摘要:

94 MORGAN THE IGNITION OF EXPLOSIVE IX.-Fhe Ignition of Explosive Gases by Electric Sparks." By JOHN DAVID MORGAN. SOME time ago an investigation was carried out by Dr. R. V. Wheeler and Prof. W. M. Thornton on the ignition of explosive gases by sparks produced in signal bell circuits (Home Office Report on Electric Signalling with Bare Wires R. V. Wheeler and W. M. Thornton June 1916). They used iron-core coils in con-junction with mechanical means for breaking the circuit Corn-menting on the results obtained they state : "It may be said that ignition by a rapid break flash a t a low circuit voltage depends on the inductance voltage a t which the flash is formed and the igniting power of the flash is proportional to the product Li (where L is the inductance of the circuit and i the current prior to breaking the circuit).When the break of the circuit is made slowly the igniting power of the flash has been found to depend upon its energy +Li2. There are thus two limit-ing conditions for the igniting power of the flash; a t the one the inductance voltage is of importance a t the other the energy. For any given gaseous mixture there is a range of rapidity of break over which the two types of ignition blend so that under certain conditions the igniting power of the flash may be proportional * Published with the permission of the Advisory Council for Scientific and Industrial Research GASES BY ELECTRIC SPARKS. 95 neither directly to i nor to 9 but to some intermediate value of it.” Then referring to a previous report (Home Office Report on Batt.ery Bell Signalling Systems R.V. Wheeler January 1915), khey cite a case i n which it was found that the igniting power of the break flash could be expressed by the relationship J,il-4= constant. The figures by Wheeler and Thornton in support of the conclusion that Li is constant are given in table I. TABLE I. Inductance (L). Henries. 0-27 0-47 0.70 0.90 1.04 1.18 1-27 1-31 1-60 2.00 Igniting current (i) at 25 volts. Ampere. 0-82 0.45 0.26 0.20 0.17 0-156 0.145 0.13 0.11 0.09 Li. 0.220 0.212 0.182 0- 180 0.177 0.183 0.184 0.170 0.176 0.180 I n the same report they give the number of layers of wire on the magnets used by them together with the igniting currents, These are given in table 11.I have added a third column giving the product N V where N=number of layers. As the layers each have the same number od convolutions N is proportional to the turns. It will be noticed that it can also be said that N2i2 is constant a quantity which has not the same pnysical significance as Li. The expressions are only comparable when each contains either of the terms i or 9. TABLE 11. Layers of wire on magnet ( N ) . 4 8 12 16 18 20 22 24 28 32 Igniting current (i). 0.82 0.45 0.26 0.20 0.17 0.155 0.145 0.13 0.11 0.09 N V . 10.8 12.8 9.7 10.0 9.3 9.6 10.0 9-7 9.6 8.4 I n the earlier report by Dr. Wheeler a table is given from which the number of layers on the magnet coil can be deduced an 96 MORGAN THE IGNITION OF EXPLOSNE the igniting current is added.lated N%2 and the figures are given in table 111. Using these figures I ha.ve calcu-TABLE 111. Number of layers ( N ) . Igniting current (i). Pi2. 20 0.17 11.6 16 0.23 13.6 12 0.33 16.6 8 0.66 19.2 6 0.96 32-6 The figures in the third column show that in this case the pro-duct N2i2 is by no means constant but progressively increases. When the flux produced by the current is linked with the whole of the windings the product N2i2 is proportional to the electro-kinetic energy of the system so long as the permeability is constant. When the linkage is imperfect or the permeability varies the energy is not proportional to N2i2. From the resulh above referred to it is found that when a low tension igniting spark is defined in terms of the coil constants ( N or L ) and the current (i) prior to the spark the energy required to produce a spark that will ignite a gas mixture of given composition appears to be constant in some cases and not constant in others.Experiments with low tension sparks have led me to suspect that such results as those above mentioned though apparently diverse have some constant factor in common and that the dis-parities are due to the manner in which the resiilts are expressed. There is not implied by this remark any suspicion of the accuracy of the work done by Wheeler and Thornton. They were concerned mainly with determining what circuit conditions could give rise €0 dangerous sparks and from that point of view the results were expressed in terms of practical utility.The question raised is as t o whether the results as expressed can be employed to determine the property of the spark on which ignition depends. I therefore decided to make a new investigation with low tension sparksj and arrange the experiments to cover a wide range of different magnetic conditions. Six short air-coae coils were made according to the particulars given in table IV. TABLE IV. 1 100 2 2 200 4 3 300 6 4 400 8 5 600 10 6 700 14 No. Number of turns. Number of layers GASES BY ELECTRIC SPARKS. 97 Two iron cores of relatively large cross-section were also made, one a laminated bar and the other a closed laminated frame for use with the same coils. The experiments were divided into! three groups which were distinguished only by the differences in the magnetic conditions of the cores.Diagrammatic representations of the coils are shown in Fig. 1. Current was obtained from a 12-volt accumulator. The circuit was completed by a variable FIG. 1. Air-core coil 0,pen iron,-core coil. Closed ivon-core coil. resistance of negligible inductance an ammeter and a ‘flick’ con-tact breaker the latter being enclosed in the explosion chamber. The contact breaker consisted of a flexible steel prong capable of being rotated into contact with a fixed steel stem and then flicked over the stem. A coal gas and air mixture of constant composi. tion was used throughout the investigation. The least currents required to produce ignition are given in table V.VOL. cxv. 98 MORGAN THE IGNITION OF EXPLOSIVE TABLE V. Air-core Coils. No. of layers ( N ) . Current (i) amperes. 2 4.6 4 2.05 6 1.2 8 0.83 10 0.575 14 0.35 Open Iron-core Coils. No. of layers ( N ) . Current (i.) amperes. 2 1-05 4 0.51 6 0-35 8 0.26 10 0.2 1 14 0.15 Closed Zrm-core Coils. No. of layers ( N ) . Current (i) ampere. 2 0.63 4 0.32 6 0.2 8 0.16 10 0.13 14 0.09 N2i2. 81 67.4 54 44 33 24 N V . 4.4 4.3 4.4 4.3 4-4 4.4 N V . 1.6 1.64 1.44 1.64 1.69 1.6 Figs. 2 and 2a give the results graphically. It will be noticed that the product N2i2 is not constant for the air-core coils although it tends t o a'constant value a t the upper value of N and is constant with the open iron and clwed iron-core coils although the value of i V 2 9 is different in the latter two cases.I n other words the results may be said t o be similar in kind to those obtained in Wheeler and Thornton's investigations. The present investigation differs from those as recorded in the cited reports of Wheeler and Thorntm in that I have carried out measurements on the circuits after interruption. The first step consisted in the use of an arrangement as shown in Fig. 3. This is a Wheatstone bridge in conjunction with a ballistic galyancl 'meter. The inductance coil a non-inductive balance resistance b , ammeter c flick contact breaker d variable non-inductive resist-ance e and battery f are all (exceptling 6 ) as used i n the explwion experiments.u and b are shunted by non-inductive resistances T of sufficiently low resistance to eliminate sparking a t d when the circuit is broken. Using with each coil the current values require GASES BY ELECTRIC SPARKS. 99 to give the igniting sparks the observed ‘(kicks” were plotted against N . The straight lines indicate that for each group the energy associated with the system prior to interruption was constant but they give no information as t o These art3 given in Fig. 4. a b 6 1.2 5 1.0 4 0.8 3 0.6 2 0-4 1 0.2 8 10 12 14 N 0 2 4 6 a = air-core coil. b = open iron-core coil. c= closed iron-core coil. 2 4 6 8 10 12 1 4 N a = air-core coil. b=open iron-me odl. c = Closed iron-core mil. E 100 MORGAN THE IGNITION OF EXPLOSIVE whether the energy was the same for each group.The induct-ances were therefore measured and found to give +Liz=constant for each group but different for different groups. As nothing is gained by quoting all the values of all the induct.ances only the largest for each group is recorded in table VI. TABLE VI. Air-core coil 14 layer ..................... 0.01 0-0006 joule. Open iron-core coil 14 layer ............ 0.07 0.0008 .. Closed iron-core coil 14 layer ............ 0.56 0.0023 .. L. ;Liz. It is clearly not permissible to conclude that the energy pro-jected into the sparks in the explosion experiments is constant for a constant magnetic condition but different when that condition FIG. 3. is changed until it is proved that; the differences found are not accounted for by cosre or other losses.A further step involving direct spark measurements was therefore necessary. After try-ing various schemes the apparatus shown diagrammatically in Fig. 5 was adopted. a is the flick contact breaker used in the explosion experiments. This is enclosed in an ebonite chamber, b to which a capillary tube is sealed. Two things appeared a t first to render this device useless. The heat developed by the current passing through the contact breaker when closed was sufficient tol interfere with proper measurement of the heating effect of the spark produced on opening the contact breaker. Further it was difficult t o maint,ain a perfectly gas-tight joint around the rotatable stem carrying the prong of the contact breaker. These troubles were avoided by permitting a slight leak in the chamber and observing (through a microscope) only the “kick” given to the liquid thread in the capillary tube.Usin GASES BY ELECTBIC SPARKS. 101 the coils and current values employed in the explosion experi-menb it was found that the “kicks” were the same throughout. It follows that the sparks obtained in the three widely varying groups of experiments were identical as regards their impulsive thermal effects. I do not think it can be argued from the above that the FIG. 4. spark i ~ a = air-core coil. b =open iron-core coil. c = closed iron-core cc~il. energy was the same in all cases although this possibility is not excluded. The final step consisted in an attempt to determine definitely whether %he energies of the different sparks were the same or not.For this purpose a high tension winding of fine wire and many turns was placed on one of the limbs of the closed iron core a 102 MORGlAN THE IQNI?l!ION OF EXPLOSIVE shown in dotted lines Fig. 1 and connected to a small permanent gap in a spark plug a Fig. 6 . The sparks produced were very small and several had to be produced in succession to give a deflection definitely readable through the microscope. I n place of the flick contact breaker in the primary circuit a cam-operated interrupter such as is used in ignition apparatus for internal-combustion engines was employed. With this interrupter twelve FIG. 5. sparks were obtained from each complete rotmation of the cam. The chamber was made perfectly gas-tight; and the deflections were different in character from those of the previous experiment in that they were relatively slow.Taking each of the coils in turn and using the current values obtained in the explosion experi-ments the deflections obtained after one complete rotation of the cam were observed. I n all cases they were found to be the same. FIG. 6. It follows that the total heating effect of the same number of sparks from each coil was the same; consequently the sparks were of equal energy. Seeing that the sparks in all three groups of experiments gave the same impulsive thermal effects and the sparks in one group gave the same energy effects it is permissible to argue that the energies of all the sparks in the three groups were the same GASES BY ELECTRIC SPARKS.103 The conclusion of the investigation is therefore that over the wide range of different Conditions examined tbhe igniting sparks had this in common-that they all liberated the same amount of heat energy a result which is not evident from measurements on the spark circuit prior to the production of the sparks. Regarding single spark ignition of explosive gases initially a t atmospheric temperature and pressure the main resulta of in-vestigations which have been published in recent years and which can be regarded as well established appear to be as follows: (1) With a low tension spark the least spark energy required t o ignite a given gas mixture diminishes with increase of the voltage impressed on the spark circuit prior to the production of trhe spark (The least energy required to &.artt a gaseous explosion, W.M. Thornton Phil. Mag. 1914 [vi] 28 734). (2) When the circuit voltage is constant the spark energy required for ignition of a given gas mixture by a low tension spark is constant (see above). (3) With a high tension spark (which consists of a capacity component preceding an inductance component,) the incendivity of the spark (or ability to cause ignitipn) can be increased by increasing the proportion of energy in the initial part of the spark without increasing the total energy of the spark (" Spark Ignition," J. D. Morgan Engineering November 3rd 1916). (4) The incendivity of a condenser or capacity spark is greater than that of an inductance spark dissipating the same amount of energy (Thornton Zoc.cit.). (5) With a capacity spark the least energy required for ignition of a given gas mixture diminishes as the spark voltage increases (Thornton Zoc. c i t . ) . These results clearly establish Dhe fact that the incendivity of a spark does not depend on the total energy of the spark. It is generally supposed that the energy required to produce ignition of a given inflammable gas mixture is constant for similar physical conditions. If the assumption is correct then the fact that the total energy of the least igniting spark is found experi-mentally to vary with the conditions under which t3he spark is produced suggests that not all of the spark energy is utilised in the process of ignition but only a portion at the commencement of the spark.It is of course possible that the inflammability of a gas as determined by the least energy required to produce igni-tion is not' constant' for identical physical conditions of the gas but i t would appear to be useless to attempt an investigation of this point by spark measurements having regard t o the facts above mentioned. It is important to note that a spark is a varyin 104 JEPIXCOTT THE PHYSICAL CONSTANTS OF NICOTINE. PART I. source of heat which very rapidly reaches its maximum intensity and then less rapidly disappears. Experiments prove that increase of the initial intensity of a spark results in increased incendivity. As already stated t,his suggests that ignition is due only to the initial part of the spark and that in every spark there is a certain amount of unused energy which makes no contribution to the process of ignition. The proportion of unused energy must diminish as t,he initial intensity increases but a t present any measurements of the effective portion of the spark appear to be impmsible. It follows from this suggested theory of unused energy that any attempts to specify t,he inflammability of a gas in terms of the total energy of the least igniting spark must necessarily yield the diverse results which have hitherto been obtained. THE MARKS AND CLERK LABORATORY, 13 TEMPLE STREET BIRMINGHAM. [Received November 21st 191 8.

ISSN:0368-1645    

DOI:10.1039/CT9191500094

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

104 JEPIXCOTT THE PHYSICAL CONSTANTS OF NICOTINE. PART I. X.-The Physical Constants of Nicotine. Part I. Spectjic Rotatory Power of Nicotine in Apueous Solution. By HARRY JEPHCOTT. NICOTINE has been purified and its constants have been recorded by Landolt (" Optical Rotation of Organic Substances ") Nasini and Pezzolato (Zeitsch. physikal. Chem. 1893 12 Sol) Gennari (ibid. 1896 19 130) Rein (Diss. Berlin 1896) Piibram and Glucksmann (Monutsh. 1897 18 303) Ratz (ibid. 1905 26, 1241) and Winther (Zeitsch. p'hysilcal. Chem. 1907 60 563). All with the exception of Ratz relied on the distillation in hydrogen of anhydrous nicotine. Ratz utilised two methods, namely fractional distillation in a vacuum and the formation of nicotine zinc chloride followed by distillation.Their results for the specific rotation which show considerable variation are as follows : Landolt .................................... Nasini and Pezzolato .................. Gennari .................................... Hein ....................................... Pfibram and Glucksmann ............ Rrttz (by fractional distillation) ...... .. (from double salt) ............... Winther .................................... bl?. D;*. 161.55 1~01101 161.29 -162.84 1.01071 164.18 1.01049 164.91 1.0095 166.77 -169.0 to 169.54 1.00925 163.85 JEPHCOTT THE PHYSICAL CONSTANTS OF NICOTINE. PABT I. 105 It appeared probable that the variation was due to the presence of the alkaloids nicoteine nicotelline and nicotimine which occur with nicotine and it was decided to purify nicotine by the method utilised by Pictet and Rotschy (Ber.1901 34 696) when isolating these alkaloids. Nicotine which had been prepared from tobacco by steam distillation was dissolved in a slight excess of hydro-chloric acid and treated with sodium nitrite a t low temperature. The nicotine was subsequently liberated by alkali dehydrated and fractionally distilled under diminished pressure. Considerable loss of nicotine occurred owing to the formation of oxidation producte during the treatment with nitrite. A quantity about 2600 grams in all of commercial nicotine was also converted into nicotine zinc chloride twice recrystallised, and the nicotine liberated dehydrated and fractionally distilled under diminished pressure in a manner similar to that of Ratz In the cold, nicotine readily f orrns highly-coloured oxidation products on ex-posure to the air.When hot this oxidation is extremely rapid, and water is also absorbed. At the temperature of distillation the vapour readily attacks cork or rubber used for connexions. Well.-fitting ground-glass joints are essential but there proved to be na necessity to flood the apparatus with hydrogen if a sufficiently high vacuum were maintained (20-40 mm. pressure). The nicotine prepared in this way was colourless and almost without oidour in the cold. When kept in bottles filled to the stopper and away from the light nicotine remains colourless only the slightest yellow tint being noticed after six months and no change in rotatory power (compare Piibram lac.&t. p. 303). For pure nicotine the density and rotatory power were found t o be as follows: (loc. cit.). The distillation was a source of much trouble. D?. [a];,". Purified through nitroso-compound . . . . . . 168.52 Purified through double chloride (1) . . . 1.00925 168.61 168.40 1.00920 Y Y YP , (2) ... 1.00925 ? Y YY Y 99 ) (3) ... 1.00925 168.66 The three sets of figures for the double chloride method refer to three separate and distinct preparations of pure nicotine in that way. Many dilutions of this nicotine with water were prepared and the specific gravity and specific rotatory power for them observed. The rotations were measured with a Schmidt and Haensch half-shade polarimeter using a tube having a length of 100.04 mm 106 JEPHOTT ; TRE PHYSICA5 CONSTANTS OF NICOTINE.PA€LT 1. Percen-t a p by weight. 95.068 91.084 89.471 88.338 83.336 81-842 77-006 750538 84.868 69.202 67-538 64.423 63.960 60.773 59.898 59.649 56.241 64.289 53.096 51.969 60.134 48.949 46.632 46.183 46.015 100 Grams in 100 100.926 96.801 93.323 91.781 90-820 86.132 84-632 79.921 78.551 77.764 71.963 70.231 66.91 8 66.440 63.110 62.131 61.895 58.260 56.245 54,934 53.750 51.777 50.513 48.062 47.629 47.412 C.C. D?. 1.00925 1.01823 1.02458 1.02583 1*02810 1.03356 1-03439 1-03784 1.03836 1.03839 1,03990 1.03988 1-03890 1.03894 1-03846 1.03728 1-037 65 1.03614 1.03603 1.03463 1.03428 1.03278 1.03194 1.03065 1.03 13 1 1.03037 cay:.168.61 153-06 141.65 138.73 134.11 123.21 121.48 111.47 108.39 108.69 100.47 97-82 95.63 94.02 93.69 95.12 91.27 89.27 90.12 86-91 89.03 88.19 86.23 86-79 --Percen-tage by weight. 44.004 41-718 40.237 38.798 38,065 37.986 35.098 34.877 32-141 30.973 30,637 30,291 28.151 26,473 24.975 20.963 20-726 169023 12.963 11.508 10.012 9.921 7.417 6.604 4-998 2-505 Grams in 100 45-296 42.882 41.308 39.804 39.025 38.950 35,920 35-696 32.810 31.607 31.253 30.915 28.664 26.930 25.369 21.235 20.995 15.156 13.027 11.579 10.061 9.971 7.441 6.622 5.006 2.504 C.C. DT . 1-02936 1.02790 1.02661 1.02592 1.02522 1.02538 1-02341 1-02351 1.02107 1.02048 1.02010 1.02060 1.01820 1.01725 1.01588 1.01300 1.01239 1.00880 1.00492 1-00611 1.00611 1.00494 1-00317 1.00276 1,00163 0.99970 [.I:.86.47 86.7 1 85.09 83-79 85-2 1 84-98 83.52 83-39 81.83 82.48 82.67 82.60 81.95 81.78 81.67 80.64 80.06 79-79 79.43 78.66 79.20 79.94 79-25 80.48 83.15 8a.99 The effect of temperature on the density and rotatory power both of pure nicotine and certain of its aqueous solutions has also been observed. For t.his purpose a jacketed polarimeter tube was Nicotine in aqueous 9olution. 1-05 1.04 1-03 .g 2 1.02 6 1.01 Percmtage by weight. employed a Sprengel tube being used for t,he densities.It was not convenient in every cas0 to observe both density and angle at, t.he same temperature and the density a t the temperature a JEPHCOTT THE PHYSICAL CONSTANTS OF NICOTINIS. PART I. 107 which the rotatory power was observed was obtained from a graph constructed from the recorded densit,ies. Pure Nicotine. Temperature. 20". 21.1'. 40". 60". 80". 97.7'. Dz O ............ 1.00925 1.00865 0.99424 0.97799 0.96184 0-94534 Temperature. 20° 29.5 41.5 62 62 69.6 86.4 92.0 Df (from graph). 1.00926 1.0017 0.9924 0.9840 0,9760 0.9699 0-9567 0.9521 [a];. 168.20" 168.71 169.09 169.61 169.74 169.94 169.73 169.7 1 Owing t o the so-called closed curve of solubility of nicotine in water it is not possible to observe the rotatory power and density of solutions containing between 7 and 87 per cent.of nicotine a t all temperatures up to looo since separation occurs at about 60°. Two solutions were therefore prepared which would fall outside this closed curve and contained 6-638 per cent. and 88.338 per cent. of nicotine. For these the following figures were found: Percentage Grams in Temperature. by weight. 100 C.C. D" [a]:. 20" ............... 6.638 6-682 140275 76.82 85 ............... 6.638 6.4188 0.96328 95.29 20 ............... 88.338 90.820 1.02810 134.16 90 ............... 88.338 86.936 0.98412 150.34 It will be observed that the change in rotmatory power is marked. On cooling to 20° the 6 per cent. solution a t Once showed its original rotatory power but the 88 per cent.solution did not revert to its former value for some days although an immediate fall to about [a]," 138.0 took place. Difficulty occurs in determin-ing the rotatory power of pure nicotine and its more concentrated solutions since owing presumably to light absorption it is zuxes-sary to match a greyish-pink against a grey when taking polari-metric readings. I n the case of the more concentrated aqueous solutions the difficulty is greatly increased owing to the very marked changes in density. In observing the angle of the 88 per cent. solution a t 90° even with a rapid stream of water circu-lating round the jacket the change in density by cooling a t the exposed surface of the end plates was so marked as t o make i t almost impossible t o get light to pass khrough the tube and th 108 JEPHCOTT !FHE PHYSICAL CONSTANTS OF NICOTINE.PART I. rotation recorded must be considered liable to an error of lo. No such difficulties were experienced with the 6 per cent. solution. The graphs for density and specific rotatory power of nicotine in aqueous solution both exhibit a series of maxima and these agree with molecular proportions of nicotine and water. This indica.tion of the formation of a series of hydratea is confirmed by an examination of the freezing points of nicotine solutions. Between 40 and 80 per cent. the time taken for hydrate-form-ation is appreciable and t h e abnormal points marked were found in cases of solutions when the rotation was observed immediately after mixing.A solution containing 69.2 per cent. of nicotine showed no change in rotation after keeping for twelve months. The ‘‘ OJosed Curve of Solubility ’’ fop Nicotime. The formation of hydrates of nicotine and their decompositlion at higher temperatures shows the true nature of the “closed curve of solubility.” Nicotine is only sparingly soluble in water and water is only sparingly soluble in nicotine but hydrates of nicotine are miscible wit,h either a state of balance existing a t any given temperature between nicotine its hydrates and water. When the temperature rises the hydrate-formation reverses, and on the concentration of fr0e nicotine becoming greater than the solubility of nicotine in water at that temperature separation occurs. By choosing concentrations of nicotine and water such that the limit of solubility of the one in the other was not exceeded, it was possible as shown above to note the marked rise in rota-tory power as tqhe concentration of free nicotine increased with the rise in temperature and it is to be expected that with conve~ence for observing the angle a t a sufficiently high temperature the true rotatory power of nicotine in water would be obtained. I am indebted to Mr. George Dean Head of the Chemistry Department of the Institute for valuable suggestions and advice, and t o tihe Chemical Society for a grant towards the cost of this research. WEST HAM MUNICIPAL TECHNICAL INSTITUTE. [Received November l l t h 1918.

ISSN:0368-1645    

DOI:10.1039/CT9191500104

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

THE SUB-ACETATE AND SUB-SULPRATE OF LEAD. 100 XI .-The Sub-acetate and Sub-sulphate of Lead. By HENRY GEORGE DENHAM. IN recent papers the author has shown how lead sub-oxide may be converted into the sub-haloid salts by the action of alkyl kaloid vapour (T. 1917 111 29; 1918 113 249); in the present paper a somewhat similar method has been used for the preparation of lead sub-acet'ate and sub-sulphate. In all these experiments the lead sub-oxide was prepared by the deco,mposition of pure lead oxalate according to the method previously described (Zoc. c i t .). The same precautions have been followed in order t o secure thorough preliminary heating of the reacting gases the vapair being passed t.hrough a capillary spiral tube contained in the oven before it came in contact with the sub-oxide.The only modification necessary in the distillation has been that no drying agent was used in the apparatus and it was necessary to heat electrically all t.he leading tubes in order t o prevent undesired condensation and to secure a steady rate of distillation. Prepration of Lead Sub-acetnte. Preliminary experiments were carried out with methyl acetate. About 10 C.C. of a carefully dried sample of this substance were distilled through about 0.75 gram of lead sub-oxide the duration of the experiment being approximately ninety minutes. Analysis of the product indicated that a t 310° the sub-acetate decomposes completely metallic lead being formed whilst' a t temperatures much below this the reaction proceeded too slowly to appear promising.Ethyl acetate behaved similarly and an experiment was then carried out with acetic anhydride. Lead sub-oxide mixed with about four times its weight of powdered glass was prepared in two bulbs (for details see T. 1917, 111 29) and the apparatus filled with oxygen-free nitrogen. About 8 C.C. of carefuIIy fractionated acetic anhydride were distilled through the bulbs a t 195O as recorded on a standardised platinum thermometer. This slow distillation generally lasted about eighty t'o ninety minutes. The oven was then cooled to about 180° and the apparatus was exhausted by means of a Sprengel pump. The bulbs were then sealed off and were available for analysis. By this VOL. cxv. 110 DENHAM THE SUB-ACETATE AND SUB-SULPHATE OF LEAD. prwdure any trace of acetic anhydride could be removed from the bulb without causing any decomposition of the sub-acetate.Traces of water were found to be retained most tenaciously by the sub-acetate. A few samples which were quite free from moisture were prepared but in general, although the ratio of lead to acetate in the compound agreed with the theoretical ratio for lead sub-acetate from 1 to 3 per cent. of water was also present. The presence of the water was repeatedly verified by the action of heat a liquid which rendered anhydrous copper sulphate blue being fairly readily expelled. Traces of acetic acid were generally present in nearly all tvhe samples of acetic anhydride used and this probably accounted for the presence of water in the sub-acetate. However as the anhydrous and the hydrated sub-acetate showed no difference in solubility and general properties anhydraus acetic anhydride was used only in certain control experiments.One difficulty still remained. Found P b = 77.6 77.9 77.9 ; C,H,O,= 22.3 22.0 22.2. CH3*COJ?b requires Pb = 77.82 ; C2H302= 22-18 per cent. In seven experiments made with acetic anhydride containing traces of acetic acid the average of the analyses was Pb=75*8; c2H30,=21'5. There is a possible hydrate of the formula (CH,*C0,Pb),,H20 which contains P b = 75-3 per cent. and it appears probable that where acetic anhydride containing traces of acetic acid is used the product is the hydrate containing more or less of the anhydrous sub-acetate. Thus in two experiments in which the same sample of acetic anhydride was used after a dis-tillation lasting ninety minutes the percentage of lead was : (a) bulb 1 75'4 bulb 2 75.2; ( b ) bulb 1 75.1 bulb 2 75.2.Properties of the Sub-acetate. In order to obtain evidence of the existence of the sub-acetate, determinations of the conductivity of a saturated solutioii of the substance and of the normal dehydrated acetate were carried out in absolute alcohol a t 25O. The apparatus and method previously described (Zoc. c i t . ) were again used in order that traces of oxygen might be excluded when the sub-acetate was used. The resistance of the alcohol was 90,000 ohms whilst that of a saturated solution of the normal acetate was 4100 ohms and of the sub-acetate, ( a ) 6100 ( b ) 6400 ( c ) 6000 ohms. As further evidence of the existence of a definite sub-acetate of lead experiments on the decomposit.ion of the normal acetate and the sub-acetate were undertaken.A sample of the anhydrou DENHAM TH381 SUB-AmTATE AND SUB-SULPBATE Crl? ILEAD. 111 normal acetate was heated in a vacuum and the temperature slowly raised. A t 200° a very slow evolution of gas occurred be&g rather brisker a t 240O. The temperature was then kept constant and the pump kept in action for nineteen hours. Gas was still very slowly evolved and it was found that the acetate had scarcely changed colour and there was a considerable crop of long white, needle-like crystals which had vdatilised out of the bulb into the relatively cooler leading tube within the oven. A t 200° gas was slowly evolved the evolution becoming brisker a t 240O.After seven hours a t 240° gas was still being evolved slowly and a small volatilised band of white amorphous basic material was' found outside the furnace whilst the material in the bulb had undergone a marked change. It was now full of long, needlelike greyish crystals. This change from a finely crystal-line bluish-grey substance into a mass of grey needlelike crystals, was very marked as too was the entire absence of the volatilised, white needle-like crystals obtained in the decomposition of the normal acetate. The behaviour on heating the different acetates in a vacuum is so different that it would be difficult to maintain the view that the sub-acetate is a heterogeneous mixture of metal and normal acetate and these results coupled with the different conductivity of the saturated solutions must rather be held to am-firm the view of the chemical individuality of the sub-acetate.The sub-acetate exhibits the s m e behaviour towards acids as other-sub-salts of lead namely it is rapidly decomposed into metal and normal salt. A sample of the sub-acetate was then similarly treated. Lead Sub-sulphate. Methyl mlphate was distilled through lead sub-oxide a t 280° foil' about seventy-five minutes the manipulation being similar to that already described for the sub-haloid salts of lead (Zoc. c i t . ) . No difference in behaviour or in appearance was detected in the products prepared from lead sub-oxide or from the sub-oxide diluted with four timss its weight of silica. On t4he other hand, when the distillation was carried out a t 310° and the silica omitted the resultJng grey mass was seen under the microscope to contain clusters of white crystals in a dark background and was clearly heterogeneous.In the sub-sulphate prepared according t o the above method the lead was e s t h h d by conversion into lead sulphate and the sulphate by treating the sub-salt with dilute nitric acid evapora ating to dryness washing out the lead nit'rate and weighing the 3r 112 DENHAM THB S03-A.CfBTATB AND SUB-SULPHATE OF LEAD. residue in a Gooch crucible as lead sulphat,e. Owing to the presence of traces of carbonaceous mat*ter the precipitate was generally faintly grey until after gentle ignition. Found Pb=81.25 81-62 81.30 81.29; So,=18.65 18.56, 18-80 18.62.PbSO requires Pb = 81.18 ; SO = 18-82 per cent. Properties of the Sub-sulphate. The action of acids on the sub-sulphate is similar to their ac&n on the sub-haloid salts. A solution of ammonium acetate when boiled with the substance leaves a deposit of spongy lead. I n order to test the chemical individuality of a saturated solution of the salt determinations of the conductivity in water and alcohol a t 18O were made. The resistance of the water was 27,000 ohms, whilst that of a saturated solution of lead sulphate was 3030 ohms, and that of the sub-sulphate was (a) in air 3100 ohms and ( b ) in a vacuum 3200 ohms. The difference is so slight that it appears highly probable that there is decomposition into lead and lead sulphate although no visible change occurred in the appearance of the residue.The resistance of the alcohol was 90,000 ohms whilst that of a saturated solution of lead sulphate was 93,000 ohms and of the sub-sulphate 75,000 ohms. Although a much more marked difference was obtained the evidence afforded by the conductivity method was still so incon-clusive that further evidence as to the individuality of the salt was sought by investigating the influence of temperature on the sub-sulphate. Were the substance a heterogeneous mixture of lead and lead sulphate a rise in temperature above the melting point of lead would be expected to cause a pronounced change in the appearance of the finely divided lead. Before heating the sample, some of it was carefully observed under the microscope and no sign whatever of heterogeneity was noticed but the whole appeared a unifom iron-grey.The temperature was raised 120° above the melting point of lead for a period of four hours. On cooling the microscope failed to reveal any change whatsoever in the appear-ance of the salt. The entire absence of anything in the nature of minute globules of lead certainly supports the contention that this greyish substance is definitely lead sub-sulphate. Conclusion. (1) Lead sub-acetate has been obtained by the action of acetic anhydride on lead sub-oxide a t 195O SYNTHESIS OF AMMONIA AT HIGH TEMPERATURES. PART 111. 113 (2) The substance is bluish-grey and behaves similarly to other sub-salt8 of lead. (3) Its solubility in alcohol differs slightly from that of the normal acetate but the behaviour of the two acetates on heating in a vacuum supports the view of the chemical individuality of the sub-acetate. (4) The sub-sulphate has been prepared by the action of methyl sulphate vapour on the sub-axide a t 280O. (5) The substance is dark grey; conductivity experiments indicate that? it decomposes on solution in water but it appears more soluble in alcohol than does the normal sulphate. (6) On heating the substance 120° above the melting point! of lead no change in its appearance could be det.ected or any sign of globules of lead. I n conclusion the author begs to thank the Walter and Eliza Hall Trust for the facilities placed a t his disposal for the prosecu-tion of this work. SHE DEPARTMENT OF CHEMISTRY, UNIVERSITY OF QUEENSLAND, BRISBANE. [Received January 14th 1919.

ISSN:0368-1645    

DOI:10.1039/CT9191500109

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

SYNTHESIS OF AMMONIA AT HIGH TEMPERATURES. PART 111. 113 XII.-TJLe Synthesis of Ammonia at High Temperatures. Part 111. By EDWARD BRADFORD MAXTED. IN previous communications (T. 1918 113 168 386) some accountl has been given of the formation of ammonia in a rapidly cooled high-tension arc and in water-cooled flames and evidence has been brought forward to show that the percentage of ammonia in equilibrium with nitrogen and hydrogen after decreasing with increasing temperature passes through a minimum value and a t very high temperatures increases with increasing temperature a result which may also be shown thermodynamically. A determination of t,he equilibrium ammonia-content a t the temperature of the high-tension arc ( J . SOC. Chent. Id. 1918 37, 232) gave approximately 1.7 per cent.by volume for the equil-ibrium percentage a t atmospheric pressure under the experimental conditions employed and yields of ammonia up to 1.5 per cent. could be recovered by suitable cooling 114 MAXTED THB SYNTHESIS OF AMMONIA This reversal in the direction of variation of the equilibrium ammonia-percentage with temperature appears t o be sufficiently interesting to justify further study and it is proposed in the p r e sent paper t,o deal wit'h the formation of ammonia in an arc of larger size and more usual character than those hitherto employed. For the production of the arc single-phase 50-cycle alternating current supplied a t a maximum pot'ential of 375 volts was trans-formed to high tension by means af an oil-immersed static trans-former having a step-up factor of 31.5.It was fuund easily possible to obtain an appreciable concen-tration of ammonia by almost any method by which the mixture of nitrogen and hydrogen was brought into contact with the arc flame with subsequent rapid cooling for instance by means of a blown arc similar to that used by McDougall and Howles (Proc. Mamchester Phil. SOC. 1900 44 No. 13) for the synthesis of n i t r i c oxide but in such cases a considerable proportion Qf the gas mix-ture blown into the arc failed to reach the requisite uniform high temperature and for a preliminary study of the maximum per-centage of ammonia formed as distinguished from the maximum quantity formed with a given expenditure of electrical energy it was considered preferable t o allow the arc to burn freely in the reacting gas mixture and to draw off samples of gas by means of a silica tube of small diameter placed in close proximity to the arc.The lat'ter part of the present paper was carried out with a view to bringing additional evidence that the formatign of ammonia a t high t'emperatures really takes place by the direct union of hydrogen and nitrogen and not by $he subsequent reduc-tion of nitric oxide formed from traces of oxygen in the reacting gases. It should further be stated in this connexion that 'the mixture of nitrogen and hydrogen employed in all experiments reported both in this and in the previous papers was as far as pmsible free from oxygen and in no case contained sufficient of this to account for such secondary formation of any appreciable part of the ammonia obtained.EXPERIMENTAL. The apparatus employed is shown in the figure. The electrodes A and B are of platinum and terminate in small spheres slightly more than 1 mm. in diameter. C is a t'hick-walled capillary silioa tube its upper end being opened out and flattened so as t o form a slit approximately 4 mm. long and 1.5 m. wide. The silic AT HIGH TEMPERAT'URES. PART In. 116 wall bounding the ends of this was ground away and in the depressions thus formed a t each end of the silica slit the electrodes rested the lower part of the tube being circular in section and about 1.5 mm. in internal diameter. The arc was enclosed in a large inverted flask provided with a side-tube and three-way tap D for preliminary exhaustion and subsequent admission of the gas to be subjected to the aotion of the arc this gas normally passing into the flask a t D and leaving the syst'em by way of the silica tube already described.For the following measurements the current employed for arc-formation was limited by the interposition oli an adjustable resist-ance on the low-tension side of the transformer. The platinum electrodes became quickly white hot and the arc flame burned steadily across the slit and was, to a certaih degree drawn into the tube by the current of gm. Sufficient cooling for the recovery of the greater portion of the ammonia formed and for the prevenlhn of the fusion of the silica tube was obtained without water-cooling provided that a thick-walled silica capillary was used and that the arc employed was not too large.Samples of gas taken a t various rates were analysed by passage through N/lO-acid and in some cases by allow-'& + ing a small volume to pass through Nessler's solution practically identicall results being obtained from each The quantity of ammonia observed is. influenced necessarily not only by the temperature of the arc, but also by heating and cooling factors. With very slow currents of gas heating to arc temperature occurs satisfactoriIy but the ammonia formed undergoes considerable decomposition owing to the slowness with which it leaves the region of madmum tempera-ture. Passage of the gas too quickly through the arc results in imperfect heating such rapid passage however involving rapid cooling and consequently a more complete retention of the ammonia formed.It will be seen from table I that the concentration of the ammonia recovered a t the ordinary temperature first of all rises rapidly with increasing velocity of passage then passes a maximum method of analysis. &nil 116 MAXTED THE SYNTHESIS OF AMMONIA value the percentage of amionia subsequently falling gradually with etill greater velocities of passage. This form of the concentra-tion-velocity curve is a necessary result of the nature of the heat-ing and cooling factors discussed above. The issuing gas of course had a strong odour of ammonia a t all the rates of flow studied and the percent.ages obtained were of the same order of magnitude as those previously observed with small arcs not produced directly by a high-tension current of the usual sinusoidal wave form.For this series of experiments 0.04 ampere a t a potential of 3250 volts was taken for arc-formation. TABLE I. Gas Mixture ATitrogen 25 per cent.; Iiydroyen 75 p e r cent. Rate of flow of gas in litres per hour. o s . 5 0.57 0.85 1.14 2.1 (2.1 Concentration of ammonia per cent. by volume. 0.49 0.6 1.2 1.04 0.58 0.56) Rate of flow of gas in litros per hour. 3.4 (3.4 4.0 6.1 7.5 (7.5 C Gncentration of ammonia per cent. by volume. 0.49 0.45) 0.43 0.40 0.36 0.32) It appears desirable at this point' t'o discuss the evidence that the formation of ammonia at high temperatures takes place by the direct union of nitrogen and hydrogen and not secondarily by the reduction of nitric oxide formed from nitrogen and traces of oxygen in the reacting gas.The point is of fundamental import-ance in any consideration of the variation of the ammonia equil-ibrium with temperature and for this reason has been examined in such a way as to place beyond doubt t-he directl nature of the synthesis of ammonia a t arc temperatures. It' may easily bs shown from a Consideration of the nitric oxide equilibrium particularly on account of the small partial pressure of the nitrogen in the gas mixture employed such mixture consist-ing uniformly of 25 per cent. of nitrogen and 75 per cent. of hydrogen that a trace of oxygen amounting t o 1 per cent. by volume or less will not accounh for the percentage of ammonia obtained even assuming that' all the nitric oxide which can be formed under the conditions of experiment is quantitatively reduced to ammonia.The amount of nitric oxide that can be formed from nitrogen and oxygen a t partial pressures of the order mentioned is depressed by the ratio of partition of oxygen between hydrogen and nitrogen to a very small fraction of the alread AT HIGH TEMTERATURES. PART 111. 117 small percentage which may be calculated as capable of being formed from a consideration of the nitric oxide equilibrium only. I n spite however of the small order of magnitude of the per-centage of ammonia that might be formed secondarily from the traces of oxygen which are always present in commercial gases it was considered preferable both for the work described in the present paper and for all measurements of the formation of ammonia a t arc temperature previously reported to employ a gas known to1 be free from oxygen within the limits of the ordinary methpds of analysis.This gas was prepared i n a manner similar to that used by Haber and Van Oordtl (Zcitnch. nnorg. Chena. 1905 44 341) for their determinations of the ammonia equilibrium a t lower tempera-tures in the presence of a catalyst by decomposing ammonia by passage through a heated iron tube the mixture of nitrogen and hydrogen produced being carefully and thoroughly freed from ammonia by treatment with sulphuric acid and compressed for convenience into a previously exhausted steel cylinder by means of a tot-ally immersed compressor of such design as to render impossible any penetration of air to the gas during compression.Each cylinder of nitrogen and hydrogen prepared in this way was carefully tested for absence of ammonia before use by bubbling a considerable volume through Nessler's solution. The gas-mixture contained certainly less than 0.1 per cent. of oxygen from which percent age the ammonia capable of being formed secondarily would be negligible and in any case incapable of accounting for a yield of ammonia of 1 per cent. or more. I n a few preliminary measurements a gas was used which had been made by the catalytic removal of traces of oxygen from a mixture of commercial hydrogen and nitrogen by passage over a heated metal but whilst the resulting gas was equally satisfactory from the point of view o€ the yield of ammonia obtained by passage through an arc the preparation of an oxygen-free mixture in this way was more troublesome than by the firstl method.I n addition to employing a gas free from oxygen it was con-sidered interesting t o examine the synthesis a t arc temperature under such conditions that the same volume of nitrogen and hydrogen was repassed a number o€ times through the arc the ammonia formed a t each passage being absorbed and measured. It is obvious that any trace of oxygen would particularly by reason of the hydrogen present be removed during the first few passages through the arc and that the conversion t o ammonia of an approximately constant percentage of the gas-mixture during F 118 MAXTED THE SYNTHESIS OF AMMONIA.PART III. each successive passage would confirm beyond doubt the direct nature of the synthesis. The experimental method employed consisted in confining a known volume of an oxygen-free mixture of nitrogen and hydrogen in a graduated vertical glass capillary tube about 1 metre long. The upper end of this tube was fused on to a second short hori-zontal capillary tube containing platinum wire electrodes 0.5 mm. apart between which a small induction arc as described in a previous communication could be formed this second capillary tube ending in a small absorption pipette filled with dilute sulphuric acid. The lower end of the graduated capillary tube was sealed by means of mercury covered with a small quantity of sulphuric acid and by the regulated motion of this seal up and down the graduated tube the thread of gas could be passed and repassed through the arc as often as desired.An approximately uniform rate of passage was obtained by making the graduated capillary tube one limb of a U-tube and causing the required motion by means of a mercury flow this being normally regulated so that each double passage through the arc occupied about six minutes when 1 C.C. of the gas mixture was taken for experiment. Working as above described the ammonia formed during each upward passage was removed by the small absorption pipette sealed to the other end of the short capillary arc tube whilst that pro-duced during each downward passage was absorbed by sulphuric acid clinging to the side of the graduated capillary.The arc tube was of course not allowed to become wet on account of the danger of fracture and the thread of gas after its introduction passed no joints by means of which penetration of air might occur. Table I1 summarises the results obtained in two experiments of this nature the estimation of ammonia being in this case carried out volumetrically by noting the contraction after each passage. A preliminary small expansion occurred on starting the arc and passage was only begun after the volume had become more or less constant . The yields of ammonia are much the same as those previously found for such arcs by other methods of analysis and with more accurate control over the rate of passage. Probably by reason of the more rapid nature of the cooling the yields are slightly higher than those obtained with the larger arc described in the first part of the present paper.Each cm. of the graduated capillary corre-sponded with 0.01 C.C. of gas so that the volume could be read off with fair accuracy to 0.001 C.C TRE EFFECT OF SOME SIMPLE ELECTROLYTES ETC. 119 TABLE 11. Contrahtion Vol. of gas No. of pas- after doublo passed through sages since be- passage through Percentage of No. of arc. ,ginning of arc. ammonia expt. C.C. formed. expt. C.C. 1 0.74 1 (original volume) 0.715 0.69 0.67 0445 0-627 0.605 0.59 2 0,825 (original volume) } 0-795 0.77 0.75 0.723 0.70 0.68 0.655 0-63 0.605 0.596 0.575 0.655 0.532 0.51 0-49 0.475 3 4 6 8 10 12 14 16 2 4 G 8 10 12 14 16 18 20 22 24 26 28 30 32 34 0.025 0.025 0.02 0.025 0.018 0.022 0.015 0.02 0-03 0.025 0.02 0.027 0.023 0.02 0.025 0.025 0-025 0:Ol 0.02 0.02 0-023 0.022 0.02 0.015 0.015 1.7 1.7 1-5 1.9 1.4 1.8 1-2 1.7 1.8 1.6 1.3 1.8 1.6 1.4 1.8 1.9 2.0 0.5 1.7 1.7 2-0 2.0 1.9 1.6 1.6 The experimental conditions including control of rate of flow and the method of analysis were not suitable for very accurate measurements but the approximate constancy of the yield of ammonia and especially the absence of any indication that a normal amount of ammonia is formed during the first passage and little or none during subsequent passages appears to demonstrate without doubt the direcb nature of t3he synthesis a t high temper a t ures. [Received December 23rd 191 8.

ISSN:0368-1645    

DOI:10.1039/CT9191500113

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

TRE EFFECT OF SOME SIMPLE ELECTROLYTES ETC. 119 XIIT.-The Efect of some Simple Electrolytes on the Temperature of Maximum Density of Wuter. By ROBERT WRIGHT. ROBETTI (Ann. Chim. Phys. 1867 [iv] 10 461; 1869 17 370) has given a fairly exhaustive account of the early work carried out B f 120 WRIGHT THE EFFECT OF SOME SIMPLE ELECTROLYTES on the determination of the temperature of maximum density of water and of a few salt solutions. A considerable portion of this work is clue t o Despretz ( A i ) i 7 ? . C‘him. Phys. 1839 [ii] 70 49; 1840 73 296) and the most important result is embodied in the following law iianied after that investigator “ The lowering of the temperature OP the point of maximum density of water caused by the addition of a solute is directly proportional t o the concen-tration of the latter.” An attempt was made by Rosetti to coiinect t’he lowering of the temperature of maximum density brought about’ by the addition of a solute with the lowering of the freezing point pro’duced by the same cause but it was found impossible t o formulate any general law f o r although the ratio of the two lowerings was csmtant.for any given solute at different’ concentrations still a different ratio was obtained by the use of a second solute. In other words whilst the lowering of the freezing point-being con-iiected with the osmotic pressure o l the solution-depends oaly on the concentration of the solute molecules the lowering of the point of maximum densit-y depends 011 the iiature as well as on the number of dissolved molecules.Coppet in a series of researches (A1212. Cliim. I.’hys. 1894 [vii], 3 246 268; Conzpt. rend. 1897 125 533; 1899 128 1559; 1900, 131 178; 1901 132 1218; 1902 134 lZO8) has determined the molecular lowering of the temperature of maximum density for a number of salts of the alkalis that is the lowering produced by a gram-molecule of salt per litre and the following table contains the more important of his results : TABLE I. Chloride. Bromide. Iodide. Rubidium ............ 11.7 13.2 15.6 Potassium.. ............. 11.6 12.8 15-4 Sodium .................. 13.2 14.5 17.0 Lithium ............... 6.0 7.0 8.3 Ammonium ............ 7.2 8.7 11.1 From an examination of these Lignres Coppet points out’ that of the three acid radicles the iodide has the greatest and the chloride the least effect and as a general conclusion states that’: “Le rapport entre les abaisserrients produit par le chlorure et le bromure (ou le bromure e t le iodure) du m6me mQtal est sensible-ment le meme pour tous les mdtaux du groupe.” The ratio varies between the values 0.78 and 0.91.From the results of the present investigation carried out wit ON THE TEMPERATURE 0%' MAXIMUM DENSITY OF WATER. 121 monobasic inorganic acids and their sa1t.s with univalent metals it will be shown that the lowering produced by any given salt con-forms to a simple general rule and can in fact be calculated from the known lotwerings produced by other salts. The results of the melasurements are given in table 11 which contains the figures obtained for solutions varying in strength between semi- and one-sixteenth-molecular the normal br molecular lowerings being calculated from those of lower concentration TABLE 11.M/16. Jl/S. A! 14. .................. 0-7 1.3 HC1 -1.4- LiCl ................... .................. 1.G 3.1 NaCl -. &>. 8 .................. 1.4 KC1 -_ ............... 2 . 0 1.8 _- -NH,CI __ llensity of 8dt Molecular M 12. lowering. 2.6 6.2 2.8 5.6 G-2 12-4 5-6 11.0 3.B 7.2 .................. 0.9 1.8 3.7 7.4 HBr .................. 1.9 3.8 7.6 LiBr .................. 1.8 3-7 7.4 14.5 NaBr __ .................. 1.6 3.2 6.5 13.0 KBr -_ ............... 1.2 2.8 4.7 9.4 8.8 .................. 1.2 i d HI ................... 1.8 3.3 9.2 Lil.. -NaI ..................1.0 2.0 4.0 16.4 14.8 KI .................. 0.9 1.8 3.7 10.8 HNO ............... 0.8 1.6 3-1 12.4 ............... 1.6 3.1 12.4 20.0 NaNO ............... 1-3 3.5 5.0 18.0 14-4 ___ - -NH,Br -_ .). -> -- .-NH,I 1.4 9.7 _. LiNO -KNO ............... 1.1 8.2 4.5 NH,NO ............ 0.9 1-8 3-6 I t will be seen a t once that the results agree with the law of Despretz the semi-molecular solutions giving twice the depression of the corresponding fourth-molecular. Further it is obvious that the lowering is not connected with the osmotic pressure as the values shown for the molecular lowerings of differeni; solutes vary greatly; nor is a consideration of the difference in the degree of ionisation sufficient to account f o r this abnormality since the various solutions of any given colncentration are practJcally ionised to the same extent.The regularity running through all the measurements can readily be seen if the difference between the lowering shown by any acid and say its sodium salt is considered. This difference for the four .................. 0.7 -_ _ _ _ 122 WRIGHT THE EFBEOT OB SOME SIMPLE ELECTROLYTES acids tabulated has the values 7*2,7.4,7*6 and 7.6 ; thus thereplace-ment of the hydrogen ion by sodium causes a practically constant increase in the molecular lowering. A similar increase is found when potassium is used instead of sodium the average value being 5-75 whilst for ammonium the value is 2.0. Further the same effect is observed in the case of the acid radicle; thus the replace-ment of chlorine by bromine Tncreases the molecular lowering by 2.1 whilst the sibstitution of iodine for chlorine causes an increase of 3'7.From a consideration of these results it is evident that each acidic or basic radicle has its own effect on tho lowering of the point of maximum density and that the effect produced by a salt is equal to the sum of the lowerings caused by the metallio and acidic radicles. Hence if we take the molecular lowering of hydrochloric acid-which gave the smallest effect of all the sub-stances examined-as standard we can obtain the molecular lower-ing of any salt or acid by the addition of two numbers one corre-sponding with the acidic and hhe other Fith the basic radicle of the salt. It will a t once be seen that there is a close resemblance between the above conclusion and Valson's law of moduli which states that the density of a normal salt solution is the sum of an acidic and a basic effect and can in fact be Calculated by adding to the density of a normal solution of a standard s u b s t a n c e ammonium chloride-two figures or moduli one characteristic of the acidic and the other of the basic radicle of the salt.The moduli for the lowering of the point of maximum density are given in table 111 and the molecular lowering of any salt can be found by adding to the molecular lowering of hydrochloric acid (5.2) the two moduli corresponding with the given salt. For ex-ample the calculated lowering for potassium nitrate would be 5-2(hydrochloric acid) + 5*75(potassiurn) + 7*2(nitrate) =18*15 the actual value found being 18.0.Several values for each modulus calculated from different salts are shown in the table together with the mean value derived from them. TABLE 111. C1. Br. I. NO,. Average. ............ Li 0.6 0.2 0.4 0.0 0-3 Na ............ 7.2 7.4 7.6 7.6 7-45 K ............ 5.8 5.6 6.0 5.6 5.75 NH ......... 2.0 2.0 2.0 2.0 2.0 Br 2.2 2.0 2.4 2.0 2.2 2.2 I 3.6 3.6 4.0 3.8 3.6 3.7 NOa ......... 7.2 6.8 7.6 7.0 7.2 7.2 H. Li. Ne. K. NH,. Average. ............ .............. ON THE TEMPERATURE OE’ MAXIMUM DENSITY OF WATER. 123 It should be noted that a similar set of moduli could be calcu-lated from the molecular lowerings given by Coppet although as a rule his values would not be identical with those tabulated; the results however approximate to one another fairly closely con-sidering the difference in the experimental methods employed.We may next consider the results obtained with the weak mane basic organic acids in comparison with their highly ionised salts. Formic acetic and propionic acids together with their sodium and ammonium salts have been examined. TABLE IV. N 18. - Formic acid ............ Na salt .................. 1.6 Acetic acid ............ N a salt .................. 1-5 Na salt .................. 1.5 - NH salt ............... NH salt -Propionic acid ......... -NH salt --............... ............... N/4. 1.7 3.2 1.7 1.8 3.0 1.6 2.0 3.0 1.7 N/2. 3.6 3.6 3.7 3.1 4.0 3.4 --N. 7.2 12.8 7.2 7.4 12.0 6.2 8.0 12.0 6.8 The results do not show the normal change 7.6 which was obtained with strong acids when the hydrogen atom was replaced by sodium but the difference between the values for the sodium and ammonium salts is constant in all three cases and is identical with that obtained in the case of the inorganic acids.In other words the highly ionised salts of organic acids behave in the normal manner whilst the feebly ionised acids themselves are abnormal. The dibasic acids with their acid aiid neutral salts are also of interest. TABLE V. Sulphuric acid ......... NaH salt .................. Na salt .................. Oxalic acid ............ NaR salt.. ................ Na salt .................. Succinic acid ............ NaH salt ..................Ne salt .................. MI1 6. M 18. 3.0 2.0 4-0 2.0 4.0 -1.7 - 2.5 1.5 2.9 -M 14. M. 6.1 24.4 - 32.0 - 32.0 3.0 12.0 I 19.2 - 32.0 3.4 13.6 - 20.0 I 23.2 It will be seen that the replacement of one hydrogen atom b 124 WRIGHT THE EFBECT OF SOME SIMPLE ELECTROLYTES sodium in the two stronger acids gives values approximating to the normal whilst succinic acid gives a slightly lower value thus re-sembling the weak monobasic acetIc and propionic acids. I n all cases, the replacement of the second hydrogen atom is quite abnormal and differs widely in the three cases. From the normal behaviour of the acid salt it may be colncluded thafu the ions of sodium hydrogen sulphate consist mainly of Na' and HSO,' and not H and NaSO,'.It should be noticed that as the greatest concentration examined in these acids was iV/4 the results are not so accurate as with the monobasic acids. The results obtained for the salts of the bivalent metals show great irregularities probably on account cf the complex ions which are present. For eixarnple the molecular lowering obtained for barium chloride was 24.6 and for barium nitrate 32.8 from which the two values 14.2 and 8.0 are obtained for t.he modidus of barium.' Similar varying results can be obtained from the figures given by Coppet and Miiller (Compt. reird. 1902 34 1208) f o r the loweriiigs shown by the halogen salts of barium and calcium. TABLE VI. Blolocular lowering. Modulus. Barium bromide .................. 25-14 26-28 10.9 Bariuiz- iodide .....................29.24 29.42 11.7 Calcium chloride ............... 18.0 18.3 7-8 Calcium bromide ............... 20.12 20.93 5-7 Calcium iodide ..................... 26.09 26-63 8.7 It will be seen at once thatl there is no regularity comparable with the case of the univalent metals. E X P E R I M E N T A L . The apparatns employed is shown in the diagram; it consists of a dilatometer with a capacity of about 50 C.C. and fitted with a stem 25 cm. long and of 0.5 mm. bore. To co'mpensate f o r tho change in volume with temperature a portion of the bulb is filled with mercury; the fraction of the total dilatometer volume thus filleld is equal to the ratio between the coefficients of cubical es-pansion of glass and mercury so that on a change of temperature, the expansion or contraction of the metal exactly compensates the expansion or contraction of the bulb t'he volume of the latter unoccupied by the mercury thus remaining constant.The dilahineter is filled by rneanr of a tap funnel and a vacuun ON THE TEMPERATURE OF MAXIMUM DENSITY OF WATER. 125 pump. The stem of the dilatometer passes through a rubber cork fitted into the opening of the tap funnel which contains the liquid to be int'roduced into the dilatometer. The funnel and the attached dilatometer is now inverted and connexim made between it and a filter pump. As the pressure is lowered the air in the dilatometer bulb bubbles through the liquid in the funnel and on detaching from the pump the liquid is forced into1 the dilatometer bv the action of the atmospheric pressure.A second and a third exhaustion are usually necessary and the last trace of air in the bulb is removed by heating. The dilatometer with t.he funnel still attached is now placed in a vacuum-jacketed vessel filled with brine a t about 5O and allotwed to cool. When the apparatus has attained the temperature of the surrounding liquid i t is disconnected from the tap funnel and a few shavings of ice are added to the liquid in the vacuum flask; air is then driven through the cooling mixture so as to stir it until the ice has melted. The apparatus is now left for a quarter of an hour to allow the dilatometer to aswme the temperature of the bath; this tempera-ture is then not'ed and the level of the liquid in the dilatometer tube measured ; the apparatus is again left' and readings are taken at five-minute intervals until the liquid in the dilatometer ceases t o contract; this precaution is necessary in order to ensure that the whole apparatus is in a state olc thermal equilibrium.A furbher small quantity of ice is now added so as to lower the temperature a fraction of a degree and the process repeated. After several additions of ice the liquid in the dilatometer reaches its poii?t of maximum density, and on further cooling i t expands As this point. is approached the coefficient of expansion of the liquid diminishes so that i t is difficult t.0 deter-iniiie the exact temperature of maximum density, and the readings given are only accurate t o 0 - 2 O . After a measurement the instrument is warmed within about so as to expel a little of the contents and is then inverted so that the mercury runs out.This mercury is dried and reserved for the next deter-mination whllst the rest of the contents of the dilatometer are removed by means of t,he filter pump. The instrument is then rinsed with the next liquid t o be investigated and after the re 126 THE EFFECT OF SOME SIMPLE ELECTROLYTES BTC. introduction of the mercury it is filled with the solution and the measurement made as before. The coefficient of expaasion of the glass was calculated between the ordinary temperature And looo by filling the instrument with mercury and weighing the quantity expelled when heated in a steam-jacket whilst the volume of the bulb was measured by filling with water and weighing a t a known temperature.The stem of the instrument was not graduated but the level of the liquid below the upper end was determined by means of a depth gauge fitted with a vernier; by !this means a change of level of 0.1 mm. could be detected and, moreover the labour of regraduation of the stem after an accident was avoided. A few other points may be noted. Conclusions. (1) The lowering of the temperature of the maximum density of water produced by the addition of a solute is directly proper-tional to the concentration of the latter (law of Despretz). (2) The lowering produced by a highly ionised binary elecicro-lyte is composed of two separate independent effects one due to the acid radicle and the other due to the basic radicle of the electr ol yt e . (3) The lowering produced by a highly ionised binary electrolyte of molecular concentration can therefore be calculated by the addi-tion of two moduli to the lowering produced by a molecular soln-tion of a chosen standard substance. The chosen standard was N-hydrochloric acid which gives a lowering of 5'2. (4) The acid salts of the dibasic acids behave normally but the neutral salts of such acids and the salts of the bivalent metals do not follow any simple rule in their effect on the temperature of the maximum density. (5) Feebly ionised organic acids show abnormal effects but the highly ionised salts derived from them behave in the normal manner. CHEMICAL LABORATORY, QUEEN'S UNIVERSITY BELFAST. [Received December 2184 191 8.

ISSN:0368-1645    

DOI:10.1039/CT9191500119

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

DE POLSR AND NOK-POLAR VALENCY. 127 XIV.-Polar. and Norc-polas. VaZeracy. By RAJENDRALAL DE. IN a paper recently published Briggs (T. 1917 111 267) asks: “What is the valency of cobalt in chloropentammine cobaltic chloride C 0 F H s CI,?” This question has suggested the view set forth in the present paper. From the study of the optical properties of the tetraethylene-diamminep-aminonitrodicobaltic salts, 0 en,Co/ 'been X, \NO,/ NH 1 Werner (Ber. 1913 46 3674) concludes that there is no essential difference between the principal and auxiliary valency bonds. Evidently this conclusion may be applicable only to the bonds within the complex radicle (that is bonds employed in uniting radicles co-ordinated with the cobalt atom). The bonds outside the complex radicle are employed in combining radicles which exist as ions.Their nature is thus entirely different from that of the former ones. A distinction ought therefore to be maintained between the bonds outside the complex radicle and those within it. We can find an explanation of the valency outside the ccunplex radicle which is polar in type from Sir J. J. Thornson’s theory of valency. To understand the mechanism of it let us picture the structure of an atom derived by Thomson. According to him the atom consists of corpuscles moving in a sphere of uniform pmitive electrification and its valency depends on the ease with which corpuscles can escape from or be received by the atom. Difficul-ties however arise in explaining the valencies within the complex radicle in the above manner they being non-polar in type.During the disintegration of radioactive substances the negative charges of electricity are carried by &rays and the positive charges by a-rays. The &rays consist of expelled particles-not atoms of matter but free atoms of negative electricity or “ electrons.” An a-particle however consists of two atomic charges of pcrsitive electricity combined with a helium atom-a substance inert in the chemical sense. It may therefore be assumed that the pmitive electricity can have an attraction for the mass itself even if there be no charge of negative electricity on it. Thgmson (“Rays of Positive Electricity and their Application to Chemical Analysis,” p. 40) also observes that molecules with positive! charges are quit 128 DE POLAR AND NON-POLAR VALENCY.co8mmon whilst those witah negative charges of elect~city are very rare. This property which the positive electricity possesses affords an explanation of the phenomena of the valencies inside the corn-plex radicle of a complex salt. I n order t o explain the phenomena of the above valencies we shall conside'r Rutherf o'rd's view as regards the constitution of an atom. According t o him a positive nucleus is situated in the centre whilst electrons move around it in various concentric rings. We shall conceive this nucleus as having a binding capacity for the radicles which am co-ordinated with a metallic atom in the case of complex salts. It is significant that no positive radicles, such as ammonium tetramethylammonium etc.which can exist as cations have been observed t o combine with a metallic atom forming a complex radicle. Negative radicles such as C1 (chloro-), NO (nitro-) etc. however do form a complex radicle with a metallic atom. These1 negative radicles also carry negative charges of electricity when they exist as anions. Let us form a picture of the mechanism as conceived above. We have the positive nucleus of the metallic atom (capable of forming a complex radicle) in the centre and around it there are various concentric rings along which the electrons move. We may assumel that adjacent t o the outermost ring of electrons constituting the atomic structure there are the neutral molecules f o r example, NH, H,O etc. or the negative radicles f o r example C1 NO,, etc.or b0t.h these neutral and negative radicles held by the influence of the positive nucleus of the metallic atom concerned. Accordingly in the case of tetraethylenediamzine-p-aminonitro-dicobaltic salts radicles within the complex radicle may be sup-fmed to be1 abtached to the positive nuclei of its cobalt atoms and thereby the valencies within the1 complex radicle being taken to be all alike the two cobalt atoms become linked to1 the two groups in the middle namely NO and NB, in a similar way. The conditions favourable to the formation of complex salts may now be stated. The number of concentric rings in the struc-ture of an atom gro~ws large as the atomic weight increases and, thereby the structure also becomes more complex According to Rutherford however (Soddy " The Chemistry of the Radio-elements," 1914 Part 11 p.39) the mass of an atam is concen-trated in an exceedingly small central nucleus. Hence with the decreasei in the atomic volume only i.he rings will decrease in size, and the outermost ring will approach nearer to the nucleus. We have already supposed the radicles co-ordinated with a metallic atom to be placed adjacent to its outermost ring of electrons and also bound by its nucleus. Evidently t.he attracti-on of the nucleu D E POLAR AND NON-POLAR VALENCY. 129 fo8r the mass of the radicles would increase where there are possi-bilities of their being placed near to the nucleus that is to say, where the atomic volume is small. I n fact metals that. are cap-able of forming complex salts as for example chromium iron, manganese cobalt nickel copper ruthenium rhodium palladium, osmium iridium platinum gold etc.are situated on the troughs of Lothar Meyer’s atomic volume curve. Here it may also be mentioned that Ephraim ( B e y . 1912 45 1322; 1913 46 3103; 1914 47 1828; Zeitsch. physiknl. Chenz. 1913 81 513 539; 83 196) from his st’udy of the strength of the auxiliary valencies of various metals has drawn the conclusion that the strength of the auxiliary valencies falls with the increase of the atomic volume of the metal concerned. We thus find a further support f o r the abo’ve assumption. It will be observed that the metals which form complex salts are mostly found both in the (‘ ous ” and the (‘ic’’ state of their ionic condition as for instance we have Cr” (chromous) Cr”’ (chromic) Co” (cobaltous) Co”’ (cobaltic) etc.It may also possibly be that the “ous ’’ condition of the metallic ion is more favourable to the formation of a complex radicle. During the reduction of a metallic ion from the “ i c ” to the “ ous ” state there is an alteration in the electric charge of its rings and the proba-bility is that this alteration is confined to the outermost ring (Soddy ibid.). Evidently in the (‘ ous ” condition of the metallic atom there is a less number of electrons in its outermost\ ring. Keeping in view the structure of an atom it would be natural to expect that ordinarily the outer rings of electrons would offer themselves as a shield against the attraction of the positive nucleus f o r thel radicles which may be co-ordinated with a metallic atom.The case is however different in its ‘( ous ’’ state for there being produced a weakness in the shield due t o a less number of electrons in the ring the attraction of the1 nucleus will obtain an oppor-tunity of manifesting itself by forming a complex radicle. It is known that chromic chloride has to be reduced t o the chromous state for the preparation of chrom-ammonia salts (C’hristensen, J . pr. Chem. 1881 [ii] 23 54). Similarly in the preparation of cobalt-ammonia and platinum-ammonia compounds (Gerhardt, Annalen 1850 76 307) the starting materials are the ( ( ous” salts of the metal concerned. Last-ly it is found that the formation of a complex anion is a more general phenomenon than the formation of a complex cation ; for example there’ are compounds of the type1 [M(C,O,),]R, where M may be Vd Cr Mn Fe Co Rh R1 As Sb or Bi (Werner, (‘New Ideas on Inorganic Chemistry,” p.116 ed. 1911). I 130 DE POLAR AND NOR-POLAR VALENCY. seems poasible that there is a cmnexion betwwn the increase of attraction of a metallic atom for these negative radicles (co-ordinated with it) and the cause which occasions the presence of negative charges of electricity on them when they exist as anions. We have already supposed that t'he valencies outside the comples mdicl0 are caused by electrons of the outermost ring constituting the atomic structure. These electrons may therefore be termed walenee-dectrons. Obviously the number of the valence-electrons of a metallic atom corresponds with that of its maximum valencies outside the complex radicle.I n the case of the complex metal-ammonia compounds this maximurn valency is exhibited when all the radiclm co-ordinated witK the metallic atom are NH or H20, and when a negative radicle is introduced into the above complex radicle the number of valencies outside the complex one is decreased (that is the number of valenceelectrons appears to become less). We may call those valence-eleckons which seem t,o have vanished in this way bozcnd valence-electrons and those which have caused the appearance of valencies outside the complex radicle free wdemce-electrons. We may also notice that the maximum number of free valence-electrons (that is electrons which can escape from a metallic atom forming a complex cation) is the same as the maximum number of electrons which can be received by the atom in addition to its own valence-electrons when it' forms a part of a complex anion.For illustrating this point we may cite the com-pounds (i) [Co(NH3),]C13 where the complex radicle is a ter-valent cation (ii) K,[Co(NO,),] where the complex radicle is a tervalent anion and (iii) [ (NH,),Co(NO,),] a nm-electrolyte. In the third compound no electron has escaped or been received by the metallic atom but all the three valencz-electrons along with the three univalent negative radicles have been bound by its posi-tive nucleus. Regarding the question a t hand namely that of the number of valencies in chlorqpentamminecobaltio chloride it may be said that here the cobalt atom contains three valence-electrons-one is bound along with the univalent chlor+radicle mordinated with cobalt and the remaining two have caused the appearance of valencies of polar Oype outside the complex radicle.Besides these three valenceelectrons the metallic atom possesses six valency bonds of non-polar type caused by the attraction of its positive nucleus. The structure of the complex radicle as conceived above explains also the phenomenon of the directional nature of the auxiliary valency bonds indicated by the stereoisomeric compounds of com-plex metal-ammonia salts for the nucleus being centrally placed in the structure of an atom (metal) has an advantage in exertin DE POLdR AND NON-POLAR VALENCY. 131 its attraction along different directions which the electrons moving in their orbits cannot possibly have.The assumption of the nuclear attraction however need not be confined to these cases of complex derivatives alone. The phenomena of non-polar valencp may in general be considered to have arisen from this attzaction. The kind of valency exhibited in organic compounds is a typical non-polar one. I f w0 compare ths valencies of the carbon atam with those of metallic ones employed in co-ordinating radicles with them we find that both these two kinds are non-polar and direc-tional in nature (shown by the stereoiscmerides of the carbon compounds and those of complex metal-ammonia derivatives). This similarity in their character may indicate the probability of their being brought about by the same cause namely by the attraction of the positive nucleus of an atom.The assumption receives further support from the small at.omic volume of carbon (as shown in Lothar Meyer’s atomic volume curve). It has already been supposed that ths attraction of the nucleus for radicles should increase as the atomic volume decreases and this should tend ta a maximum when the volume becomes very small. Nernst is of opinion that the forces by which the carbon atoms in a crystal of diamond are held together are identical with the attraction of its four valencies called into play in the formation of organic compounds that is to say (‘the forces of cohesion are identical in nature with the forces of chemical affinity” (“The Theory of Solid State,” p. 6). The cohesive forces are found to increase with.the decrease of the atomic volume of elements. They may therefore arise from tfie very same nuclear attraction of atoms mentioned before. An inspection of the behaviour of carbon and its compounds might help in giving some light in this direction. I n the process of the synthesis of diamond an immense pressure is brought about by the contraction of iron in which carbon has been dissolved. Evidently for effecting union (that is saturation of the valencies of carbon atoms) the atoms are required to be brought very near to one another. It may also be noted that in the case of the carbides of metals the carbides Li,C, CaC, etc., where the metals are of large atomic volumes are decomposed by water whilst the carbides Cr,C, Cr,C etc. where the metals in combination are placed on a trough in the atomic volume curve (that is are of small atomic volumes) form stable compounds.Taking into consideration that the mass of an atom is concentrated in an exceedingly small central nucleus in the structure it seems possible that carbon atoms would exert only a very feeble attrac-tion when placed a little apart or when combined with metals of large atomic volumes. The various rings of electrons around th 132 DE POLAR AND NON-POLAR VALENCY. nucleus which have already been compared to shields may also occasion a further hindrance in their union. Further light will bel thrown on the above if the followiiig view is taken of the constitution of triphenylmethyl. It is found that in solution triphenylmethyl has a molecular weight corresponding with the formula (CPh,) (Gomberg and Cosne Ber.1904 37, 2033). This is what may be expected from its mode of preparation : 2CPh,Br + 2Ag = 2AgBr + CPh,*CPh,. As the compound is very reactive even a t a low temperature it has been assumed that i t is rather a derivative of tervalent carbon. Exposure to the air even for a very short time is sufficient to transform it into a peroxide' of the constitution CPh,*O*O*CPh,. We may however represent the constitution of triphenylmethyl as CPh ... CPh,. The weak attraction between the two carbon atoms is shown by the dotted line. The feebleness of their attrac-tion may be due to the inability of the carbon atoms to approach very near t o each other on account of the hindrance caused by the large phenyl groups attached to them.The hindrance referred t o may be of the type1 similar to that of steric hindrance (Wegscheider, Monntsh. 1895 16 148) and their reactivity may be due to the possibility of their drawing small atoms very near t o them. View-ing the constitution given for the oxidation product" it' is seen that by the intervening of two' oxygen atoms the large radicles have been placed apart' and by the union of the' two carbon atoms with two oxygen atoms (small indeed compared with the triphenyl-methyl radicle) a stable compound has been formed. According t o our assumption radicles bound by the positive nucleus should not show any polar character. Alt,hough the valency of carbon is ordinarily non-polar there are a few organic compounds where it seems t o function as polar as for instance i n hydrogen cyanide and in organic acids where we have thel radicles *CIN or *NiC and R.CO,* respectively besides hydrion.There are also sodium acetylide CHiCNa silver acetylide C2Ag, and cuprous aceltylide C2Cun where' the hydrogen atoms of acetylene have been displaced by metallic atoms. I n order to explain this anomaly we may consider Sir J. 3. Thornson's observation that "when the discharge tube cont'ains such gases as CH, CO, CO, where there are 110 bonds between two carbon atoms in the mole-cule we find negatively charged carbon atoms but no negatively charged molecules. When hocwever we use compounds such as acetylene HCiCH ethylene H,C:CH, o r ethane H,C*CH, where, according to the usual interpretation of the constitution of these subst4ances there are bonds between carbon atoms in the molecule, then we find molecules as well as atoms of carbon with the negativ DE POLAR AND NON-POLAR VALEBTCY 133 charge” (Zoc.cit.). He is also of the opinion that on account of the unsaturated valencies of the carbon atoms in the molecule it has been possible for the negative corpuscles to become attached to them (ibid.). A similar explanation may be applicable in the above cases. I n them more than one bond of carbon has been occupied with the other element combined with it and a corpuscle received from an adjacent hydrogen atom may become attached t o the remaining part of the compound thus giving rise to their polar character. Compounds such as LiH H,O NH, etc. Ni(CO), Co2(CO),, etc.and also groups of atonis forming radicles such as CO, NO,, SO, etc. being formed by non-polar valencies may have their origin in the nuclear attraction. We may also ascribe the forces by which atoms and molecules in a crystal are held together to the same attraction. These forces have been supposed to be caused by residual valency which has also been assumed to bring about the solution of a substance in a solvent (Baly “Spectroscopy,” 1912, 11. 487). The phenomena of solution should necessarily be con-sidered t o be due t o the same attraction of the nucleus. I n these cases the size of the molecules may account. for the feeble character of their binding. Lastly all catalytic substances which are employed in gaseous reactions may be supposed t o owe their cata-lytic action to the positive nuclei of the atoms in them.Indeed, the study of the dissociation of the hydrogen molecule into atoms, and other similar studies have convinced Langmuir ( J . Amer. Chem. Soc. 1916 38 2221) that prior t o the dissociation absorp-tion of hydrogen by tungsten wire due t o its secondary valency, does take place. We see therefore t.hat the nuclear attraction plays a great part in all chemical phenomena. Regarding the number of valencies of the non-polar type for different elements it may be noted that carbon (placed in the first trough of Lothar hleyer’s atomic vdume curve) has four valencies, whilst other elements (placed in subsequent troughs of the curve) generally have six. I n the case of the complex platinum-ammonium salts however the derivatives of the platinous salts, for example [(NH,),Pt]Cl, tetra-amminoplatinous chloride show the number of auxiliary (lion-polar) valencies t o be four whilst those of the platinic salts for example [(NH,),PC]Cl, hexa-amminoplatinic chloride the number is six. The increase of two non-pollar valenciea in the latter case has been attended with an increase of two polar ones. Also the directions of these valencies, in the former case lie in a plane whilst’ in the latter case there are two additional directions lying in the same line perpendicular to the above plane. Whether and how the electrons constitutin 134 DUICRANT THE INTERACTION OF the atomio structure influence the number and directions of the non-polar valencies of different elements awaits further study. My best thanks are due to Prof. P. C. RSy for his kind help and encouragement. PRESIDENCY COLLEUE CALCUTTA. ISLAMIA COLLEGE PEBHAWAR INDIA. [Becedved October 2nd 191 7.

ISSN:0368-1645    

DOI:10.1039/CT9191500127

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

134 DUERANT THE INTERACTION OF XV.-The Interaction of Stannous and Arsenious Chlorides. By REGINALD GRAHAM DURRANT. THE action of stannous chloride on arsenious oxide dissolved in hydrochloric7 acid was first noticed by A. Bettendorf (Sitzungsber. ATiederrheiw Ges. Bonn 1869 128 *) two years after his discovery of yellow arsenic [ibid. 1867 67 and (full paper) Annalen 1867 144, H e records the formation of a voluminous brown precipitate which proved to be arsenic (96-99 per cent.) with traces of non-removable tin. He showed that the rate of precipitation increase8 with ascending specific gravity of the arsenious solution. By dissolv-ing magnesium ammonium arsenate in acid he made a standard solution and treated this with stannous chloride in varying dilutions of hydrochloric acid.(His figures will be quohed later on.) From these results ho showed that the reaction is extremely delicate. It may be utilised for determining arsenic in sulpliuric or crude hydro-chloric acid. During a distillation with the latter he observed a faint yellow coloration which disappeared after a few hours. Arsenic was found to be present in this sample of hydrochloric acid, but he was unable to prove that the fading coloration was due to arsenic. The observation of this yellow coloration has decided me to record a v0ry remarkable yellow precipitate which in 1914 I exhibited as (( yellow arsenic ” to the Science Masters’ Association in London. The precipitate was quite bright yellow a t first and was always kept in the dark except when shown for short periods.After a year 1101. -* I a m indebted to Dr. Hatchett Jackson who recently procured me a rescript of this paper from the Bodleian Library STANNOUS AND ARSENIOUS CHLORIDES. 135 it had become a dull mustard colour being still in the original well-corked flask and surrounded by the original solution (a mixture of arsenious and stannous chlorides in nearly normal hydrochloric acid). Every effort was made t o repeat this but in vain. When filtered off the precipitate appeared very dull and shrunken on the paper. After washing it was specially tested for sulphur (sinoe arsenious sulphide is yellow) but no trace of sulphur was found. The presenoe of arsenic was proved. On many p i n t s I find that my observations have been anticipated by Rettendorf in particular the possibility of making the reaction a means of differentiating arsenic from antimony.E x P E R I ni E N T A L. The Nature of the Arsenic Prec,i@tnted. Arsenic is probably in a colloidal state before it is prscipitated, for (i) the precipitate invariably contains a trace of tin salts (chloride as well as tin) and this cannot be removed completely by prolonged washing ; (ii) two similar solutions (reactants 0.44N- and 3N-hydrochloric acid) were left corked for two days and remained quite clear. One was then diluted with an equal volume of water. After four days both had deposited arsenic. A third solution a t the start was made up to the lower of the above concentrations and remained perfectly clear for twenty-five days. The appearance of solid arsenic is always preceded by a pale buff tint; from this a buff-brown precipitate falls and is best observed from such admixtures as yield a very slow deposit.I f this deposit, after washing is immediately shaken with carbon disulphide arsenic is found to be dissolved. Tho yield is rather greater if carbon rlisulphide is shaken violently with the two chloride solutions while they are interacting. On five occasions small pale particles were observed to rise from the clear disulphide solution during spontane-ous evaporation. They moved about rapidly congregating in the centre of the surface then darkened and finally settled on tho bottom of the dish in the form of grey arsenic. Erdmann (Zeitsch. anorg. Chem. 1902 32 453) obtained arsenic soluble in carbon disulphide by reducing arsenious oxide with zinc dust in the presence of the solvent.Very small quantities were obtained by the author in this way. These results and those referred t o in the Introduction indicate that the very earliest deposit of arsenic is of the yellow type but that unless certain unascertained conditions obtain the yellow variety spontaneously becomes brown or grey 136 DURRANT TRE INTERAOTIO’N OF Nature and Conditions of the Reaction. The obvious equation is 2AsC1 + 3SnC1 = 3SnC1 + ZAs and when weights 04 the reactants correspnding with this equation are placed in hydrochloric acid of sufficiently high concentration the action rezches completion in a few hours. With other weights excess of either reactant corresponds with calculation.The action has been proved to be irreversible for if finely divided arsenic is boiled with solutions of stannic chloride in the presence of hydrochloric acid of varying concentration in no case d6es the resulting solution give any precipitate with mercuric chloride. A very careful experiment was made in order to ascertain if the anhydrcus chlorides react. Fresh arsenious chloride was so arranged that on movement of the handle of an air-pump some would drop on to dry powdered stan-nous chlo,ride-also under the receiver. After four days’ final drying with phosphoric oxide the experiment was made. Beyond the faintwt darkening no discoloration occurred. On exposure t o air a distinct brown colour overspread the powder and when a drop of water was added a heavy crusting of arsenic appeared immedi-ately.General Method of Estimu.tin,q the Rate of Progress of Action. Separate solutions containing known weights of the two chlo’rides were mzde u p in known concentrations of hydrochloric acid. Por-tions of these solutions were evaluated separately by means of standard permanganate. The results were found t o agree with the known concentrations. All stock flasks were re-tested from time t o timel. Small dry flasks were placed in a large thermostat and into these definite volumes of both chloride solutions were introduced by separate pipettes. After definite intervals water was added. The dilution effectively stops the action. The contents of each flask were then filtered and uniformly washed. Standard permanganate was used t o determino the amounts of stannous and arsenious chlorides remaining in the filtrates and wash-water.The action of the permanganate may be expressed : 2AsC13 + 2 0 = 2AsOC1 \ As the filtrates required less permanganate than did the sum of { 3SnCle + 3 0 = 3SnOC1, STANNOUS AND ARSENfOUS (3HLORTDES. 137 the separate solutions the deficit became a measure of the change which 'had occurred. Two-fifths of this deficit were due to the pre cipitation of arsenic and the rest to the formation of stannic chloride in the reaction : 3SnClB+ 2AsC1 + 3SnC1 + 2As. Errors.-The sources of error in this process are (1) imperfect washing (2) loss by adsorption (3) oxidation of stannous chloride due to access of air. The two first considered together were found t o give rise to an error probably less than 2 per cent.The third source of error was almost eliminated by keeping the stock solutions of stannous chloride in a well-coked flask and by introducing carbon dioxide immediately after use on every occasion. I n the same way the reaction took place in small corked flasks in which the air was displaced by carbon dioxide. Air had access only during the process of filtration. Calculations.-The recognised integration equations for first and second order reactions were applied to a large number of 'determina-tions. I n no case did the velocity constants conform to the second order. The results quoted are from the firsborder equation, 1 a - 1% t where a = 100 x = percenta.ge of change and t = time in minutes.Hence the mean value of k for each set of experiments represents a special figure by which the relative speeds may be com-pared. TABLE I. t = 12.5O. N/4-Permanganate used. Normalities S'nC1 = W507 AsC13= 0.584 HC1= 6.06. Complete oxidation should correspond with a deficit of 45.6 C.C. Interval, minutes. 2 5 8 10 12 15 20 30 40 50 65 100 120 180 Deficit, 3-66; 9.3 16.65 17.05 26-25 29-4 33.85 38.45 40.1 40.8 41.9 42-85 43-6 43-9 C.C. Percentage chmqe. 8.0 20.8 36.5 L37.41 57.5 64.5 74.2 84.3 87.9 89.5 91.9 93.9 95.6 96.3 k x 102. 1-81 2.03 2.46 r2.031 3-09 3.00 2-94 2.68 2-29 2-96 2.21 2.97 2-40 Mean 2-57 P.681 138 DURRANT THE INTERACTION OF Various further unimolecular values of k were obtained.These were found tci depend more on the concentration of hydrochloric acid than on anything else. The results made it pmsible to choose suitable concentrations for systematic study. Influence of IT ydroc hloric A cid. In the following experiments 0.2500 gram of stannous chloride ( 8 7 6 6 4-85 R W v e velocitiu of the reaction 3SnC1 i- 2AsC1 = 3SnC1 + 2As, See Table XI. Tgmperature = 1 2 9 due to altmt&ns of hydrochlol.ic concentration. acted on the equivalent weight of arsenious chloride in each case. The concentration of hydrochloric acid alone was varied. TABLE 11. t = 1 2 O . Reactant Normality = 0.298. Normality Range of change, of HCl. per cent. 10.09 40-6 1 8-10 36-64 7.25 32-63 6-77 13-63 6.60 2 1-69 6.11 41-63 7.09 34-78 6.34 26-64 4.85 19-63 Mean value, k x lo2.21.2 13.6 4.7 6 3.43 1-40 0.944 0.436 0.293 0.029 STANNOUS AND ARSENIOUS UHLOZUDES. 130 The curve obtainsd by plotting these relative velocities against concentration of hydrochloric acid between 4.85N and 8*10N is exceedingly regular. Its sharpest curvature is in the neighbourhd of 6.5N. I f the regularity persisted u p to the limit of possible hydrochloric acid concentration (about 10*3N) then the velocity a t 10*09~Y would be well over a thousand times what it is a t 4-85N-as measured it is only 723 times as great. Influence of Simultaneous Change ic Concentration of Reactants. I n all these experiments the concentration of hydrochloric acid remained constant a t 6 N .Four 250 C.C. flasks-A B A B,-contlained respectively, SnC1 = 1-74N AsCl3= 1-76N SnC1 = Om87N As(&= 0.88fl. The concentration of hydrochloric acid became 6N as soon as the mark in each flask was reached. Equal volumes from A and B were mixed in six small flasks, and after 4 6 8 10 12 and 14 minutes respectively their filtrates were titrated with AT/ 4-permanganate. In the same way equal volumes from A and 13 were treated from seven flasks after 24 32 48 64 80 96 and 112 minutes, respectively the filtrates being titrated with iV/ 8-permanganate. I n each set the range of progress was from 30 to 70 per cent. For A B set mean value k x 102=4'33. For A,B set mean value k x lO2=O0.557. Hence k/k =7*77 for the range between 30 and 70 per cent.t =18.4. The range between 30 and 40 per cent. however gave k l k = 5 * 5 . E'fJect of altering the Concentration of Each Reactant Sepmately. Preliminary work had appeared to show that arsenious chloride reacts as a second and stannous chloride as a first power. The following solutions were prepared tested and preserved with all possible care. Five C.C. of stannous chloride solution reacted with 5 C.C. of arsenious chloride solution in each case. The washing was strictsly uniform so that errors hence arising were similar. The mean results (2) and (4) in the following table are fairly concordant. The results from comparison of (l) (4) and (5) confirm the preliminary work with respect to arsenious chloride which is seen t o react! as a second power.The period preceding the first appearance of arsenic from a solution of its chloride a t one-fifth the original concentration was noticed to be just about twenty-five times as great as it had been. Those of (3) and (5) are more YO -1 40 TABLE 111. HCl= 6 N . t = 16.7'. (1) N-AsCl acting on N-SnC1 in 12 minutes required c.c.N/4-KMn04 Required by theory after 33.3 per cent. change. Mean of 2 readinns 27.85 26.66 (2) N-AsCl, (3) N-AsCl, (4) N-SnCl, (5) N-SnC1, This suggested Nesslerisation ; o ; N / ~ - s ~ c ~ in 12 minutes on N/3-SnC12 in 12 minutes on NIZ-AsCl in 48 minutes on N/3-AsC13 in 108 minutes ?) 22.3 23.3 $ 9 20.8 22.2 $9 22.55 23.3 ¶# 20.9 22-2 a method of working t o a standard tint as in moreover the method compares the earlier &ages of action on which calculations are more appropriately based.sulphide on a very dilute solution of lead acetate. The tlint used in table IV was obtained by t'he action of hydrogen TABLE IV. HCl= 61Y. t = 10'. Times to reach Stannous Arsenious chloride. chloride } N NP N/3 1 /c2 Total Ratio Staindard Tint are yiven in Seconds. + N . + N / 2 . + N/3. Total. Ratio. ,& 30 110 260 400 1.0 1.0 50 220 460 730 1-82 1-73 40 160 360 560 1.40 1.41 120 490 1080 1 4-08 9 1 4 9 A similar set of nine readings referred to another artificial standard tint gave ratios powers of AsCl, 1 4.3 10.0; powers of SnCl, 1 1-37 1-80. The N/3-stannous chloride solution on testing was found t o have deteriorated slightly; the others had not.A solution of N/4-stannous chloride was made. Using N / 2-arsenious chloride against N,' 2- and N /4-stannous chloride, the times were 230 and 320 seconds respectively giving a ratio 1 /1*39 again closely approaching 1/ d2. The results here given lead to the conclusion that in this reaction arsenious chloride reacts as a second power and stannous chloride reacts to the power of the s p a r e root of its concentration STANXOUS AND ABSENLOVS CHLORIDES. 141 The figure 5.5 nded in the last paragraph for the chasge between 30 and 40 per cent. is quite consistent with the results here given since 22 x 43 = 5.64. The action of stannous chloride to the square root of its con-centration is also in agreement with Bettevdorf's figures (Zoc.cit., 1869). H e took 0.001 gram of arsenic dissolved in 1 C.C. in each of five experimente adding this to a definite amount of stannous chloride solution in the presence of hydrochloric acid. I n the four last experiments he also added 50 100 200 and 400 C.C. of hydro-chloric acid (presumably of similar concentration). An immediate precipitate occurred in the first experiment and the arsenic appeared in 5 8 12 and 20 minutes respectively in the others. Neglecting 1 C.C. of arsenious chloride + an unknown volume of stannous chloride solution originally taken his concentrations were 1 2 4 8 his times were 1 1.6 2.4 4 figures which approach 1:1.41:2:2*83 but exceed them in each case because of the influence of the second power action of amenioua chloride present in very small relative amount.(His experimentcl were made to show the delicacy as regards arsenic.) Effect of Dihtirm with Water. The stock solutions when mixed were a t concentrations HC1=6N and reactants each a t 0*88N. When undiluted this mixture produced 70 per cent'. change in twelve minutes. The dilutions (in ten steps) finally brought ali the concentrations to one-third of the above. The hydrochloric acid normalities and the state of change after five days are noted in each case. t=16O. 6N 5*45N and 5N had reached complete change. 4.61N 89 per cent. 4.29N 59 per cent'. 4N 24-4 per cent. 3-75N 14.2 per cent. 3.53N 5.6 per cent., 3-3N 3 per cent. 3rV 1 per cent. and 2N no change and no subsequent sign of action after 29 days.This retarding action was made use of in all previous experiments when titrations with permanganate were made the dilution with water being sufficient to reduce the concentration to one-third or IAY. Summary. (1) There is evidence that arsenic in process of precipitation is I n certain circumstances partly soluble in carbon disulphide. arsenic may appear as a yellow deposit. VOL. axv 142 INTERACTION OF STANNOUS AND ARSENIOUS CELORIDES. (2) The anhydrous chlorides (arsenious and stannous) do not interact. (3) Acceleration of t'he action is caused chiefly by increase in the concentration of hydrochloric aoid next by that of arsenious chloride and least of +11 by that of stannous chloride. Arsenious chloride acts as a second power and stannous chloride to the power of the square root of its concentration.Conclusions. The various phenomena and the figures given can be account.ed for on the hypothesis that this action is between chloride ions, arsenious ions and the stannous complex H,SnCr,. Stoppage by dilution must be due to the destruction of arsenious ions by hydrolytic action. (1) Chloride ions proceed partly from arsenious chloride and partly from hydrochloric acid and they act as a first power. The velocity constants found in table I1 are thus explained. HCl normality. k x 10'. k/k. Cl'/cl'. 10.09 8.10 7-28 7-09 6.77 6-60 6-34 6.1 1 4-85 1-57 2-83 1.37 2.35 1.64 2-16 3.22 10.00 7.09 3.55 1.54 2.08 1-58 1.88 2.66 0.28 Aggregate 26.04 26.66 In the last column the numerator gives the sum of chloride ions due to arsenious chloride and those due to increased hydrochloric acid concentration ; the denominator is constant and represents the chloride ions due to the 0.298fl-arsenious chloride which is constant throughout the table.In the lower portion of the table, the arsenious chloride is not wholly ionised; in the upper portdon, hydrochloric acid becomes less ionised a t its higher concentrations. As is seen the aggregafe acceleration as directly proportional to the increase of chloride cmcentratiom. (2) Positively charged aqenious ions also act as a first power. Arsenious chloride as a whole appears t.herefore to act as a second power. (3) That a compound of hydrochloric acid and stannous chloride exists in solution was indicated by Young ( J . Amer. Chem. SOC., 1901 23 21 450) and several stannochlorides corresponding wit ELIMINATION OF THE CARBETHOXYL QROUP E"0. 143 the formula MzSnC14 have recently been described (compare Druce, Chem. News 1918 117 193). In the reaction this complex must be decompased in order t o produce stannic chloride and this decam-position may account for the complex acting to the power of the square root of its concentration. According t o accepted theory the order of a reaction is governed by the slowest reactant. The order here is unholecular and the slowest reactant is t-his complex. Essentially the action consists in the disintegration of the complex by circumambient ions. THE COLLEUE, MARLBOROUGH. [Rereiued July 30th 1918.

ISSN:0368-1645    

DOI:10.1039/CT9191500134

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

ELIMINATION OF THE CARBETHOXYL QROUP E"0. 143 XV1.-Experiments on the Elimination of the Carb-ethoxyl Group from Tautomeric Systems. Part I. Derivatives of Inden e. By CHRISTOPHER KELE INGOLD and JOCELYN FIELD THORPE. THERE have been placed on record within recent years (T. 1905, 87 1669 1685; 1911 99 2187 and subsequent papers of the same series) a number of experiments dealing with substances possessing the kind of tautomerism which is associated with the three-carbon system CHCC. These experiments have for the mmt part dealt with glutaconic acid and its alkyl derivatives and the conclusion was reached that glutaconic acid itself has the symmetrical or " normal " structure (11) t'he unsaturated or " labile " form (I) being too unstable t o have any but a momentary existence.CO,H*CWCH:CH-CO,H CO,H b~ CH,. t ! ~ CO,H . (I. 1 (114 When however alkyl groups were introduced into the three-carbon system the unsaturated form was found to become very noticeably more stable with increasing weight of the substituents. It was thought desirable to extend these investigations to sub-stances possessing the three-carbon t'automerio complex but con-taining groups other than carboxyl attached to its terminal carbon atoms-preferably to some substance in which the possible a 144 INGOZD AND TEOEPE ELIMINATION OF THE sym9let.q of the molecule could be tested without in any way tampering with the three-caqbon system. Such a substance presents itself in the hydrocarbon indene the analogy of which to gluhconio acid becomes apparent when the formulae are written together thus: CO,H*CH 'Z>CH ( '\CTT I '2>CH Uo$?H*'H CO,H*CH C'O,H*CH /'&I I >CH I !,,>,,* \PH I \ I (1.1 (111).(11.1 (IV. 1 It was hoped originally that the accuracy either of I11 or of IV might be proved by preparing solid substituted indenes from a-hydrindones of the types V and VI, If the unsubstituted three-carbon system of the indene nucleus is symmetrical as would be expected from analogy t o unsubstituted glutaconic acid the ketones V and VI should yield the same indene whilst if unsymmetrical two different indenes should result . We have not yet been able to elaborate methods leading to the preparation of suitable ketones of the types V and VI in sufficiently large quantities to ensure the success of this method of attack.In the meantime however we have made use of more easily available materials to obt4ain evidence bearing on the subject and in par-ticular to investigate a reaction which has been repeatedly observed among esters of the glutaconic series and appears to be peculiar to tautomeric compounds. In 1905 the observation was made (Rogerson and Thorpe T., 1905 87 1702) that ethyl y-cyano-a@y-trimethylglutaconate readily passed into ethyl carbonate and ethyl y-cyano-apy-tri-methylcrotonate under the influence of cold sodium ethoxide : CO,Et*CMe(CN)*CMe:CMe*CO,Et + EtOH + CHMe( CN)*CMe:CMe*CO,Et + CO (OE t)2. Since that time fairly extensive use has been made of this reac-tion in the preparation of a series of alkylated glutaconic esters (Thole and Thorpe T.1911 99 2187). Thus the monoalkylated products derived from Conrad and Guthzeit's yellow sodium com-pound (Annulen 1883 222 259) yielded ethyl carbonate along with tribasia esters: (CO,Et),CR*CH:C(CO,Et) + EtOH + CO2Et.C HR CH :C( CO2E t)a + CO( OEt) CARBETHOXYL GROUP PROM T A U T ~ I C SYSTBMB PART I. 145 The tribasic esters did not decxmpme when treated with excess of the same reqent but on further alkylation gave ay-dialkyl deriv-atives which reacted readily to form ethyl carbonate and dialkylahd glutaconic esters : CO,Et*CR:CH*CR’(CO,Eti) + EtOH + CO,Et.CR CH*CHR/*CO,E f + CO (OE t),. The study of these and similar casw led to a generalisation regarding the determining cause of these reactions. They have always been found to be peculiar in substances of the glutaconic hype to those in which all the terminal hydrogen atoms of the three-carbon system have been substituted.It was therefore inferred that the tendency in such cases to acquire the hydrogen atom necessary to enable the substance to pass into its tautomeric form is such that a carbethoxyl group readily becomes detached from the molecule and replaced by an atom of hydrogen under the influence of a suitable reagent. We shall have occasion more than once to make use of this general rule. The ethyl carbonate reaction is therefore very closely bound up with the tautomerim of the three-carbon system. One would not t.herefore expect derivatives of vinylacetic acid such as those represented by formuls V I I and VIII in which the double bond would be purely static to exhibit this reaction to any marked degree.(1 ) Bz*CH .. CH2 C E ~ ~ H CH Ph-C c/GH4-’C;s 6R( CN) C0,Et 6 R( CN)mCO,E f (46R((3N) *COEti (mT. 1 (VIII.) (1x4 It was therefore decided to prepare an ester of the type IX and investigate its behaviour towards Gold sodium ethoxide. The similarity with V I I and V I I I is clear. I f the double bond in the ester IX really possesses the same stable character w0 should for similar reasons expect it to be unreactive. This conclusion is in agreement with the generalisation above cited; for if the three-carbon system (l) (2) (3) (see formula IX) in the indene ring is non-tautomeric and the double bond quite static between the carbon atoms (2) and (3) then since this same double bond enters also into the three-carbon system (2) (3) (4) the latter must be non-tautomeric as well.Its normal form would clearly be incap-able of existence since the central carbon atom (3) is rendered permanently quaternary by the double bond. I n such an eshr we should not in view of the above-mentioned generalisation, expect ta find any tendency to acquire an atom of hydrogen which 146 INGOLD AND THORPE ELIMINATION OF THE if it were acquired could not possibly be mobile. If on the con-trary we found that an ester of the type IX actually did possess a noteworthy tendency to acquire a hydrogen atom in place of its carbethoxyl group we should have to look on the fact as evidence of the tautomeric or dynamic character of the three-carbon system (l) (2) (3) of the indene ring.This follows by simply reversing the argument. Actually we have succeeded in preparing a number of indenyl 3-cyanoacetic esters of the type IX and have found that the lower members of the series possess a very marked ten-dency to lose their carbethoxyl group as ethyl carbonate when treated with quite a small quantity of sodium ethoxide a t 30°. The ester in which R=Me for example when treated with as little as one-sixth of a molecule of sodium ethoxide reacts a t 30° in the course of a few minutes. The yield of the decarbeth-oxylated nitrile is 60 per cent. the remainder of the material passing into an insoluble substance of high molecular weight. I n all the cases of this reaction investigated there was a greater or less quantity of insoluble by-product formed along with the nitrile X and ethyl carbonate./'CH + Et@R -+ (',cH6>CH -I- CO(OEt),. "-CR(CN)*CO,Et CHR-CN \/:- I I @a: (X.1 With homologous alkyl derivatives (R=Et and R=Pr.) the reaction becomes successively more sluggish and an increased quantity of by-product is formed the yield of nitrile consequently diminishing. This is quite analogous to all that has been observed in regard to the same reaction when applied to the glutaconic esters (T. 1911 99 2192). Two points to which no analogy has as yet been investigated or observed among the glutaconic esters, require however special notice. The ester for which R=allyl was found to be very much more reactive than the corresponding n-propyl derivative. I t s reactivity was quite of a similar order to that of the methylated ester.The other point is that a branched chain in the alkyl group appears to inhibit the reaction practically ahgether. Thus the esters for which R was isopropyl, isobutyl and isoamyl gave no nitrile after remaining for twenty-four hours with one-sixth of a molecular proportion of sodium ethoxide a t 30°. In order to obtain a comparative check on these results we decided to investigate an indenyl-2-cyanoacetic ester of the type XI. This clearly differs from IX only in the fact that in XI th CARBETHOXYL UROUP FROM TAIJTOMERIO SYSTEMS. PART I. 147 cyanoacetic residue is attached t o the central carbon atom of the indene system. Now if the double bond in XI is entirely static as regards possible interchange across the system (l) (2) (3) then the carbon atam (4) will be the terminal carbon atom of one three-carbon system only namely the system (3) (2) (4).It should therefore differ but little in reactivity from the carbon atom (4) in the corresponding ester of type IX. If on the other hand the system (l) (2) (3) of XI possesses a mobile hydrogen atom and a mobile double bond it is clear tlhat a hydrogen atom attached to the carbon atom (4) will have a double possibility of '' wandering "; it might wander either to (1) or to (3). We might, therefore in view of the general rule expect to find an ester of the type XI even more prone than the corresponding ester of the type IX to exchange its carbethoxyl group for an atom of hydrogen. Experiment shows the lat'ter supposition to be amply justified.The ester prepared was that for which R=Me. With one-twentieth molecular proportion of sodium ethoxide there was obtained after three minutes atl 1 5 O a practically quantitative yield of the corresponding nitrile (XI1 R =Me). This connexion between the ease of elimination of the carb-ethoxyl group and the potential mobility of the hydrogen attached to the carbon of the cyanoacetic residue suggests a possible ex-planation of the broad facts both in the indene and glutaconic series in regard to the effect of the size of an alkyl group on the ease of the reaction. It seems likely t o be connected with the fact that when heavier alkyl groups were introduced into the gluhconio molecule they were found to increase the stability of the un-saturated form and consequently to reduce the predominance of the normal and the potential mobility of the tautomeric hydrogen atom (since tautmerism depends 0x1 the possibility of the exist-ence of the normal form).An ester in which the degree of tauto-merism of the three-carbon system has been so reduced by the entrance of a large alky1 group would in view of the generalisa-tion be expected to exhibit a smaller tendency t o acquire an a b m of hydrogen and this is what is actually found to be the case. I n complete accord with the great ease with which the ester XI exchanges its carbethoxyl group for an atom of hydrogen and with the presumed excessive mobility of the latter is the behaviour o€ the unmethylated ester XIV. The esters IX and XI wer 148 IRGOLD AND THORPE ELIMINATION OF THI obtained by alkylating the esters XI11 and XIV r e a p t i d y .These esters differ in acidity in the sense that as one would expect from the different reactivities of t,heir alkyl derivatives the cyano-acetic hydrogen shm of indenyl-2-cyanmetic eater (XIV) is more loosely attached than that of the corresponding indenyl-3-deriv-ative (XIII). Thus ethyl indenyl-2-cyanoacetate is a weak acid I A C H I 2>C*CH(CN)*C0,Et @Y(@CH 6H( CN)*CO,Et \PH (XIII.) (XIV.) forming a sodium salt which is not hydrolysed in aqueous solution, being decomposed only by slightly acid substances such as carbonic acid. Ethyl indenyl-3-cyanoacetate on the other hand only forms a sodium salt in complete absence of water. Jt is perhaps worOh noticing that when either of the indenyl-cyanoacetic esters (XIII and XIV) are converted into or liberated f ram their salts a deep crimson colour is immediately developed.This fades in the course of a few seconds both the free esters and the solid salts being colourless. Another colour change which was regularly observed in the course of these experiments took place when the alkylated esters (IX and XI) were treated with sodium ethoxide. An indigo-blue colour immediately developed and gradually faded as the elimina-tion of the carbethoxyl group proceeded. The preparation of the indenylcyanoacetio esters (XIII and XLV) was readily accomplished by condensing a-hydrindone or 8-hydrindone with ethyl cyanoacetate in the presence af piperidine or diethylamine : +CH,(CN)*CO,Et + \ ’kB”>CA +H,O bH(CN)*CO,Et \/--c When ethyl indenyl-3-cyanoacetate was hydrolysed either by acid or by alkali the cyano-acid (XV) was formed although not without considerable decomposition.This acid on heating above its melting point gave off carbon dioxide and from the dark UARBETHOXYL GROUP FROM TAUTOMERIO SYSTEMS. P U T I. colourad residue indenyl-3-acetonitrile (XVI) wa.s isolahd by 1 ''Cb>~R !-c \/ ()"Hp>m CH,-CN \/-c ~IH(CN).CO,H (XVJ (XVZ.) vacuum distillation. This is the first member of the. series of homologous nitriles of which X is the type. It cannot of course, be prepared directly from the cyano-ester (XIII) by the action of sodium ethoxide for reasons already indicated. Neither the compound XVI nor any of its homologues appears to form a sodim compound when treated with alcoholic sodium ethoxide and all attemph to introduce another alkyl group into these compounds using sodium or potassium ethoxide and an alkyl iodide met with failure.The same was the a s e when the methylatd nitrile XII derived from j3-hydrindone was used. E X P E R I M E N T A L . The a-hydrindone required for these experiments was prepared f m j3-phenylpropionic acid by a met4hod essentially the same as that described by Kipping (T. 1894 65 680) but with the intro-duction of certain modifications which so improved the yield as ta make this substance far more easily available than it has hitherto been. &PhentyZpr@onyE Chloride .-It was found advantageous to use thionyl chloride in the preparation of this substance instead of phosphorus pentachloride.8-Phenylpropionic acid (100 grams) was mixed with an equal weight of thionyl chloride in a flask fitted with an efficient condenser. The reaction was started by gentle heat and allowed to proceed for one and a-half to two hours when the evolution of gas had ceased. The contents of the flask were then transferred t o a Claisen distillation flask and heated a t looo/ 25 mm. until all the thionyl chloride had distilled over. The resi-due was then fractionated under 22.5 mm. pressare and 110 grams boiling a t 121-122O were collected. The theoretical yield is 112 grams. a-Hy&ndone .-Pure 8-phenylpropionyl chloride being thus available it was found possible to carry out the internal con-densation whereby hydrogen chloride is eliminated and cthydr-indone produced with much better results than Ripping was able to obtain with the impure chloride at his disposal Whilst he seldom obtained more than a 56 per yield it was found that with the pure chloride a yield of 75 per cent..was always secured. Th 150 INUOLD AND THOBPE ELIMINATION OF THE reaction with the pure chloride is far more violent than wihh the impure product and hence the mixture must be heated for a few minutes only With this exception the details given by Hipping were closely followed. &Hydrindme.-The 8-hydrindone required for these experi-ments was prepared by the improved modification (P. 1911 27, 108) of the original process described by Moore and Thorpe (T., 1908 93 165).Condensatiom of a-Hydrindone with Ethyl Cynnoacetate in the Presence of Secondary Rases Ethyl Indenyl-3-cyanoacetate (XIII p. 148). Since a-hydrindone readily dissolves in ethyl cyanoacetate i t is not necessary t o use any solvent in this condensation. A solution of 19 grams of the ketone in 16 grams of the ester was treated with 6.5 grams of diethylamine and the mixture allowed to remain a t 40° for twenty-four hours. A t the end of that t h e the tube, which contained a stiff paste of crystals of the condensation pro-duct was cooled for an hour a t Oo and the crystals were drained on porous porcelain. The compound separates from alcohol in colourless needle-shaped crystals melting a t 104O ; it is moderately soluble in dry ?ther and readily so in benzene chloroform or acetone.The yield represents about 55 per cent. of the theoretical, and is but little affected when piperidine is used in place of diethylamine : 0.1031 gave 0.2805 CO and 0.0538 H,O. 0.2492 , 13.8 C.C. N2 a t 19O and 742.6 mm. N=6*19. C,,H1,O,N requires C = 74.0 ; H = 5.7 ; N = 6.2 per cent. The ester reacts with alcoholic sodium ethoxide forming a sodium compound from which the ester is regenerated by the action of water. There is no doubt but that this sodium com-pound contains the metal attached to the cyanoacetic residue and that therefore the ester described above has the constitution assigned to it,. When alcoholic sodium ethoxide was added to the ester a deep crimson colour was invariably formed. This faded after a few seconds to a bright yellow which persisted so long as the solution remained alkaline.C=74.20; H=5.80. Condensation of a-Hyd&done with Ethyl Cyanoacetate in the Presence of A ZcohoJic Sodium Ethoxide. The condensation with sodium ethoxide appears to be of a con-siderably more complex character than when secondary bases are used. Thus when an alcoholic solution of a-hydrindone is adde UARBETHOXYL GROUP FROM TAUTOMERIC SYS!t'EMS. P U T I. 151 to a hot suspension in alcohol of the s o d i m compound of ethyl cyanoacetate there is formed a mixture of substances which may be precipitated by adding water. This mixtnre consists chiefly of two compounds melting a t 143O and 88-89O respectively which may be separated and obtained in a s t a h of purity by fractional crystallisation first from alcohol and finally from a mixture of absolute alcohol and benzene.The former compound was identi-fied with anhydrobis-a-hydrindone (Found C = 87-74 ; H = 5.70. Calc. G=87*8; H=5-7 per cent.) which is recorded as melting a t 142-143* (Kipping T. 1894 65 495). Ethyl 2 3f-Di-indenyl-3-cyanoacetate, /-\ '\ / I /"CH 1 2>C*C/-j \/-c ~ H - C H , bH(CN)*CO Et The substance melt5ng a t 88-89O may be made to become the principal product if the order in which the condensing substances are mixed is reversed 3.3 Grams of a-hydrindone were dissolved in a small quantity of hot. alcohol and a hot solution of 0.6 gram of sodium and 2.8 grams of ethyl cyanoacetate in 15 grams of alcohol was slowly added. A few minutes after the addition was complete the solution was rapidly cooled and poured into water.Hydrochloric acid was then added and the oily precipitate ex-tracted with ether the extract washed with dilute sodium carbonate solution and with water and then dried. The solid residue obtained on evaporation of the ether when recrystallised from alcohol weighed 0.8 gram: C=80*78; H=5*68. 0.1545 gave 0.4575 CO and 0-0790 H,O. 0.1818 , 6.7 C.C. N2 a t 17O and 766.1 mm. N=4*23. Ethyl 2 3fdiindenyl-3-cyanoacetate separates from the usual solvents in pinkish-buff needles melting a t 88-89O. It is oxidised instantly by cold alkaline pemanganate. With alcoholic sodium cthoxide it forms a yellow sodium compound from which the original ester can be regenerated. C,H,,O,N requires C= 80.9 ; H = 5.6 ; N = 4.1 per cent.liydrolysis of Ethyl ZnuEenyl-3-cyanmcetate Znc2enyl-3-cyanoacetic Acid (XV p. 149). The hydrolysis of the ester melting a t 104O is a matter of some difficulty owing to the ease with which it undergoes deep-seate 152 1;BQOLD AND TAOECPE ELIMINATION OF THE decomposition with acids and alkalis. Thas on boiling with acids (dilute hydrochloric or sulpburic) only a 6 per cent. yield of the acid is obtained. The acid can be produced in 36 per cent. yield by alkaline hydrolysis but only by working within very narrow limits. Four grams of the eshr were treated with 8 C.C. of 4N-sodium hydroxide and the mixture was heated as rapidly as possible to the boiling point and maintained there for twenty seconds with vigorous shaking. The oil dissolved forming a clear red solution which was kept boiling for thirty seconds longer and then rapidly cooled.The crystalline sodium salt which separated was collected dissolved in water and the solution after passing hhrough a wet filter acidified with hydrochloric acid. The acid separated as a white precipitate which crystlallised from alcohoI in small prisms melting and decomposing a t about ZOOo the melt-ing point depending on the rate of heating. The point of instant-aneous decamposition as measured by the Maquenne block is 2 3 7 O . The acid is sparingly soluble in water or dry ether : 0*1251 gave 0.3326 CO and 0.0509 H,O. 0.2164 , 13.8 C.C. N a t 19O and 755 mm. N=7.24. C=72*51; H=4-52. Cl,H90,N requires C = 72.4 ; H = 4.5 ; N = 7.1 per cent. Indeny I- 3 -ace t onit r il e (XV I p .1 49). The pure recrystallised acid (4.4 grams) was heated a t 250° until the evolution of carbon dioxide had ceased. The dark-caloured oil which remained was then distilled under diminished pressure and the colourless distillate cooled in ice. The solid residue which melted below the ordinary temperature was recrystallised from light petro,leum below Oo and obtained in long colourless needles melting ate 18O : 0.0820 gave 0.2568 CO and 0.0426 H,O. 0.1430 , 11.3 C.C. N a t 19 and 761.2 mm. N=9.06. CI1H,N require6 C=852; H=5*8; N=9.0 per cent. The attempts which were made t'a alkylate this nitrile did not meet with any success and we were quite unable to find the con-ditions by which the nitrile could be hydrolysed to the correspond-ing acid.C=85*41; H =5*77. ,4 lkyhtion. of Ethyl IndenyyL3-cyanoacetate and the Elimination of the Cwbethozvl Group Ethd a-lndemyl-3-a-cyanlo-I n order to prepare this subskance 12 grams of the ester melt CARBETHOXYL QROW FROM TAUTOMERIC! SYSTEHS. PART I. 153 ing a t 104O were dissolved in the least possible quantity of alcohol a t 70° and added to a solutiun of 1.2 grams of sodium in 16 grams of alcohol. Ten grams of methyl iodide were then added and the mixture was heated until the yellow colour had entirely dis-appeared and the solution had b e m e neutral an operation which usually required ten minutes. The addition of w&r precipibted an oil which when extracted by ether yielded a solid residue after the solvent had been evaporated.The compound crystallises from a mixt'ure of light petroleum and ether in large cubes melting at 60°; it is readily soluble in the usual organic solvents excepting light petroleum. The yield was 70 per cent. of the theoretical: 0.1418 gave 01.3900 CO and 0.0816 H,O. 0.2818 , 14.4 C.C. N a t 19O and 783 mm. N=5-92. C=74.96; H=6.39. @15H&N requires C = 74.7 ; H = 6.2 ; N= 5.8 per cent. Six grams of the carboxylic ester were dissolved in cold alcohol and an alcoholic solution containing 0.1 gram of sodium was added. The solution was kept at' 30° for a short time when the blue colour which had developed was discharged and the liquid had a strong odour of ethyl carbonate. The liquid was poured through a filter, water was added and the precipitate which was formed was induced to solidify by shaking.It' was then collected dried and extracted with hot light petroleurn the nitrile being deposited from the solvent on cooling in long colourless needles melting a t 118O. It may also be recrystallised from dilute alcohol. The yield is 60 per cent. of the theoretical : 0-1032 gave 0.3227 CO and 0.0603 H,O. C=85*28; H=6*49. 0.2118 , 15-4 C.C. N a t 2 3 O and 771 mm. N=8-30. The nitrile could not be hydrolysed and all attempts to i n t r e (&HI1N requires C =85*2 ; H= 6.5 ; N = 8.3 per cent. dnce another alkyl group into it were without success. Ethyl a-ZndengL3-a- cymo-n- b utyrat e , >C* C Et (CN )* C0,Et. PH,*CH C,H,-This ester was prepared in the same way as the methyl derivative It is a colourless oil which boils a t ZOOo/ already described.25 mm.: 0.1304 gave 0.3604 CO and 0.0785 H,O. 0.2363 , 11.6 C.C. N a t 2 2 O and 768 mm. N=5*62. C=75*38; H=6.69. C,,R,,O,N requires C=75-3; H=6*7; N = 5 3 per cent 154 MGOLD AND THORPE ELIIKISATZOX OF THE a-Zndemy l-3-n- b ut yronitril e ?H2'cH>C*CH Et*CN. c,*,-This nitrile was produced from the carboxylic ester by the action of a small quantity of alcoholic sodium et,hoxide under the same conditions as those which were described for the methyl derivative. The crude solid precipitated by water was extracted with hot alcohol and the nitrile obtained from the alcoholic extract by the addition of water. It crystallises from light petroleum in long needles melting a t 76O. The yield is 20 per cent. of the theoretical : 0.1306 gave 0.4067 CO and 0.0835 H,O.0.1882 ,) 12.6 C.C. N2 at 23O and 771 m. N=7*64. CI3Hl3N requires C=85*2; H=7*1; N=7.7 per cent. C=84*93; H=7.11. Ethyl a-lndenyl-3-accyan~o-n-ua~e~atc, ~H2BCH>C*CPru(CN)*C0,Et. C,H,-This ester was produced by the acttion of n-prop91 iodide on the sodium compound of ethyl indenyl-3-cyanoacetate in alcoholic solution. The reaction was complete after heating for forty-five minutes and the product was then isolated in the usual way. The ester is an oil which boils a t 21Oa/2O mm. : 0.1259 gave 0.3502 CO and 0.0797 H,O. 0.2169 , 10.0 C.C. N a t 2 2 O and 768 mm. N=5-26. C=75*86; H=7*03. C,,H,,O,N requires C = 75.8 ; H = 7.1 ; N = 5.2 per cent. This compound was prepared in the same manner as the ethyl derivative although in the present instance the reaction proceeded much less readily.It was isolated in the usual way and crystal-lised from light petroleum in cdourless needles melting a t 67O. The yield was only 10 per cent. of the theoretical: 0.1028 gave 0.3210 CO and 0*0710 H,O. 0.2018 ,? 12.8 C.C. N a t 23O and 768 mm. N=7.20. C=85.16; H=7-68. C,,H,,N requires C=85*3; H=7*6; N=7*1 per cent. Ethyl a-Zndenyl-3-a-cyanoisovalera t e , > C CPr@( CN) CO Et . vH2*CH C6E4--isoPrapyl iodide was found to react with the sodium compoun CARBETHOXYL GROUP PROM TAUTOMERIC SYSTEMS. PART I. 155 of ethyl indenyl-3-cyanoacetate in the same manner as n-propyl iodide and the product was isolated in the 8ame way. In this case the ester was obtained as a colourless oil which boiled a t 260°/ 120 mm.and solidified in the receiver. The solid crystallised from light petroleum in colourless prisms melting a t 72O. The yield represented 60 per cent. of the theoretical : 0.1115 gave 0.3105 CO and 0,0716 H,O. 0.1859 ) 8.6 C.C. N a t 22O and 768 mm. N=5*28. Cl7Hl9O2N requires C = 75.8; H = 7.1 ; N = 5.2 per cent. This ester was scarcely changed by alcoholic sodium ethoxide under the experimental conditions which caused the other esters to lose their carbethoxyl groups as ethyl carbonate. Most of the original ester and a small amount of insoluble matter were C=75-95; H=7*15. recovered. Ethyl a-Zndenyl-3-a-cyanoallylacetat e, >C*C(CH,*CH:CH,)( CN)*CO,Et. C H,*CH b6H4-Ally1 iodide reacted with the sodium compound of ethyl indenyl-3-cyanoacetate in boiling alcoholic solution in the course of a few seconds.The product was isolated in the usual way and crystal-lised from light petroleum containing a little dry ether in nearly cubical crystals melting a t 65O. The yield was 65 per cent. of the theoretical : C=76-63; H=6*41. 0.1240 gave 0~3484 CO and 0.0715 H,O. 0.2954 )) 13.6 C.C. N a t 19O and 764 mm. N=5*31. C17H1702N requires C = 76.4; H = 6.4 ; N = 5.2 per cent, a-Zndeny Z-3-ally lace t mit rile ) yIJ2'CH>C*CH(CN) *CH ,* CH,:CH,. C@4-The action of a trace of alcoholic sodium ethoxide on the ester caused the carbet'hoxyl group to be eliminated and gave a yield of 40 per cent of the corresponding nitrile the same conditions being employed as those described in the former experiments.The nitrile crystallises from light petroleum in colourless needlm melt-ing a t 108O: @=86.28; H=6.75. 0.1064 gave 0.3366 CO and 0.0647 H,O. 0.2732 ,) 17.6 C.C. N2 a t 23O and 768 am. N=7*31. C,,H,@ requires C=86*2; H=6*7; N=7.1 per cent 156 INGOLD AND TBORPE ELIMINATION OP THE This ester was prepared in the usual manner from imbutyl iodide It distilled a t 260°/40 mm. as C=76.43; H=7-33. and ethyl indenyl-3-cyaaoacetate. a pale yellow oil : 0.1956 gave 0.5481 CO and 0.1290 H,O. 0-2600 , 11-6 C.C. N a t 22O and 761 mm. N=5.07. Like the isopropyl derivative this ester did not lose its carb-ethoxyl group by treatment with cold sodium ethoxide. After being submitted t o the same experimental conditions as the other esters the recovered material gave on analysis C = 76.89 H = 7.56, N = 5.13 indicating that it was practically unchanged.(The de-carbethoxylated compound Cl,H17N requires C = 85.3 ; H = 8.1 ; N=6.6 per cent.) Cl,H,102N requires C = 76.3 ; H = 7.4 ; N = 4.9 per cent. Ethyl a - l d e n yl-3-a-cyanoiso hept oat e, When prepared from the ester melting at 104O and isoamyl iodide and isolated in the usual way this ester distilled a t 270"/ 34 nun. as an almost colourlees oil: 0.1680 gave 0.4749 CO and 0.1173 H,O. 0.2127 , 9.0 C.C. N at 22O and 766 mm. N=4.80. The carbethoxyl group could not be eliminated under the customary experimental conditions. The material recovered from the solution of sodium ethoxide gave on analysis C=77.31, H=7*92 N=4*95 indicating that it consisted of the unchanged compound (ClsHlsN the carbethoxyl-free compound requires C=85*3 H=8.5 N = 6 - 2 per cent.).C=77-08; H=7-76. C19H2302N requires C = 76.8 ; H = 7.7 ; N =4.7 per cent. Condensatiom of #3-€€y&h&me with Ethyl Cyanoacetate in the Presence of Secondary Bases. When a mixtiure of B-hydrindone and ethyl cyanaacetah is treated with a secondary base such as piperidine or diethylamine, there is generally formed a mixture of two crystalline compounds melting at 116O and 176O respect.ively. The latter contained no nitzogen and gave on analysis C = 87.62 H = 5.81 (CIBHl,O requires C=87-8; H=5.7 per cent.). It is therefore probabl CARBETHOXYL QROUP FROM TAUTOMERIO SYSTEMS. PART I. 157 identical with anhydrobis-P-hydrindone the melting point of which is given as approximately 170° (Heusler and Schieffer Ber.1899, 32 32). The amount of bis-compound formed varies very much with the conditions and unless the condensation is kept well under control it may become the sole product. Ethyl Zr.demyl-2-cyanoacetate (XIV p. 148). By exercising care it was found possible to obtain a solid pro-duct containing as much as 65 per cent. of ethyl indenyl-2-cyano-acetate and 35 per cent. of anhydrobis-B-hydrindone. Ten grams of P-hydrindone were dissolved in 9 grams of ethyl cyanoacetate, and the solution was cooled below 1 8 O while 30 drops of diethyl-amine were added. After the addition of each drop the solution was immediately shaken and well cooled in running water. After completing the addition of the base the tube containing the mix-ture was immersed in cold water for thirty minutes when it was withdrawn and allowed t o remain a t the ordinary temperature for forty-eight hours.At the end of that time the stiff paste of crystals which filled the tube was spread on porous porcelain and allowed to remain until colourless. The crude solid mixture of condensation product.s which usually weighed about 13 grams was rubbed to a fine powder under a little dry ether and roughly separated by extracting with four times its weight of boiling 95 per cent. alcohol the bulk of tche bis-compmnd being left un-dissolved. The crude ester deposited by the filtrate melted between 90° and l l O o . It was finely powdered and stirred into an excess of 4N-sodium hydroxide a t 30° the whole diluted with an equal bulk of water quickly filtered and t'reated with aqueous sodium hydrogen carbonate in excess.The precipitated ester was caused t o solidify by shaking and then collected and triturated with water. After draining and rwrystallising from alcohol it was obtained in long colourless needles melting a t 116O: 0.1261 gave 0.3417 CO and 0.0646 H,O. 0'1834 , 9.7 C.C. N a t 169 and 772-5 mm. N=6.25. The compound is very readily soluble in hot alcohol but apar-ingly so in cold. It is also very readily soluble in cold benzene, chloroform or acetone and sparingly so in ether or light petroleum. It tends to form coloured products when its alkaline solution is exposed t o the air and the yield obtained by the sodium hydroxide separation t'heref ore depends greatly on the speed with which the operations are Carrie out.The separation was also effected by means of a long series of frac-VOL. CXVI. C=73*91; H=5-70. C,,H,,O,N requires C = 74.0 ; H = 5.7 ; N = 6.2 per cent 158 ELIMINATION OF THE CARBETHOXYL GROUP ETC. PART I. tional crystallisations from alcohol. The ester obtained by both methods proved to be the same .substance showing that the form-ation of a sodium salt had not involved any isomeric change and that the compound must therefore have the structure assigned to it. The ester is readily soluble in 4iT-sodium hydroxide and is not reprecipitated when a large bulk of water is 'added. It is insoluble, however in sodium carbonate and is therefore precipitated from the hydroxide solution by carbon dioxide or a bicarbonate.During the precipitation by either of these reagents or by an acid a transient red colour always appeared. A similar transient colour was invariably observed when an alcoholic solution of the ester was treated with aqueous or alcoholic potassium hydroxide or alcoholic sodium ethoxide. Sodium Bem'vative.-One gram of the ester was dissolved in twice the theoretical quantity of 4J-sodium hydroxide a t 50°. On cooling a colourless crystalline sodium derivative separated out. The alkaline liquid was poured off from the crystals which were then washed with ice-water and dried in a vacuum over phosphoric oxide : 0.3002 gave 0.0860 Na,SO,. C,,H,O,NNa requires Na = 9-24 per cent. When kept in a closed space the sodium compound slowly decom-poses acquiring a green colour but if spread in a thin layer over a large area in a dry atmosphere it can be kept for several weeks.Although the compound itself is colourless its solution in water is orange. This solutioa on acidification becomes deep red for a few moments the colour quickly fading as the free est'er separates out. Na = 9-28. Met h y lntion of E't h y 1 Indenyl- 2-c yanoac e t at e and the Elimination of the Carbethoxyl Group Ethyl a-lndenyl-2-a-cyamo-propio na t e C H,<(g> C CM e ( CN ) C 0 I! t . The methylation of ethyl indenyl-2-cyanoacetate was accom-plished both by the action of methyl iodide on the dry sodium campound suspended in alcohol and by the more usual process of treating the free ester with alcoholic sodium ethoxide and methyl iodide.The est'er was precipitated with water and extracted with ether. After washing the extractl with water and drying the ether was evaporated and the residual oil crystallised from light petroleum containing a t'race of ether. The ester separated in dense colourless prisms melting a t 5 6 O . The yield was about 70 per cent.. of the theoretical PREPARATJON OF MONOMETHYLAMINE FROM CHLOROPICRIN. 169 0.1035 gave 0.2837 CO and 0.0580 H,O. 0.1653 , 8.4 C.C. N a t 1 8 O and 779 mm. N=5.90. C=74-23; H=6.22. C,,H,,O,N requires C= 74.7 ; H = 6.2 ; N = 5-8 per cent. The elimination of the carbetholxyl group of ethyl indenyl-2-cyanopropionate was found to proceed with great ease in the presence of a small quantity of sodium ethoxide. Thus with one-twentieth of a molecular proportion of sodium at; 1 5 O the reaction was complete in about three minutes. On adding water the nitrile separated out. After allowing the suspension to remain for twenty-four hours it was filtered and the solid dried and recrystal-lised from light petroleum from which it separated in long colour-less needles melting a t 92O: 0.1011 gave 0.3167 CO and 0.0591 H,O. 0.1179 , 8.5 C.C. N a t 20° and 764 mm. N=8*22. The yield was practically quantitative. All attempts t o hydrolyse this nitrile resulted in deep-seated decompositions taking place and we were unable to isolate the corresponding acid. Several attempts also were made to introduce anot?her methyl group into the molecule but without success. C=85*43; H=6-49. CI2H,,N requires C=85*2; H=6*5; N=8.3 per cent. IMPERIAL COLLEGE OF SCIENCE AND TECHNOLOGY, SOUTH RENSINGTON [Received December 6th 191 8.

ISSN:0368-1645    

DOI:10.1039/CT9191500143

出版商:RSC    

年代:1919

数据来源: RSC

摘要:

PREPARATJON OF MONOMETHYLAMINE FROM CHLOROPICRIN. 189 X VI I.- The Prsepara t i o n 9 f Mon omet hyylarnine from 01 I o S Y ~ > ici *in. By PERCX FARADAY FRANKLAND FREDERICK CHALLENGER and NOEL ALBERT NICHOLLS. THE products of the reduction of chloropicrin seem to vary with the nature of the reducing agent. With stannous chloride and hydrochloric acid cyanogen chloride is produced (Raschig Ber., 1885 18 3326). The occasional formation of traces of ammonia was noticed by this chemist but as a rule after removing the tin by means of hydrogen sulphide the product was found to he free from ammonium chloride and the hydrochlorides of hydroxylamine and methylamine. Iron filings and acetic acid (Geisse Annaren, 1859 109 282) or tin and hydrochloric acid (Wallach ibid.1877, 184 51) give rise t o monomethylamine, CCl,*NO + 12H = CH,*NH + 3HCl-t 2H20 160 ZRANKLAND CHALLENGER AND NICHOLLS PREPARATION Since chloropicrin may easily be obtained in large quantities it appeared desirable more closely to investigate its reduction owing to the importance of monomet,hylamine in synthetic organic chemistry. It would be inferred from Geisse’s paper that the base he obtained was free from ammonia whiM Wallach states that his product was comparatively very pure and the yield good. By employing fine iron filings and hydrochloric acid we have found that the composition of the reduction product depends on the conditions of the experiment. The use of iron and hydro-chloric acid in the theoretical quantities (six atomic proportions of iron and nine molecular proportions of acid to one of chloropicrin) in such a way as t o prevent the formation of ferrous or ferric hydroxides gave a product rich in ammonium chloride.If chloro-picrin is shaken with iron filings and water the mixture becomes extremely hot and a vigorous reaction sets in which however, gradually slackens if no acid is added. By adopting the method employed in the reduction of aromatic nitro-compounds or of nitromethane and nitroethane (Krause Chern. Z e i t . 1916 40, SlO) the reaction proceeds satisfactorily in the presence of only about one-fortieth of the theoretical amount of hydrochloric acid, and a practically theoretical yield of methylamine hydrochloride is obtained. This usually contains about 4 per cent. of ammonium chloride but in some of our experiments the quantity of this impurity has been still further reduced.The best results have been obtained by slowly adding the chloropicrin to a well-stirred mixture of iron filings and acidified water. The gradual addition of iron filings t o a mixture of acidified water and chloropicrin did not seem to be very satisfactory so far as could be seen from the few experiments made in this direction. Some reductions carried out by gradually adding chloropicrin to boiling alkaline ferrous hydroxide failed t o confirm the results of Geisse (Zoc. c i t . ) who states that by this method no ammonia is produced. We obtained a product containing about 20 per cent. of ammonium chloride. The details of a typical large-scale experiment may be briefly outlined.Five hundred grams of fine iron filings were gradually shaken into a large earthenware jar containing 2500 C.C. of water and 60 C.C. of concentrated hydrochloric acid. I n this way the filings were thoroughly moistened and the tendency to clogging was diminished. The jar was fitted with a stirrer and placed in a little cold water; 250 grams of chloropicrin were then gradually added in the course of one-and-a-quarter hours. Too rapid addi-tion of the chloropicrin caused the mixture to froth over. Owing to the large amount of hydrated oxide of iron produced the stirring was as efficient as possible otherwise chloropicrin escaped. reaction through being enclosed in masses of iron filings or oxide OF MONOMETHYT~AMNE FROM CHLOROPICRIYS. 161 The temperature rose considerably and was maintained a t about 50° when the odour of chloropicrin Was found to have disappeared after about three hours.The mixture was then ,gradually added to a boiling solution of sodium hydroxide contained in a large iron can into which steam was blown. The methylamina was absorbed in hydrochloric acid the solution evaporated and the residue dried a t l l O o until constant weight was attained. The crude dry hydrochloride was obtained in this way in a yield of 95.5 per cent., and contained 53.1 per cent. of chlorine corresponding with an ammonium chloride content of only 3.5 per cent. That ammonium chloride is actually produced during the reduc-tion of chloropicrin was shown by treating cold concentrated aqueous solutions of the crude hydrochlorides with gaseous hydrogen chloride.The precipitated solid was collect,ed carefully freed from adhering hydrochloric acid and analysed when it was found to be almost pure ammonium chloride. The analyses of the crude methylamine hydrochloride were checked in some instances by an estimation of the platinum in the platinichloride. The hydrochlorides were evaporated with an excess of chloroplatinic acid solution and the dry residue was extracted with absolute alcohol whereby only platinum tetrachloride is removed. The possibility of a partial separation of the platinichlorides of the two bases would thus appear t o be excluded. Szcmmary of R eszclts. Section A .-In the following experiments the quantity of acid was very small and the amount of iron theoretically required for the liberation of 12 atomic proportions of hydrogen (supposing sufficient acid had been present) was employed.The temperature was usually allowed to rise to about 50-70°. Experiment. 1. 2. 3. 4. 5. 6. Chloropicrin grams 500 250 260 25 25 26 Iron grams 1000 500 500 50 50 50 Water C.C. ............ 3500 2500 2600 200 200 200 Hydrochloric acid C.C. 100 60 60 12 32 10 Crude hydrochloride, Theoretical weight, c1 in crude hydro-Hence percentage Pt in crude platini-Hence percentage ............ grams ............... 190 98 94 9.5 10.0 9.6 grams ............... 205 102.5 102.5 10.2 10.2 10.2 chloride ............... 53.3 53.1 53.6 52.9 52.8 63.1 m*c1 ............... 5.0 3.5 7.0 2.0 1.5 3-5 chloride ...............41.53 41.43 - - - 41.33 ............... __ 1.10 NH,Cl 6.5 2.75 - -(CH;NH,),PtCI requires Pt = 41.36 per cent, NH,Cl requires C1= 66.5. (NH,),PtCl requires Pt =43*96. CH;NH,CI requires C1= 62.6 162 PREPARATION OF MONOMETHYLAMINE FROM CHLOROPICRIN. Section B.-In the experiments described in this section the quantity of acid employed was much larger (up to 9 molecular proportions not including the three f omed during the reduction), and the iron as in A . The chloropicrin and the acid were both added gradually t o the iron filings. The percentage of ammonium chloride is seen to have increased considerably. Experiment. Chloropicrin grams.. ......................... Iron grams .................................... Water C.C. ....................................Hydrochloric acid C.C. ..................... Yield of dry hydrochloride grams Theoretical weight grams ............... CI in crude hydrochloride .................. ...... Hence percentage NH,Cl .................. 1. 25 50 100 2.00 9 10.2 58.0 40.0 2. 25 50 50 150 6.5 10.2 60.9 60.0 3. 50 100 100 300 15.0 20.5 60.5 60.0 S e c t i m C.-In these experiments the chloropicrin was gradu-A con-Experiment I.-Chloropicria 25 grams ; ferrous sulphate 550 Dry hydrochloride 7 grams. Analysis in sa.mples of about 0.2 and 0.1 gram C1=56*0 55.2. Expem’memt 11.-Quantities as in above. Dry hydrochloride 9 grams. Analyses in samples of about 0-5 gram C1=54*8 54.8 54-6. ally added to a boiling alkaline ferrous sulphate solution. siderable amount of ammonia was formed. grams,; sodium hydroxide 300 grams; water 1800 C.C. Theory 10.2. Mean = 55.6 whence NH,Cl= 22 per cent. Mean = 54.7 whence NH,Cl= 15 per cent. Interaction of Methylamine und 1 2 4-Trinitrobenzene, With 1 2 4-trinitrobenzene the alcoholic solution of the base gave an almost immediate deposit consisting of yellow needles melt-ing a t 175-176O and a t 176O after one crystallisation. The formation of 2 4-dinitromethylaniline (m. p. 176-177O) by this method does not seem t,o have been described. THE \UNIVERSITY, BIRMINGHAM. [Received January ZOtlb 1919.

ISSN:0368-1645    

DOI:10.1039/CT9191500159

出版商:RSC    

年代:1919

数据来源: RSC

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THE ALKALOIDS OF ROLARRRENA CONGOLENSIS STAPF. 163 XV 111.- The Alkaloids of Holarrhena congolensis, Stapf By FRANK L’EE PYMAN. FRBRE JUST. GILLET S.J. a missionary in the Belgian Congo, reported some years ago that on chewing the leaves of Hdacrrhem congolensis Stapf a local anaesthetic effect was produced on the mucous membrane of the mouth. This led the author t o examine the alkaloids of the plant in 1913 when a new base termed holarrhenifie @2AH380N2 was isolated together with the alkaloid conessine which has been obtained previously by several authors from other species of Holarrhena. The physiological action of conessine and holarrhenine was studied by J. H. Burn ( J . Yharmacol, 1915 6 305) who found that whilst they had a local anEsthetic action this property was of no practical value since they produced local necrosis when injected subcutaneously.Since it is improbable that the author will continue this investi-gation it is desired to put on record the properties of holarrhenine and also the results of a few experiments on conessine carried out a t that time. These are for the most part in agreement with the recent work of Giemsa and Halberkann (Arch. Pharm,. 1918 256, 201)) and confirm the formula C,4H40N supported by these authors, not that--CBH3,N2-put forward by Ulrici (Arch. Pluwm. 1918, 256 57). Giemsa and Halberkann’s view that conessine contains two dialkylamino-groups is not shared by the present author who found conessine to contain only three alkyl groups (no doubt methyl groups) attached to the nitrogen atom.Moreover Polstmff and Schirmer (Ber. 1856 19 84) showed that conessine dimetho-hydroxide yields on heating a crystalline base together with ‘‘ ammonia ” (doubtless trimethylamine). It is therefore probable that conessine contains an iV-methyl group forming a link in a heterocyclic ring to which a side-chain bearing a dimethylamino-group is attached. Holarrhenine resembles conessine in containing three N-alkyl groups. It yields a momoacetyl derivative, C%H4,,O2N9 which is diacidic whence it follows that holarrhenine contains a hydroxyl group. EXPERIMENTAL. Isolation of the Alkaloids. Twenty-nine kilograms of the bark of the trunk of Holarrhena congdensis Stapf were percolated with very dilute hydrochlori 164 P Y U N ALfiEBxIoIDS OF HOLARREENA OONWLF;NSIS STBPF.acid. The liquor was made alkaline With ammonia and extracted with chloroform. After distillation of the solvent the dark, viscous residue was extracted first with light petroleum and then with ether. The light petroleum extract was shaken with dilute hydrochloric acid the base regenerated with sodium carbonate and extracted wit'h light petroleum. The extract was distilled and the residue dissolved in a solution of 0.7 part of hydrated oxalic acid in 4 parts (by weight) of alcohol. On keeping a cdourless crystal-line hydrogen oxalate (m. p. 249O) separated in a yield amounting to 0.9 per cent. of the bark. The oxalate was dissolved in water, the base regenerated by sodium carbonate and extracted with light petroleum. After distilling the extract the residue was dis-solved in a little acetone and kept when conessine separated in colourless plates amounting t o 0.25 per cent.of t h e bark. A further quantity was obtained by working up the mother liquor. The ethereal extract of the total alkaloids was extracted with dilute hydrochlorio acid and this was basified with ammonia and extracted first with light petroleum and then with ether. The light petroleurn extract was worked up as before for conessine. The ethereal extract was concentrated and left for some time when a small quantity of holarrhenine crystallised out. Conessiw . The base employed in this investigation was purified by crystal-lisation from acetone which is particularly suitable for the purpose, as Giemsa and Halberkann have remarked.The base is only sparingly soluble in cold acetone but dissolves in boiling acetone to the extent of approximately 10 per cent. On cooling it separates in large colourless plates which apparently contain acetone of crystallisation for they effloresce quickly in the air, becoming free from solvent. Found C = 81'0 80.7 ; H = 11.3 11'4 ; N = 7.9 ; Me(attached to C,,H,,N requires C = 80.8 ; I3 = 11.3 ; N = 7.9 ; Me(attached to N) = 12.6 per cent. The molecular weight was determined by the cryoscopic method 0.2330 in 29.92 benzene gave A t = -O*10Bo. The base melted a t 125O (con.). N) = 12'5 13.0. in benzene: M.W. =361. 0-4442 , 29.92 , ,) A t = -0.213'. M.W. =349. CZ4Hk0N2 requires M.W. =356*5. The specific rotatory power of the base was determined in chloro-form solution PYMAN ALLOIDS OF HOLARRHIHA CONGOLENSIS.STAPF. 165 The specific rotatory pw0r of a specimen of the hydrobromide (containing 2.4 per cent. of water) was determined in aqueous solution : %+0.56O; c=3*858; 15.2 dcm.; [a],,+7*4O for the anhydrous salt. Conessin4e hydrogtn oxalate forms prisms readily soluble in hat, but rather sparingly so in cold water and sparingly soluble in alcohol. It melts and decomposes at 280' (corr,) and is anhydrous. Found C = 62.5 ; H = 8.1, C24H40Nz,2C,H,04 (536.5) requires C = 62.6 ; H = 8.3 per cent. Hdarrhenine C,,H,ON,. The crude base was first purified by crystallisation from ethyl acetate when it melted a t 190° and then converted into the hydro-bromide. This salt was crystallised from water and washed with acetone.It was then reconverted into the base and this was recrystallised from ethyl acetate when it separated in silky needles which melted at 197-198O (oorr.). It is insoluble in water readily soluble in alcohol or chloroform but sparingly so in cold ethyl acetate acetone or ether. Found C=77*5 77.6 77.3; H=10*2 10.3 10.7; N=7.7; It suffers no loss a t looo. Me(attached to N ) = l l * l 12'2. C,H,ON (37004) requires C = 77.8 ; H = 10.3 ; N =7*6 Me(attached t o N)=12.2 per cent'. The specific rotatory power was determined in chloroform solution : % - 0.75' ; ~ ~ 5 . 2 4 8 ; 1=2 dm.; [~],-7*1O. The kyhobrumide cryshllises from water in flat needles which It is readily soluble in The air-dried salt con-melt at 265-268O (corr.) after drying.hot somewhat sparingly so in cold water. tains 3H20 (Found H20 =9*0. Calc. H20 = 9.2 per cent.). Found in salt dried at looo C=54.4; H=8.2; Br=29*8. C,HB0N,,2HBr (532.3) requires C=54.1; H =7.6; Br=30*0 per cent. The specific rotatory power was determined in aqueous solution: %+1*02O; c=4*630; Z=2 dcm.; [a],+ll*OO or +12-lc for the anhydrous salt. -4 cetylhoZarrhenine prepared by the action of acetic anhydride and anhydrous sodium acetate on holarrhenine crystallises f porn e&ne in large colotirlws oblong plateg which melt a t 180° (con.). VOL. OXVr 166 PYMAN META-SUBSTITUTED It is insoluble in water sparingly soluble in cold alcohol acetone, or ether but readily so in chloroform. Found C=75-7; H=9*9; N=6.8. Equivalent to HC1 using methyl-orange = 202. C28H100$T2 (412.5) requires C =75*7 ; H= 9-8 ; N = 6.8 per cent. [Received Pebruury 4th 1919.1 THIE WELLUOME ~ ~ ~ P M I C A L WORKS. D~TBORD KENT

ISSN:0368-1645    

DOI:10.1039/CT9191500163

出版商:RSC    

年代:1919

数据来源: RSC