit.) involving the preparation of the silver salt from the ammonium salt followed by the decomposition of the former by hydrogen sulphide.It then melted a t 29" and agreed in physical and chemical pro-perties with bisdiethylglycollylcarbamide prepared synthetically (Found C = 54.2 54.0; H = 8-1 8.3; N = 9.8 9.7. Calc. for Hydrolysis of Bisdiethylglycolly1carbamide.-(a) The oil b. p. 283-286' (21 g.) was refluxed for 48 hours on the steam-bath with alcoholic potash from potassium hydroxide (21 g.) dissolved in the minimum of water and 100 C.C. of alcohol. Ammonia was evolved during the whole period of heating. The mixture yielded on dilution and ether extraction an oil b. p. 164"/25 mm. (10 g.). This quickly solidified and on crystallisation from ether gave diethylglycollamide m. p. 88" in colourless hexagonal plates (Found N = 1043. C,Hl,O,N requires N = 10.7%). The aqueous liquors on acidification likewise yielded an acid fraction (10 g.) which on distillation boiled for the most part at 115-130°/10 mm.There was a small amount of unchanged material b. p. 152-155"/10 mm. The main fraction quickly solidified and crystallised from petroleum (b. p. 60-80") in colourless needles, m. p. 80" not depressed by admixture with synthetic diethyl-glycollic acid m. p. 81". (b) The same oil (40 g.) hydrolysed under the same conditions for 3 hours only yielded diethylglycollamide (15 g.) and unchanged material (10 g.). No diethylglycollic acid could be isolated. (c) The oil (13 g.) boiled on the sand-bath for 1 hour with 2N-caustic soda gave no diethylglycollamide and the acid fraction yielded only unchanged material (12.5 g.). Bis-a-ethxy-a-ethyZbutyryZcarbarmide.-The silver salt (19 g.) of bis-diethylglycollylcarbamide (Found Ag=40.1.C,,H,,O5N&g2,2H,O requires Ag = 40.1%) from the saturated acid oil b. p. 283-286", C13H2405N2 C = 54.1 ; H = 8.3; N = 907%) THE DIRECT COMBINATION OF ETHYLENIC HYDROCARBONS ETC. 307 after being dried a t loo" was heated with ethyl iodide (25 c.c.) for 15 minutes silver iodide was removed by filtration and the oil (12 g.; 97% of theory) which was insoluble in caustic soda, distilled a t 160-170"/60 mm. The oil so obtained had a char-acteristic odour of garlic and b. p. 240" (Found C = 59.0 ; H = 9.3. C,,H,,O,N requires C = 59-3; H = 9.3%). A preparation in a similar way from synthetic bisdiethylgiycollylcarbamide yielded the same product. Hydrolysis of Bis-a-ethoxy-u-ethylbutyry1carbamide.-The ethoxy-carbamide (20 g.) was hydrolysed for 12 hours on the steam-bath with alcoholic potash from potassium hydroxide (20 g.) in the minimum of water and 200 C.C. of alcohol. After the removal of excess alcohol in a vacuum and dilution ether extraction gave an oil (10 g.) b. p. 141-144"/11 mm. which solidsed after remaining a few hours a t 0". cc-Ethoxy- a-ethylbutyramide when pure melts a t 38" and is very soluble in most organic solvents but practically insoluble in light petroleum. It could not be crystallised satisfactorily and was apparently best purified by repeated distillation in a vacuum (Found N = 8.7. The aqueous liquors from this preparation yielded practically no acid fraction, and ethoxyethylbutyramide was found to be extremely resistant to the hydrolytic action of alkali. C,H,,O,N requires N = S+3~0). The author desires to express his indebtedness to the Directors of Messrs May and Baker Ltd. for permission to publish the results embodied in the above paper to Dr. A. J. Emins for his interest in the investigation and to Mr. M. A. Phillips for assistance in much of the experimental work. MESSRS MAY AND BAKER LTD., WANDSWOHTH S.W. 18. RESEARCH LABORATORY, [Received. July 3rd 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700295

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

THE DIRECT COMBINATION OF ETHYLENIC HYDROCARBONS ETC. 307 XLVII1.-The Direct Combination of Ethylenic Hydro-carbons with Hydrogen Xzclphites. By ISRAEL KOLKER and ARTHEX LAPWORTH. AGENTS such as ozone which attack the simplest compounds, have been distinguished (as " Class I ") by Lapworth and MeRae (J. 1922 121 2741 ; compare also Lapworth &fern. fManchester Phil. Xoc. 1920 64 iii 11) from others (" Class I1 ") which M 308 KOLKER AND LAPWORTH THE DIRECT COMBINATION OF are inert towards ethylenic hydrocarbons but which nevertheless are additive to the ethylenic group when the latter occurs in the a-position with respect to a carbonyl cyano or similar group. It is significant that all the known agents of the second class are either (IIa) metallo-compounds or (IIb) compounds of the general type H-Z in which the hydrogen atom is capable of being replaced by the action of metals.Examples of sub-class IIa are Grignard reagents potassium cyanide and sodio-derivatives of ketones esters and nitriles . Examples of IIb are HCN HCH(CO,Et), HNR,R, the last includ-ing amines hydroxylamines and hydrazines . The electronic theory of metallic compounds suggests that the radical of each agent of class IIa is capable of existence in all cases as a negatively charged ion Z-. In some cases the free ion Z- is identical in consti-tution with the radical as it occurs in the compound H-Z (example H-NH,) ; in other cases it is probably not ; (example : H-CH,.NO,) but the structural difference is such that intracon-version readily takes place in either direction.As is well known, agents of sub-class IIb also form addition products with many saturated carbonyl compounds. Not all compounds which have the characters defined in the preceding paragraph can be referred to Class IIb ; thus powerful acids are by definition excluded from this class as they attack ethylenic compounds of all types. It is further necessary to observe that in referring any agent to Class IIb there are restrictions as to the experimental conditions prevailing while the agent is applied. For example hydrogen cyanide may properly be referred to Class IIb when applied in presence of an alkaline catalyst but not in presence of an acid catalyst unless it has been shown that under the same conditions the combination is inert or nearly so toward ethylenic hydrocarbons.Within the range occupied by IIb which must be limited a t one extreme by acids too weak to attack ethylenic compounds at measurable speed and at the other extreme by very feebly ionisable compounds such as ammonia there does not at present appear to be any direct relation between the additive efficiency of the agent and the electro-affinity of the anion. Thus many very weak acids appear almost or quite unable to form stable addition products with carbonyl compounds. With reference to Class I1 as a whole it is probably true that no compounds of which the ion Z- has a very high affinity for the charge can be included in either sub-class (compare Lapworth, Zoc. cit.). There are for example no cases recorded where the potassium or sodium salts of powerful acids form additive corn ETHYLENIC HYDROCARBONS WITH HYDROGEN SULPHITES.309 pounds with carbonyl compounds. The powerful acids have already been excluded for the reasons above stated. From the preceding considerations it is clear that any agent which forms addition products with the carbonyl group of aldehydes and ketones or with the ethylenic linking in ap-unsaturated carbonyl compounds may safely be referred to sub-group IIb only when it is known that the agent does not attack ethylenic hydrocarbons under comparable conditions; in many cases as in the instance of ammonia experimental evidence is already extensive and <o uniformly negative that this indifference may confidently he inferred whilst in other cases further investigation is required.The correct classification of agents additive to ethylenic com-pounds is of the utmost importance in studying the influence of atoms and groups on the properties of others in the same molecule. The authors have made a careful study of two series of agents previously referred in the papers above specified (Zoc. cit.) to Class 11. The experiments carried out by the authors and by other workers in these laboratories on the possible addition of hydrogen cyanide and metallic cyanide to ethylenic hydrocarbons including cycio-hexene and styrene have given uniformly negative results. As the addition products in these cases would have been nitriles easily convertible into carboxylic acids and so capable of detection even in traces it may be concluded that metallic cyanides and hydrogen cyanide in absence of acid catalysts are indeed highly selective ant1 that when they do attack an ethylenic linking the latter is almost certainly affected by conditions similar to those which ohtr~in iri @-unsaturated ketones.The other series of reagents tested were sulphites and iuore especially hydrogen sulphites. The sole instance hitherto recorded (so far as we have been able to discover) of a hydrocarbon combining directly with hydrogen sulphites is that of styrene and even in that, case the published evidence was inconclusive (Miller dnticrlctr, 1877 189 340; LabbB Bull. SOC. chim. 1893 [iii] 22 1077; Dupont and Labaune Sci. Ind. BzZZ. 1912 [iii] 7 3). In thr: case of styrene moreover there was an element of doubt whether phenyl can exercise the same influence on a double bond as carbonyl can.Similar uncertainty existed in the theoretical interpretation of the observations of Dupont and Labaune (loc. cit.) nho obtained additive products of hydrogen sulphites with unsaturatctl alcohols. The results obtained by the present authors remove all doubt on many of these moot points. Hydrogen sulphites combine directly with ethylenic hydrocarbons and the failure of previous investi 310 KOLKER AND LAPWORTH THE DIRECT COMBINATION OF gators fully to establish this fact is attributable to the unsuitable experimental conditions used. Special precautions to ensure intimate contact between the hydro-carbons and the aqueous solutions are usually but not invariably necessary.They may consist in emulsifying with the aid of purified kieselguhr. Contrary to expectations dilution of the sulphite solution possibly by an effect on the solubility of the hydrocarbons, favoured the interaction. A not less important practical feature in the later experiments was the use of ammonium hydrogen sulphite instead of the sodium or potassium salt. This device admits of the ready removal of any excess of the reagent by boiling with sufficient barium hydroxide, when insoluble barium sulphite is formed ammonia is expelled, and such organic addition products as are not destroyed during this process are easily isolated as soluble barium salts. Pinene dipentene cyclohexene crude " amylene " and even the completely symmetrical ethylene combine readily under favourable conditions with hydrogen sulphites usually in the cold yielding products which for the most part appear to be the salts of the expected saturated sulphonic acids ; but these are usually mixed with a variable proportion of other salts apparently isomeric with the sulphonates.These secondary products unlike the true sul-phonic acids are hydrolysed by dilute acids or alkalis and are probably salts of the alkyl hydrogen sulphites though some slight doubt attaches to this view of their constitution. These salts appear to be considerably more stable than the salts of alkyl hydrogen sulphites prepared by union of sulphur dioxide with sodium alkyl-oxides but this may be due to stabilisation by the other salts present ; indeed the authors have observed (1) that the hydrolysis of the salts of methylethionic acid SO,H*CH(CH,)*CH,*SO,H (which normally is readily effected by dilute acids) takes place much more slowly if excess of salts of methylisethionic acid, SO,H *CH (CH,) *CH,* OH , are present and (2) that pure barium methylethionate decomposes a t loo" but in presence of 9-10 times its weight of isethionate does not decompose appreciably below 150".It is just possible however, that two series of alkyl sulphurous acids exist. It seems probable that carbonyl compounds react with bisulphite, as with metallic cyanide by first capturing the anion. Ethylenic hydrocarbons evince no definite preference for anions and may react with bisulphites either by first capturing the hydrogen ion or by uniting with the unsaturated centres of the sulphite molecules much as they unite with ozone and possibly in both ways.The gross result of the process of addition of hydrogen sulphite ETHYLENE HYDROCARBOKS WITH HYDROGEN SULPHITES. 31 1 to ethylenic hydrocarbons may thus be represented by the following scheme as adapted for sodium hydrogen sulphite : CHR,R,*CR,R,-SO,Xa A CHRIR,*CR,R,*O*SO,Nat. CRIR,:CR,R + NaHSO / Hydrogen sulphites must now therefore be omitted from the list of reagents of Class 11. E x P E R I ni E N T A L. Throughout this section the term “ molar ” and the symbol M applied to a hydrogen sulphite solution denote a solution containing one gram-molecule per litre. Inorganic sulphite in solutions of the reaction products was assumed to be absent when mineral acids in the cold caused no evolution of sulphur dioxide and when iodine was not decolorised.General Method of !Treatment of Insoluble Fluid Compounds with ,4mmonium Bisulphite Xolzction .-Usually the fluid unsaturated compound was shaken vigorously at intervals during several days with M/4-ammonium hydrogen sulphite and kieselguhr. The kicdguhr was then separated by filtration wished with boiling water and the united filtrates were heated with excess of barium 1 1 droxide until ammonia ceased to be evolved. The whole was then neutralised with dilute sulphuric acid the precipitated barium sulphite and sulphate were filtered off and washed with boiling water, the filtrates being finally evaporated to dryness on the steam-bath, Xtudies of the Influence of Conditions on Speed of Addition oj’ Ammonium Bisulphite to cycloHexene .-Owing to adsorption of solutes by the kieselguhr used as emulsifying agent i t was found necessary in comparative experiments to convert the addition product into barium salt and then to isolate and weigh this.I n one series of four experiments the following results were obtained using 5 C . C . of cgclohexene in mch instance with N j 4 -ammonium hydrogen sulphite solution. Volume of f1~/4-NM,HSO3 solution used ............ 240 C . C . 480 C . C . Excess of NH,HSO more than theory ............ 25yA 1500,b Yield (yo of theory) without kieselguhr ............ 16.8 40.11 Yield (yo of theory) with kieselguhr ............... 19.3 5 7 .o I n another series of three parallel experiments using the same quantity namely 5 c.c of cyclohexene with the same weight of ammonium bisulphite in each experiment but dissolved in different weights of water all with shaking a t intervals during 10 days the following results were obtained.In this series no kieselguhr was 11sed 312 KOLKER AND LAPWORTH THE DIRECT COMBINATION OF ............ Strength of bisulphite solution 2M M 12 C.C. of bisulphite solution .................. 60 120 240 Weight of crude barium salt obtained ... 1-29 1-51 2.26 Yield of crude product yo of theory ... 10.3 12.1 18.0 It is evident from the f i s t series that kieselguhr has a very f avourable influence on the yield especially when a considerable excess of hydrogen sulphite is used. The two series taken in conjunction show that the yield improves with the dilution of the hydrogen sulphite at least up to M / 4 ; the volumes of fluid to be evaporated however set a limit to the practical application of this fact.Examination of Products from cyclol3exene.-( a) With sodium hydrogen sulphite. When cyclohexene (30 c.c.) was shaken at intervals with N/2-hydrogen sulphite solution (1800 c.c.) for 8 days the resulting aqueous solution separated from unchanged cyclohexene (found 20 c.c.) evaporated to dryness and extracted with 96-98% spirit a white powder (1.9 g.) was obtained (Found Na = 12-3. C,H,,*SO,Na requires Na = 12.3y0). This powder gave no sulphuric acid when boiled with excess of dilute hydrochloric acid, and was free from inorganic sulphite; on hydrolysis with boiling sodium hydroxide however it yielded a little inorganic sulphite, estimated from titrations with iodine to represent 6-7.5y0 of sodium cyclohexyl sulphite.cycloHexene (36 c.c.), M/4-ammonium bisulphite solution (3360 c x.) and kieselguhr (120 g.) were shaken together at intervals during 10 days. On working up the product as on p. 31 1 a brown solid was obtained which on recrystallisation yielded white hexagonal plates of barium cyclo-hexanesulphonate identical with that obtained by the method of Borsche and Lange from cyclohexyl chloride through the sulphinic acid (Bey. 1905 38 2766) [Found H20 = 13.5; Ba (in dried salt) = 29.6. (C6Hl1*SO,),Ba,4H2O requires H,O = 13.4; Ba (in anhydrous salt) = 29.7y0]. The identity was established by direct comparison of the barium salts and of the sulphanilides (m.p. 85").* * The following new derivatives of cyclohexanesulphonic acid were pre-pared and examined during the course of the work. Sodium salt prisms, readily soluble in water and in dilute alcohol (Found Na = 11.1. C 6H,,.SOsNa,H20 requires N a = 1 1.3y0). Ammonium salt hygroscopic and exceedingly soluble in water ; very readily soluble in 98% spirit crystallising therefrom in granules. Magnesium salt rhombic plates by spontaneous evaporation of an aqueous solution. Copper salt small light green rhombic plates moderately soluble in water [Found : H,O = 15.4. (C6Hll.SOs)2Cu,4H,0 requires H20 = 15.6%]. SuZphonyZ chloride analysed by Borsche and Lange and described by them as an oil, separates from ether in rhombic plates m.p. 106'. Sulphonamide may be crystallised from water and melts at 93-94O. (b). With ammonium hydrogen sulphite. Very readily soluble in water ETHYLENIC HYDROCARBONS WITH I-IYDROGEN SULPHITES. 313 The nature of the crude brown solid product was investigated. When boiled for 4 hours with a large excess of 12% sodium hydroxide it yielded sulphite corresponding with 2% of alkyl sul-phite. When boiled with 10-150/ hydrochloric acid it did not >ield any sulphate but some sulphur dioxide was detected. When 3-5 g. were boiled for 6 hours with 15% sulphuric acid (50 c.c.), some siilphur dioxide was evolved the solution turned light yellon-in colour and a slight aromatic odour was observed The product of this hydrolysis could not be isolated but after removal of con-stituents soluble in ether and neutralisation of the solution with barium carbonate evaporation yielded 3.1 g.of pure bariuni r,!/~.lohexanesulphonate. It woulcl thus seem that the material contains a t least 90 % of ammonium cgclohexanesulphonate together with a small quantity of an organic compound which yields sul-pliurous acid or sulphite on hydrolysis.* This compound could not be isolated but it was observed that the mother-liquor remaining after separation of cyckohesanesulphonate from the crude product a t first gave with ferric chloride a deep red coloration similar to that obtained with sulphites and sulphinates; later this test gave a negative result so that the compound causing this coloration was evidently unstable either to water or to air or to both.Ethylene and Ammonium Hydrogen Xulphite .-Ethylene wab hrought into contact with M/4-ammonium sulphite ( 2 litres) in a large bottle a t about atmospheric pressure with occasional shaking. At first the solution absorbed nearly its own bulk of the gas during each interval of 24 hours when the residual gas with any gaseous impurities in it was allowed to escape and was then replaced by fresh ethylene. After this process had been repeated daily during a fortnight about 5 litres of ethylene had been absorbed and the original speed of absorption reduced by about four-fifths. The liquid was then worked up in the usual way and 13 g. of crude barium salts were obtained. * It is difficult to reconcile the properties of this secondary constituent n-ith tho assumption that it is sodium cyclohexyl sulphitc as it has resisted thi operations used in preparing the crude product.For comparison, sodium cyclohexyl sulphite was made by passing sulphur dioxide into (a) A solution of sodium in cyclohexanol and precipitating with alcohol ( b ) zt. suspension of sodium cyclohoxyl oxide in benzene and then draining thG solid on porous earthenware. The solid obtained by either process was, like other salts of alkyl sulphurous acids previously described extremely unstable losing sulphur dioxide on exposure to air and being immediately ligdrolysed in aqueous solution with liberation of inorganic sulphite (Found in sodium cyclohexyl sulphite made by process ( b ) Na = 13.4. C,H,,~SO,Na rc-quires Na = 12.4%. 0-346 G.dissolved in water required 39-5 C.C. of N/lO-I, while one molecule of sulphite from C,H,,-SO,Na requires 37.2 c.c.). ( For coniments on these points compare introductory section.) ix 314 THE DIRECT COMBINATION OF ETHYLENIC HYDROCARBONS ETC. The salts consist mainly of barium ethanesulphonate but also, as in the case of cyclohexene of small quantities of other salts, which give a red coloration with ferric chloride and are somewhat stable towards alkalis but unstable towards boiling mineral acids, which cause evolution of sulphur dioxide but no liberation of sulphuric acid [Found in barium salt H20 = 9.2; Ba (in anhydr-ous salt) = 38.6. (C2H5-S03)2Ba,2H,0 requires H20 = 9.2; (C2H5*S03)2Ba requires Ba = 38.7y0]. water, and easily recrystallised from ether forming prisms m.p. 59-GO” (James J . p r . Chem. 1882 [ii] 26 384 gives the melting point of ethanesulphonamide as 56”). Commercial “Amylene ” and Ammonium Hydrogen Sulphitc-Combination was here so rapid that in 7 days with occasional shaking 5.3 C.C. of “ amylene ” were almost completely absorbed by M/4-ammonium hydrogen sulphite solution without kieselguhr. On working up in the usual way 9.4 g. of crude soluble barium salt (86% of theory) were obtained [Found Ba = 31.5. (C,H,,~SO,) Ba requires Ba = 31-3y0]. The crude salt did not decolorise permanganate nor absorb bromine it gave no sulphur dioxide or sulphuric acid when boiled for several hours with 15% hydrochloric acid and 95% of the original product was recoverable. “ Amylene ” was exceptional among the hydrocarbons examined in yielding nothing but true sulphonic derivatives.As the ‘‘ amylene ’’ used was the mixture of several isomerides obtained from fuse1 oil the products were not further examined. Dipentene andAmmonium Hydrogen Su1phite.-Dipentene (15 c.c.), ammonium hydrogen sulphite (M/4 ; 2000 c .c .) and kieselguhr (50 g.) shaken at frequent intervals during 14 days gave 12.1 g. of barium salts at least 90% of which consist of barium menthne-disulphonate [Found H,O (lost at 160O) = 4.0. requires H20 = 4.0%. In the anhydrous salt ; found Ba = 31.4, S = 15.1; theory requires Ba = 31.6 S = 14-7y0]. This salt is readily soluble in water forms clusters of needles, and is stable to boiling mineral acid. The mother-liquors obtained on recrystallising the salt from water decolorise a little bromine or permanganate and slowly evolve some sulphur dioxide when boiled with dilute sulphuric acid.Pinene and Ammonium Hydrogen Su1phite.-From pinene (32 c.c.), ammonium hydrogen sulphite (M/4 ; 2000 c.c.) and kieselguhr (70 g.) after 12 days 7.4 g. of mixed soluble barium salts were isolated but retained an odour resembling pinene after repeated The sulphonamide made from this salt was soluble in C~~H18(S03)2Ba>H?, METHOD OF MEASURING THE DIELECTRIC CONSTANTS OF LIQUIDS. 315 extraction with absolute alcohol. The crude product differed appreciably from that obtained from any other hydrocarbon inas-much as the proportion of hydrolysable salt was nearly 45% of the whole. When 2 g. were boiled with 15% sulphuric acid much sulphur dioxide was evolved and appreciable quantities of an oil having a terpene-like odour appeared.After removing the oil with ether and the sulphuric acid with barium carbonate only 1.1 g. of stable barium salt were recovered. The crude product, which was free from inorganic sulphate also discharged the colour of an unusually large proportion of bromine. ORUANIC CHEXICAL LABORATORIES, THE UNIVERSITY MANCRESTER. [Received November 7 t h 1924.1 ADDENDuM.-Throughout this paper the terms (‘ hydrogen sulphite ” and (( bisulphite ” are used interchangeably and without regard to the question of the constitution of salts t o which these names have commonly been applied in the past THE DIRECT COMBINATION OF ETHYLENIC HYDROCARBONS ETC. 307 XLVII1.-The Direct Combination of Ethylenic Hydro-carbons with Hydrogen Xzclphites.By ISRAEL KOLKER and ARTHEX LAPWORTH. AGENTS such as ozone which attack the simplest compounds, have been distinguished (as " Class I ") by Lapworth and MeRae (J. 1922 121 2741 ; compare also Lapworth &fern. fManchester Phil. Xoc. 1920 64 iii 11) from others (" Class I1 ") which M 308 KOLKER AND LAPWORTH THE DIRECT COMBINATION OF are inert towards ethylenic hydrocarbons but which nevertheless are additive to the ethylenic group when the latter occurs in the a-position with respect to a carbonyl cyano or similar group. It is significant that all the known agents of the second class are either (IIa) metallo-compounds or (IIb) compounds of the general type H-Z in which the hydrogen atom is capable of being replaced by the action of metals.Examples of sub-class IIa are Grignard reagents potassium cyanide and sodio-derivatives of ketones esters and nitriles . Examples of IIb are HCN HCH(CO,Et), HNR,R, the last includ-ing amines hydroxylamines and hydrazines . The electronic theory of metallic compounds suggests that the radical of each agent of class IIa is capable of existence in all cases as a negatively charged ion Z-. In some cases the free ion Z- is identical in consti-tution with the radical as it occurs in the compound H-Z (example H-NH,) ; in other cases it is probably not ; (example : H-CH,.NO,) but the structural difference is such that intracon-version readily takes place in either direction. As is well known, agents of sub-class IIb also form addition products with many saturated carbonyl compounds.Not all compounds which have the characters defined in the preceding paragraph can be referred to Class IIb ; thus powerful acids are by definition excluded from this class as they attack ethylenic compounds of all types. It is further necessary to observe that in referring any agent to Class IIb there are restrictions as to the experimental conditions prevailing while the agent is applied. For example hydrogen cyanide may properly be referred to Class IIb when applied in presence of an alkaline catalyst but not in presence of an acid catalyst unless it has been shown that under the same conditions the combination is inert or nearly so toward ethylenic hydrocarbons. Within the range occupied by IIb which must be limited a t one extreme by acids too weak to attack ethylenic compounds at measurable speed and at the other extreme by very feebly ionisable compounds such as ammonia there does not at present appear to be any direct relation between the additive efficiency of the agent and the electro-affinity of the anion.Thus many very weak acids appear almost or quite unable to form stable addition products with carbonyl compounds. With reference to Class I1 as a whole it is probably true that no compounds of which the ion Z- has a very high affinity for the charge can be included in either sub-class (compare Lapworth, Zoc. cit.). There are for example no cases recorded where the potassium or sodium salts of powerful acids form additive corn ETHYLENIC HYDROCARBONS WITH HYDROGEN SULPHITES.309 pounds with carbonyl compounds. The powerful acids have already been excluded for the reasons above stated. From the preceding considerations it is clear that any agent which forms addition products with the carbonyl group of aldehydes and ketones or with the ethylenic linking in ap-unsaturated carbonyl compounds may safely be referred to sub-group IIb only when it is known that the agent does not attack ethylenic hydrocarbons under comparable conditions; in many cases as in the instance of ammonia experimental evidence is already extensive and <o uniformly negative that this indifference may confidently he inferred whilst in other cases further investigation is required. The correct classification of agents additive to ethylenic com-pounds is of the utmost importance in studying the influence of atoms and groups on the properties of others in the same molecule.The authors have made a careful study of two series of agents previously referred in the papers above specified (Zoc. cit.) to Class 11. The experiments carried out by the authors and by other workers in these laboratories on the possible addition of hydrogen cyanide and metallic cyanide to ethylenic hydrocarbons including cycio-hexene and styrene have given uniformly negative results. As the addition products in these cases would have been nitriles easily convertible into carboxylic acids and so capable of detection even in traces it may be concluded that metallic cyanides and hydrogen cyanide in absence of acid catalysts are indeed highly selective ant1 that when they do attack an ethylenic linking the latter is almost certainly affected by conditions similar to those which ohtr~in iri @-unsaturated ketones.The other series of reagents tested were sulphites and iuore especially hydrogen sulphites. The sole instance hitherto recorded (so far as we have been able to discover) of a hydrocarbon combining directly with hydrogen sulphites is that of styrene and even in that, case the published evidence was inconclusive (Miller dnticrlctr, 1877 189 340; LabbB Bull. SOC. chim. 1893 [iii] 22 1077; Dupont and Labaune Sci. Ind. BzZZ. 1912 [iii] 7 3). In thr: case of styrene moreover there was an element of doubt whether phenyl can exercise the same influence on a double bond as carbonyl can.Similar uncertainty existed in the theoretical interpretation of the observations of Dupont and Labaune (loc. cit.) nho obtained additive products of hydrogen sulphites with unsaturatctl alcohols. The results obtained by the present authors remove all doubt on many of these moot points. Hydrogen sulphites combine directly with ethylenic hydrocarbons and the failure of previous investi 310 KOLKER AND LAPWORTH THE DIRECT COMBINATION OF gators fully to establish this fact is attributable to the unsuitable experimental conditions used. Special precautions to ensure intimate contact between the hydro-carbons and the aqueous solutions are usually but not invariably necessary. They may consist in emulsifying with the aid of purified kieselguhr.Contrary to expectations dilution of the sulphite solution possibly by an effect on the solubility of the hydrocarbons, favoured the interaction. A not less important practical feature in the later experiments was the use of ammonium hydrogen sulphite instead of the sodium or potassium salt. This device admits of the ready removal of any excess of the reagent by boiling with sufficient barium hydroxide, when insoluble barium sulphite is formed ammonia is expelled, and such organic addition products as are not destroyed during this process are easily isolated as soluble barium salts. Pinene dipentene cyclohexene crude " amylene " and even the completely symmetrical ethylene combine readily under favourable conditions with hydrogen sulphites usually in the cold yielding products which for the most part appear to be the salts of the expected saturated sulphonic acids ; but these are usually mixed with a variable proportion of other salts apparently isomeric with the sulphonates.These secondary products unlike the true sul-phonic acids are hydrolysed by dilute acids or alkalis and are probably salts of the alkyl hydrogen sulphites though some slight doubt attaches to this view of their constitution. These salts appear to be considerably more stable than the salts of alkyl hydrogen sulphites prepared by union of sulphur dioxide with sodium alkyl-oxides but this may be due to stabilisation by the other salts present ; indeed the authors have observed (1) that the hydrolysis of the salts of methylethionic acid SO,H*CH(CH,)*CH,*SO,H (which normally is readily effected by dilute acids) takes place much more slowly if excess of salts of methylisethionic acid, SO,H *CH (CH,) *CH,* OH , are present and (2) that pure barium methylethionate decomposes a t loo" but in presence of 9-10 times its weight of isethionate does not decompose appreciably below 150".It is just possible however, that two series of alkyl sulphurous acids exist. It seems probable that carbonyl compounds react with bisulphite, as with metallic cyanide by first capturing the anion. Ethylenic hydrocarbons evince no definite preference for anions and may react with bisulphites either by first capturing the hydrogen ion or by uniting with the unsaturated centres of the sulphite molecules much as they unite with ozone and possibly in both ways.The gross result of the process of addition of hydrogen sulphite ETHYLENE HYDROCARBOKS WITH HYDROGEN SULPHITES. 31 1 to ethylenic hydrocarbons may thus be represented by the following scheme as adapted for sodium hydrogen sulphite : CHR,R,*CR,R,-SO,Xa A CHRIR,*CR,R,*O*SO,Nat. CRIR,:CR,R + NaHSO / Hydrogen sulphites must now therefore be omitted from the list of reagents of Class 11. E x P E R I ni E N T A L. Throughout this section the term “ molar ” and the symbol M applied to a hydrogen sulphite solution denote a solution containing one gram-molecule per litre. Inorganic sulphite in solutions of the reaction products was assumed to be absent when mineral acids in the cold caused no evolution of sulphur dioxide and when iodine was not decolorised.General Method of !Treatment of Insoluble Fluid Compounds with ,4mmonium Bisulphite Xolzction .-Usually the fluid unsaturated compound was shaken vigorously at intervals during several days with M/4-ammonium hydrogen sulphite and kieselguhr. The kicdguhr was then separated by filtration wished with boiling water and the united filtrates were heated with excess of barium 1 1 droxide until ammonia ceased to be evolved. The whole was then neutralised with dilute sulphuric acid the precipitated barium sulphite and sulphate were filtered off and washed with boiling water, the filtrates being finally evaporated to dryness on the steam-bath, Xtudies of the Influence of Conditions on Speed of Addition oj’ Ammonium Bisulphite to cycloHexene .-Owing to adsorption of solutes by the kieselguhr used as emulsifying agent i t was found necessary in comparative experiments to convert the addition product into barium salt and then to isolate and weigh this.I n one series of four experiments the following results were obtained using 5 C . C . of cgclohexene in mch instance with N j 4 -ammonium hydrogen sulphite solution. Volume of f1~/4-NM,HSO3 solution used ............ 240 C . C . 480 C . C . Excess of NH,HSO more than theory ............ 25yA 1500,b Yield (yo of theory) without kieselguhr ............ 16.8 40.11 Yield (yo of theory) with kieselguhr ............... 19.3 5 7 .o I n another series of three parallel experiments using the same quantity namely 5 c.c of cyclohexene with the same weight of ammonium bisulphite in each experiment but dissolved in different weights of water all with shaking a t intervals during 10 days the following results were obtained.In this series no kieselguhr was 11sed 312 KOLKER AND LAPWORTH THE DIRECT COMBINATION OF ............ Strength of bisulphite solution 2M M 12 C.C. of bisulphite solution .................. 60 120 240 Weight of crude barium salt obtained ... 1-29 1-51 2.26 Yield of crude product yo of theory ... 10.3 12.1 18.0 It is evident from the f i s t series that kieselguhr has a very f avourable influence on the yield especially when a considerable excess of hydrogen sulphite is used. The two series taken in conjunction show that the yield improves with the dilution of the hydrogen sulphite at least up to M / 4 ; the volumes of fluid to be evaporated however set a limit to the practical application of this fact.Examination of Products from cyclol3exene.-( a) With sodium hydrogen sulphite. When cyclohexene (30 c.c.) was shaken at intervals with N/2-hydrogen sulphite solution (1800 c.c.) for 8 days the resulting aqueous solution separated from unchanged cyclohexene (found 20 c.c.) evaporated to dryness and extracted with 96-98% spirit a white powder (1.9 g.) was obtained (Found Na = 12-3. C,H,,*SO,Na requires Na = 12.3y0). This powder gave no sulphuric acid when boiled with excess of dilute hydrochloric acid, and was free from inorganic sulphite; on hydrolysis with boiling sodium hydroxide however it yielded a little inorganic sulphite, estimated from titrations with iodine to represent 6-7.5y0 of sodium cyclohexyl sulphite.cycloHexene (36 c.c.), M/4-ammonium bisulphite solution (3360 c x.) and kieselguhr (120 g.) were shaken together at intervals during 10 days. On working up the product as on p. 31 1 a brown solid was obtained which on recrystallisation yielded white hexagonal plates of barium cyclo-hexanesulphonate identical with that obtained by the method of Borsche and Lange from cyclohexyl chloride through the sulphinic acid (Bey. 1905 38 2766) [Found H20 = 13.5; Ba (in dried salt) = 29.6. (C6Hl1*SO,),Ba,4H2O requires H,O = 13.4; Ba (in anhydrous salt) = 29.7y0]. The identity was established by direct comparison of the barium salts and of the sulphanilides (m.p. 85").* * The following new derivatives of cyclohexanesulphonic acid were pre-pared and examined during the course of the work. Sodium salt prisms, readily soluble in water and in dilute alcohol (Found Na = 11.1. C 6H,,.SOsNa,H20 requires N a = 1 1.3y0). Ammonium salt hygroscopic and exceedingly soluble in water ; very readily soluble in 98% spirit crystallising therefrom in granules. Magnesium salt rhombic plates by spontaneous evaporation of an aqueous solution. Copper salt small light green rhombic plates moderately soluble in water [Found : H,O = 15.4. (C6Hll.SOs)2Cu,4H,0 requires H20 = 15.6%]. SuZphonyZ chloride analysed by Borsche and Lange and described by them as an oil, separates from ether in rhombic plates m. p. 106'. Sulphonamide may be crystallised from water and melts at 93-94O.(b). With ammonium hydrogen sulphite. Very readily soluble in water ETHYLENIC HYDROCARBONS WITH I-IYDROGEN SULPHITES. 313 The nature of the crude brown solid product was investigated. When boiled for 4 hours with a large excess of 12% sodium hydroxide it yielded sulphite corresponding with 2% of alkyl sul-phite. When boiled with 10-150/ hydrochloric acid it did not >ield any sulphate but some sulphur dioxide was detected. When 3-5 g. were boiled for 6 hours with 15% sulphuric acid (50 c.c.), some siilphur dioxide was evolved the solution turned light yellon-in colour and a slight aromatic odour was observed The product of this hydrolysis could not be isolated but after removal of con-stituents soluble in ether and neutralisation of the solution with barium carbonate evaporation yielded 3.1 g.of pure bariuni r,!/~.lohexanesulphonate. It woulcl thus seem that the material contains a t least 90 % of ammonium cgclohexanesulphonate together with a small quantity of an organic compound which yields sul-pliurous acid or sulphite on hydrolysis.* This compound could not be isolated but it was observed that the mother-liquor remaining after separation of cyckohesanesulphonate from the crude product a t first gave with ferric chloride a deep red coloration similar to that obtained with sulphites and sulphinates; later this test gave a negative result so that the compound causing this coloration was evidently unstable either to water or to air or to both. Ethylene and Ammonium Hydrogen Xulphite .-Ethylene wab hrought into contact with M/4-ammonium sulphite ( 2 litres) in a large bottle a t about atmospheric pressure with occasional shaking.At first the solution absorbed nearly its own bulk of the gas during each interval of 24 hours when the residual gas with any gaseous impurities in it was allowed to escape and was then replaced by fresh ethylene. After this process had been repeated daily during a fortnight about 5 litres of ethylene had been absorbed and the original speed of absorption reduced by about four-fifths. The liquid was then worked up in the usual way and 13 g. of crude barium salts were obtained. * It is difficult to reconcile the properties of this secondary constituent n-ith tho assumption that it is sodium cyclohexyl sulphitc as it has resisted thi operations used in preparing the crude product.For comparison, sodium cyclohexyl sulphite was made by passing sulphur dioxide into (a) A solution of sodium in cyclohexanol and precipitating with alcohol ( b ) zt. suspension of sodium cyclohoxyl oxide in benzene and then draining thG solid on porous earthenware. The solid obtained by either process was, like other salts of alkyl sulphurous acids previously described extremely unstable losing sulphur dioxide on exposure to air and being immediately ligdrolysed in aqueous solution with liberation of inorganic sulphite (Found in sodium cyclohexyl sulphite made by process ( b ) Na = 13.4. C,H,,~SO,Na rc-quires Na = 12.4%. 0-346 G. dissolved in water required 39-5 C.C. of N/lO-I, while one molecule of sulphite from C,H,,-SO,Na requires 37.2 c.c.).( For coniments on these points compare introductory section.) ix 314 THE DIRECT COMBINATION OF ETHYLENIC HYDROCARBONS ETC. The salts consist mainly of barium ethanesulphonate but also, as in the case of cyclohexene of small quantities of other salts, which give a red coloration with ferric chloride and are somewhat stable towards alkalis but unstable towards boiling mineral acids, which cause evolution of sulphur dioxide but no liberation of sulphuric acid [Found in barium salt H20 = 9.2; Ba (in anhydr-ous salt) = 38.6. (C2H5-S03)2Ba,2H,0 requires H20 = 9.2; (C2H5*S03)2Ba requires Ba = 38.7y0]. water, and easily recrystallised from ether forming prisms m. p. 59-GO” (James J . p r . Chem.1882 [ii] 26 384 gives the melting point of ethanesulphonamide as 56”). Commercial “Amylene ” and Ammonium Hydrogen Sulphitc-Combination was here so rapid that in 7 days with occasional shaking 5.3 C.C. of “ amylene ” were almost completely absorbed by M/4-ammonium hydrogen sulphite solution without kieselguhr. On working up in the usual way 9.4 g. of crude soluble barium salt (86% of theory) were obtained [Found Ba = 31.5. (C,H,,~SO,) Ba requires Ba = 31-3y0]. The crude salt did not decolorise permanganate nor absorb bromine it gave no sulphur dioxide or sulphuric acid when boiled for several hours with 15% hydrochloric acid and 95% of the original product was recoverable. “ Amylene ” was exceptional among the hydrocarbons examined in yielding nothing but true sulphonic derivatives.As the ‘‘ amylene ’’ used was the mixture of several isomerides obtained from fuse1 oil the products were not further examined. Dipentene andAmmonium Hydrogen Su1phite.-Dipentene (15 c.c.), ammonium hydrogen sulphite (M/4 ; 2000 c .c .) and kieselguhr (50 g.) shaken at frequent intervals during 14 days gave 12.1 g. of barium salts at least 90% of which consist of barium menthne-disulphonate [Found H,O (lost at 160O) = 4.0. requires H20 = 4.0%. In the anhydrous salt ; found Ba = 31.4, S = 15.1; theory requires Ba = 31.6 S = 14-7y0]. This salt is readily soluble in water forms clusters of needles, and is stable to boiling mineral acid. The mother-liquors obtained on recrystallising the salt from water decolorise a little bromine or permanganate and slowly evolve some sulphur dioxide when boiled with dilute sulphuric acid. Pinene and Ammonium Hydrogen Su1phite.-From pinene (32 c.c.), ammonium hydrogen sulphite (M/4 ; 2000 c.c.) and kieselguhr (70 g.) after 12 days 7.4 g. of mixed soluble barium salts were isolated but retained an odour resembling pinene after repeated The sulphonamide made from this salt was soluble in C~~H18(S03)2Ba>H?, METHOD OF MEASURING THE DIELECTRIC CONSTANTS OF LIQUIDS. 315 extraction with absolute alcohol. The crude product differed appreciably from that obtained from any other hydrocarbon inas-much as the proportion of hydrolysable salt was nearly 45% of the whole. When 2 g. were boiled with 15% sulphuric acid much sulphur dioxide was evolved and appreciable quantities of an oil having a terpene-like odour appeared. After removing the oil with ether and the sulphuric acid with barium carbonate only 1.1 g. of stable barium salt were recovered. The crude product, which was free from inorganic sulphate also discharged the colour of an unusually large proportion of bromine. ORUANIC CHEXICAL LABORATORIES, THE UNIVERSITY MANCRESTER. [Received November 7 t h 1924.1 ADDENDuM.-Throughout this paper the terms (‘ hydrogen sulphite ” and (( bisulphite ” are used interchangeably and without regard to the question of the constitution of salts t o which these names have commonly been applied in the past

ISSN:0368-1645    

DOI:10.1039/CT9252700307

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

METHOD OF MEASURING THE DIELECTRIC CONSTANTS OF LIQUIDS. 315 XLIX.-A Method of Measusing the Dielectric Con-stants of Liquids. By LEONARD ALFRED SAYCE and HENRY VINCEXT AIRD BRISCOE. THE introduction of the triode valve has made possible many accurate methods for the measurement of physical constants and it has been employed by several workers in the determination of dielectric constants. Considerable accuracy has thus been attained in the measurement of dielectric constants approaching unity, v i x . those of the gases (Carman and Lorance PhyLysical Rev. 1922, 20 715; Gill Radio Rev. 1921 2 450; Wagstaff Phil. Hag., 1924 [vi] 47 66)) but the dielectric constants of liquids which are much greater than unity have not hitherto been measured with similar accuracy (Whiddington Proc.Camb. Phil. Xoc. 1921 20, 445; Hyslop and Carman Physical Rev. 1920 15 243). This is mainly due to the difficulty of securing absolute constancy in the operation of valve-maintained circuits (Whiddington Engineering, 1920 110 384; Wagstaff loc. cit.) and of obtaining a variable condenser combining a large range of variation with a su%cient accuracy of setting (Hyslop and Carman loc. cit.). Further in previous methods the dielectric has been stressed in a circuit directly coupled to a triode and in such circuits although the funda-mental frequency may be known yet the wave-form is not usually sinusoidal but may be resolved into many harmonics some of M* 316 SAYCE AND BRISCOE A METHOD OF considerable amplitude. Possibly this is not seriously disadvan-tageous in work upon gases but in the case of dielectrics in which the variation of dielectric constant with frequency is appreciable it is evident that precise measurements of this property can be made only if the applied stress be of sine wave-form.The following method has therefore been developed in order to secure the conditions here seen to be required for the accurate measurement of relatively large dielectric constants. General PrincipZes.-If oscillatory currents are maintained in the circuit L,C by means of a triode connected as shown in Pig. 1, the magnitude of the direct component of the current in the anode circuit uf the triode is a function of the magnitude of the oscillatory currents in L,C (Dowling Proc. Roy. Dublin SOC. 1921 16 185).If now a second oscillatory circuit L3C3 is loosely coupled to LlC2, little or no energy is withdrawn from the latter until the natural frequency of L3C3 approaches that of L,C,. Resonance between the two circuits is then shown by a sudden decrease in the direct component of anode current of the triode. If the coupling between L and L3 is sufficiently tight the reduction in the anode current will continue throughout a considerable change of L3C3 for the latter circuit is forced into resonance with L,C over a considerable range of adjustment and then suddenly " breaks away " from the control of L,C,. The coupling between L and L3 can however be so adjusted that when a gradual change is made in the adjustment of C the anode current steadily decreases to a minimum and thereafter steadily increases.These conditions afford an extremely sensitive null method of observing when L3C3 is adjusted to a given fre-quency i.e. the frequency of L,C,. If the frequencies of the two circuits are of the order of 106- per second the resonance point is shown so critically that with ordinary precautions C can be reset with an error not exceeding 0-005ppF. - If now another condenser, C4 of unknown capacity be connected in parallel with C, then in order to restore resonance between the two circuits a reduction i SIEASURING THE DIELECTRIC CONSTANTS OF LIQUIDS. 31 7 the value of C is necessary such reduction being a measure of the capacity of C,. Thus unknown capacities can be measured accw-ately in terms of C, the frequency a t which the measurement i.: made being that of L,C,.The coupling between the two ckcnits is so loose that the stress applied t o the dielectric of the unknonn condenser C, is very small and has a wave-form free from the distortion almost inevitable in a valre-maiiitaiiiecl circuit. BJ. this method the messurement of ail uilk110~11 condenser involr-cis two null galvanometer adjustments and in practice these are made within such a short time that errors due to slight variation3 ill the frequency of L,C, due to variations in batteries tic.. zic insignificant. The Bxperinaeiztal Nethod.-The practical application of the above principles to the measurement of the dielectric constants of liquids presents two main problems : (1). The construction of a condenser of fixed dimensions in ti liich (lither a vacuum air or the substance under investigation may be used as dielectric a t will.For convenience this is hereafter called the * ' dielectric container." (2). The construction of a variable condenser having the relatively wide range of 5OOpp.P and yet such that it can be set and reaid with an error not exceeding 0.005ppF. (1). The capacity of the dielectric container is measure6 'BI lien full of air or evacuated and again when full of the liquid under examination the ratio of the latter capacity to the former being the dielectric constant of the liquid a t the temperature and fre-quency employed. The type of condenser that has been found most suitable is shown in Fig. 2. It resembles an elongated Demar flask and consists of two glass tubes like large " boiling-tubes." one sealed inside the other.Access to the annular space betn-em these tubes is given by the tubes G and H. Platinuni electrodes me fused through the bottom of the inner tube and through t'lie side of the outer tube. Both internal surfaces of the annular apace are silvered to the height shown and these silver films constitute the "plates" of the condenser. It was thought advisable to thicken the silver films by several successive applications of the silvering solution. A small glass elbow-tube ,J is cemented to the outer tube where the platinum electrode pierces it aiid mercury, poured into the little cup so formed provides a means of making a connexion to the outer silver coating. A little mercury is also poured into the inner tube to cover the other platinum electrode and connexion with it is made by a long stiff wire.At the top of this wire is cemented a small glass cup containing mercury aiid having a little hook of glass rod fused on a t one side. A stiff wire 318 SAYCE AND BRISCOE A METHOD OF coming from the remainder of the apparatus normally rests on this glass hook but is transferred to the adjoining mercury cup in order to switch the condenser into circuit. The condenser is immersed in a thermostat so that the water-level is a few milli-metres below the top a,nd the thermostat and outer silver coating of the condenser are connected to the " earthed" side of the remaining apparatus. FIG. 2. FIG. 3. P Y ( 2 ) . The wide-range variable condenser is an assembly of six condensers of fixed capacity with a small one of variable capacity.The former are labelled from " a " to " f " and are made of the following approximate values C = lOppP C = ZOppF C = 40ppF Cd = 80ppF C = lGOppF Cf = 320ppP. The small variable condenser is variable over a range of 10ppcF. It is per-manently in circuit but any or all of the fixed-capacity condensers may be switched in parallel with it by means of mercury cups and bridges. Each fixed-capacity condenser is made with interleaved aluminium plates separated by air. One set of plates is connected to an earthed metal base-plate and to an earthed tin-plate screen which envelops the condenser the other set of plates being con-nected to a brass rod which acts as the '' live '' terminal MEASURING THE DIELECTRIC CONSTANTS or LIQUIDS.319 The construction of the small variable condenser is shown in Fig. 3. It consists essentially of a single semi-circular vane M, free to rotate between two semi-annular rings N. The frame-work of the condenser comprises two triangular brass end-plates P, held apart by three vertical rods Q. Each end-plate is provided with a* longitudinally-drilled steel screw R and these two screws are the bearings for the conical ends of a rotatable spindle S. The spindle carries a thick semi-circular brass plate M accurately turned on both faces whilst mounted on the spindle. The two fixed plates of the condenser are two semi-annular rings N made of heavy brass and accurately turned secured respectively to two triangular ebonite platforms T which may be fixed a t any suitable position upon the vertical supporting rods.At the top FIG. 4. of the spindle is clamped a brass boss V carrying a plane galvanometer mirror W and a fibre arm X about 15 om. long. The framework of the condenser and therefore the rotating vane is earthed by attachment to an earthed base-plate as also is a tin-plate screen which covers the effec-tive parts of the condenser. The two semi-annular rings are connected to a stiff wire which passing through a hole in the screen constitutes the '. live " terminal. The position of the spindle is read by means of a telescope and a semi-circular scale about 150 cm. in length as shown in Fig. 4. The mirror on the spindle is a t the centre of the scale and the telescope is aligned upon it thus a rotation of the spindle of 90" corresponds to about 1500 mm.on the scale. The reading of the scale can be made within 0.2 mm. and the adjustment of the rotation of the spindle with this degree of accuracy is accomplished quite simply in the following manner. To the tip of the fibre arm X a long thread is attached which passes to one end of a wooden lever L 30 cm. long pivoted a t its middle point. To the other end of the lever is attached a second thread which is wound upon a thin brass rod provided with a knob and rotating stiffly in a cork that is clamped rigidly. Turning the knob thus rotates the spindle of the condenser. The threads ar 320 SAYCE AND BRISCOE A METROD OF kept taut and the spindle is returned in the other direction by the tension of a stout rubber band.The wooden lever is introduced into the system in order that the adjusting knob may be near the hand of the operator whilst he is a t the telescope at a distance from the conde’hser. The design of variable condenser here described has the following important advantages : (1) Consistency of resetting is obtained by the use of conical bearings. (2) Great accuracy of setting and reading is attained in the manner already described. (3) Freedom from external capacity effects is ensured by the earthing of the moving system adequate screening and remote control. (4) The calibration curve is free from the irregularities that arise in the usual vane type of condenser through the effects of the spacing washers and supports.( 5 ) A simple adjustment of the range of capacity within wide limits is attained by alteration of the positions of the eborrite platforms T (Fig. 3). The complete assembly of the apparatus is shown diagram-matically in Fig. 1. The dielectric container C, and the wide-range condenser C3 are connected in parallel with an inductance, L3 which for frequencies of the order of 106- per second consists of 30 well-spaced turns of No. 16 S.W.G. copper wire wound upon a spirally-grooved ebonite tube 9 cm. in diameter. L and L, are “honeycomb ” inductances of the type commonly used in radio-telegraphy; C is a variable condenser of the ordinary vane type having a maximum capacity of approximately 300ppF ; and C is a mica-dielectric “ by-pass ” condenser of approximately 0.01 yF.B is a dry-cell battery of 50 volts and B a 4 volt. 100 amp.-hour accumulator ; G is a uni-pivot galvanometer having a sensi tivity of about 1pA. per scale division. R, a potentiometer of 5000 and R, a resistance of 9000 are adjusted so as to neutralise the greater part of the anode current through G (Dowling Zoc. cit. p. 175). Although the construction of Cv was adapted to secure a recti-linear relationship between scale reading and capacity it was intercalibrated throughout its range by substituting for Ca a very small fixed-capacity condenser the capacity of which was measured in terms of scale divisions of C at a large number of places along the scale of the latter. If the “ scale-division capacity ” ratio had been truly rectilinear the apparent value of the very small condenser would have been precisely the same at all points alon JIESSURISG THE DIELECTRIC CONSTAKTS O F LIQUIDS.321 the scale. The apparent values obtained gave the data necesaary for the preparation of a correction-curve to express all readings in terms of “ mean scale divisions.” Finally the capacities of the six fixed-capacity condensers C to Cf were measured in terms of scale divisions of Cv (for C = (‘v C 2 Ca + C, C 5 Ca + (3 t C’v, and so on). The capacity corresponding to a mean scale division of C is thus the unit in all measurements. Having thus intercalibrated C, the capacity of C, coiitainiiig dry air a t a known pressure and a t the temperature of the ther-mostat is measured in terms of C,. To do this C is switched out of circuit and with C a t a large setting L,C is adjusted to approximate resonance with L,C,.Exact resonance between t 110 two circuits is then obtained by varying C’ and is shown by a sharp minimum reading of the galvanometer G and the reading of C ‘ , is taken. C is then switched into circuit and C is reduced in value until resonance i q again obtained between the two circuits. This reduction in C is a measure of the capacity of Clcab). Finally, C4 is filled with the liquid under examination (at the temperature of the thermostat) and its capacity measured as beiore. The latter capacity C(q(liquid) divided by the former C4(sir) gives the dielectric constant of the liquid to a standard of 1 1, at the temperature and frequency of the measurement.Shortly lieforc or after the measurement the frequency is determined by means o€ a heterodyne waTY-e-meter (Sayce Expt. Wireless 1923, 1 70). The value of the dielectric constant so obtained can lie corrected to a vacuum standard by making use of recent deter-minations of the specific inductive capacity of eir (Carman anti Lorance Physicul Rev. 1922 20 715; GiIl Radio lieu. 1921 2, 450; Wagstaff Phil. Nag. 1924 [vi] 47 66). Experimentul Difficulties and Precautions.-When fist applied , the method gave inconsistent results due to slight temperature changes in the valve in the oscillator coils and particularly in the variable condenser C,. Sudden changes in the temperature of the valve were prevented by enveloping it in cotton-wool. The influence of sunlight upon the apparatus was so marked that it was found desirable to obscure the windows of the laboratory and illuminate the apparatus by artificial light.Ultimately the air of the room was kept a t a fairly constant temperature and as an additional precaution the condensers C to Cz were intercalibrated with C before and after each determination. Results.-The following results obtained with benzene are given, not as having any absolute significance but simply as an example of the degree of consistency so far observed in repeated meamre-ments on the same material. This we regard as a n importan 322 FAIRBROTHER AND MASTIN : criterion of the precision of the method. The benzene was rigorously purified by fractional distillation and fractional crystallisation and was finally distilled over phosphorus pentoxide but without any attempt to attain intensive drying.Frequency 65 x 103 cycles per second. E (air = 1) ............... 2.2380 2.2392 2.2396 2.2389 Dielectric Constant of Benzene a t 25.5". Mean 2.2389 Diff. from mean ......... -0.0009 +0.0003 +0.0007 -0.0001 Mean difference from mean &0.0005. It is interesting to make a comparison as to consistency between our results and those of Turner (2. physikaZ. Chem. 1900 35 385), who using the method of Nernst (ibid. 1894 14 622) applied to carefully purified benzene obtained the following data which are commonly cited as the most accurate available. The frequency was low but unspecified and the results were corrected to 18". F ............... 2.290 2-291 2.285 2.288 2.293 2.292 2.286 Diff.from Mean 2.289. mean ...... $0.001 +0*002 -0.004 -0.001 +0-004 +0.003 -0.003 Mean difference from mean &O-003. During our measurements no special precautions were taken to maintain room temperature constant and there is much evidence that even the small differences here recorded are due to small changes in the temperature of the various parts of the apparatus. Hence it seems probable that under more constant temperature conditions still greater precision may be attained by the method. Note.-Since the completion of the above measurements a further contribution to the measurement of dielectric constants has been made by Grutzmacher (2. Physik 1924 28 342). Results for benzene stated to the fourth decimal place and from internal evidence probably significant to the third decimal place are there given but as only one result is recorded for each temperature we are unable to compare the consistency of the measurements with that obtained by our method.ARMSTRONG COLLEGE, NE WCASTLE -UPON -TYNE. [Received October 1 Ith 1924. METHOD OF MEASURING THE DIELECTRIC CONSTANTS OF LIQUIDS. 315 XLIX.-A Method of Measusing the Dielectric Con-stants of Liquids. By LEONARD ALFRED SAYCE and HENRY VINCEXT AIRD BRISCOE. THE introduction of the triode valve has made possible many accurate methods for the measurement of physical constants and it has been employed by several workers in the determination of dielectric constants. Considerable accuracy has thus been attained in the measurement of dielectric constants approaching unity, v i x .those of the gases (Carman and Lorance PhyLysical Rev. 1922, 20 715; Gill Radio Rev. 1921 2 450; Wagstaff Phil. Hag., 1924 [vi] 47 66)) but the dielectric constants of liquids which are much greater than unity have not hitherto been measured with similar accuracy (Whiddington Proc. Camb. Phil. Xoc. 1921 20, 445; Hyslop and Carman Physical Rev. 1920 15 243). This is mainly due to the difficulty of securing absolute constancy in the operation of valve-maintained circuits (Whiddington Engineering, 1920 110 384; Wagstaff loc. cit.) and of obtaining a variable condenser combining a large range of variation with a su%cient accuracy of setting (Hyslop and Carman loc. cit.). Further in previous methods the dielectric has been stressed in a circuit directly coupled to a triode and in such circuits although the funda-mental frequency may be known yet the wave-form is not usually sinusoidal but may be resolved into many harmonics some of M* 316 SAYCE AND BRISCOE A METHOD OF considerable amplitude.Possibly this is not seriously disadvan-tageous in work upon gases but in the case of dielectrics in which the variation of dielectric constant with frequency is appreciable it is evident that precise measurements of this property can be made only if the applied stress be of sine wave-form. The following method has therefore been developed in order to secure the conditions here seen to be required for the accurate measurement of relatively large dielectric constants.General PrincipZes.-If oscillatory currents are maintained in the circuit L,C by means of a triode connected as shown in Pig. 1, the magnitude of the direct component of the current in the anode circuit uf the triode is a function of the magnitude of the oscillatory currents in L,C (Dowling Proc. Roy. Dublin SOC. 1921 16 185). If now a second oscillatory circuit L3C3 is loosely coupled to LlC2, little or no energy is withdrawn from the latter until the natural frequency of L3C3 approaches that of L,C,. Resonance between the two circuits is then shown by a sudden decrease in the direct component of anode current of the triode. If the coupling between L and L3 is sufficiently tight the reduction in the anode current will continue throughout a considerable change of L3C3 for the latter circuit is forced into resonance with L,C over a considerable range of adjustment and then suddenly " breaks away " from the control of L,C,.The coupling between L and L3 can however be so adjusted that when a gradual change is made in the adjustment of C the anode current steadily decreases to a minimum and thereafter steadily increases. These conditions afford an extremely sensitive null method of observing when L3C3 is adjusted to a given fre-quency i.e. the frequency of L,C,. If the frequencies of the two circuits are of the order of 106- per second the resonance point is shown so critically that with ordinary precautions C can be reset with an error not exceeding 0-005ppF. - If now another condenser, C4 of unknown capacity be connected in parallel with C, then in order to restore resonance between the two circuits a reduction i SIEASURING THE DIELECTRIC CONSTANTS OF LIQUIDS.31 7 the value of C is necessary such reduction being a measure of the capacity of C,. Thus unknown capacities can be measured accw-ately in terms of C, the frequency a t which the measurement i.: made being that of L,C,. The coupling between the two ckcnits is so loose that the stress applied t o the dielectric of the unknonn condenser C, is very small and has a wave-form free from the distortion almost inevitable in a valre-maiiitaiiiecl circuit. BJ. this method the messurement of ail uilk110~11 condenser involr-cis two null galvanometer adjustments and in practice these are made within such a short time that errors due to slight variation3 ill the frequency of L,C, due to variations in batteries tic..zic insignificant. The Bxperinaeiztal Nethod.-The practical application of the above principles to the measurement of the dielectric constants of liquids presents two main problems : (1). The construction of a condenser of fixed dimensions in ti liich (lither a vacuum air or the substance under investigation may be used as dielectric a t will. For convenience this is hereafter called the * ' dielectric container." (2). The construction of a variable condenser having the relatively wide range of 5OOpp.P and yet such that it can be set and reaid with an error not exceeding 0.005ppF. (1). The capacity of the dielectric container is measure6 'BI lien full of air or evacuated and again when full of the liquid under examination the ratio of the latter capacity to the former being the dielectric constant of the liquid a t the temperature and fre-quency employed.The type of condenser that has been found most suitable is shown in Fig. 2. It resembles an elongated Demar flask and consists of two glass tubes like large " boiling-tubes." one sealed inside the other. Access to the annular space betn-em these tubes is given by the tubes G and H. Platinuni electrodes me fused through the bottom of the inner tube and through t'lie side of the outer tube. Both internal surfaces of the annular apace are silvered to the height shown and these silver films constitute the "plates" of the condenser. It was thought advisable to thicken the silver films by several successive applications of the silvering solution.A small glass elbow-tube ,J is cemented to the outer tube where the platinum electrode pierces it aiid mercury, poured into the little cup so formed provides a means of making a connexion to the outer silver coating. A little mercury is also poured into the inner tube to cover the other platinum electrode and connexion with it is made by a long stiff wire. At the top of this wire is cemented a small glass cup containing mercury aiid having a little hook of glass rod fused on a t one side. A stiff wire 318 SAYCE AND BRISCOE A METHOD OF coming from the remainder of the apparatus normally rests on this glass hook but is transferred to the adjoining mercury cup in order to switch the condenser into circuit.The condenser is immersed in a thermostat so that the water-level is a few milli-metres below the top a,nd the thermostat and outer silver coating of the condenser are connected to the " earthed" side of the remaining apparatus. FIG. 2. FIG. 3. P Y ( 2 ) . The wide-range variable condenser is an assembly of six condensers of fixed capacity with a small one of variable capacity. The former are labelled from " a " to " f " and are made of the following approximate values C = lOppP C = ZOppF C = 40ppF Cd = 80ppF C = lGOppF Cf = 320ppP. The small variable condenser is variable over a range of 10ppcF. It is per-manently in circuit but any or all of the fixed-capacity condensers may be switched in parallel with it by means of mercury cups and bridges.Each fixed-capacity condenser is made with interleaved aluminium plates separated by air. One set of plates is connected to an earthed metal base-plate and to an earthed tin-plate screen which envelops the condenser the other set of plates being con-nected to a brass rod which acts as the '' live '' terminal MEASURING THE DIELECTRIC CONSTANTS or LIQUIDS. 319 The construction of the small variable condenser is shown in Fig. 3. It consists essentially of a single semi-circular vane M, free to rotate between two semi-annular rings N. The frame-work of the condenser comprises two triangular brass end-plates P, held apart by three vertical rods Q. Each end-plate is provided with a* longitudinally-drilled steel screw R and these two screws are the bearings for the conical ends of a rotatable spindle S.The spindle carries a thick semi-circular brass plate M accurately turned on both faces whilst mounted on the spindle. The two fixed plates of the condenser are two semi-annular rings N made of heavy brass and accurately turned secured respectively to two triangular ebonite platforms T which may be fixed a t any suitable position upon the vertical supporting rods. At the top FIG. 4. of the spindle is clamped a brass boss V carrying a plane galvanometer mirror W and a fibre arm X about 15 om. long. The framework of the condenser and therefore the rotating vane is earthed by attachment to an earthed base-plate as also is a tin-plate screen which covers the effec-tive parts of the condenser. The two semi-annular rings are connected to a stiff wire which passing through a hole in the screen constitutes the '.live " terminal. The position of the spindle is read by means of a telescope and a semi-circular scale about 150 cm. in length as shown in Fig. 4. The mirror on the spindle is a t the centre of the scale and the telescope is aligned upon it thus a rotation of the spindle of 90" corresponds to about 1500 mm. on the scale. The reading of the scale can be made within 0.2 mm. and the adjustment of the rotation of the spindle with this degree of accuracy is accomplished quite simply in the following manner. To the tip of the fibre arm X a long thread is attached which passes to one end of a wooden lever L 30 cm. long pivoted a t its middle point.To the other end of the lever is attached a second thread which is wound upon a thin brass rod provided with a knob and rotating stiffly in a cork that is clamped rigidly. Turning the knob thus rotates the spindle of the condenser. The threads ar 320 SAYCE AND BRISCOE A METROD OF kept taut and the spindle is returned in the other direction by the tension of a stout rubber band. The wooden lever is introduced into the system in order that the adjusting knob may be near the hand of the operator whilst he is a t the telescope at a distance from the conde’hser. The design of variable condenser here described has the following important advantages : (1) Consistency of resetting is obtained by the use of conical bearings. (2) Great accuracy of setting and reading is attained in the manner already described.(3) Freedom from external capacity effects is ensured by the earthing of the moving system adequate screening and remote control. (4) The calibration curve is free from the irregularities that arise in the usual vane type of condenser through the effects of the spacing washers and supports. ( 5 ) A simple adjustment of the range of capacity within wide limits is attained by alteration of the positions of the eborrite platforms T (Fig. 3). The complete assembly of the apparatus is shown diagram-matically in Fig. 1. The dielectric container C, and the wide-range condenser C3 are connected in parallel with an inductance, L3 which for frequencies of the order of 106- per second consists of 30 well-spaced turns of No.16 S.W.G. copper wire wound upon a spirally-grooved ebonite tube 9 cm. in diameter. L and L, are “honeycomb ” inductances of the type commonly used in radio-telegraphy; C is a variable condenser of the ordinary vane type having a maximum capacity of approximately 300ppF ; and C is a mica-dielectric “ by-pass ” condenser of approximately 0.01 yF. B is a dry-cell battery of 50 volts and B a 4 volt. 100 amp.-hour accumulator ; G is a uni-pivot galvanometer having a sensi tivity of about 1pA. per scale division. R, a potentiometer of 5000 and R, a resistance of 9000 are adjusted so as to neutralise the greater part of the anode current through G (Dowling Zoc. cit. p. 175). Although the construction of Cv was adapted to secure a recti-linear relationship between scale reading and capacity it was intercalibrated throughout its range by substituting for Ca a very small fixed-capacity condenser the capacity of which was measured in terms of scale divisions of C at a large number of places along the scale of the latter.If the “ scale-division capacity ” ratio had been truly rectilinear the apparent value of the very small condenser would have been precisely the same at all points alon JIESSURISG THE DIELECTRIC CONSTAKTS O F LIQUIDS. 321 the scale. The apparent values obtained gave the data necesaary for the preparation of a correction-curve to express all readings in terms of “ mean scale divisions.” Finally the capacities of the six fixed-capacity condensers C to Cf were measured in terms of scale divisions of Cv (for C = (‘v C 2 Ca + C, C 5 Ca + (3 t C’v, and so on).The capacity corresponding to a mean scale division of C is thus the unit in all measurements. Having thus intercalibrated C, the capacity of C, coiitainiiig dry air a t a known pressure and a t the temperature of the ther-mostat is measured in terms of C,. To do this C is switched out of circuit and with C a t a large setting L,C is adjusted to approximate resonance with L,C,. Exact resonance between t 110 two circuits is then obtained by varying C’ and is shown by a sharp minimum reading of the galvanometer G and the reading of C ‘ , is taken. C is then switched into circuit and C is reduced in value until resonance i q again obtained between the two circuits. This reduction in C is a measure of the capacity of Clcab).Finally, C4 is filled with the liquid under examination (at the temperature of the thermostat) and its capacity measured as beiore. The latter capacity C(q(liquid) divided by the former C4(sir) gives the dielectric constant of the liquid to a standard of 1 1, at the temperature and frequency of the measurement. Shortly lieforc or after the measurement the frequency is determined by means o€ a heterodyne waTY-e-meter (Sayce Expt. Wireless 1923, 1 70). The value of the dielectric constant so obtained can lie corrected to a vacuum standard by making use of recent deter-minations of the specific inductive capacity of eir (Carman anti Lorance Physicul Rev. 1922 20 715; GiIl Radio lieu. 1921 2, 450; Wagstaff Phil. Nag. 1924 [vi] 47 66).Experimentul Difficulties and Precautions.-When fist applied , the method gave inconsistent results due to slight temperature changes in the valve in the oscillator coils and particularly in the variable condenser C,. Sudden changes in the temperature of the valve were prevented by enveloping it in cotton-wool. The influence of sunlight upon the apparatus was so marked that it was found desirable to obscure the windows of the laboratory and illuminate the apparatus by artificial light. Ultimately the air of the room was kept a t a fairly constant temperature and as an additional precaution the condensers C to Cz were intercalibrated with C before and after each determination. Results.-The following results obtained with benzene are given, not as having any absolute significance but simply as an example of the degree of consistency so far observed in repeated meamre-ments on the same material.This we regard as a n importan 322 FAIRBROTHER AND MASTIN : criterion of the precision of the method. The benzene was rigorously purified by fractional distillation and fractional crystallisation and was finally distilled over phosphorus pentoxide but without any attempt to attain intensive drying. Frequency 65 x 103 cycles per second. E (air = 1) ............... 2.2380 2.2392 2.2396 2.2389 Dielectric Constant of Benzene a t 25.5". Mean 2.2389 Diff. from mean ......... -0.0009 +0.0003 +0.0007 -0.0001 Mean difference from mean &0.0005. It is interesting to make a comparison as to consistency between our results and those of Turner (2.physikaZ. Chem. 1900 35 385), who using the method of Nernst (ibid. 1894 14 622) applied to carefully purified benzene obtained the following data which are commonly cited as the most accurate available. The frequency was low but unspecified and the results were corrected to 18". F ............... 2.290 2-291 2.285 2.288 2.293 2.292 2.286 Diff. from Mean 2.289. mean ...... $0.001 +0*002 -0.004 -0.001 +0-004 +0.003 -0.003 Mean difference from mean &O-003. During our measurements no special precautions were taken to maintain room temperature constant and there is much evidence that even the small differences here recorded are due to small changes in the temperature of the various parts of the apparatus. Hence it seems probable that under more constant temperature conditions still greater precision may be attained by the method. Note.-Since the completion of the above measurements a further contribution to the measurement of dielectric constants has been made by Grutzmacher (2. Physik 1924 28 342). Results for benzene stated to the fourth decimal place and from internal evidence probably significant to the third decimal place are there given but as only one result is recorded for each temperature we are unable to compare the consistency of the measurements with that obtained by our method. ARMSTRONG COLLEGE, NE WCASTLE -UPON -TYNE. [Received October 1 Ith 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700315

出版商:RSC    

年代:1925

数据来源: RSC