摘要:

322 FAIRBROTHER AND MASTIN : L.-8tudies in Electro-endosmosis. Part III. By FRED FAIRBROTHER and HAROLD MASTIN. IN the first paper of this series (J. 1924 125 2319) a method was described for the measurement of electro-endosmosis and a t the same time of the potential gradient across the diaphragm. Th STUDIES IN ELECTRO-ENDOSMOSIS. PART III. 323 method was illustrated by measurements of the effect of acid and alkali on the electro-endosmosis through a diaphragm of carborun-dum powder. An account is now given of the effect of a number of other ions on the same diaphragm. With the exception of a few experiments of Perrin using sodium bromide and lanthanum nitrate in neutral or weak alkaline solution, there appear to be no data respecting the effect of ions other than hydrogen and hydroxyl on the electro-endosmosis through a diaphragm of carborundum powder.A word may be said on the choice of a suitable diaphragm material for making unambiguous electro-endosmotic measurements. This is not particularly easy. It is clearly desirable that there should be no doubt as to whether the surface of the solid phase is attacked chemically by the solute or solvent. I n this connexion it is illumin-ating to study the conductivity of a dilute solution in some powder which en masse may appear quite resistant chemically as for example powdered crystalline alumina. The conductivity of the mixture alters considerably with time increasing or decreasing according to the previous history of the powder. Quartz par-ticularly if finely powdered in some solutions suffers from the same complaint in a lesser degree.Carborundum on the other hand; possesses a surface which is very resistant to chemical action. E X P E R I31 E K T A L. The experimental details of the measurements were as given in Part I . The potassium salts were obtained as pure as possible by recrystallisation ; the aluminium chloride was Kahlbaum’s “ Kauf -liche.” The dilute solutions were made up by the progressive dilution of stronger standard ones. The aluminium chloride and thorium nitrate solutions were made from stock solutions originally of about M 110-strength ; these were standardised after the hydroxide had settled out. The factor of the aluminium chloride was 0.86 and of the thorium nitrate 0.91 both with respect to the kation.It is desirable as McBain ( J . Physical Chem. 1924 28 706) has pointed out to give the full experimental data in view of the assumptions made in calculating 6. I n the present case this mould require a prohibitive amount of space for the figures. On the other hand it would be misleading to give averages of the velocities and potential gradients since t; is not a linear function of these magnitudes. The following plan has therefore been adopted in Table I, V refers to the volume of liquid transported in each experiment, whilst T and E refer respectively to the time and the potential gradient across the diaphragm in a single typical estimation. Fro 324 FAIRBROTHER AND MASTIN : these figures CT has been calculated. Under y&v are given the average values of ( from N different observations.The present estimations, with the exception of those in barium chloride solutions were in general much more uniform and reproducible than those in wate.r or acid or alkaline solutions. (has been calculated in each case on the basis of the calibration of the diaphragm with N/lO-potassium chloride. Electrolyte. KCI 9 9 7 ) 9 9 99 K2s04 97 9 7 9 9 K4'ke( CN) 9 , ,? 9 9 9 , AlG, (F = 0.85) Conc. N/50,000 N 112,500 N/3125 N1781.2 N/195*3 Nl48.8 N/50,000 N 112,500 N/3125 N/781-2 Nl195.3 N /50,000 N I 12,500 N/3125 Nl781.2 N1195.3 N/48-8 N/100,000 N /50,000 N/12,500 N13125 N/781-2 N 1195.3 N148.8 N/800,000 N /400,000 N /200,000 N/100,000 7 9 N/50,000 9 N 112,500 7 9 N/3125 N 1781.2 Nj195.3 Th&O3)4 (F = 0-91) Nl800,OOO Y ' N)400;000 9 N /200,000 9 7 N /100,000 3 N /50,000 ? Y N/12,500 9 ) A713125 ? 9 Nl781.2 ?P Nl195.3 TABLE T.V T E C.C. secs. volts. 0.30 33.7 69.0 0.20 31.6 53.6 0.15 27.3 51.5 0.10 34.1 35.0 0.05 35.0 26.8 0.02 29-2 21-4 0.20 31.9 43.1 0.15 33-8 34.7 0-05 33-1 15-5 0.07 33.4 24.3 0-04 33.1 19-5 0.15 29.1 45.9 0.10 25.3 40-7 0.10 42.8 26.4 0.04 38.0 16.0 0.04 32-0 19.5 0.02 34.7 12.0 0-10 26.1 43.8 0.10 26.2 50.1 0.10 31.5 43.7 0.05 30.8 33-8 0-02 26.3 17-8 0.03 40.6 49.1 0.02 38.4 38.1 0.20 24.5 68.8 0.15 26.6 63-6 0.06 31.6 77.7 Small but di 0.05 26-6 0.06 26.7 0.10 32.1 0.10 42.0 0.05 28.4 0.25 30.4 0.15 35.0 0.01 23-9 0.10 22-7 0.10 22.8 0-15 26.1 0.15 30.6 0.10 26-6 0.07 26-7 CT volt.-0.0729 - 0.0667 - 0.0602 - 0.0473 - 0*0301 -0*0181 - 0.082 1 -0.0722 -0.0550 -0.0487 - 0.0350 -0.0634 -0.0548 - 0.0500 -0.0372 - 0.0362 -0.0271 - 0.0494 -0.0430 -0.0410 -0.0271 - 0.0241 - 0.0085 - 0.0039 -0.0670 -0.0501 -0.0138 istinctly positive c car borundum . 57.6 +0.0184 31-3 +0*0406 41.9 +0*0420 33-8 +0*0398 28.3 +O-0351 65.6 -0.0708 42.8 -0.0565 20.0 -0~0118 70.6 +0*0352 46.2 f0.0536 40.6 +0-0799 33.7 +0*0822 28.8 +Om0737 23.9 +0.0619 -37. 14 14 13 12 11 11 16 18 9 8 10 13 16 14 10 4 16 12 12 12 8 10 7 ti 14 12 18 car. volt. -0.0729 - 0.0666 - 0.0604 - 0.0469 - 0.0302 -0.0171 -0.0820 -0.0722 - 0.0542 -0.0487 - 0.0351 - 0.0633 - 0.0541 - 0.049 1 -0.0371 - 0.0338 -0.0262 -0.0486 -0-0431 -0.0410 - 0.0282 - 0.0244 - 0.0085 - 0.0054 - 0.0670 -0*0501 - 0.01 3 7 :herge on the 14 +0*0184 19 +O-0402 15 +0*0422 11 +0*0398 12 +0*0350 18 -0.0'706 9 -0,0574 12 -0.0116 16 +0.0352 16 +0*0536 11 +0*0798 12 +0.0822 16 +0.0735 16 +0.0618 The mean values of [ are shown graphically on the accompanying diagram STUDIES IN ELECTRO-ENDOSMOSIS.PART III. 325 The values for distilled water showed greater variation than those for the solutions ; - 0.0698 volt the mean of fifteen independent determinations has been adopted &s a probable figure.The results may be summarised as follows Anions have com-paratively little effect ; the quadrivalent f errocyanide ion appears to be slightly abnormal. Kations tend to annul and then in the FIG. 1. +008 +OOO +0.04 0 i - 8 b -0.02 -0.01 -003 -005 W 4-0 100,000 case of ter- and quadri-valent ions to reverse the sign of the charge of carborundum in water which is originally negative. The effect becomes much more marked as one passes from univalent potassium to bivalent barium and on to ter- and quadri-valent ions. Al"' and Th"" give a maximum positive charge to carbon-indum at about N/4000. It may be noted that Al"' and Th"" produce an appreciable effect even a t a concentration of 5.0 x lO-eN the sign of the charge being reversed a t lO-5N.At these dilutions 326 STUDIES IN ELECTRO-ENDOSMOSIS. PART 111. the conductivity due to the added salt is of the same order as or even less than the conductivity of the water. 10-5N-Aluminium chloride contains only a few tenths of a milligram of salt per litre. I n very low concentrations of potassium salts the value of [ is higher (more negative) than in water. This may be discounted to some extent on account of experimental error due to contamination with atmospheric carbon dioxide. On the other hand in N/50,000-potassium sulphate was more negative than the most negative water value obtained. There are no electro-endosmosis results with which the present ones can be directly compared but there is a striking similarity between them and Kruyt's (Kolloid-Z.1918 22 81) values for the effect of kations on stream potentials in glass capillary tubes. Kruyt found that the charge of the glass capillary tube was reversed in sign in aluminium chloride of a concentration of 1 micro-mol. per litre which is even lower than that found for carborundum in the present work. Kruyt also obtained maximum negative values for the charge on glass in extremely dilute solutions of several salts. A close parallel to this increase of negative charge in very dilute solution is found in some recent work of Alty (Proc. Roy. SOC., 1924 106 315) who found that the velocity of cataphoresis of air bubbles in water varied with the conductivity of the water. He states " The results . . . indicate that the reduction of charge does not commence until a definite concentration of ions is reached, while below this the ions have the reverse effect and augment the bubble velocity." The foregoing results indicate that with carbor-undum at any rate in solutions of potassium salts the same is true.I n solutions of salts of ter- and quadri-valent ions the concentrations below which an increase of negative charge could take place are so very low that experimental errors due to carbon dioxide and other dissolved impurities make it very difficult to o b fain trustworthy data. Sunzm ary . (1) The effect of anions and kations on electro-endosmosis through a diaphragm of carborundum powder has been examined. Kations tend to annul the (negative) electrokinetic potential of carborundum against aqueous electrolytes and in the case of ter-and quadri-valent ions to charge the carborundum positively against the solution.Anions have comparatively little effect. (2) Al"' and Th"" reverse the sign of the charge a t concen-trations of only a few micro-mols. per litre. (3) I n very low concentrations of potassium salts the carborundum is more negative than in water THE HOMOGENEOUS THERMAL DECORIPOSITION ETC. 327 (4) The present results show a great similarit'y to Kruyt's results for stream potentials in glass capillary tubes. The authors are indebted to the Chemical Society Research Fund and to the Brunner Mond Research Grant to this Department for assistance in the above work. THE UNIVERSITY &IA4NCHESTER. [Received Decetrtbei. 15th 1924. 322 FAIRBROTHER AND MASTIN : L.-8tudies in Electro-endosmosis.Part III. By FRED FAIRBROTHER and HAROLD MASTIN. IN the first paper of this series (J. 1924 125 2319) a method was described for the measurement of electro-endosmosis and a t the same time of the potential gradient across the diaphragm. Th STUDIES IN ELECTRO-ENDOSMOSIS. PART III. 323 method was illustrated by measurements of the effect of acid and alkali on the electro-endosmosis through a diaphragm of carborun-dum powder. An account is now given of the effect of a number of other ions on the same diaphragm. With the exception of a few experiments of Perrin using sodium bromide and lanthanum nitrate in neutral or weak alkaline solution, there appear to be no data respecting the effect of ions other than hydrogen and hydroxyl on the electro-endosmosis through a diaphragm of carborundum powder.A word may be said on the choice of a suitable diaphragm material for making unambiguous electro-endosmotic measurements. This is not particularly easy. It is clearly desirable that there should be no doubt as to whether the surface of the solid phase is attacked chemically by the solute or solvent. I n this connexion it is illumin-ating to study the conductivity of a dilute solution in some powder which en masse may appear quite resistant chemically as for example powdered crystalline alumina. The conductivity of the mixture alters considerably with time increasing or decreasing according to the previous history of the powder. Quartz par-ticularly if finely powdered in some solutions suffers from the same complaint in a lesser degree.Carborundum on the other hand; possesses a surface which is very resistant to chemical action. E X P E R I31 E K T A L. The experimental details of the measurements were as given in Part I . The potassium salts were obtained as pure as possible by recrystallisation ; the aluminium chloride was Kahlbaum’s “ Kauf -liche.” The dilute solutions were made up by the progressive dilution of stronger standard ones. The aluminium chloride and thorium nitrate solutions were made from stock solutions originally of about M 110-strength ; these were standardised after the hydroxide had settled out. The factor of the aluminium chloride was 0.86 and of the thorium nitrate 0.91 both with respect to the kation. It is desirable as McBain ( J .Physical Chem. 1924 28 706) has pointed out to give the full experimental data in view of the assumptions made in calculating 6. I n the present case this mould require a prohibitive amount of space for the figures. On the other hand it would be misleading to give averages of the velocities and potential gradients since t; is not a linear function of these magnitudes. The following plan has therefore been adopted in Table I, V refers to the volume of liquid transported in each experiment, whilst T and E refer respectively to the time and the potential gradient across the diaphragm in a single typical estimation. Fro 324 FAIRBROTHER AND MASTIN : these figures CT has been calculated. Under y&v are given the average values of ( from N different observations.The present estimations, with the exception of those in barium chloride solutions were in general much more uniform and reproducible than those in wate.r or acid or alkaline solutions. (has been calculated in each case on the basis of the calibration of the diaphragm with N/lO-potassium chloride. Electrolyte. KCI 9 9 7 ) 9 9 99 K2s04 97 9 7 9 9 K4'ke( CN) 9 , ,? 9 9 9 , AlG, (F = 0.85) Conc. N/50,000 N 112,500 N/3125 N1781.2 N/195*3 Nl48.8 N/50,000 N 112,500 N/3125 N/781-2 Nl195.3 N /50,000 N I 12,500 N/3125 Nl781.2 N1195.3 N/48-8 N/100,000 N /50,000 N/12,500 N13125 N/781-2 N 1195.3 N148.8 N/800,000 N /400,000 N /200,000 N/100,000 7 9 N/50,000 9 N 112,500 7 9 N/3125 N 1781.2 Nj195.3 Th&O3)4 (F = 0-91) Nl800,OOO Y ' N)400;000 9 N /200,000 9 7 N /100,000 3 N /50,000 ? Y N/12,500 9 ) A713125 ? 9 Nl781.2 ?P Nl195.3 TABLE T.V T E C.C. secs. volts. 0.30 33.7 69.0 0.20 31.6 53.6 0.15 27.3 51.5 0.10 34.1 35.0 0.05 35.0 26.8 0.02 29-2 21-4 0.20 31.9 43.1 0.15 33-8 34.7 0-05 33-1 15-5 0.07 33.4 24.3 0-04 33.1 19-5 0.15 29.1 45.9 0.10 25.3 40-7 0.10 42.8 26.4 0.04 38.0 16.0 0.04 32-0 19.5 0.02 34.7 12.0 0-10 26.1 43.8 0.10 26.2 50.1 0.10 31.5 43.7 0.05 30.8 33-8 0-02 26.3 17-8 0.03 40.6 49.1 0.02 38.4 38.1 0.20 24.5 68.8 0.15 26.6 63-6 0.06 31.6 77.7 Small but di 0.05 26-6 0.06 26.7 0.10 32.1 0.10 42.0 0.05 28.4 0.25 30.4 0.15 35.0 0.01 23-9 0.10 22-7 0.10 22.8 0-15 26.1 0.15 30.6 0.10 26-6 0.07 26-7 CT volt.-0.0729 - 0.0667 - 0.0602 - 0.0473 - 0*0301 -0*0181 - 0.082 1 -0.0722 -0.0550 -0.0487 - 0.0350 -0.0634 -0.0548 - 0.0500 -0.0372 - 0.0362 -0.0271 - 0.0494 -0.0430 -0.0410 -0.0271 - 0.0241 - 0.0085 - 0.0039 -0.0670 -0.0501 -0.0138 istinctly positive c car borundum . 57.6 +0.0184 31-3 +0*0406 41.9 +0*0420 33-8 +0*0398 28.3 +O-0351 65.6 -0.0708 42.8 -0.0565 20.0 -0~0118 70.6 +0*0352 46.2 f0.0536 40.6 +0-0799 33.7 +0*0822 28.8 +Om0737 23.9 +0.0619 -37. 14 14 13 12 11 11 16 18 9 8 10 13 16 14 10 4 16 12 12 12 8 10 7 ti 14 12 18 car. volt. -0.0729 - 0.0666 - 0.0604 - 0.0469 - 0.0302 -0.0171 -0.0820 -0.0722 - 0.0542 -0.0487 - 0.0351 - 0.0633 - 0.0541 - 0.049 1 -0.0371 - 0.0338 -0.0262 -0.0486 -0-0431 -0.0410 - 0.0282 - 0.0244 - 0.0085 - 0.0054 - 0.0670 -0*0501 - 0.01 3 7 :herge on the 14 +0*0184 19 +O-0402 15 +0*0422 11 +0*0398 12 +0*0350 18 -0.0'706 9 -0,0574 12 -0.0116 16 +0.0352 16 +0*0536 11 +0*0798 12 +0.0822 16 +0.0735 16 +0.0618 The mean values of [ are shown graphically on the accompanying diagram STUDIES IN ELECTRO-ENDOSMOSIS.PART III. 325 The values for distilled water showed greater variation than those for the solutions ; - 0.0698 volt the mean of fifteen independent determinations has been adopted &s a probable figure. The results may be summarised as follows Anions have com-paratively little effect ; the quadrivalent f errocyanide ion appears to be slightly abnormal.Kations tend to annul and then in the FIG. 1. +008 +OOO +0.04 0 i - 8 b -0.02 -0.01 -003 -005 W 4-0 100,000 case of ter- and quadri-valent ions to reverse the sign of the charge of carborundum in water which is originally negative. The effect becomes much more marked as one passes from univalent potassium to bivalent barium and on to ter- and quadri-valent ions. Al"' and Th"" give a maximum positive charge to carbon-indum at about N/4000. It may be noted that Al"' and Th"" produce an appreciable effect even a t a concentration of 5.0 x lO-eN the sign of the charge being reversed a t lO-5N. At these dilutions 326 STUDIES IN ELECTRO-ENDOSMOSIS.PART 111. the conductivity due to the added salt is of the same order as or even less than the conductivity of the water. 10-5N-Aluminium chloride contains only a few tenths of a milligram of salt per litre. I n very low concentrations of potassium salts the value of [ is higher (more negative) than in water. This may be discounted to some extent on account of experimental error due to contamination with atmospheric carbon dioxide. On the other hand in N/50,000-potassium sulphate was more negative than the most negative water value obtained. There are no electro-endosmosis results with which the present ones can be directly compared but there is a striking similarity between them and Kruyt's (Kolloid-Z. 1918 22 81) values for the effect of kations on stream potentials in glass capillary tubes.Kruyt found that the charge of the glass capillary tube was reversed in sign in aluminium chloride of a concentration of 1 micro-mol. per litre which is even lower than that found for carborundum in the present work. Kruyt also obtained maximum negative values for the charge on glass in extremely dilute solutions of several salts. A close parallel to this increase of negative charge in very dilute solution is found in some recent work of Alty (Proc. Roy. SOC., 1924 106 315) who found that the velocity of cataphoresis of air bubbles in water varied with the conductivity of the water. He states " The results . . . indicate that the reduction of charge does not commence until a definite concentration of ions is reached, while below this the ions have the reverse effect and augment the bubble velocity." The foregoing results indicate that with carbor-undum at any rate in solutions of potassium salts the same is true. I n solutions of salts of ter- and quadri-valent ions the concentrations below which an increase of negative charge could take place are so very low that experimental errors due to carbon dioxide and other dissolved impurities make it very difficult to o b fain trustworthy data. Sunzm ary . (1) The effect of anions and kations on electro-endosmosis through a diaphragm of carborundum powder has been examined. Kations tend to annul the (negative) electrokinetic potential of carborundum against aqueous electrolytes and in the case of ter-and quadri-valent ions to charge the carborundum positively against the solution. Anions have comparatively little effect. (2) Al"' and Th"" reverse the sign of the charge a t concen-trations of only a few micro-mols. per litre. (3) I n very low concentrations of potassium salts the carborundum is more negative than in water THE HOMOGENEOUS THERMAL DECORIPOSITION ETC. 327 (4) The present results show a great similarit'y to Kruyt's results for stream potentials in glass capillary tubes. The authors are indebted to the Chemical Society Research Fund and to the Brunner Mond Research Grant to this Department for assistance in the above work. THE UNIVERSITY &IA4NCHESTER. [Received Decetrtbei. 15th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700322

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

THE HOMOGENEOUS THERMAL DECORIPOSITION ETC. 327 LI. -A Comparison between the HomogePzeous. Thermal Decomposition of lVitrous Oxide and it?s Heterogeneous Catalytic Decom positicm on the Surfuce of P l a t i ~ ~ J i m . By CYRIL XORVAS HINSHELWOOD and CHARLES ROSS PRICHARD. Mum interest lies in the problem of the conditions under which catalytic reactions take place a t solid surfaces and for the elucid-ation of such heterogeneous changes one of the first necessities seems to he the careful comparison of a number of catalysed with the corresponding uiicatalysed reactions. But no complete study allpears hitherto to have been made of a simple change caused to proceed on the one hand in the homogeneous gaseous phase and on the other hand at the surface of a solid catalyst.The difficulty has always been to realise experimentally the conditions for isolating the two types of reaction so that they may be separately investi-gated. Such a comparative study is made in this paper for the thermal decomposition of nitrous oxide. The kinetics of the homogeneous reaction were described in a previous paper (Proc. Roy. Xoc. 1924 [.A] 106 284) and experiments on the hetero-geneous reaction a t the surface of a platinum wire are now added. The homogeneous reaction is bimolecular and at 795" is unaffected by the presence of platinum foil; thus if any reaction takes place a t the snrface of the platinum it is slow compared with the homo-geneous change and cannot) be measured. If however a wire is heated electrically it should be possible to find a temperature where the surface reaction attains a measurable speed and by keeping the bulk of the gas cold the homogeneous reaction should be elimin-ated since at a distance from the wire of the order of a mean free path the temperature of the gas falls several hundred degrees below that of the wire.It was realised that the homogeneous reaction proceeding in a thin layer of gas round the wire might be a serious factor but experiments made with two different platinum wires over a range of temperature from GOO-1200" showe 328 HINSHELWOOD AND PRICEARD A COMPARISON BETWEEN that the reaction under these conditions was the true surface reaction. The Apparatus.-The essential part of the apparatus consists of a cylindrical bulb about 16 cm. long and 3.5 cm.in diameter with the platinum wire stretched axially and sealed through small plugs of glass at the ends. Leads of negligible resistance connect with the battery of accumulators rheostat ammeter and a voltmeter in parallel with the heated wire. Capillary tubes lead to a Gaede pump nitrous oxide supply and a capillary manometer. The reaction bulb is kept immersed in melting ice. Determination of the Temperature of the Wire.-Simultaneous readings of ammeter and voltmeter while the wire was heated gave its resistance to within 0-2y0. Prom this the temperature of the wire was calculated the resistance at 0" and the temperature-resistance curve of the wire having been separately measured. A correction which amounted to about 5y0 was made for the resist-ance of the unheated portion of the wire passing through the seals.Since the brightness of the wire appeared uniform along the whole length the temperature was probably quite uniform as was to be expected from the axial situation of the wire and the absence of any bends or loops. With regard to constancy and reproducibility, the temperature was probably controllable to within a degree or two in the region of lOOO" and although this cannot be claimed for the absolute values of the temperature owing to the end corrections, these values should be substantially correct. It may be mentioned here that the two wires with rather different temperature-resistance curves gave concordant values for the temperature coeficient of the reaction velocity. Thermal equilibrium was established within a second when the current was switched on and remained quite steady as long as the bulb was kept in ice.Method of Experiment.-Nitrous oxide a t a known pressure was let into the apparatus a t 0". The current was switched on for a suitable period measured by a stop-watch and then switched off. The wire cooled instantly and the pressure of the gas was again measured at 0". The increase gave the amount of decomposition. The current was then switched on again and the process repeated. As the reaction proceeded the thermal conductivity of the gas changed slightly and rather more energy had to be supplied to keep the temperature constant. With nitrous oxide at a pressure of 200 mm. an initial voltage of 10.00 would need to be raised t o 10.20 during the reaction to keep the resistance of the wire at its original value.Pigs. 1 and 2 show that quite regular curves are obtained by plotting decomposition against time. When t'he wire was in goo THE HOMOQENEOUS THERMAL DECOMPOSITION ETC. 329 condition very concordant results could be obtained as the following figures show ; Time (secs.) ......... 300 600 900 yo ........................ 37 The I.laJluence of Pressure.-The inthence of pressure is remark-able the percentage decomposition in a given time increasing as the initial pressure of nitrous oxide diminishes in striking contrast with the homogeneous reaction. The curves in Fig. 1 obtained with wire 2 a t 909O illustrate this. There is no question of the results being affected by a drift in the activity of the platinum since a final experiment a t 200 mm.FIG. 1. 100 200 300 400 Time in seconds. Influence of initial pressure on catalytic decomposition of nitrous oxide. The p i n t s mrked with circles on the 200 mm.-cwse were obtained in the first agreed well with the first. The times required for half the nitrous oxide to decompose " half-life," were as follows : experiment of the whole series ; those marked with crosses in the last. Initial pressure of N,O in mm. ...... 50 100 200 400 Half-life in seconds ..................... 110 145 242 395 Another set of experiments with wire 1 at 889" gave Initial pressure .................. 100 200 400 - - Half-life in seconds ............ 540 590 1290 1230 3690 The explanation is as follows. It is shown in the next section that the oxygen formed in the decomposition retards the reaction.The retardation depends upon the fraction of the platinum surfac 330 HINSHELWOOD AND PRICHARD A COMPARISON BETWEEN covered by adsorbed oxygen and this in turn depends upon the absolute pressure of the oxygen not upon its pressure relative to that of the nitrous oxide. Hence the retardation by oxygen is through every stage of the reaction greater for high than for low initial pressures of nitrous oxide. The InJZuence of Added Oxygen and of Nitrogen.-Nitrogen appeared to have a slight retarding influence but almost negligible in comparison with that of oxygen. These influences are shown by the following table and by the curves in Fig. 2 : 200 mm. N,O 28 43 200 mm. N,O + 100 mm.N ............ 22.5 38.5 48-5 55 200 mm. N,O + 200 mm. N ............ 19.5 34 43 61 Per cent. decomposed in 100 200 300 400secs. .............................. 53.5 60 ............ 4 G 10 200 mm. N,O + 100 mm. 0 2 . FIQ. 2. Time in seconds. Temperature 910". Influence of oxygen o n the catalytic decompositwn of nitrous oxide. Initial pressure of N,O = 200 rnm. The quantitative relation between oxygen pressure and initial velocity was now examined. Nitrous oxide and oxygen at known pressures were introduced and the wire was heated for 60 seconds. The percentage decomposition in this time gave an approximate measure of the reaction velocity. Between the experiments the wire was heated to a standard higher temperature (1500") in a vacuum to drive out any oxygen which had started to dissolve in the wire.Temperature 911'. p = average pressure (mm.) of oxygen. P = observed rate of reaction as percentage in 60 seconds. p ............ 23 40 74.5 112 159 206 257 305 r ............ 46 35 29 20 14 10 10 10 s ............ 44 36 26 20 15 12-5 10.4 9 Pressure of N,O 200 mm. in each case. s = rate calculated from the expression 64/(1 + 0.02 p ) THE HOMOGENEOUS THERMAL DECOMPOSITIOK ETC. 331 Thus the oxygen adsorption seems to follow an isotherm of the type discussed in Freundlich's '' Kapillarchemie," 2nd edition, 1922 p. 17.5 et seq. If c be the fraction of the surface covered bl- the retarding film and 1 - r the fraction free then for equilibrium. equating the rate of coiidensation and the rate of evaporation at R given oxygen Iressure,p,we have c l r = c z ( l - r ) p c1 and c being constants whence 1 - u = c J ( c l + C ~ I ) = l ' ( 1 621).where b = c2/c1. Thus the rate of reaction should be proportional to 1!'(1 + bp). The bottom line of the above table shows that this is adequately fulfilled. The DynawLics of the Reaction .-All the observed phenomena are adequately expressed by the equation whence The equation may be tested by the folloning criteria : 1. For a given pressure of oxygen the initial rate of reaction is proportional to the pressure of nitrous oxide or expressed as a percentaqe is independent of the pressure. Thus xith 100 mm. 0, added initially the following initial rates were found 100 mm. l?u',O 1.0% per minute; 30 mni. N,O l . O q per minute 100 inm.S20 1.0% per minute. 2 . The retarding influence of added oxygen is satisfactorily expressed. 3. It expresses the decrease in the ' half-life " of the nitrous oxide with diminishing pressure. Thus the '' half-life," T is given by l / k i ( l T a b ) log 2 - ab/2/ if we take the half-life a t 200 min a i unity and b as 0.020. the values are : . 100 nun. 200 mm. 400 mm. . . . . . 0.51 1.00 1.53 4 set of ratios found for a wire having a b value of approximately 0.020 \+ere actually 0.60. 1.00. 1.83. 4. Its quantitative accuracy niaj- be tested as follows. If in the integrated equation we put 1 it log a ' ( a - x) = k, and x it = v. it mill be seen that k, should be a linear function of v a h the linearity of the relation is a characteristic test of the form of the equation not influenced by the choice of the constants.which only determine the slope of the line and its intercepts on the axes. Since 2' = (a $. l/b)t%,7E - k,b the slope will be CL + l / b and the intercept on the v axis will be - k / b whence k and b may be found. The following two experiments are quoted as typical of many 332 HINSHELWOOD AND PRICHARD A COMPARISON BETWEEN X. 10 20 30 40 50 60 70 80 t (secs.). 20 50 90 150 225 337 500 740 Temperature 91 1 '. Q 2 = x l t . l l t log a/(a -k = 0.500 0.00558 0.400 0.00473 0.333 0.00422 0.266 0.00364 0.222 0-00332 0.178 0.00296 0-140 0.00267 0.108 0.00249 = 95. - x). 2 + 0.190. 0.690 0.590 0.523 0.456 0.412 0.368 0-330 0.298 21 + 0.190 - -ktn a + lib.123.8 124.6 124-1 125.7 124.0 124.3 123.8 119.8 Av. 124-3 The linear relationship is shown by Pig. 3 and by the last column. The intercept on the line k,, = 0 is - 0.190. Thus k / b = 0.190 and since a + l / b = 124.3 we have k = 0.00647 and b = 0.0341. Temperature 741". a = 95. 2. t (secs.). V. k,. v + 0.0135. (V + 0-0135)/km. 10 20 30 40 50 60 whence 315 0.0318 0.000353 0-0453 750 0.0267 0-000315 0.0402 1400 0-0214 0.000271 0.0349 2250 0.0178 0.000243 0-0313 3450 0.0145 0.000216 0.0280 5150 0.0116 0.000194 0.0251 k = 0.000400 and b = 0.0296. FIG. 3. 129-3 127.8 128.6 128.8 129.5 128-9 0.1 0.2 0.3 0.4 0.5 2). It will be seen that whereas k varies in these two experiments 16-fold between 741" and 911" the variation in b is very much smaller.Thus the retarding effect of the oxygen does not vary very markedly with temperature. The Influence of Temperature .-Two series of experiments were made with different wires. First wire. Fig. 4 shows the effect of temperature on the initia TRE HOMOUENEOUS THERMAL DECOMPOSITION ETC. 333 velocity as measured by the reciprocal of the time required for the decomposition to reach 10% (initial pressure 200 mm.)-this initial velocity being used so that any influence of the oxygen retardation would be reduced to a minimum. The value of the heat of activation obtained from the slope of the curve is 35,000 calories per gram-molecule and is seen to be constant within the limit of experimental error..t = Time (secs.) for decomposition to reach 10%. To (abs.) t. log, t. 1/Tx 10’. To (abs.) t . log, t. 1/TklO7. 1506 13 1.11 6642 1109 470 2.67 9,023 1448 9 0.95 6906 1085 500 2.70 9,214 1394 25 1.40 7172 994 4,300 3.63 10,060 1324 38 1.58 7554 944 9,300 3.97 10,590 1204 140 2.15 8307 893 29,000 4.46 11,200 FIQ. 4. i p x 107. Influence of temperature on the heterogeneous decomposition of nitrow oxide on CI platinum wire. Second wire. as that of the first. 3 times as active. The initial pressure of nitrous oxide was 200 mm. The surface area of this wire was 1.5 times as great At corresponding temperatures it was about The following is a brief summary of the results. Time in seconds for decomposition to go from To 0- 10- 30- To 0- 10- 30-(abs.).10%. 30%. 50%. (abs.). 10%. 30%. 50%. 1323 12.5 27 37 1180 26 77 147 1275 18 35 49 1130 90 290 550 1228 19 48 88 1065 116 534 1,400 1184 20 70 135 1014 315 1085 2,050 1181 32 88 180 954 1230 6570 25,20 334 HINSHELWOOD AND PRICHARD A COMPARISON BETWEEN The heats of activation were obtained separately for the ranges 0-lo% 10-30~0 30-50% from the graphs of l/T and log 1. The values were 33,000 36,800 and 42,500. Whence by extra-polation to zero decomposition the value 31,500 is found. Applying an equal correction to the previous value of 35,000 we have for the heat of activation corresponding to initial velocities First wire 33,500 calories \ Second wire 31,500 calories Mean 32950u cazories* Behaviour of the Platinum. Final Proof that the Reaction is Heterogeneous.-The activity of the annealed platinum wires was satisfactorily reproducible unless they had been in contact with oxygen at fairly high pressure.This treatment tended to cause a gradual and progressive diminution in activity from one experiment to another indicating an actual solution of the oxygen in the plati-num distinct from the reversible surface adsorption. The following experiments carried out at the end when there was no longer any need to keep the wire in a constant condition bring the effect clearly to light. The wire which in its normal condition had caused the decomposition of 46% in 200 seconds at 910" and 200 mm. N,O, was heated at about 1400" in an atmosphere of oxygen and allowed to cool in the oxygen which was then pumped off.It now caused the decomposition of 3% only under the same conditions as before. After heating in a vacuum once more to a high temperature it regained more than its original activity decomposing 56.5% in 200 seconds. It is important to note that since poisoning the wire by dissolved oxygen can cut down the rate of change from 46% in 200 seconds to 3y0 the heterogeneous nature of the reaction is conclusively shown. Compariscm of the Heterogeneous Decomposition of Nitrous Oxide with its Homogeneous Decomposition.-The homogeneous reaction depends upon the collision of two molecules whose energy together exceeds 58,500 calories (in terms of gram-molecules). The catalytic decomposition on the other hand is a unimolecular process. The unimolecular change N,O = N + 0 could not occur homogene-ously at 1000" at more than a negligibly small rate compared with the other reactions since it would involve the production of atomic oxygen and the absorption of about 60,000 calories.The heat of activation would therefore probably be enormous. In the catalytic reaction the function of the surface is thus to act as an acceptor for atomic oxygen thereby rendering possible a unimolecular in place of a bimolecular process. This must be regarded as the principal function of the catalyst. What makes the odd oxygen atom more easily detachable is it THE HOMOGENEOUS THERMAL DECOMPOSITION ETC. 335 affinity either for the platinum or for atomic oxygen already on the platinum. Three mechanisms are conceivable 1. Nitrous oxide gives its oxygen atom to the bare platinum surface.A retarding film of atomic oxygen forms. 2a. Nitrous oxide reacts by striking atomic oxygen already on the platinum. 2b. Nitrous oxide reacts with atomic oxygen in gaps in a film of the latter (mechanism anal-ogous to that suggested for interaction of nitrous oxide and hydrogen on platinum). (1) is the natural and probably correct explanation. leading to the correct equation for the reaction velocity. The one difficulty which i t presents arises from Langmuir's statement (Trans. Furuday SOC. 1922 17 653) that even at 1500" Abs. and very low pressures platinum remains completely covered with atomic oxygen. If this is true the retarding film which forms during the decomposi-tion of nitrous oxide and which is only half completed a t about 60 mm.0, would have to be of a new kind namely a layer of molecular oxygen adsorbed on the primary layer of atomic oxygen. Mechanism (2a) otherwise inadmissible would then have to be assumed. But Langmuir's statement may not be true of the platinum wires used by us and then there is no need to go beyond (1). (It will not do to assume that the presence of nitrous oxide interferes with the completion of the oxygen film since this would imply fairly strong adsorption of the nitrous oxide itself in which case the velocity equation would not be of the right form.) (2b) could apply only if the atomic oxygen film covered nearly the whole surface from quite small pressures because otherwise the greatest velocity would not be a t the beginning of the reaction when there is little or no oxygen present.Nitrous oxide reacting in gaps in a nearly complete film would obey the equation-d[N,O]/dt = Ic[NzO]/[O,]. This demands inverse proportionality of rate to oxygen pressure to which simple form the actual relation does not reduce. The balance of evidence is in favour of (1) and an oxygen film half complete a t 60 mm. With regard to the various energy relationships : Homogeneous reaction E = 58,500 calories for 2 gram-molecules. Surface reaction, Although the real physical significance of E is abundantly shown for homogeneous reactions in surface reactions it is a more complex quantity. If the attempted extrapolation of E to zero decompo-sition really eliminates the influence of the oxygen film then it is probable that 30,000 calories is of the right order for the actual energy of activation.It would then appear that the catalytic reaction has a great advantage over the hypothetical homogeneous unimolecular reaction which would demand a minimum activation of 60,000 calories per gram-molecule. E = 32,500 calories for 1 gram-molecule 336 MITCHELL THE HYDROLYTIC DECOMPOSITION OF The average activation required by a single molecule in the bimolecular homogeneous reaction is 29,250 calories so that, molecule for molecule the catalytic reaction appears to have little advantage from the point of view of energy; we may therefore conclude that the main function of the catalyst in this case is to render possible a unimolecular process in place of one requiring the co-operation of two simultaneously activated molecules.It may perhaps be pointed out in conclusion that any attempt to place a " quantum " interpretation upon. the fact that the experimentally determined E for the catalytic reaction is about half that for the homogeneous reaction is to be deprecated. Such attempts are not in the least justified. Summary. The heterogeneous thermal decomposition of nitrous oxide on a platinum wire has been investigated between 600" and 1200°, the homogeneous change at these temperatures being eliminated by heating the wire only. The reaction is retarded by oxygen and proceeds relatively faster at low than at high pressures. The velocity is represented by the equation : The experimentally determined heat of activation in the catalytic reaction is 32,500 calories per gram-molecule.A comparison is made of this catalytic reaction with the homo-geneous bimolecular decomposition and with the hypothetical homogeneous unimolecular decomposition and the mechanism of the catalysis discussed. - d",O]/dt = W,O1/(1 + b[0,1). We are indebted to the Royal Society for a grant with which part of the apparatus used in this investigation was purchased. PHYSICAL CHEMISTRY LABORATORY, BALLIOL COLLEGE AND TRINITY COLLEGE, OXFORD. [Received October 28th 1924. THE HOMOGENEOUS THERMAL DECORIPOSITION ETC. 327 LI. -A Comparison between the HomogePzeous. Thermal Decomposition of lVitrous Oxide and it?s Heterogeneous Catalytic Decom positicm on the Surfuce of P l a t i ~ ~ J i m . By CYRIL XORVAS HINSHELWOOD and CHARLES ROSS PRICHARD.Mum interest lies in the problem of the conditions under which catalytic reactions take place a t solid surfaces and for the elucid-ation of such heterogeneous changes one of the first necessities seems to he the careful comparison of a number of catalysed with the corresponding uiicatalysed reactions. But no complete study allpears hitherto to have been made of a simple change caused to proceed on the one hand in the homogeneous gaseous phase and on the other hand at the surface of a solid catalyst. The difficulty has always been to realise experimentally the conditions for isolating the two types of reaction so that they may be separately investi-gated. Such a comparative study is made in this paper for the thermal decomposition of nitrous oxide.The kinetics of the homogeneous reaction were described in a previous paper (Proc. Roy. Xoc. 1924 [.A] 106 284) and experiments on the hetero-geneous reaction a t the surface of a platinum wire are now added. The homogeneous reaction is bimolecular and at 795" is unaffected by the presence of platinum foil; thus if any reaction takes place a t the snrface of the platinum it is slow compared with the homo-geneous change and cannot) be measured. If however a wire is heated electrically it should be possible to find a temperature where the surface reaction attains a measurable speed and by keeping the bulk of the gas cold the homogeneous reaction should be elimin-ated since at a distance from the wire of the order of a mean free path the temperature of the gas falls several hundred degrees below that of the wire.It was realised that the homogeneous reaction proceeding in a thin layer of gas round the wire might be a serious factor but experiments made with two different platinum wires over a range of temperature from GOO-1200" showe 328 HINSHELWOOD AND PRICEARD A COMPARISON BETWEEN that the reaction under these conditions was the true surface reaction. The Apparatus.-The essential part of the apparatus consists of a cylindrical bulb about 16 cm. long and 3.5 cm. in diameter with the platinum wire stretched axially and sealed through small plugs of glass at the ends. Leads of negligible resistance connect with the battery of accumulators rheostat ammeter and a voltmeter in parallel with the heated wire.Capillary tubes lead to a Gaede pump nitrous oxide supply and a capillary manometer. The reaction bulb is kept immersed in melting ice. Determination of the Temperature of the Wire.-Simultaneous readings of ammeter and voltmeter while the wire was heated gave its resistance to within 0-2y0. Prom this the temperature of the wire was calculated the resistance at 0" and the temperature-resistance curve of the wire having been separately measured. A correction which amounted to about 5y0 was made for the resist-ance of the unheated portion of the wire passing through the seals. Since the brightness of the wire appeared uniform along the whole length the temperature was probably quite uniform as was to be expected from the axial situation of the wire and the absence of any bends or loops.With regard to constancy and reproducibility, the temperature was probably controllable to within a degree or two in the region of lOOO" and although this cannot be claimed for the absolute values of the temperature owing to the end corrections, these values should be substantially correct. It may be mentioned here that the two wires with rather different temperature-resistance curves gave concordant values for the temperature coeficient of the reaction velocity. Thermal equilibrium was established within a second when the current was switched on and remained quite steady as long as the bulb was kept in ice. Method of Experiment.-Nitrous oxide a t a known pressure was let into the apparatus a t 0". The current was switched on for a suitable period measured by a stop-watch and then switched off.The wire cooled instantly and the pressure of the gas was again measured at 0". The increase gave the amount of decomposition. The current was then switched on again and the process repeated. As the reaction proceeded the thermal conductivity of the gas changed slightly and rather more energy had to be supplied to keep the temperature constant. With nitrous oxide at a pressure of 200 mm. an initial voltage of 10.00 would need to be raised t o 10.20 during the reaction to keep the resistance of the wire at its original value. Pigs. 1 and 2 show that quite regular curves are obtained by plotting decomposition against time. When t'he wire was in goo THE HOMOQENEOUS THERMAL DECOMPOSITION ETC.329 condition very concordant results could be obtained as the following figures show ; Time (secs.) ......... 300 600 900 yo ........................ 37 The I.laJluence of Pressure.-The inthence of pressure is remark-able the percentage decomposition in a given time increasing as the initial pressure of nitrous oxide diminishes in striking contrast with the homogeneous reaction. The curves in Fig. 1 obtained with wire 2 a t 909O illustrate this. There is no question of the results being affected by a drift in the activity of the platinum since a final experiment a t 200 mm. FIG. 1. 100 200 300 400 Time in seconds. Influence of initial pressure on catalytic decomposition of nitrous oxide. The p i n t s mrked with circles on the 200 mm.-cwse were obtained in the first agreed well with the first.The times required for half the nitrous oxide to decompose " half-life," were as follows : experiment of the whole series ; those marked with crosses in the last. Initial pressure of N,O in mm. ...... 50 100 200 400 Half-life in seconds ..................... 110 145 242 395 Another set of experiments with wire 1 at 889" gave Initial pressure .................. 100 200 400 - - Half-life in seconds ............ 540 590 1290 1230 3690 The explanation is as follows. It is shown in the next section that the oxygen formed in the decomposition retards the reaction. The retardation depends upon the fraction of the platinum surfac 330 HINSHELWOOD AND PRICHARD A COMPARISON BETWEEN covered by adsorbed oxygen and this in turn depends upon the absolute pressure of the oxygen not upon its pressure relative to that of the nitrous oxide.Hence the retardation by oxygen is through every stage of the reaction greater for high than for low initial pressures of nitrous oxide. The InJZuence of Added Oxygen and of Nitrogen.-Nitrogen appeared to have a slight retarding influence but almost negligible in comparison with that of oxygen. These influences are shown by the following table and by the curves in Fig. 2 : 200 mm. N,O 28 43 200 mm. N,O + 100 mm. N ............ 22.5 38.5 48-5 55 200 mm. N,O + 200 mm. N ............ 19.5 34 43 61 Per cent. decomposed in 100 200 300 400secs. .............................. 53.5 60 ............ 4 G 10 200 mm. N,O + 100 mm.0 2 . FIQ. 2. Time in seconds. Temperature 910". Influence of oxygen o n the catalytic decompositwn of nitrous oxide. Initial pressure of N,O = 200 rnm. The quantitative relation between oxygen pressure and initial velocity was now examined. Nitrous oxide and oxygen at known pressures were introduced and the wire was heated for 60 seconds. The percentage decomposition in this time gave an approximate measure of the reaction velocity. Between the experiments the wire was heated to a standard higher temperature (1500") in a vacuum to drive out any oxygen which had started to dissolve in the wire. Temperature 911'. p = average pressure (mm.) of oxygen. P = observed rate of reaction as percentage in 60 seconds. p ............ 23 40 74.5 112 159 206 257 305 r ............46 35 29 20 14 10 10 10 s ............ 44 36 26 20 15 12-5 10.4 9 Pressure of N,O 200 mm. in each case. s = rate calculated from the expression 64/(1 + 0.02 p ) THE HOMOGENEOUS THERMAL DECOMPOSITIOK ETC. 331 Thus the oxygen adsorption seems to follow an isotherm of the type discussed in Freundlich's '' Kapillarchemie," 2nd edition, 1922 p. 17.5 et seq. If c be the fraction of the surface covered bl- the retarding film and 1 - r the fraction free then for equilibrium. equating the rate of coiidensation and the rate of evaporation at R given oxygen Iressure,p,we have c l r = c z ( l - r ) p c1 and c being constants whence 1 - u = c J ( c l + C ~ I ) = l ' ( 1 621). where b = c2/c1. Thus the rate of reaction should be proportional to 1!'(1 + bp).The bottom line of the above table shows that this is adequately fulfilled. The DynawLics of the Reaction .-All the observed phenomena are adequately expressed by the equation whence The equation may be tested by the folloning criteria : 1. For a given pressure of oxygen the initial rate of reaction is proportional to the pressure of nitrous oxide or expressed as a percentaqe is independent of the pressure. Thus xith 100 mm. 0, added initially the following initial rates were found 100 mm. l?u',O 1.0% per minute; 30 mni. N,O l . O q per minute 100 inm. S20 1.0% per minute. 2 . The retarding influence of added oxygen is satisfactorily expressed. 3. It expresses the decrease in the ' half-life " of the nitrous oxide with diminishing pressure. Thus the '' half-life," T is given by l / k i ( l T a b ) log 2 - ab/2/ if we take the half-life a t 200 min a i unity and b as 0.020.the values are : . 100 nun. 200 mm. 400 mm. . . . . . 0.51 1.00 1.53 4 set of ratios found for a wire having a b value of approximately 0.020 \+ere actually 0.60. 1.00. 1.83. 4. Its quantitative accuracy niaj- be tested as follows. If in the integrated equation we put 1 it log a ' ( a - x) = k, and x it = v. it mill be seen that k, should be a linear function of v a h the linearity of the relation is a characteristic test of the form of the equation not influenced by the choice of the constants. which only determine the slope of the line and its intercepts on the axes. Since 2' = (a $. l/b)t%,7E - k,b the slope will be CL + l / b and the intercept on the v axis will be - k / b whence k and b may be found.The following two experiments are quoted as typical of many 332 HINSHELWOOD AND PRICHARD A COMPARISON BETWEEN X. 10 20 30 40 50 60 70 80 t (secs.). 20 50 90 150 225 337 500 740 Temperature 91 1 '. Q 2 = x l t . l l t log a/(a -k = 0.500 0.00558 0.400 0.00473 0.333 0.00422 0.266 0.00364 0.222 0-00332 0.178 0.00296 0-140 0.00267 0.108 0.00249 = 95. - x). 2 + 0.190. 0.690 0.590 0.523 0.456 0.412 0.368 0-330 0.298 21 + 0.190 - -ktn a + lib. 123.8 124.6 124-1 125.7 124.0 124.3 123.8 119.8 Av. 124-3 The linear relationship is shown by Pig. 3 and by the last column. The intercept on the line k,, = 0 is - 0.190.Thus k / b = 0.190 and since a + l / b = 124.3 we have k = 0.00647 and b = 0.0341. Temperature 741". a = 95. 2. t (secs.). V. k,. v + 0.0135. (V + 0-0135)/km. 10 20 30 40 50 60 whence 315 0.0318 0.000353 0-0453 750 0.0267 0-000315 0.0402 1400 0-0214 0.000271 0.0349 2250 0.0178 0.000243 0-0313 3450 0.0145 0.000216 0.0280 5150 0.0116 0.000194 0.0251 k = 0.000400 and b = 0.0296. FIG. 3. 129-3 127.8 128.6 128.8 129.5 128-9 0.1 0.2 0.3 0.4 0.5 2). It will be seen that whereas k varies in these two experiments 16-fold between 741" and 911" the variation in b is very much smaller. Thus the retarding effect of the oxygen does not vary very markedly with temperature. The Influence of Temperature .-Two series of experiments were made with different wires.First wire. Fig. 4 shows the effect of temperature on the initia TRE HOMOUENEOUS THERMAL DECOMPOSITION ETC. 333 velocity as measured by the reciprocal of the time required for the decomposition to reach 10% (initial pressure 200 mm.)-this initial velocity being used so that any influence of the oxygen retardation would be reduced to a minimum. The value of the heat of activation obtained from the slope of the curve is 35,000 calories per gram-molecule and is seen to be constant within the limit of experimental error.. t = Time (secs.) for decomposition to reach 10%. To (abs.) t. log, t. 1/Tx 10’. To (abs.) t . log, t. 1/TklO7. 1506 13 1.11 6642 1109 470 2.67 9,023 1448 9 0.95 6906 1085 500 2.70 9,214 1394 25 1.40 7172 994 4,300 3.63 10,060 1324 38 1.58 7554 944 9,300 3.97 10,590 1204 140 2.15 8307 893 29,000 4.46 11,200 FIQ.4. i p x 107. Influence of temperature on the heterogeneous decomposition of nitrow oxide on CI platinum wire. Second wire. as that of the first. 3 times as active. The initial pressure of nitrous oxide was 200 mm. The surface area of this wire was 1.5 times as great At corresponding temperatures it was about The following is a brief summary of the results. Time in seconds for decomposition to go from To 0- 10- 30- To 0- 10- 30-(abs.). 10%. 30%. 50%. (abs.). 10%. 30%. 50%. 1323 12.5 27 37 1180 26 77 147 1275 18 35 49 1130 90 290 550 1228 19 48 88 1065 116 534 1,400 1184 20 70 135 1014 315 1085 2,050 1181 32 88 180 954 1230 6570 25,20 334 HINSHELWOOD AND PRICHARD A COMPARISON BETWEEN The heats of activation were obtained separately for the ranges 0-lo% 10-30~0 30-50% from the graphs of l/T and log 1.The values were 33,000 36,800 and 42,500. Whence by extra-polation to zero decomposition the value 31,500 is found. Applying an equal correction to the previous value of 35,000 we have for the heat of activation corresponding to initial velocities First wire 33,500 calories \ Second wire 31,500 calories Mean 32950u cazories* Behaviour of the Platinum. Final Proof that the Reaction is Heterogeneous.-The activity of the annealed platinum wires was satisfactorily reproducible unless they had been in contact with oxygen at fairly high pressure. This treatment tended to cause a gradual and progressive diminution in activity from one experiment to another indicating an actual solution of the oxygen in the plati-num distinct from the reversible surface adsorption.The following experiments carried out at the end when there was no longer any need to keep the wire in a constant condition bring the effect clearly to light. The wire which in its normal condition had caused the decomposition of 46% in 200 seconds at 910" and 200 mm. N,O, was heated at about 1400" in an atmosphere of oxygen and allowed to cool in the oxygen which was then pumped off. It now caused the decomposition of 3% only under the same conditions as before. After heating in a vacuum once more to a high temperature it regained more than its original activity decomposing 56.5% in 200 seconds.It is important to note that since poisoning the wire by dissolved oxygen can cut down the rate of change from 46% in 200 seconds to 3y0 the heterogeneous nature of the reaction is conclusively shown. Compariscm of the Heterogeneous Decomposition of Nitrous Oxide with its Homogeneous Decomposition.-The homogeneous reaction depends upon the collision of two molecules whose energy together exceeds 58,500 calories (in terms of gram-molecules). The catalytic decomposition on the other hand is a unimolecular process. The unimolecular change N,O = N + 0 could not occur homogene-ously at 1000" at more than a negligibly small rate compared with the other reactions since it would involve the production of atomic oxygen and the absorption of about 60,000 calories.The heat of activation would therefore probably be enormous. In the catalytic reaction the function of the surface is thus to act as an acceptor for atomic oxygen thereby rendering possible a unimolecular in place of a bimolecular process. This must be regarded as the principal function of the catalyst. What makes the odd oxygen atom more easily detachable is it THE HOMOGENEOUS THERMAL DECOMPOSITION ETC. 335 affinity either for the platinum or for atomic oxygen already on the platinum. Three mechanisms are conceivable 1. Nitrous oxide gives its oxygen atom to the bare platinum surface. A retarding film of atomic oxygen forms. 2a. Nitrous oxide reacts by striking atomic oxygen already on the platinum. 2b. Nitrous oxide reacts with atomic oxygen in gaps in a film of the latter (mechanism anal-ogous to that suggested for interaction of nitrous oxide and hydrogen on platinum).(1) is the natural and probably correct explanation. leading to the correct equation for the reaction velocity. The one difficulty which i t presents arises from Langmuir's statement (Trans. Furuday SOC. 1922 17 653) that even at 1500" Abs. and very low pressures platinum remains completely covered with atomic oxygen. If this is true the retarding film which forms during the decomposi-tion of nitrous oxide and which is only half completed a t about 60 mm. 0, would have to be of a new kind namely a layer of molecular oxygen adsorbed on the primary layer of atomic oxygen. Mechanism (2a) otherwise inadmissible would then have to be assumed.But Langmuir's statement may not be true of the platinum wires used by us and then there is no need to go beyond (1). (It will not do to assume that the presence of nitrous oxide interferes with the completion of the oxygen film since this would imply fairly strong adsorption of the nitrous oxide itself in which case the velocity equation would not be of the right form.) (2b) could apply only if the atomic oxygen film covered nearly the whole surface from quite small pressures because otherwise the greatest velocity would not be a t the beginning of the reaction when there is little or no oxygen present. Nitrous oxide reacting in gaps in a nearly complete film would obey the equation-d[N,O]/dt = Ic[NzO]/[O,]. This demands inverse proportionality of rate to oxygen pressure to which simple form the actual relation does not reduce.The balance of evidence is in favour of (1) and an oxygen film half complete a t 60 mm. With regard to the various energy relationships : Homogeneous reaction E = 58,500 calories for 2 gram-molecules. Surface reaction, Although the real physical significance of E is abundantly shown for homogeneous reactions in surface reactions it is a more complex quantity. If the attempted extrapolation of E to zero decompo-sition really eliminates the influence of the oxygen film then it is probable that 30,000 calories is of the right order for the actual energy of activation. It would then appear that the catalytic reaction has a great advantage over the hypothetical homogeneous unimolecular reaction which would demand a minimum activation of 60,000 calories per gram-molecule.E = 32,500 calories for 1 gram-molecule 336 MITCHELL THE HYDROLYTIC DECOMPOSITION OF The average activation required by a single molecule in the bimolecular homogeneous reaction is 29,250 calories so that, molecule for molecule the catalytic reaction appears to have little advantage from the point of view of energy; we may therefore conclude that the main function of the catalyst in this case is to render possible a unimolecular process in place of one requiring the co-operation of two simultaneously activated molecules. It may perhaps be pointed out in conclusion that any attempt to place a " quantum " interpretation upon. the fact that the experimentally determined E for the catalytic reaction is about half that for the homogeneous reaction is to be deprecated. Such attempts are not in the least justified. Summary. The heterogeneous thermal decomposition of nitrous oxide on a platinum wire has been investigated between 600" and 1200°, the homogeneous change at these temperatures being eliminated by heating the wire only. The reaction is retarded by oxygen and proceeds relatively faster at low than at high pressures. The velocity is represented by the equation : The experimentally determined heat of activation in the catalytic reaction is 32,500 calories per gram-molecule. A comparison is made of this catalytic reaction with the homo-geneous bimolecular decomposition and with the hypothetical homogeneous unimolecular decomposition and the mechanism of the catalysis discussed. - d",O]/dt = W,O1/(1 + b[0,1). We are indebted to the Royal Society for a grant with which part of the apparatus used in this investigation was purchased. PHYSICAL CHEMISTRY LABORATORY, BALLIOL COLLEGE AND TRINITY COLLEGE, OXFORD. [Received October 28th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700327

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

336 MITCHELL THE HYDROLYTIC DECOMPOSITION OF LI1.-The Hydrolytic Decomposition of Phosphorus Trichloride . By ALEC DUNCAN MITCHELL. THE reactions of phosphorous and hypophosphorous acids which have been studied by the author during the last 4 years have led to the conclusion that each of these acids exists in two forms of which one is relatively inert (especially in the case of hypophos PHOSPHORUS TRICHLORIDE 337 phorous acid) and the other is mainly responsible for the reducing properties. Certain considerations have been advanced which point to tautomeric structures in each case thus : HPO(OH) =s= (HO),P and H,PO(OH) HP(OH),. Kinetic studies of the reactions indicate that the more strongly reducing isomeride is normally present in only very small propor-tions and comparison with the properties of organic analogues has been shown to suggest a tervalent phosphorus structure for this isomeride whereas the more stable normal form of each acid con-tains a quinquevalent phosphorus atom.(The term ‘‘ quinque-valent ” is here applied for convenience in the classical sense and without prejudice to the more probable co-ordinated structure.) Such an hypothesis receives further support from a consideration of the properties of nitriles and isonitriles in which again the more pronounced reducing properties are associated with the lower valency of the carbon atom and the greater stability with the higher valency. If these views be correct it would be expected that during the decomposition of phosphorus trichloride by water the compound P(OH) would be formed as an intermediate stage which would change rapidly but not instantly into the ordinary form of phos-phorous acid.Such a change would not be expected to be imtan-faneous because the reverse change in the equilibrium has been found to be measurable. The object of the present research was to test the truth of this deduction and it may be stated a t once that although there are certain complications there is considerable evidence in favour of its validity and therefore of the fundamental hypothesis. E x P E R I M E N T A L. The phosphorus trichloride used was the pure article of commerce and wag carefully redistilled shortly before use. Its purity ww checked by decomposing it with water and after several hours, carrying out (a) a volumetric estimation of chloride and ( b ) a titr-ation of the acidity produced using both methyl-orange and phenolphthalein as indicators the corresponding titres being very closely in the ratio 4 5 as required; the results showed the purity to be 99.6 and 994% as calculated from (a) and (b) respectively.Equal weights of phosphorus trichloride (usually 1 or 2 C.C. = 1.60 or 3.20 g.) were sealed up in thin glass bulbs; one was broken by vigorous shaking in a measured volume of water at a temperature (found by control experiments) such that the heat of reaction raised the The method at first adopted was as follows. VOL. CXXVII. 338 MITCHELL TEE HYDROLYTIC DECOMPOSITION OF whole mixture to 25" ; after 15 seconds of such shaking the solution appeared homogeneous and was at once mixed with a known volume of standasdised iodine solution.Definite portions were withdrawn by a pipette from time to time and titrated by standard sodium thiosulphate solution. Other bulbs were similarly broken and the resulting solutions kept for definite periods before being allowed to react with iodine under exactly the same conditions. The first solution effected reduction very much more rapidly than one which had been kept for say 30 minutes and the latter in turn was con-siderably more reactive than one which had been kept for say, 4 hours. By constructing curves showing the relation between velocity of reaction and concentration of unchanged iodine it was found that the velocity did not fall to the normal value until after the expiration of a t least 2 hours where the normal value is that given for the same concentration of iodine by a solution which has stood for 24 hours or by an artificial mixture of the appropriate amounts of phosphorous and hydrochloric acids.Table I shows the results of a typical experiment in which 3-20 g. of phosphorus trichloride and 200 C.C. of water (giving 201.2 C.C. of solution) react with 10 C.C. of approximately N / 2 iodine the reaction being started (i) 15 seconds and (ii) 24 hours after breaking the bulbs. Titres are shown after intervals of time in minutes for 10 C.C. against N/100-sodium thiosulphate. TABLE I. Time. 0 1 6 9.5 16 22 30 62 115 190 245 321 37 1 (i. ) Titre. 23-59 21.03 18-59 17.42 16-25 15.65 15.20 14.30 13.30 11.98 11.17 10.07 9.33 Difference.2.56 5-00 6.17 7-34 7.94 8.39 9.29 10.29 11-61 12-42 13.52 14.26 -Time. 0 54 116 171 223 275 351 405 4 80 536 (ii.) Titre. 23-59 20.74 19.16 17.87 16.73 15-67 14.17 13-20 11-87 11-00 Difference. 2-86 4.43 5-72 6.86 7-92 9.42 10.39 11-72 12-59 -The initial velocity of (i) is about 60 times that of (ii) but they become equal within the limits of experimental error for equal concentrations of iodine a t a stage corresponding to about 115 minutes after the initial decomposition in (i). I n another experi-ment using double the concentrations of phosphorus trichloride, the control was broken 3 days before starting reaction with iodine, and the other tube 31 minutes before.The curves connecting velocity of reaction with concentration of iodine differed widely a PHOSPHORUS TRICHLORIDE . 339 first but became sensibly identical a t an iodine concentration corresponding to 150 minutes of the second reaction-or 181 minutes after the initial decomposition. It was thus obvious that the "nascent ') solution contained one or more constituents other than normal phosphorous acid, which reacted very readily with iodine and were lacking in a solu-tion which had been similarly made and kept for 24 hours. Tn order to follow the decomposition from another point of view) and also to see whether these differences were caused by the tran-,kilt esi:tence of an osychloride solutions were made as belore, and after 13 seconds rapidly titrated by 2s-sodium hydroxide.* The end-point thus reached was not permanent and the subsequent further development of acidity was followed by X/5-alldi.In other espximents measured portions of the solution were with-clrawn from time to time and titrated with alkali. Both methods showed that only about 98$< of the final acidity was attained within 1 minute and that the remainder was developed with decreasing rapidity during the next 30 minutes after which no further increase could be detected. This type of experiment is exemplified in Table 11 which is placed later in another connexion. The hypo-thetical (HO),P would probably resemble phosphoric acid in its basicity and in any case it would not behave in such a way that its change to HPO(OH) would result in an increase of acidity; its existence would therefore not account for these observations.The results just described made it clear that a compound of the type P(OH),Cl persists for some 30 minutes under the con-ditions of experiment and this might be responsible for a part, a t least of the enhanced reducing power. It was therefore necessary to make some more precise measurements on the persistence of this increased reducing power in order to ascertain definitely \vhether it outlasted the increase of acidity or in other words whether it actually persisted for a period of some hours or whether it became inappreciable after 30 minutes. A more crucial type of experiment was devised 3.2 g. (2 c.c.) of phosphorus trichloride and 200 C.C.of water a t 18.4" were shaken for 15 seconds and attained the temperature of 25"; a t short intervals 20 C.C. of this mixture were mixed with 1 C.C. of N/%iodine and kept for 1 minute; the mixture n~ then rapidly dilutod and titrated with S/50-sodium thiosulphate. The deficiencies in titre corresponding to iodine reduced in the * The titres recorded refer t o phenolphthalein as indicator but parallel results were obtained with methyl-orange so that the use of the more alkaline (and-point does not appear t o have hastened the decomposition of the inter-inediste osychloride. Such a possibility is also excluded by the fact that similar results were obtained by duconiposing with excess of alkali. N 340 MITCHELL THE HYDROLYTIC DECOMPOSITION OF portions used after 1,* 2 5-5 11 and 17 minutes were 2-56 1.64, 1.29 1.19 and 1.16 c.c.respectively and the deficiency then decreased very slowly being still perceptible after 4 hours after 24 hours it was 0-15 c.c. of which 0.08 c.c is due to the ordinary reaction in the 1 minute involved. Experiments of this type showed definitely that the abnormally high reducing power outlasted the increase of acidity. Moreover, numerous experiments showed that in the 20 minutes following the initial alkali titration at least 89% (and usually about 93%) of the additional alkali had been added whereas in the same period the reactivity towards iodine had decreased by 57% at most (and usually by only 4!%-tio~0) ; the hypothetical oxychloride does not, therefore account for the whole of the observed exaltation in reduc-ing power.Table I1 illustrates two parallel experiments in each of which approximately 2 C.C. of phosphorus trichloride were decomposed by 100 C.C. of water; after definite intervals (of t minutes) 10 C.C. of the resulting solutions were (i) titrated with 2N/5-sodium hydr-oxide (ii) allowed to react for 1 minute with 1 C.C. of NIZ-iodine. The table shows for (i) the alkali titre and for (ii) the iodine con-sumption in C.C. as measured by N/50-sodium thiosulphate; in the case of (i) the titrated liquid was allowed to stand for a further period of t' minutes (at the ordinary temperature) and the titration again completed (giving the values shown as final titres) the end-points thus obtained being definite for 24 hours.TABLE 11. t. 1 3 5 9 13 18 34 1320 Titre. 27-58 27-80 28.01 28.13 28.15 28.23 28.30 28.29 Final t'. titre. 24 28.15 25 28.20 34 28.24 100 28-26; 100 28-22 90 28-27 80 28.30 -(ii.) Iodine t. consumed. 0.67 2.75 2.8 2.25 7 1.87 10 1.69 14 1-38 23 1.18 50 0.90 82 0.64 218 0-43 1440 0.12 Normal 0.12 reaction. Numerous experiments have all given similar results and the curves plotted from the decrease of iodine consumption with time differ in type from those representing increase of acidity with time and indicate in agreement with the data quoted above that * On a separate experiment PHOSPHORUS TRICHLORIDE. 34 1 a pronounced and much more persistent reducing effect is super-imposed upon any similar effect which might be attributed to an oxychloride.The smallness of the titration differences and of the earlier time-intervals makes it impossible to attempt a mathematical analysis of the superimposed reducing effects but it is possible to state that the development of acidity proceeds roughly according to a unimolecular law. The hydrolysis was always accompanied by a very slight but definite smell of “ pliosphine,” although its formation did not become pronounced except a t much higher temperatures. It was believed that the anslytical figures quoted which were obtained after similar decomposition together with the use of control experiments through-out precluded the possibility that any of the excess reduction might be due to this trace of by-product but in order to test this possi-bility still further a few experiments were carried out with freshly prepared solutions made from phosphonium iodide which u7as intentionally not purified.About 0-2 g. was dissolved in 100 C.C. of water thus giving a concentration considerably greater than any possible concentration of phosphine in the foregoing experiments. Within a few seconds the solution was tested with regard to (i) its acidity and (ii) its effect on iodine solution. I n the former case the slight acidity remained constant for several days and in the latter case the small iodine consumption was instantaneous and showed no decrease when tested a t intervals of several hours. I n neither respect therefore is there any evidence that the results recorded are in any way due to the accidental presence of traces of impurities of this type.The reduction of mercuric chloride instead of iodine gives results similar to those described herein but these were not investigated in detail. It may be mentioned that the oxychloride POCl is described in t.he literature and that the corresponding arsenic compound is known to react with minimal quantities of water to give As(OH),Cl, but the phosphorus analogue is not recorded. Summary. 1. The solution obtained by the hydrolytic decomposition of phosphorus trichloride has abnormally pronounced reducing proper-ties when first formed; after some hours under the conditions of experiment they become normal. 2 . The solution increases in acidity for about &hour although about 98% of the find acidity is developed almost instantly; the intermediate formation of an oxychloride such as P(OH),Cl would account for this observation 342 BOOTH AND BOWEN THE HEATS OF SOLUTION 3.The duration of increased reducing power is far longer than can be attributed to the intermediate oxychloride and it is suggested that it may be due to the second form of phosphorous acid P(OH),, which does not immediately change to the ordinary form HPO(OH),. 4. The existence of such a second form has already been postuhted by the author on other grounds. UNIVERSITY OF LONDON, SOUTH KENSINGTON S. W. [Received November 20th 1924. 336 MITCHELL THE HYDROLYTIC DECOMPOSITION OF LI1.-The Hydrolytic Decomposition of Phosphorus Trichloride .By ALEC DUNCAN MITCHELL. THE reactions of phosphorous and hypophosphorous acids which have been studied by the author during the last 4 years have led to the conclusion that each of these acids exists in two forms of which one is relatively inert (especially in the case of hypophos PHOSPHORUS TRICHLORIDE 337 phorous acid) and the other is mainly responsible for the reducing properties. Certain considerations have been advanced which point to tautomeric structures in each case thus : HPO(OH) =s= (HO),P and H,PO(OH) HP(OH),. Kinetic studies of the reactions indicate that the more strongly reducing isomeride is normally present in only very small propor-tions and comparison with the properties of organic analogues has been shown to suggest a tervalent phosphorus structure for this isomeride whereas the more stable normal form of each acid con-tains a quinquevalent phosphorus atom.(The term ‘‘ quinque-valent ” is here applied for convenience in the classical sense and without prejudice to the more probable co-ordinated structure.) Such an hypothesis receives further support from a consideration of the properties of nitriles and isonitriles in which again the more pronounced reducing properties are associated with the lower valency of the carbon atom and the greater stability with the higher valency. If these views be correct it would be expected that during the decomposition of phosphorus trichloride by water the compound P(OH) would be formed as an intermediate stage which would change rapidly but not instantly into the ordinary form of phos-phorous acid.Such a change would not be expected to be imtan-faneous because the reverse change in the equilibrium has been found to be measurable. The object of the present research was to test the truth of this deduction and it may be stated a t once that although there are certain complications there is considerable evidence in favour of its validity and therefore of the fundamental hypothesis. E x P E R I M E N T A L. The phosphorus trichloride used was the pure article of commerce and wag carefully redistilled shortly before use. Its purity ww checked by decomposing it with water and after several hours, carrying out (a) a volumetric estimation of chloride and ( b ) a titr-ation of the acidity produced using both methyl-orange and phenolphthalein as indicators the corresponding titres being very closely in the ratio 4 5 as required; the results showed the purity to be 99.6 and 994% as calculated from (a) and (b) respectively.Equal weights of phosphorus trichloride (usually 1 or 2 C.C. = 1.60 or 3.20 g.) were sealed up in thin glass bulbs; one was broken by vigorous shaking in a measured volume of water at a temperature (found by control experiments) such that the heat of reaction raised the The method at first adopted was as follows. VOL. CXXVII. 338 MITCHELL TEE HYDROLYTIC DECOMPOSITION OF whole mixture to 25" ; after 15 seconds of such shaking the solution appeared homogeneous and was at once mixed with a known volume of standasdised iodine solution. Definite portions were withdrawn by a pipette from time to time and titrated by standard sodium thiosulphate solution.Other bulbs were similarly broken and the resulting solutions kept for definite periods before being allowed to react with iodine under exactly the same conditions. The first solution effected reduction very much more rapidly than one which had been kept for say 30 minutes and the latter in turn was con-siderably more reactive than one which had been kept for say, 4 hours. By constructing curves showing the relation between velocity of reaction and concentration of unchanged iodine it was found that the velocity did not fall to the normal value until after the expiration of a t least 2 hours where the normal value is that given for the same concentration of iodine by a solution which has stood for 24 hours or by an artificial mixture of the appropriate amounts of phosphorous and hydrochloric acids.Table I shows the results of a typical experiment in which 3-20 g. of phosphorus trichloride and 200 C.C. of water (giving 201.2 C.C. of solution) react with 10 C.C. of approximately N / 2 iodine the reaction being started (i) 15 seconds and (ii) 24 hours after breaking the bulbs. Titres are shown after intervals of time in minutes for 10 C.C. against N/100-sodium thiosulphate. TABLE I. Time. 0 1 6 9.5 16 22 30 62 115 190 245 321 37 1 (i. ) Titre. 23-59 21.03 18-59 17.42 16-25 15.65 15.20 14.30 13.30 11.98 11.17 10.07 9.33 Difference. 2.56 5-00 6.17 7-34 7.94 8.39 9.29 10.29 11-61 12-42 13.52 14.26 -Time.0 54 116 171 223 275 351 405 4 80 536 (ii.) Titre. 23-59 20.74 19.16 17.87 16.73 15-67 14.17 13-20 11-87 11-00 Difference. 2-86 4.43 5-72 6.86 7-92 9.42 10.39 11-72 12-59 -The initial velocity of (i) is about 60 times that of (ii) but they become equal within the limits of experimental error for equal concentrations of iodine a t a stage corresponding to about 115 minutes after the initial decomposition in (i). I n another experi-ment using double the concentrations of phosphorus trichloride, the control was broken 3 days before starting reaction with iodine, and the other tube 31 minutes before. The curves connecting velocity of reaction with concentration of iodine differed widely a PHOSPHORUS TRICHLORIDE .339 first but became sensibly identical a t an iodine concentration corresponding to 150 minutes of the second reaction-or 181 minutes after the initial decomposition. It was thus obvious that the "nascent ') solution contained one or more constituents other than normal phosphorous acid, which reacted very readily with iodine and were lacking in a solu-tion which had been similarly made and kept for 24 hours. Tn order to follow the decomposition from another point of view) and also to see whether these differences were caused by the tran-,kilt esi:tence of an osychloride solutions were made as belore, and after 13 seconds rapidly titrated by 2s-sodium hydroxide.* The end-point thus reached was not permanent and the subsequent further development of acidity was followed by X/5-alldi.In other espximents measured portions of the solution were with-clrawn from time to time and titrated with alkali. Both methods showed that only about 98$< of the final acidity was attained within 1 minute and that the remainder was developed with decreasing rapidity during the next 30 minutes after which no further increase could be detected. This type of experiment is exemplified in Table 11 which is placed later in another connexion. The hypo-thetical (HO),P would probably resemble phosphoric acid in its basicity and in any case it would not behave in such a way that its change to HPO(OH) would result in an increase of acidity; its existence would therefore not account for these observations.The results just described made it clear that a compound of the type P(OH),Cl persists for some 30 minutes under the con-ditions of experiment and this might be responsible for a part, a t least of the enhanced reducing power. It was therefore necessary to make some more precise measurements on the persistence of this increased reducing power in order to ascertain definitely \vhether it outlasted the increase of acidity or in other words whether it actually persisted for a period of some hours or whether it became inappreciable after 30 minutes. A more crucial type of experiment was devised 3.2 g. (2 c.c.) of phosphorus trichloride and 200 C.C. of water a t 18.4" were shaken for 15 seconds and attained the temperature of 25"; a t short intervals 20 C.C.of this mixture were mixed with 1 C.C. of N/%iodine and kept for 1 minute; the mixture n~ then rapidly dilutod and titrated with S/50-sodium thiosulphate. The deficiencies in titre corresponding to iodine reduced in the * The titres recorded refer t o phenolphthalein as indicator but parallel results were obtained with methyl-orange so that the use of the more alkaline (and-point does not appear t o have hastened the decomposition of the inter-inediste osychloride. Such a possibility is also excluded by the fact that similar results were obtained by duconiposing with excess of alkali. N 340 MITCHELL THE HYDROLYTIC DECOMPOSITION OF portions used after 1,* 2 5-5 11 and 17 minutes were 2-56 1.64, 1.29 1.19 and 1.16 c.c.respectively and the deficiency then decreased very slowly being still perceptible after 4 hours after 24 hours it was 0-15 c.c. of which 0.08 c.c is due to the ordinary reaction in the 1 minute involved. Experiments of this type showed definitely that the abnormally high reducing power outlasted the increase of acidity. Moreover, numerous experiments showed that in the 20 minutes following the initial alkali titration at least 89% (and usually about 93%) of the additional alkali had been added whereas in the same period the reactivity towards iodine had decreased by 57% at most (and usually by only 4!%-tio~0) ; the hypothetical oxychloride does not, therefore account for the whole of the observed exaltation in reduc-ing power. Table I1 illustrates two parallel experiments in each of which approximately 2 C.C.of phosphorus trichloride were decomposed by 100 C.C. of water; after definite intervals (of t minutes) 10 C.C. of the resulting solutions were (i) titrated with 2N/5-sodium hydr-oxide (ii) allowed to react for 1 minute with 1 C.C. of NIZ-iodine. The table shows for (i) the alkali titre and for (ii) the iodine con-sumption in C.C. as measured by N/50-sodium thiosulphate; in the case of (i) the titrated liquid was allowed to stand for a further period of t' minutes (at the ordinary temperature) and the titration again completed (giving the values shown as final titres) the end-points thus obtained being definite for 24 hours. TABLE 11. t. 1 3 5 9 13 18 34 1320 Titre. 27-58 27-80 28.01 28.13 28.15 28.23 28.30 28.29 Final t'.titre. 24 28.15 25 28.20 34 28.24 100 28-26; 100 28-22 90 28-27 80 28.30 -(ii.) Iodine t. consumed. 0.67 2.75 2.8 2.25 7 1.87 10 1.69 14 1-38 23 1.18 50 0.90 82 0.64 218 0-43 1440 0.12 Normal 0.12 reaction. Numerous experiments have all given similar results and the curves plotted from the decrease of iodine consumption with time differ in type from those representing increase of acidity with time and indicate in agreement with the data quoted above that * On a separate experiment PHOSPHORUS TRICHLORIDE. 34 1 a pronounced and much more persistent reducing effect is super-imposed upon any similar effect which might be attributed to an oxychloride. The smallness of the titration differences and of the earlier time-intervals makes it impossible to attempt a mathematical analysis of the superimposed reducing effects but it is possible to state that the development of acidity proceeds roughly according to a unimolecular law.The hydrolysis was always accompanied by a very slight but definite smell of “ pliosphine,” although its formation did not become pronounced except a t much higher temperatures. It was believed that the anslytical figures quoted which were obtained after similar decomposition together with the use of control experiments through-out precluded the possibility that any of the excess reduction might be due to this trace of by-product but in order to test this possi-bility still further a few experiments were carried out with freshly prepared solutions made from phosphonium iodide which u7as intentionally not purified.About 0-2 g. was dissolved in 100 C.C. of water thus giving a concentration considerably greater than any possible concentration of phosphine in the foregoing experiments. Within a few seconds the solution was tested with regard to (i) its acidity and (ii) its effect on iodine solution. I n the former case the slight acidity remained constant for several days and in the latter case the small iodine consumption was instantaneous and showed no decrease when tested a t intervals of several hours. I n neither respect therefore is there any evidence that the results recorded are in any way due to the accidental presence of traces of impurities of this type. The reduction of mercuric chloride instead of iodine gives results similar to those described herein but these were not investigated in detail. It may be mentioned that the oxychloride POCl is described in t.he literature and that the corresponding arsenic compound is known to react with minimal quantities of water to give As(OH),Cl, but the phosphorus analogue is not recorded. Summary. 1. The solution obtained by the hydrolytic decomposition of phosphorus trichloride has abnormally pronounced reducing proper-ties when first formed; after some hours under the conditions of experiment they become normal. 2 . The solution increases in acidity for about &hour although about 98% of the find acidity is developed almost instantly; the intermediate formation of an oxychloride such as P(OH),Cl would account for this observation 342 BOOTH AND BOWEN THE HEATS OF SOLUTION 3. The duration of increased reducing power is far longer than can be attributed to the intermediate oxychloride and it is suggested that it may be due to the second form of phosphorous acid P(OH),, which does not immediately change to the ordinary form HPO(OH),. 4. The existence of such a second form has already been postuhted by the author on other grounds. UNIVERSITY OF LONDON, SOUTH KENSINGTON S. W. [Received November 20th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700336

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

342 BOOTH AND BOWEN THE HEATS OF SOLUTION LII1.-The Heats of Solution and of Decomposition of Chlorine Dioxide. By HENRY BOOTH and EDMUND JOHX BOWEN. THE heats of solution and of decomposition of chlorine dioxide are not recorded in the literature. On account of the increasing con-nexions recognised a t %he present day between structural theories and thermochemical data it was thought that these measurements would be valuable. As a convenient source of chlorine dioxide free from chlorine the method of preparation due to Bray (2. physikd. Chem. 1906 54 463) was used giving a gas containing about an equal volume of carbon dioxide which did not interfere with the measurements to be described. Analyses were also carried out by the method devised by Bray which was found to give accurate results.Heat of Solution.-A dried mixture of chlorine dioxide and carbon dioxidewas passed into about 200 C.C. of water contained in avacuum-jacketed calorimeter the neck of which was closed by a stopper carrying leading-in and exit tubes a Beclcmann thermometer the electrical calibrating coil and a syphon for emptying. After the passage of a suitable quantity of gas the rise of temperature was noted and the liquid run out and analyaed. Stirring was per-formed effectively by the gas current and by gentle shaking from time to time. The carbon dioxide and chlorine dioxide passing through were estimated; the heat loss owing to their specific heats was negligible but a correction was applied for the latent heat of the water vapour carried away in the gas stream deduced from separate.experiments with air. The temperature rises were repro-duced by expending electrical energy in a h e nichrome coil sealed in a very thin elongated glass bulb using an accurate voltmeter and ammeter which had been used for other calorimetric work. The mean of a large number of determinations was 6600 & 200 calories per mol. independent of the concentration of the solutio AND OF DECOMPOSITION OF CHLORINE DIOXIDE. 343 produced. It is interesting to compare this with the heat of solution of chlorine monoxide 9400 calories (Thomsen). Heat of Decomp&ion.-A vacuum- jacketed narrow-necked vessel was fitted with a cemented-in stopper carrying a leading-in tube and a small spark-gap. A thin-walled glass capillary tube reached to the centre of the vessel and contained a thermo-junction com-posed of 40 gauge copper and constantan wire.This was connected to a sensitive voltmeter. The vessel previously evacuated was filled to a pressure less than atmospheric with a dried chlorine dioxide-carbon dioxide mixture and the gas fired with a small spark. The explosions were never violent under these conditions. A typical graph of the voltmeter readings is shown in Fig. 1. After FIG. 1. 1 2 3 4 6 6 7 8 Time in minutes. an initial large rise of temperature the gas quickly came intro equilibrium with the walls of the vessel which had a heat capacity large compared with that of the gas. Over a long period (a-b), the rate of cooling of the walls assumed a constant small value, permitting s n easy extrapolation to the time of the explosion.For calibration a loop of fine nichrome wire was introduced, the calorimeter being filled with air and a suitable amount of electrical energy expended in it during a period of about 10 seconds, controlled by an accurate stop-watch. The wattage was measured with a voltmeter and ammeter which had been used before for calorimetric work. Curves of exactly the same character as Fig. 1 were obtained. A correction of 7% was found t o be necessary because of the heat conducted away along the leads of the calibrat-ing coil. The heat capacity of the coil introduced a negligible correction. In 18 preliminary measurements the amount of chlorine dioxid 344 BOOTH AND BOWEN THE HEATS OF SOLUTION ETC. in the calorimeter during each experiment was determined by measuring the pressure using a capillary mercury manometer the percentage of chlorine dioxide in the gaseous mixture being deter-mined by separate analyses.The mean value of these results was 23,500 calories per mol. In the final experiments an evacuated vessel of known volume was connected in parallel with the calorimeter during the filling so that the same gaseous mixture entered both vessels. After discon-nexion potassium iodide solution was allowed to enter and the liquid titrated. Other experiments showed that no undecomposed chlorine dioxide remained in the calorimeter after the explosion. ResuZts.4alories per division of millivoltmeter 1.1 10. Titrating flask-volume 275.0 C.C. Calorimeter-volume 480.0 C.C.Neutral iodine titre (c.c.) of flask. No. N 120. 1 15-25 2 25.00 3 15.45 4 15.25 6 3 1-55 Mols. C10, x l o 3 in calorimeter. 1.33 2.18 1.35 1.33 2-75 Extrapolated thermo-couple divisions. Calories. 26.5 29.4 47-5 52-7 26-0 28.7 27.0 30.0 60.0 66.6 Heat of decom-position per mol. 22,100 24,100 21,400 22,500 24,200 Weighted mean of all results 23,500 calories per mol. Taking the heat of decomposition of chlorine dioxide as 23,500 cals. per mol. from these experiments and combining it with the heat of dissociation of chlorine 55,000 cals. (Henglein 2. anorg. Chem., 1922 123 137; Wohl 2. Elektrochem. 1924 30 36) we calculate for the imaginary process of the dissociation of a chlorine dioxide molecule into a chlorine atom and an oxygen molecule (310 + 4000 cals.= C1 + 0,. This small difference of energy between a molecule and the free atoms composing it is important in connexion with the meaning to be attached to a " chemically active " molecule. The absorption spectrum of gaseous chlorine dioxide (Kabitz Diss. Bonn 1905) consists of groups of lines with an approximate constant frequency merenee. This grouping is well emphasised in the bands of the substance dissolved in carbon tetrachloride (Bowen J. 1923 123, 1199) which have almost exactly the same positions. According to the modern theory of band spectra these bands are to be attributed to changes of vibrational quanta superimposed upon an electronic activation quantum change. Calculating from the observed constant frequency difference of 2 x 1013 by the relation Q = Nhv we obtain for one vibrational quantum Q = 2000 calories CRYOSCOPIC MEASUREMENTS WITH NITROBENZENE.PART 111. 345 This deduction neglects the difference between the vibrational quanta of normal and electronically activated molecules but this difference is neglible here. We know from the application of the quantum theory to the specific heats of gases that vibrational quanta begin to make their appearance among the molecules at temperatures not far above the ordinary temperature. Since only two vibrational quanta are necessary t o give a chlorine dioxide molecule an energy equal to its dissociation products and since as shown in a later paper the gas is remarkably stable thermally it would appear that energy of vibration is not sufficient to activate s molecule chemically but that elect'ronic activation is reqnira4.BALLIOL AND TRINITY PIIYSICAL CHEMISTRY LSBORATORY, OsFoRn. [Beceivecl December 1 i t h L M, 342 BOOTH AND BOWEN THE HEATS OF SOLUTION LII1.-The Heats of Solution and of Decomposition of Chlorine Dioxide. By HENRY BOOTH and EDMUND JOHX BOWEN. THE heats of solution and of decomposition of chlorine dioxide are not recorded in the literature. On account of the increasing con-nexions recognised a t %he present day between structural theories and thermochemical data it was thought that these measurements would be valuable. As a convenient source of chlorine dioxide free from chlorine the method of preparation due to Bray (2. physikd.Chem. 1906 54 463) was used giving a gas containing about an equal volume of carbon dioxide which did not interfere with the measurements to be described. Analyses were also carried out by the method devised by Bray which was found to give accurate results. Heat of Solution.-A dried mixture of chlorine dioxide and carbon dioxidewas passed into about 200 C.C. of water contained in avacuum-jacketed calorimeter the neck of which was closed by a stopper carrying leading-in and exit tubes a Beclcmann thermometer the electrical calibrating coil and a syphon for emptying. After the passage of a suitable quantity of gas the rise of temperature was noted and the liquid run out and analyaed. Stirring was per-formed effectively by the gas current and by gentle shaking from time to time.The carbon dioxide and chlorine dioxide passing through were estimated; the heat loss owing to their specific heats was negligible but a correction was applied for the latent heat of the water vapour carried away in the gas stream deduced from separate. experiments with air. The temperature rises were repro-duced by expending electrical energy in a h e nichrome coil sealed in a very thin elongated glass bulb using an accurate voltmeter and ammeter which had been used for other calorimetric work. The mean of a large number of determinations was 6600 & 200 calories per mol. independent of the concentration of the solutio AND OF DECOMPOSITION OF CHLORINE DIOXIDE. 343 produced. It is interesting to compare this with the heat of solution of chlorine monoxide 9400 calories (Thomsen).Heat of Decomp&ion.-A vacuum- jacketed narrow-necked vessel was fitted with a cemented-in stopper carrying a leading-in tube and a small spark-gap. A thin-walled glass capillary tube reached to the centre of the vessel and contained a thermo-junction com-posed of 40 gauge copper and constantan wire. This was connected to a sensitive voltmeter. The vessel previously evacuated was filled to a pressure less than atmospheric with a dried chlorine dioxide-carbon dioxide mixture and the gas fired with a small spark. The explosions were never violent under these conditions. A typical graph of the voltmeter readings is shown in Fig. 1. After FIG. 1. 1 2 3 4 6 6 7 8 Time in minutes. an initial large rise of temperature the gas quickly came intro equilibrium with the walls of the vessel which had a heat capacity large compared with that of the gas.Over a long period (a-b), the rate of cooling of the walls assumed a constant small value, permitting s n easy extrapolation to the time of the explosion. For calibration a loop of fine nichrome wire was introduced, the calorimeter being filled with air and a suitable amount of electrical energy expended in it during a period of about 10 seconds, controlled by an accurate stop-watch. The wattage was measured with a voltmeter and ammeter which had been used before for calorimetric work. Curves of exactly the same character as Fig. 1 were obtained. A correction of 7% was found t o be necessary because of the heat conducted away along the leads of the calibrat-ing coil.The heat capacity of the coil introduced a negligible correction. In 18 preliminary measurements the amount of chlorine dioxid 344 BOOTH AND BOWEN THE HEATS OF SOLUTION ETC. in the calorimeter during each experiment was determined by measuring the pressure using a capillary mercury manometer the percentage of chlorine dioxide in the gaseous mixture being deter-mined by separate analyses. The mean value of these results was 23,500 calories per mol. In the final experiments an evacuated vessel of known volume was connected in parallel with the calorimeter during the filling so that the same gaseous mixture entered both vessels. After discon-nexion potassium iodide solution was allowed to enter and the liquid titrated.Other experiments showed that no undecomposed chlorine dioxide remained in the calorimeter after the explosion. ResuZts.4alories per division of millivoltmeter 1.1 10. Titrating flask-volume 275.0 C.C. Calorimeter-volume 480.0 C.C. Neutral iodine titre (c.c.) of flask. No. N 120. 1 15-25 2 25.00 3 15.45 4 15.25 6 3 1-55 Mols. C10, x l o 3 in calorimeter. 1.33 2.18 1.35 1.33 2-75 Extrapolated thermo-couple divisions. Calories. 26.5 29.4 47-5 52-7 26-0 28.7 27.0 30.0 60.0 66.6 Heat of decom-position per mol. 22,100 24,100 21,400 22,500 24,200 Weighted mean of all results 23,500 calories per mol. Taking the heat of decomposition of chlorine dioxide as 23,500 cals. per mol. from these experiments and combining it with the heat of dissociation of chlorine 55,000 cals.(Henglein 2. anorg. Chem., 1922 123 137; Wohl 2. Elektrochem. 1924 30 36) we calculate for the imaginary process of the dissociation of a chlorine dioxide molecule into a chlorine atom and an oxygen molecule (310 + 4000 cals. = C1 + 0,. This small difference of energy between a molecule and the free atoms composing it is important in connexion with the meaning to be attached to a " chemically active " molecule. The absorption spectrum of gaseous chlorine dioxide (Kabitz Diss. Bonn 1905) consists of groups of lines with an approximate constant frequency merenee. This grouping is well emphasised in the bands of the substance dissolved in carbon tetrachloride (Bowen J. 1923 123, 1199) which have almost exactly the same positions.According to the modern theory of band spectra these bands are to be attributed to changes of vibrational quanta superimposed upon an electronic activation quantum change. Calculating from the observed constant frequency difference of 2 x 1013 by the relation Q = Nhv we obtain for one vibrational quantum Q = 2000 calories CRYOSCOPIC MEASUREMENTS WITH NITROBENZENE. PART 111. 345 This deduction neglects the difference between the vibrational quanta of normal and electronically activated molecules but this difference is neglible here. We know from the application of the quantum theory to the specific heats of gases that vibrational quanta begin to make their appearance among the molecules at temperatures not far above the ordinary temperature. Since only two vibrational quanta are necessary t o give a chlorine dioxide molecule an energy equal to its dissociation products and since as shown in a later paper the gas is remarkably stable thermally it would appear that energy of vibration is not sufficient to activate s molecule chemically but that elect'ronic activation is reqnira4. BALLIOL AND TRINITY PIIYSICAL CHEMISTRY LSBORATORY, OsFoRn. [Beceivecl December 1 i t h L M,

ISSN:0368-1645    

DOI:10.1039/CT9252700342

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

CRYOSCOPIC MEASUREMENTS WITH NITROBENZENE. PART 111. 345 LIV.-Cryoscopic Measurements with Nitrobenzene. Purl I I I . Equilibrium in Nitrobenzene fhlutiom. By FREDERICK STANLEY BROWN. So far as the author is aware no example of chemical equilibrium in solution which obeys the law of mass action has becn studied by the freezing-point method most work in this direction has been done on strong electrolytes which do not obey this law and on associated substances where this is doubtful. While woyking on asscciated substances it was considered advisable to te5,t the experimental methods by the study of examples which undoub tedlp do obey the law of mass action polynitro-aromatic compotlnds form, with aromatic hydrocarbons molecular compounds which disso-ciate in solution in accordance with the law of inass action ;as has been shown by solubility measurements (Behrend 2.phylsilcal. Chem. 1894 15 183; Kuriloff ibid. 1897 24 697). I n this paper the dissociation of naphthalene picrate and of naphthalene-trinitrotoluene in nitrobenzene solution is investigated. Previous work (Brown and Bury J. 1024 125 2219) has shown that naphthalene is a normal solute in nitrobenzene and preliminary experiments have established the fact that trinitrotolume mid, somewhat surprisingly picric acid are also normal. E X P E R I M E N T -4 L. The experimental methods have been fully described in previous papers (Roberts and Bury J. 1923 123 2037 ; Brown and Bury, Zoc. cit.). All work described in this paper has been ca,rried out in moist nitrobenzene in contact with the salt hydrate pair N 316 BROWN CRYOSCOPIC MEASUREMENTS WITH NITROBENZENE.Na,SO,,O-10H20. It has been found advantageous to insert a tlhin copper disk as baffle plate in the inner tube about half an inch above the surface of the liquid to prevent splashing which may cause an appreciable error in the calculated concentration of the remaining solution at the end of a long series. The compounds were prepared by crystallising equimolecular proportions of the pure components from alcohol followed by slow drying in a vacuum over calcium chloride. Quick drying in a warm atmosphere results in loss of naphthalene. Naphthalene picrate was obtained in golden-yellow needles m. p. 149.5'. Naphthalene-trinitrotoluene separated as very pale yellow needles melting per-sistently at 96.4" which is a little lower than the value 97-98' given by Hepp (Annnlen 1882 215 378).Results. A + B if n represents the total mols. of compound added and a the fraction dissociated there are at equilibrium (1 - a)n mols. of undissociated compound and a n of each of the two components the total mols. of solute being (1 + a)n. By substituting this last value in Brown and Bury's equation (4) one obtains the expression where n represents mols. of solvent At is the observed depression, C and A! are the factors to compensate for the water in solution, and k has the value 55-81. 111 an equilibrium of the type AB At = 4 + At = k[(l + (4% + Qn,l/[(l + a)n + (C + 1)%1, This leads to (X = ~ ~ / n [ { A t / ( k - At)) - C] - 1 .. . - (1) If the concentrations in the mass action equation K = [A][B]/[AB] are again expressed aa mol. fractions we arrive at a value for the equilibrium constant in measurable quantities :-The results are shown in the accompanying tables each of which contains the collected data of three independent series. The first column gives the number of grams of compound per 100 grams of solvent (w) At is the observed depression a(obs.) and K arc calculated from equations (1) and (2). The values of a (calc.) have been obtained from equation (2) assuming the mean value of K . Taking into account the possible error of 0*003' in the deter-mination of At, the agreement between the observed and calcu-lated values of a and the constancy of K are satisfactory. The Free Energy of Formation of Naphthalene Picrate.Naphthalene picrate reaches its solubility limit a t a depression (Aft') of 2*380° corresponding to an actual temperature of 2.966". K = a2n/[l - a][(1 + a)n + (C + l)n,] . . . (2 PART 111. EQ LJILIBRIL31 IX KITBOBENZENE SOLUTIOK. 347 TABLE I. ~ol~zte-Na,~hthalene-trinitrotoluene (Molecnlar weight = 355.2). w. Atu. a (obs.). a (calc.). K . 1.0547 0.399" 0.9'33 0.993 0.524 2.4362 0.907 0.980 0.9s-k 0.394 2.7309 1,014 0.978 0.982 0.408 4-2 138 1.5'45 0.972 0.07 L 0.485 5.L427 1.863 0.960 0.965 0.392 6.1878 2.227 0.960 0.959 0.467 6.4683 2.319 0.957 0-957 0.455 7-243 1 2.578 0.952 0.950 0.454 7.3 5 94 2.620 0.933 0.952 0.471 8.5054 2.995 0.9'47 0.947 0.468 8.6726 8.057 0.931 0.945 0.525 9.4009 3.290 O.l)-k(j 0.942 0.504 10.645 :*cis1 0.937 0.935 0.506 11.766 4.010 0.927 0.929 0.439 Mean 0.464 TABLE 11.Solute-Naphthalene picrate (RIolecular weight = 357.3). v U' . 2.0664 2.1831 3,3670 4.2689 4.6508 5-3871 6.0586 0.3179 6.7241 At,,. 0.766" 0.806 1.225 1.532 1-662 1.908 2.127 2.210 2-33 9 a (obs.). 0.977 0.970 0.956 0,942 0.941 0.929 0.925 0.916 0.908 a (calc.). 0.971 0.969 0.955 0.945 0.940 0.932 0.925 0.923 0-918 Mean I - . 0.286 0.23 1 0.234 0.217 0.232 0.215 0-228 0.208 0.20 1 0.228 We are thus in a position to calculate its free energy of formation by means of the usual van 't Hoff isotherm :-A = RTlnN x hT2/N3 - RTlnK, where N, AT2 and AT3 represent initial concentrations of components and campound respectively expressed in the same units i.e. rnol. fractions that were used in determining K the equilibrium constant. We are concerned with the formation of the solid compound from tlic solid components. The initial concentrations will therefore be those concentrations at which the solids are in equilibrium with the saturated solution i . e . their solubilities. At the solubility limit the picrate is still considerably dissociated, but the solubility N, of the undissociated compound can be obtained direct from the freezing-point readings by plotting the logarithm of i t s mol. fraction (1 - a)u/[(l + a)n + (C + 1)n9] against the observed depression and iaaking a small extrapolation to 2.380". This leads t o a value of ATp = 0.00187.N* 348 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES The limits of solubility of the components are not reached in the range of experiments but their " ideal " solubilities a t the same temperature (3" approx.) may be calculated in mol. fractions by the method of Hildebrand (" Solubility," American Chemical Society Monograph 1924 p. 37) a justifiable proceeding in view of the fact that it has been shown that they form ideal solutions. Assuming for picric acid a molecular latent heat of fusion of 4160 cals. (Morti-mer J. Amer. Chem. Xoc. 1922 44 1416) and a melting point of 122" Nz becomes 0.1021. No specific heat data are available and neglect of these must make the result slightly low. Using the complete thermal data as given by Hildebrand (op.cit.) the calcu-lated value of N is 0-1857. By substituting the above values for iV in the van 't Hoff isotherm, and taking K = 0.228 as a mean the free energy of formation of naphthalene picrate a t 3" is 2083 cals. per mol. This is in close agreement with values given by Bronsted (2. physikal. Chern., 1912 78 284) of 2050 cals. at 20.1" from E.M.F. measurements, and of 2150 and 2190 cals. at 0 and 20° respectively from solubility data. I am indebted to the Department of Scientific and Industrial Research for a maintenance grant and to M i . C. R. Bury for having suggested this work and for advice during its progress. EDWARD DAVIES CHEMICAL LABORATORIES, UNIVERSITY COLLEGE OF WALES, ABERYSTWYTH. IReceived. December 15th 1924. CRYOSCOPIC MEASUREMENTS WITH NITROBENZENE.PART 111. 345 LIV.-Cryoscopic Measurements with Nitrobenzene. Purl I I I . Equilibrium in Nitrobenzene fhlutiom. By FREDERICK STANLEY BROWN. So far as the author is aware no example of chemical equilibrium in solution which obeys the law of mass action has becn studied by the freezing-point method most work in this direction has been done on strong electrolytes which do not obey this law and on associated substances where this is doubtful. While woyking on asscciated substances it was considered advisable to te5,t the experimental methods by the study of examples which undoub tedlp do obey the law of mass action polynitro-aromatic compotlnds form, with aromatic hydrocarbons molecular compounds which disso-ciate in solution in accordance with the law of inass action ;as has been shown by solubility measurements (Behrend 2.phylsilcal. Chem. 1894 15 183; Kuriloff ibid. 1897 24 697). I n this paper the dissociation of naphthalene picrate and of naphthalene-trinitrotoluene in nitrobenzene solution is investigated. Previous work (Brown and Bury J. 1024 125 2219) has shown that naphthalene is a normal solute in nitrobenzene and preliminary experiments have established the fact that trinitrotolume mid, somewhat surprisingly picric acid are also normal. E X P E R I M E N T -4 L. The experimental methods have been fully described in previous papers (Roberts and Bury J. 1923 123 2037 ; Brown and Bury, Zoc. cit.). All work described in this paper has been ca,rried out in moist nitrobenzene in contact with the salt hydrate pair N 316 BROWN CRYOSCOPIC MEASUREMENTS WITH NITROBENZENE.Na,SO,,O-10H20. It has been found advantageous to insert a tlhin copper disk as baffle plate in the inner tube about half an inch above the surface of the liquid to prevent splashing which may cause an appreciable error in the calculated concentration of the remaining solution at the end of a long series. The compounds were prepared by crystallising equimolecular proportions of the pure components from alcohol followed by slow drying in a vacuum over calcium chloride. Quick drying in a warm atmosphere results in loss of naphthalene. Naphthalene picrate was obtained in golden-yellow needles m. p. 149.5'. Naphthalene-trinitrotoluene separated as very pale yellow needles melting per-sistently at 96.4" which is a little lower than the value 97-98' given by Hepp (Annnlen 1882 215 378).Results. A + B if n represents the total mols. of compound added and a the fraction dissociated there are at equilibrium (1 - a)n mols. of undissociated compound and a n of each of the two components the total mols. of solute being (1 + a)n. By substituting this last value in Brown and Bury's equation (4) one obtains the expression where n represents mols. of solvent At is the observed depression, C and A! are the factors to compensate for the water in solution, and k has the value 55-81. 111 an equilibrium of the type AB At = 4 + At = k[(l + (4% + Qn,l/[(l + a)n + (C + 1)%1, This leads to (X = ~ ~ / n [ { A t / ( k - At)) - C] - 1 .. . - (1) If the concentrations in the mass action equation K = [A][B]/[AB] are again expressed aa mol. fractions we arrive at a value for the equilibrium constant in measurable quantities :-The results are shown in the accompanying tables each of which contains the collected data of three independent series. The first column gives the number of grams of compound per 100 grams of solvent (w) At is the observed depression a(obs.) and K arc calculated from equations (1) and (2). The values of a (calc.) have been obtained from equation (2) assuming the mean value of K . Taking into account the possible error of 0*003' in the deter-mination of At, the agreement between the observed and calcu-lated values of a and the constancy of K are satisfactory. The Free Energy of Formation of Naphthalene Picrate.Naphthalene picrate reaches its solubility limit a t a depression (Aft') of 2*380° corresponding to an actual temperature of 2.966". K = a2n/[l - a][(1 + a)n + (C + l)n,] . . . (2 PART 111. EQ LJILIBRIL31 IX KITBOBENZENE SOLUTIOK. 347 TABLE I. ~ol~zte-Na,~hthalene-trinitrotoluene (Molecnlar weight = 355.2). w. Atu. a (obs.). a (calc.). K . 1.0547 0.399" 0.9'33 0.993 0.524 2.4362 0.907 0.980 0.9s-k 0.394 2.7309 1,014 0.978 0.982 0.408 4-2 138 1.5'45 0.972 0.07 L 0.485 5.L427 1.863 0.960 0.965 0.392 6.1878 2.227 0.960 0.959 0.467 6.4683 2.319 0.957 0-957 0.455 7-243 1 2.578 0.952 0.950 0.454 7.3 5 94 2.620 0.933 0.952 0.471 8.5054 2.995 0.9'47 0.947 0.468 8.6726 8.057 0.931 0.945 0.525 9.4009 3.290 O.l)-k(j 0.942 0.504 10.645 :*cis1 0.937 0.935 0.506 11.766 4.010 0.927 0.929 0.439 Mean 0.464 TABLE 11.Solute-Naphthalene picrate (RIolecular weight = 357.3). v U' . 2.0664 2.1831 3,3670 4.2689 4.6508 5-3871 6.0586 0.3179 6.7241 At,,. 0.766" 0.806 1.225 1.532 1-662 1.908 2.127 2.210 2-33 9 a (obs.). 0.977 0.970 0.956 0,942 0.941 0.929 0.925 0.916 0.908 a (calc.). 0.971 0.969 0.955 0.945 0.940 0.932 0.925 0.923 0-918 Mean I - . 0.286 0.23 1 0.234 0.217 0.232 0.215 0-228 0.208 0.20 1 0.228 We are thus in a position to calculate its free energy of formation by means of the usual van 't Hoff isotherm :-A = RTlnN x hT2/N3 - RTlnK, where N, AT2 and AT3 represent initial concentrations of components and campound respectively expressed in the same units i.e. rnol. fractions that were used in determining K the equilibrium constant. We are concerned with the formation of the solid compound from tlic solid components. The initial concentrations will therefore be those concentrations at which the solids are in equilibrium with the saturated solution i . e . their solubilities. At the solubility limit the picrate is still considerably dissociated, but the solubility N, of the undissociated compound can be obtained direct from the freezing-point readings by plotting the logarithm of i t s mol. fraction (1 - a)u/[(l + a)n + (C + 1)n9] against the observed depression and iaaking a small extrapolation to 2.380". This leads t o a value of ATp = 0.00187.N* 348 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES The limits of solubility of the components are not reached in the range of experiments but their " ideal " solubilities a t the same temperature (3" approx.) may be calculated in mol. fractions by the method of Hildebrand (" Solubility," American Chemical Society Monograph 1924 p. 37) a justifiable proceeding in view of the fact that it has been shown that they form ideal solutions. Assuming for picric acid a molecular latent heat of fusion of 4160 cals. (Morti-mer J. Amer. Chem. Xoc. 1922 44 1416) and a melting point of 122" Nz becomes 0.1021. No specific heat data are available and neglect of these must make the result slightly low. Using the complete thermal data as given by Hildebrand (op. cit.) the calcu-lated value of N is 0-1857. By substituting the above values for iV in the van 't Hoff isotherm, and taking K = 0.228 as a mean the free energy of formation of naphthalene picrate a t 3" is 2083 cals. per mol. This is in close agreement with values given by Bronsted (2. physikal. Chern., 1912 78 284) of 2050 cals. at 20.1" from E.M.F. measurements, and of 2150 and 2190 cals. at 0 and 20° respectively from solubility data. I am indebted to the Department of Scientific and Industrial Research for a maintenance grant and to M i . C. R. Bury for having suggested this work and for advice during its progress. EDWARD DAVIES CHEMICAL LABORATORIES, UNIVERSITY COLLEGE OF WALES, ABERYSTWYTH. IReceived. December 15th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700345

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

348 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES LV.-Constitutional Studies in the MonocaTboxylic Acids Derived from Sugars. Part 111. The Iso-meric Tetramethyl Galactonolactones and Trimethyl A rabonolactones. By JOHN PRYDE EDMUND LANGLEY HIRST and ROBERT WILLIAM HUMPHREYS. IN Part I (J. 1923,123,1808) two isomeric tetramethyl d-galactono-lactones were described-one prepared by methylation of d-galac-tonolactone had a lzevorotation of - 29.5" and it was suggested, a 1 4-structureY whilst the other obtained by the oxidation of tetramethyl d-galactose had a dextrorotation of + 106.7". To this a 1 5-structure was assigned. Levene and Meyer ( J . Biol. Chern., 1924 60 167) using the same methods prepared two isomeric tetramethyl mannonolactones both isomerides possessing in thi I S THE &IOXOCARBOSYLIC ACIDS ETC.PART 111. 349 case dextrorotations,* as would be expected according to the Hudson rule ( J . Amer. C‘hem. Soc. 1910,32 338) if 1 4- and 1 5-structures are ascribed to these lactones. The present communication deals with further observations on these tetramethyl galactonolactones, and with an extension of the investigations which reveals a similar isomerism of trimethyl E-arabonolactone. Pischer (Ber. 1595 28 1154) has shown that the action of dry nietlhyl-alcoholic hydrogen chloride on galactose produces at least one other form of methyl galactoside in addition to the well-characterised a- and p-forms of the normal methyl hexoside. Irvine and Cameron (J. 1905 87 900) showed that this additional form or forms may be converted on methylation into a tetramethyl niethylgalactoside isomeric with the normal tetramethyl cc- and F-methyl-d-galactosides and that on hydrolysis the abnormal form gave rise to a tetramethyl d-galactose witlh a much lower dextro-rotation than that obtained from the normal cc- and p-forms.Later, Miss Cunningham (J. 1918. 113 596) correlated this third form it11 the reactive “ y ” series of sugars. With the view of eliminating complications dependent on the formation of such reactive types we have made use in certain of our investigations of the process of Haworth (J. 1915 107 S), in which the free sugar is inethylated directly by methyl sulphate and caustic soda. Nevertheless when the total product from this process was converted into tetramethyl galactose the equilibrium rotation of the latter in water was well below that quoted by previous workers (compare Irvine and Cameron J.1904 85, 1071; Schlubach and Moog Ber. 1923 56 [B] 1957). The tetramethyl galactose used in the previous work (Part I Zoc. cit.) was obtained by this direct methylation process and showed [cc], +- 54.9” in water. It was recognised a t the time that this value was belon- the standard values already quoted but no explanation of the anomaly was then forthcoming since the method used in preparing the methylated sugar mas known to give when applied to glucose a homogeneous tetramethyl glucose showing the normal rotation. The question has iiow been further investigated and the fact that direct methylation of galactose with methyl sulphate ?-ields a tetramethyl galactose with a specific rotation well below the normal value has been substantiated the explanation would appear to be that during the first stages of thc methylation while the reducing group is being substituted.isomeric methyl galactosides * Levene and Meyer (Zoc. cit. 168) say ‘. It is peculiar that the two tetra-mctliyl lactones should rotate in opposite directions. This peculiarity requires elucidation.” This is obviously in error the statement presumably referring to the acids 350 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES are formed containing respectively the 1 5- and 1 4-oxide linking. On further methylation these give rise to a mixture of tetramethrl methylgalactosides containing the amylene-oxidic form in excess.* Thus utilising as initial material a homogeneous tetramethyl galactose ([.IF + 117.3" in water) which had in turn been pre-pared from crystalline a-methyl-d-galactoside we have obtained a tetramethyl galactonolactone with a much higher dextrorotatioii than that previously quoted for the 1 5-isomeride namely 160.7" in place of 106.7".From the evidence now at our disposal we believe that the higher value must be assigned to the pure 1 5-isomeride of the lactone and that the previously described dextrorotatory lactone is not a homogeneous form but is to be regarded as a mixture of the 1 5 and 1 4 forms. Similar anomalous rotations-in this case lower still-have been observed when tetra-methyl galactose and the corresponding lactone have been pre-pared from the mixed methylgalactosides obtained from Fisclier's acid methyl alcohol process.Here the proportion of 1 4 form in the mixture is greater than can be obtained by direct methylation with methyl sulphate. From certain preparations of these mixed lactones a crystalline tetramethyl galactonamide has been obtained. The yield of recrystallised material and the result of the action of alkaline hypochlorite on the amide (compare Irvine and Pryde, 1924 125 1045) are such that further support is gained for the view that the original sugars and the lactones and amides prepared from them were mixtures of the 1 5- and 1 4-isomerides. The reaction of the pure isomeric amides is now being studied. A parallel series of investigations on the corresponding deriv-atives of Z-arabinose gave results similar to those encountered in the case of galactose.Starting from crystalline trimethyl a-methyl-I-arabinoside a dextrorototory trimethyl arabonolactone has been obtained having an initial specific rotation in water (15 minutes after solution) of + 138" falling in the course of 24 hours to + 22-4". This must be regarded as a homogeneous form and since Hirst and Robertson (following paper) have obtained evidence which establishes the presence of the 1 5 type of oxide linking in normd fully methylated arabinose it follows that the new lactone also possesses the 1 5-oxide linking. It is evident from a study * In a recent communication by Haworth Ruell and Westgarth (J. 1924, 125 2468) which appeared after the present paper had been sent in for publication the isolation of the 1 4-oxidic form of tetramethyl galactose and the corresponding lactone is described and it is pointed out that our original preparation of 1 5-tetramethyl galactonolactone contained an admixture of the 1 4 form.As is clear from the results now described we are in complete agreement with Haworth and his collaborators both as regards his correction of the earlier work and his deductions therefrom.-J. P IN THE MONOCARBOXYLIC ACIDS ETC. PART 111. 351 of the valency configuration in a compound of this type that the oxide ring although attached at one end to a non-asymmetric, terminal carbon atom must be definitely oriented eitber to the right- or to the left-hand side of the carbon chain and the applic-ation of Hudson's rule (Zoc.cit.) shows that in this trimethyl arabonolactone the ring is on the right of the carbon chain. It is also of interest to compare the dextrorotation of this rnethylatecl lactone with the lrevorotation of the non-methylated arabonolactone obtained by direct oxidation of the free sugar a case quite parallel to that of the galactose derivatives. Experiments are in progress with the view of obtaining the pure lzevorotatory isomeride of the methylated lactone by the method previously utilised for the preparation of the lzvorotatory isomeride of tetramethyl galnctono -lactone. On subjecting I-arabinose to the action of dry hydrogen chloride in methyl alcohol followed by methylation of the mixed ambinosides, the trimethyl arabinose obtainable has an equilibrium rotation in water m7ell below that found by Purdie and Rose $- 127.2" (J., 1906 89 1204) and the trimethyl arabonolactone obtained from this sugar on oxidation likewise has a rotation much below that of the homogeneous 1 5-lactone already described.Further, preparations of mixed arabinosides which when hydrolysed aizd oxidised with bromine give rise to trimethyl arabonolactones M ith anomalous low rotations also behave in an anomalous way when oxidised with nitric acid. In place of dimethyl trimethoxyglutarate, there was obtained a mixture of this compound with what is apparently the lactone of a monoearboxylic acid presumably the 1 4-trimethyl arabonolactone and the yield of trimethoxy-glutardiamide obtained from this mixture is in agreement with these views as to its composition.In our opinion these results point to the existence of isomeric arabinoses and arabonolactsnes with 1 5- and 1 4-oxygen bridges and to the fact that a mixture of the isomeric sugars is obtained 011 treating arabinose with acid methyl alcohol. It is of great interest that galactose and arttbinose exhibit this marked tendency to react in both 1 5- and 1 4-forms-the former being the normal form in both cases-undcr condition3 which so far as our own observations and those of other worker.; go lead to the production of only one form in the cases of glucose H OH H/OH HIOH $10 H H OH HtQH K OH EX1 OH ILojli HOIH HO H H E p F HO H Galactose. Arabinose. Glucose. Xylose 352 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES and xylose.In this respect the relationships between the formulae of galactose and arabinose on the one hand and between those of glucose and xylose on the other hand are suggestive. E x P E R I M E N T A L . 1 :5-!l'etramethyl d-Gaktctonolactone .-Pure recrystallised a-methyl-galactoside monohydrate ([a]';' + 177" for c = 04371 ; Fischer, loc. cit. gives Cay:' + 179") was methylated in the usual way with methyl sulphate and sodium hydroxide followed by two treatments with methyl iodide and silver oxide. The fully methylated product after distillation had n:' 1.4505 and on being heated for 5 hours a t 100" in 3% methyl-alcoholic hydrogen chloride in a sealed tube, it had the equilibrium rotation [a]:' + 96.5" (c = 0.728). Hydro-lysis by 8% aqueous hydrochloric acid produced a viscous syrup which after distillation had n::" 1.4633 and [a]t>"' + 117.3" (c = 0.996 ; equilibrium rotation in water).The tetramethyl galactose was oxidised with bromine (see Part I loc. cit.) and the resulting tetramethyl galactonolactone which distilled a t 112-116"/0-57 mm. as a mobile syrup had n:' 1-4574 and showed in water (c = 1.086) [a]:'" + 160.67" (5 minutes after the preparation of the solution) + 72.54" (after 4.5 hours) and [a]:"' + 47.58" (after 20 hours constant) [Found C = 51.08 ; H = 7-84 ; OMe = 52.7. Calc. for C,H,O,(OMe), C = 51.28 ; H = 7.69 ; OMe = 53.0y0]. On titration the typical behaviour of a lactone was observed 0.1 162 g. requiring for complete neutralisation 4.96 C.C. of N/lO-sodium hydroxide (calc.4-88 c.c.). The Direct Methyhtion of Galactose by Methyl SuEphute and Xodium Hydroxide.-Galactose ([a];' in water + 143.1" for c = 1.22; [oL]:~' + 80.84" after 18 hours) was methylated a t 30" in the cus-tomary manner until no reducing action on Fehling's solution could be detected. After repetition of the process the fully methylated product separated by fractional distillation in a vacuum had no action on alkaline or neutral permanganate. The tetramethyl methylgalactoside [Found OMe = 60.5. Calc. for C,H,0(OMe)5 OMe = 62.0%] was hydrolysed by boiling for 30 minutes with 8% aqueous hydrochloric acid and the product isolated its a viscous syrup. On fractional distillation in a vacuum, this gave a considerable residue of high b. p.and a main fraction (b. p. 130"/0.3 mm.) of tetramethyl galactose [Found C = 50.83 ; H = 8-55; OMe = 50.8. Calc. for C,H,O,(OMe), C = 50.85; H = 8.47; OMe = 52.1%] which showed ng0 1.4618 [.ID + 83.3" (c = 1-799) in water + 57" (c = 1.535) in alcohol and + 65" (c = 11.401) in benzene. In duplicate experiments products wer IK THE MONOCARBOXYLIC ACIDS ETC. PART 111. 353 ottained with physical constants almostl identical with those recorded above. Tetramethyl Ga1actonamide.-A dry alcoholic solution of tetra-inethyl galactonolactone ([.] + 106.7" ; prepared from tetra-inethyl galactose obtained by direct methylation as described above) was treated with ammonia as described by Irvine and Pryde (lor. cit.). The product crystallised after 4-5 days and on recrystallisatioii from light petroleum (Is.p. 60-80") containing a little ethyl alcohol and etlher gave tetramethyl galactonamide, m. p. 121" + 35.7" (c = 0.937) in acetone (yield about 25% of the crude product) [Found C = 47.68 ; H = 8-27 ; OMe = 47.7. Calc. for C,H,O2N(O~4e), C = 47-81 ; H = 8-37; OMe = 49*4y0]. On treating the crude ainide with an alkaline hypochlorite solution according tjo Weerman's method a small yield was obtained of a crystalline nitrogenous substance which softened a t 140°, melted a t 150" and had [.ID + 85.7" (c = 0.998) in water falling to 4- 27.5" after the substance had been treated with 3% hydro-chloric acid a t room temperature for 3 days. This coinpound is evidently analogous to the cyclic urethane resulting from the action of alkaline hypochlorite or1 tetramethyl gluconamide (Irvine and Pryde loc.cit.) but from the poor yields it is inferred that the original amide is not a homogeneous product'. Since the parent lactone must be regarded as a mixture of the 1 5- and 1 4-isomerides the structures of the amide and of the compound derived from it are not yet clear although a t present we incline to the view that the latter is derived from the amide obtained from the 1 4-lactone. The matter is being further investigated. Jfethylation of Galactose with Preliminary Galactoside Formation i?i Methyl-alcoholic Hydrogen Chloride and the Preparation of Mixed Tetramethyl Galactonolactones.-In the following series of experi-ments the galactose was dissolved in 1 yo methyl-alcoholic hydrogen chloride and heated in sealed tubes for 20 hours a t 100".The mixed galactosides were then methylated with methyl sulphate and sodium hydroxide followed by methyl iodide and silver oxide. The fully methylated product distilled steadily a t 10443-105~0"/0~48-0~52 mm. and had n:,"' 1.4500 and n::'" 1-4484 [Found OMe = 60.3 ; calc. 62.0y0]. On hydrolysis an 88% yield of crude tetramethyl galactose was obtained the bulk of which on fractional distillation showed b. p. 140"/1~0-1~2 mm ., r~;?' 1.4620 and [.ID + 70" in water (equilibrium value) [Pound : C = 50.50;? I-€ = 8-43; OMe = 51.2%]. A quantity of high-boiling residue remained. On oxidation with bromine the above preparation of tetramethyl galactose gave a tetramethyl galactono 354 PRYDE HIRST AND IIUMPHREYS CONSTITUTIONAL STUDIES lactone [Found C = 51.30 ; H = 7.73 ; OMe = 52.60/] which could be further fractionated as follows without appreciably affecting the analytical figures : I.?a;;' 1.4546; [a];"@ +61-7' falling in 24 hours to [a];** $2.38' (c = 1.066). 11. n;,5. 1.4538; [u];;~ +4S.75" falling in 24 hours to [a]:;" -0.39' (c = 1.077)-The behaviour of the lactone on titration was typical 0.2120 g. requiring 8.8 C.C. of N/lO-sodium hydroxide for complete neutralis-ation (calc. 9.06 m.). The following table records the initial specific rotations in water (a) and the refractive indices of various preparations of tetramethyl galactonolactones all of which gave good analytical figures. It will be seen that the constants vary more or less in the same sense which lends support to the vietv that the mixed forms of intermediate rotation consist of varying proportions of the 1 5- and 1 4-isomerides.Tetramethyl Galactonohctones. a. 121.; . Notes. +160" 1-4)582 1 &Form prepared from homogeneous tetra-methyl d-galactose. 3.106 1.4571 From a preparation of tetramethyl galactose obtained by direct inethylation of galactose with Me,SO,. From preparations of tetramethyl galactoso ment of gaIactose. onolactone. 1 4-Form prepared by methylation of d-galact-obtained by preliminary HCl/MeOH treat- + 61 + 48 - 29 1.4496 1 5-Trimethyl l-8rabonolactme.-The initia,l material was crystal-line trimethyl a-methyl-Z-arabinoside having [a]:'" + 225.3" in methyl alcohol (c = 1.308) and [ c c ] ~ ' + 246.1" in water (c = 0-723), which had been prepared from recrystallised a-methyl-2-arabinoside by methylation with methyl iodide and silver oxide.In various preparations of trimethyl arabonolactone considerable difficulty was experienced during the acid hydrolysis necessary for the preparation of the free sugar owing to the large amount of the methylated sugar which was decomposed with the formation of furfural. This difficulty was overcome by the following process of simultaneous hydrolysis and oxidation. A solution of the crystalline trimethyl methylarabinoside (7.7 g .) in 3 yo aqueous hydrobromic acid (85 c.c.) having been maintained at 85" for 1 hour, was treated at 75" with small quantities of bromine at intervals of 30 minutes until after 4 hours 3.5 c.c had been added.After standing for 24 hours at room temperature the solution was again heated at 75" and a further 5 C.C. of bromine were added (making cz total of 3 mols.). The excess of bromine was then removed by aeration the hydrobromic acid neutralised with silver oxide th IN THE MONOCARBOSYLIC ACIDS ETC. PART 111. 3% filtered solution saturated with hydrogen sulphide and the clear filtrate from the precipitated silver sulphide was evaporated under diminished pressure to a syrup which was dissolved in chloroform to remove some inorganic matter still present. The syrup finally obtained (6.6 g.) was heated at 100°/9 mm. for 2 hours to emure complete conversion of the acid into the lactone. Distillation in a vacuum then gave 5.15 g. of product b. p. 156"/12 mm.1~;;" 1.4595 and a second fract'ion (0.2 g.) b. p. 158"/12 mm. n:' 1.4592. The still residue weighed only 0-3 g. The main fraction was a colourless syrup with a wide range of solubility in organic solvents, acid to litmus and showing the characteristic behaviour of a lactone. It did not reduce Fehling's solution even on prolonged boiling. Analysis established its identity as trimethyl arabono-lactone [Found ,.C = 50.23 ; H = 7.45 ; OMe = 48.7. Calc. for C5H5O3(OMe), C = 50.53 ; H = 7-37 ; OMe = 48-9y0]. 0.1529 G. of the lactone required 8.1 C.C. of NIlO-sodium hydroxide for corn-plete neutralisation (calc. 8.05 c.c.) the substance behaving as an easily hydrolysable lactone. In ethyl alcohol the [%ID 3- 136" (c = 1.830) remained constant. In water the initial high i]~]:f' + 145' (by extrapolation) fell in 15 minutes to -{- 13S0 in P hour to + 112" in 2.5 hours to + 55-7" in 7 hours to + 23-6" and in 24 hours to + 22.4" (constant).On the assumption that the lactone is completely converted into the acid the latter value corresponds to [a]:' + 20.4" for trimethyl arabonic acid. For comparative purposes the latter constant was also determined as follows. 0.1356 G. of the lactone dissolved in a small quantity of water was treated with rather more than the necessary amount of sodium hydroxide to form the sodium salt of the acid ample time being given for the change to take place. A slight excess of hydro-chloric acid was then added the volume made up to 10 C.C. with water and the specific rotation determined with the minimum possible delay (50 seconds from the time of adding the acid).The value of [ot]1D7' found in this way was constant (+ 22.9" c = 1-485 as acid). It would therefore appear that in water 1 5-trimethyl arabonolactone is completely converted into the acid. Confirm-ation of this was obtained by titrating with alkali an aqueous solution of the lactone which had been kept for several hours. The behaviour then observed was that of an acid the titration proceeding at once to a sharp and permanent end-point (0.0980 g. required 5.0 C.C. of iV/lO-sodium hydroxide. Calc. 5.0 c.c.). Neither the acid nor the lactone could be obtained in a crystalline condition. The salts of the acid are very soluble in water the solubilities of the sodium potassium ammonium barium lead, and mercury salts being such that they are not precipitated eve 356 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES from moderately concentrated solutions.1 &Trimethyl arabono-lactone forms a Crystalline amide (m. p. 95-100") on saturating its solution in methyl alcohol with dry ammonia. Methylation of Arabinose with Preliminmy Arahinoside Formation in Methyl-alcoholic Hydrogen Chloride and the Preparation of Mixed Trimethyl Arabonohctones.-A typical preparation is described. 5.5 G . of arabinose was treated with methyl alcohol containing 0.2% of hydrogen chloride in a sealed tube at 105" for 24 hours. The partly crystalline product had no action on Fehling's solution. The mixture of syrup and crystals was methylated twice with methyl sulphate and sodium hydroxide and the resulting mobile syrup was distilled giving trimethyl methylarabinoside as the main fraction (2 g.) b.p. 120'/13 mm. ni:' 1.4448 [Found C = 52.50; H = 8-80; Ollle = 58-1. Calc. for C,H,O(OMe), C = 52.42; H = 8.74; OMe = 60-2y0]. It was neutral to litmus behaved as a normal stable glucosidic compound and had no action on neutral or slightly alkaline potassium permanganate solution. [a], + 79.6" (c = 3.332) in methyl alcohol. After being heated in acid methyl alcohol in a sealed tube for 8 hours a t W' the substance gave as equilibrium value [.ID + 60" a figure much below that given by crystalline preparations of the a- and p-forms of normal trimethyl methylarabinoside (+ 150" Hirst and Robertson Zoc. cit.). I n certain other preparations the mixed arabinosides were methylated with methyl iodide and silver oxide and also with the latter reagents following a preliminary treatment with methyl sulphate and sodium hydroxide.In all cases abnormal rotations were recorded for the trimethyl methylarabinosides and for the trimethyl arabinose and arabonolactones prepared from them. The following results are typical : The mixed arabinosides were methylated with methyl iodide and silver oxide; the fully methylated product was hydro-lysed with 8% aqueous hydrochloric acid and the trimethyl arabinose oxidised by bromine. During the hydrolysis very considerable furfural formation occurred. The trimethyl methyl-arabinoside (Found OMe = 59.0; calc. 60-2y0) had [.ID + 79" in water whilst the t.rimethy1 arabinose (Found OMe = 47.9; calc.48.4%) had as equilibrium value in water [.I, + 36.2". The trimethyl arabonolactone (Found C = 50.13 ; H = 7.02 ; OMe = 48*6y0) b. p. 80-90'/0~2-0~4 mm. behaved typically on titration, 0.1393 g. requiring 7-8 C.C. of N/10-sodium hydroxide (calc. 7.33 c.c.). [.ID in water + 17-45" (initial value) and - 20.95" (constant value) after 24 hours. Series I I . The mixed arabinosides were methylated by methyl sulphate and sodium hydroxide followed by methyl iodide and Series I IN THE XONOCARBOXYLIC ACIDS ETC. PART 111. 367 silver oxide ; the fully methylated product was simultaneously hydrolysed and oxidised by a mixture of hydrobromic acid and bromine as described above. The trimethyl methylarabinoside had [.ID + 59.8" in water whilst the lactone obtained from it showed in water [.ID + 55.8" (initial value) and - 13.9" (after several hours).Oxidation of ,!%fixed Trimethyl MethylarabirLosides with S i t r i c Acid.-The material (1.3 g.) prepared by methylation of mixed mcthylarabinosides with methyl sulphate and sodium hydroxide, was dissolved in 45 C.C. of nitric acid (d 1.2) and the oxidation was carried out by Hirst and Robertson's method (Zoc. cit.) the product8s being isolated as methyl esters. The colourless syrup so obtained (1.3 g.) gave on distillation 1.1 g. b. p. 155-160"/22-23 imn., 12: 1.4392. The main fract'ion was a colourless syrup soluble in water and all the usual organic solvents which showed the pro-perties of a lactone or easily hydrolysable ester. It appeared not, t o be a single substance but was shown to contain dimethyl trimethoxyglutarate since it gave a 20 7; yield of the crystalline diamide (m.13. 233') when treated with ammonia in methyl alcohol (compare €first and Robertson Zoc. cit.) (0.2 g. dissolved in 2 C.C. of methyl alcohol saturated a t 0" with ammonia gave crystals in 48 hours the final yield of pure material being 0.04 8.). On analysis figures were obtained which support the vien- that the product con-sisted of a mixture of dimethyl trimethoxyglutarate C51-130,(0Me),, and trimethyl arabonolact one C,M,O,( OiCIe),,-presulllahlp the 1 4-form. The results are tabulated below : Calc. for Calc. for CBH,O,( OMe) C,H,O,( OXe )3 Culc. for Found. (A). (B )- 30~/,9+50%B. c 76 40.2 48.0 .>0*5 40.25 OMeYL C.C.of N/lO-sodiwii hydroxide required t o hydrolyse 0.1 g. 6.7 8 5.3 6.6 7.4 7.5 7.4 7.3 36 62 49 55.5 33 %I [uj +25-8* (c = 1.430) in niothyl alcohol; [all +22' (c = 0.820) final value in water. The expenses of this research were in part defrayed by a grant from the Medical Research Council. One of the authors (R. W. R.) desires to thank the Department of Scientific and Industrial Research for a grant which enabled him to participate in the work. PHYSIOLOGY INSTITUTE C-4RDIFF. THE UNIVERSITY MANCHESTER. [Received Decem6er %nd P924. 348 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES LV.-Constitutional Studies in the MonocaTboxylic Acids Derived from Sugars. Part 111. The Iso-meric Tetramethyl Galactonolactones and Trimethyl A rabonolactones.By JOHN PRYDE EDMUND LANGLEY HIRST and ROBERT WILLIAM HUMPHREYS. IN Part I (J. 1923,123,1808) two isomeric tetramethyl d-galactono-lactones were described-one prepared by methylation of d-galac-tonolactone had a lzevorotation of - 29.5" and it was suggested, a 1 4-structureY whilst the other obtained by the oxidation of tetramethyl d-galactose had a dextrorotation of + 106.7". To this a 1 5-structure was assigned. Levene and Meyer ( J . Biol. Chern., 1924 60 167) using the same methods prepared two isomeric tetramethyl mannonolactones both isomerides possessing in thi I S THE &IOXOCARBOSYLIC ACIDS ETC. PART 111. 349 case dextrorotations,* as would be expected according to the Hudson rule ( J . Amer. C‘hem. Soc. 1910,32 338) if 1 4- and 1 5-structures are ascribed to these lactones.The present communication deals with further observations on these tetramethyl galactonolactones, and with an extension of the investigations which reveals a similar isomerism of trimethyl E-arabonolactone. Pischer (Ber. 1595 28 1154) has shown that the action of dry nietlhyl-alcoholic hydrogen chloride on galactose produces at least one other form of methyl galactoside in addition to the well-characterised a- and p-forms of the normal methyl hexoside. Irvine and Cameron (J. 1905 87 900) showed that this additional form or forms may be converted on methylation into a tetramethyl niethylgalactoside isomeric with the normal tetramethyl cc- and F-methyl-d-galactosides and that on hydrolysis the abnormal form gave rise to a tetramethyl d-galactose witlh a much lower dextro-rotation than that obtained from the normal cc- and p-forms.Later, Miss Cunningham (J. 1918. 113 596) correlated this third form it11 the reactive “ y ” series of sugars. With the view of eliminating complications dependent on the formation of such reactive types we have made use in certain of our investigations of the process of Haworth (J. 1915 107 S), in which the free sugar is inethylated directly by methyl sulphate and caustic soda. Nevertheless when the total product from this process was converted into tetramethyl galactose the equilibrium rotation of the latter in water was well below that quoted by previous workers (compare Irvine and Cameron J. 1904 85, 1071; Schlubach and Moog Ber. 1923 56 [B] 1957).The tetramethyl galactose used in the previous work (Part I Zoc. cit.) was obtained by this direct methylation process and showed [cc], +- 54.9” in water. It was recognised a t the time that this value was belon- the standard values already quoted but no explanation of the anomaly was then forthcoming since the method used in preparing the methylated sugar mas known to give when applied to glucose a homogeneous tetramethyl glucose showing the normal rotation. The question has iiow been further investigated and the fact that direct methylation of galactose with methyl sulphate ?-ields a tetramethyl galactose with a specific rotation well below the normal value has been substantiated the explanation would appear to be that during the first stages of thc methylation while the reducing group is being substituted.isomeric methyl galactosides * Levene and Meyer (Zoc. cit. 168) say ‘. It is peculiar that the two tetra-mctliyl lactones should rotate in opposite directions. This peculiarity requires elucidation.” This is obviously in error the statement presumably referring to the acids 350 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES are formed containing respectively the 1 5- and 1 4-oxide linking. On further methylation these give rise to a mixture of tetramethrl methylgalactosides containing the amylene-oxidic form in excess.* Thus utilising as initial material a homogeneous tetramethyl galactose ([.IF + 117.3" in water) which had in turn been pre-pared from crystalline a-methyl-d-galactoside we have obtained a tetramethyl galactonolactone with a much higher dextrorotatioii than that previously quoted for the 1 5-isomeride namely 160.7" in place of 106.7".From the evidence now at our disposal we believe that the higher value must be assigned to the pure 1 5-isomeride of the lactone and that the previously described dextrorotatory lactone is not a homogeneous form but is to be regarded as a mixture of the 1 5 and 1 4 forms. Similar anomalous rotations-in this case lower still-have been observed when tetra-methyl galactose and the corresponding lactone have been pre-pared from the mixed methylgalactosides obtained from Fisclier's acid methyl alcohol process. Here the proportion of 1 4 form in the mixture is greater than can be obtained by direct methylation with methyl sulphate.From certain preparations of these mixed lactones a crystalline tetramethyl galactonamide has been obtained. The yield of recrystallised material and the result of the action of alkaline hypochlorite on the amide (compare Irvine and Pryde, 1924 125 1045) are such that further support is gained for the view that the original sugars and the lactones and amides prepared from them were mixtures of the 1 5- and 1 4-isomerides. The reaction of the pure isomeric amides is now being studied. A parallel series of investigations on the corresponding deriv-atives of Z-arabinose gave results similar to those encountered in the case of galactose. Starting from crystalline trimethyl a-methyl-I-arabinoside a dextrorototory trimethyl arabonolactone has been obtained having an initial specific rotation in water (15 minutes after solution) of + 138" falling in the course of 24 hours to + 22-4".This must be regarded as a homogeneous form and since Hirst and Robertson (following paper) have obtained evidence which establishes the presence of the 1 5 type of oxide linking in normd fully methylated arabinose it follows that the new lactone also possesses the 1 5-oxide linking. It is evident from a study * In a recent communication by Haworth Ruell and Westgarth (J. 1924, 125 2468) which appeared after the present paper had been sent in for publication the isolation of the 1 4-oxidic form of tetramethyl galactose and the corresponding lactone is described and it is pointed out that our original preparation of 1 5-tetramethyl galactonolactone contained an admixture of the 1 4 form.As is clear from the results now described we are in complete agreement with Haworth and his collaborators both as regards his correction of the earlier work and his deductions therefrom.-J. P IN THE MONOCARBOXYLIC ACIDS ETC. PART 111. 351 of the valency configuration in a compound of this type that the oxide ring although attached at one end to a non-asymmetric, terminal carbon atom must be definitely oriented eitber to the right- or to the left-hand side of the carbon chain and the applic-ation of Hudson's rule (Zoc. cit.) shows that in this trimethyl arabonolactone the ring is on the right of the carbon chain. It is also of interest to compare the dextrorotation of this rnethylatecl lactone with the lrevorotation of the non-methylated arabonolactone obtained by direct oxidation of the free sugar a case quite parallel to that of the galactose derivatives.Experiments are in progress with the view of obtaining the pure lzevorotatory isomeride of the methylated lactone by the method previously utilised for the preparation of the lzvorotatory isomeride of tetramethyl galnctono -lactone. On subjecting I-arabinose to the action of dry hydrogen chloride in methyl alcohol followed by methylation of the mixed ambinosides, the trimethyl arabinose obtainable has an equilibrium rotation in water m7ell below that found by Purdie and Rose $- 127.2" (J., 1906 89 1204) and the trimethyl arabonolactone obtained from this sugar on oxidation likewise has a rotation much below that of the homogeneous 1 5-lactone already described.Further, preparations of mixed arabinosides which when hydrolysed aizd oxidised with bromine give rise to trimethyl arabonolactones M ith anomalous low rotations also behave in an anomalous way when oxidised with nitric acid. In place of dimethyl trimethoxyglutarate, there was obtained a mixture of this compound with what is apparently the lactone of a monoearboxylic acid presumably the 1 4-trimethyl arabonolactone and the yield of trimethoxy-glutardiamide obtained from this mixture is in agreement with these views as to its composition. In our opinion these results point to the existence of isomeric arabinoses and arabonolactsnes with 1 5- and 1 4-oxygen bridges and to the fact that a mixture of the isomeric sugars is obtained 011 treating arabinose with acid methyl alcohol.It is of great interest that galactose and arttbinose exhibit this marked tendency to react in both 1 5- and 1 4-forms-the former being the normal form in both cases-undcr condition3 which so far as our own observations and those of other worker.; go lead to the production of only one form in the cases of glucose H OH H/OH HIOH $10 H H OH HtQH K OH EX1 OH ILojli HOIH HO H H E p F HO H Galactose. Arabinose. Glucose. Xylose 352 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES and xylose. In this respect the relationships between the formulae of galactose and arabinose on the one hand and between those of glucose and xylose on the other hand are suggestive.E x P E R I M E N T A L . 1 :5-!l'etramethyl d-Gaktctonolactone .-Pure recrystallised a-methyl-galactoside monohydrate ([a]';' + 177" for c = 04371 ; Fischer, loc. cit. gives Cay:' + 179") was methylated in the usual way with methyl sulphate and sodium hydroxide followed by two treatments with methyl iodide and silver oxide. The fully methylated product after distillation had n:' 1.4505 and on being heated for 5 hours a t 100" in 3% methyl-alcoholic hydrogen chloride in a sealed tube, it had the equilibrium rotation [a]:' + 96.5" (c = 0.728). Hydro-lysis by 8% aqueous hydrochloric acid produced a viscous syrup which after distillation had n::" 1.4633 and [a]t>"' + 117.3" (c = 0.996 ; equilibrium rotation in water). The tetramethyl galactose was oxidised with bromine (see Part I loc.cit.) and the resulting tetramethyl galactonolactone which distilled a t 112-116"/0-57 mm. as a mobile syrup had n:' 1-4574 and showed in water (c = 1.086) [a]:'" + 160.67" (5 minutes after the preparation of the solution) + 72.54" (after 4.5 hours) and [a]:"' + 47.58" (after 20 hours constant) [Found C = 51.08 ; H = 7-84 ; OMe = 52.7. Calc. for C,H,O,(OMe), C = 51.28 ; H = 7.69 ; OMe = 53.0y0]. On titration the typical behaviour of a lactone was observed 0.1 162 g. requiring for complete neutralisation 4.96 C.C. of N/lO-sodium hydroxide (calc. 4-88 c.c.). The Direct Methyhtion of Galactose by Methyl SuEphute and Xodium Hydroxide.-Galactose ([a];' in water + 143.1" for c = 1.22; [oL]:~' + 80.84" after 18 hours) was methylated a t 30" in the cus-tomary manner until no reducing action on Fehling's solution could be detected.After repetition of the process the fully methylated product separated by fractional distillation in a vacuum had no action on alkaline or neutral permanganate. The tetramethyl methylgalactoside [Found OMe = 60.5. Calc. for C,H,0(OMe)5 OMe = 62.0%] was hydrolysed by boiling for 30 minutes with 8% aqueous hydrochloric acid and the product isolated its a viscous syrup. On fractional distillation in a vacuum, this gave a considerable residue of high b. p. and a main fraction (b. p. 130"/0.3 mm.) of tetramethyl galactose [Found C = 50.83 ; H = 8-55; OMe = 50.8. Calc. for C,H,O,(OMe), C = 50.85; H = 8.47; OMe = 52.1%] which showed ng0 1.4618 [.ID + 83.3" (c = 1-799) in water + 57" (c = 1.535) in alcohol and + 65" (c = 11.401) in benzene.In duplicate experiments products wer IK THE MONOCARBOXYLIC ACIDS ETC. PART 111. 353 ottained with physical constants almostl identical with those recorded above. Tetramethyl Ga1actonamide.-A dry alcoholic solution of tetra-inethyl galactonolactone ([.] + 106.7" ; prepared from tetra-inethyl galactose obtained by direct methylation as described above) was treated with ammonia as described by Irvine and Pryde (lor. cit.). The product crystallised after 4-5 days and on recrystallisatioii from light petroleum (Is. p. 60-80") containing a little ethyl alcohol and etlher gave tetramethyl galactonamide, m. p. 121" + 35.7" (c = 0.937) in acetone (yield about 25% of the crude product) [Found C = 47.68 ; H = 8-27 ; OMe = 47.7.Calc. for C,H,O2N(O~4e), C = 47-81 ; H = 8-37; OMe = 49*4y0]. On treating the crude ainide with an alkaline hypochlorite solution according tjo Weerman's method a small yield was obtained of a crystalline nitrogenous substance which softened a t 140°, melted a t 150" and had [.ID + 85.7" (c = 0.998) in water falling to 4- 27.5" after the substance had been treated with 3% hydro-chloric acid a t room temperature for 3 days. This coinpound is evidently analogous to the cyclic urethane resulting from the action of alkaline hypochlorite or1 tetramethyl gluconamide (Irvine and Pryde loc. cit.) but from the poor yields it is inferred that the original amide is not a homogeneous product'. Since the parent lactone must be regarded as a mixture of the 1 5- and 1 4-isomerides the structures of the amide and of the compound derived from it are not yet clear although a t present we incline to the view that the latter is derived from the amide obtained from the 1 4-lactone.The matter is being further investigated. Jfethylation of Galactose with Preliminary Galactoside Formation i?i Methyl-alcoholic Hydrogen Chloride and the Preparation of Mixed Tetramethyl Galactonolactones.-In the following series of experi-ments the galactose was dissolved in 1 yo methyl-alcoholic hydrogen chloride and heated in sealed tubes for 20 hours a t 100". The mixed galactosides were then methylated with methyl sulphate and sodium hydroxide followed by methyl iodide and silver oxide. The fully methylated product distilled steadily a t 10443-105~0"/0~48-0~52 mm.and had n:,"' 1.4500 and n::'" 1-4484 [Found OMe = 60.3 ; calc. 62.0y0]. On hydrolysis an 88% yield of crude tetramethyl galactose was obtained the bulk of which on fractional distillation showed b. p. 140"/1~0-1~2 mm ., r~;?' 1.4620 and [.ID + 70" in water (equilibrium value) [Pound : C = 50.50;? I-€ = 8-43; OMe = 51.2%]. A quantity of high-boiling residue remained. On oxidation with bromine the above preparation of tetramethyl galactose gave a tetramethyl galactono 354 PRYDE HIRST AND IIUMPHREYS CONSTITUTIONAL STUDIES lactone [Found C = 51.30 ; H = 7.73 ; OMe = 52.60/] which could be further fractionated as follows without appreciably affecting the analytical figures : I. ?a;;' 1.4546; [a];"@ +61-7' falling in 24 hours to [a];** $2.38' (c = 1.066).11. n;,5. 1.4538; [u];;~ +4S.75" falling in 24 hours to [a]:;" -0.39' (c = 1.077)-The behaviour of the lactone on titration was typical 0.2120 g. requiring 8.8 C.C. of N/lO-sodium hydroxide for complete neutralis-ation (calc. 9.06 m.). The following table records the initial specific rotations in water (a) and the refractive indices of various preparations of tetramethyl galactonolactones all of which gave good analytical figures. It will be seen that the constants vary more or less in the same sense which lends support to the vietv that the mixed forms of intermediate rotation consist of varying proportions of the 1 5- and 1 4-isomerides. Tetramethyl Galactonohctones. a. 121.; . Notes.+160" 1-4)582 1 &Form prepared from homogeneous tetra-methyl d-galactose. 3.106 1.4571 From a preparation of tetramethyl galactose obtained by direct inethylation of galactose with Me,SO,. From preparations of tetramethyl galactoso ment of gaIactose. onolactone. 1 4-Form prepared by methylation of d-galact-obtained by preliminary HCl/MeOH treat- + 61 + 48 - 29 1.4496 1 5-Trimethyl l-8rabonolactme.-The initia,l material was crystal-line trimethyl a-methyl-Z-arabinoside having [a]:'" + 225.3" in methyl alcohol (c = 1.308) and [ c c ] ~ ' + 246.1" in water (c = 0-723), which had been prepared from recrystallised a-methyl-2-arabinoside by methylation with methyl iodide and silver oxide. In various preparations of trimethyl arabonolactone considerable difficulty was experienced during the acid hydrolysis necessary for the preparation of the free sugar owing to the large amount of the methylated sugar which was decomposed with the formation of furfural.This difficulty was overcome by the following process of simultaneous hydrolysis and oxidation. A solution of the crystalline trimethyl methylarabinoside (7.7 g .) in 3 yo aqueous hydrobromic acid (85 c.c.) having been maintained at 85" for 1 hour, was treated at 75" with small quantities of bromine at intervals of 30 minutes until after 4 hours 3.5 c.c had been added. After standing for 24 hours at room temperature the solution was again heated at 75" and a further 5 C.C. of bromine were added (making cz total of 3 mols.). The excess of bromine was then removed by aeration the hydrobromic acid neutralised with silver oxide th IN THE MONOCARBOSYLIC ACIDS ETC.PART 111. 3% filtered solution saturated with hydrogen sulphide and the clear filtrate from the precipitated silver sulphide was evaporated under diminished pressure to a syrup which was dissolved in chloroform to remove some inorganic matter still present. The syrup finally obtained (6.6 g.) was heated at 100°/9 mm. for 2 hours to emure complete conversion of the acid into the lactone. Distillation in a vacuum then gave 5.15 g. of product b. p. 156"/12 mm. 1~;;" 1.4595 and a second fract'ion (0.2 g.) b. p. 158"/12 mm. n:' 1.4592. The still residue weighed only 0-3 g. The main fraction was a colourless syrup with a wide range of solubility in organic solvents, acid to litmus and showing the characteristic behaviour of a lactone.It did not reduce Fehling's solution even on prolonged boiling. Analysis established its identity as trimethyl arabono-lactone [Found ,.C = 50.23 ; H = 7.45 ; OMe = 48.7. Calc. for C5H5O3(OMe), C = 50.53 ; H = 7-37 ; OMe = 48-9y0]. 0.1529 G. of the lactone required 8.1 C.C. of NIlO-sodium hydroxide for corn-plete neutralisation (calc. 8.05 c.c.) the substance behaving as an easily hydrolysable lactone. In ethyl alcohol the [%ID 3- 136" (c = 1.830) remained constant. In water the initial high i]~]:f' + 145' (by extrapolation) fell in 15 minutes to -{- 13S0 in P hour to + 112" in 2.5 hours to + 55-7" in 7 hours to + 23-6" and in 24 hours to + 22.4" (constant). On the assumption that the lactone is completely converted into the acid the latter value corresponds to [a]:' + 20.4" for trimethyl arabonic acid.For comparative purposes the latter constant was also determined as follows. 0.1356 G. of the lactone dissolved in a small quantity of water was treated with rather more than the necessary amount of sodium hydroxide to form the sodium salt of the acid ample time being given for the change to take place. A slight excess of hydro-chloric acid was then added the volume made up to 10 C.C. with water and the specific rotation determined with the minimum possible delay (50 seconds from the time of adding the acid). The value of [ot]1D7' found in this way was constant (+ 22.9" c = 1-485 as acid). It would therefore appear that in water 1 5-trimethyl arabonolactone is completely converted into the acid.Confirm-ation of this was obtained by titrating with alkali an aqueous solution of the lactone which had been kept for several hours. The behaviour then observed was that of an acid the titration proceeding at once to a sharp and permanent end-point (0.0980 g. required 5.0 C.C. of iV/lO-sodium hydroxide. Calc. 5.0 c.c.). Neither the acid nor the lactone could be obtained in a crystalline condition. The salts of the acid are very soluble in water the solubilities of the sodium potassium ammonium barium lead, and mercury salts being such that they are not precipitated eve 356 PRYDE HIRST AND HUMPHREYS CONSTITUTIONAL STUDIES from moderately concentrated solutions. 1 &Trimethyl arabono-lactone forms a Crystalline amide (m.p. 95-100") on saturating its solution in methyl alcohol with dry ammonia. Methylation of Arabinose with Preliminmy Arahinoside Formation in Methyl-alcoholic Hydrogen Chloride and the Preparation of Mixed Trimethyl Arabonohctones.-A typical preparation is described. 5.5 G . of arabinose was treated with methyl alcohol containing 0.2% of hydrogen chloride in a sealed tube at 105" for 24 hours. The partly crystalline product had no action on Fehling's solution. The mixture of syrup and crystals was methylated twice with methyl sulphate and sodium hydroxide and the resulting mobile syrup was distilled giving trimethyl methylarabinoside as the main fraction (2 g.) b. p. 120'/13 mm. ni:' 1.4448 [Found C = 52.50; H = 8-80; Ollle = 58-1.Calc. for C,H,O(OMe), C = 52.42; H = 8.74; OMe = 60-2y0]. It was neutral to litmus behaved as a normal stable glucosidic compound and had no action on neutral or slightly alkaline potassium permanganate solution. [a], + 79.6" (c = 3.332) in methyl alcohol. After being heated in acid methyl alcohol in a sealed tube for 8 hours a t W' the substance gave as equilibrium value [.ID + 60" a figure much below that given by crystalline preparations of the a- and p-forms of normal trimethyl methylarabinoside (+ 150" Hirst and Robertson Zoc. cit.). I n certain other preparations the mixed arabinosides were methylated with methyl iodide and silver oxide and also with the latter reagents following a preliminary treatment with methyl sulphate and sodium hydroxide. In all cases abnormal rotations were recorded for the trimethyl methylarabinosides and for the trimethyl arabinose and arabonolactones prepared from them.The following results are typical : The mixed arabinosides were methylated with methyl iodide and silver oxide; the fully methylated product was hydro-lysed with 8% aqueous hydrochloric acid and the trimethyl arabinose oxidised by bromine. During the hydrolysis very considerable furfural formation occurred. The trimethyl methyl-arabinoside (Found OMe = 59.0; calc. 60-2y0) had [.ID + 79" in water whilst the t.rimethy1 arabinose (Found OMe = 47.9; calc. 48.4%) had as equilibrium value in water [.I, + 36.2". The trimethyl arabonolactone (Found C = 50.13 ; H = 7.02 ; OMe = 48*6y0) b. p. 80-90'/0~2-0~4 mm. behaved typically on titration, 0.1393 g.requiring 7-8 C.C. of N/10-sodium hydroxide (calc. 7.33 c.c.). [.ID in water + 17-45" (initial value) and - 20.95" (constant value) after 24 hours. Series I I . The mixed arabinosides were methylated by methyl sulphate and sodium hydroxide followed by methyl iodide and Series I IN THE XONOCARBOXYLIC ACIDS ETC. PART 111. 367 silver oxide ; the fully methylated product was simultaneously hydrolysed and oxidised by a mixture of hydrobromic acid and bromine as described above. The trimethyl methylarabinoside had [.ID + 59.8" in water whilst the lactone obtained from it showed in water [.ID + 55.8" (initial value) and - 13.9" (after several hours). Oxidation of ,!%fixed Trimethyl MethylarabirLosides with S i t r i c Acid.-The material (1.3 g.) prepared by methylation of mixed mcthylarabinosides with methyl sulphate and sodium hydroxide, was dissolved in 45 C.C.of nitric acid (d 1.2) and the oxidation was carried out by Hirst and Robertson's method (Zoc. cit.) the product8s being isolated as methyl esters. The colourless syrup so obtained (1.3 g.) gave on distillation 1.1 g. b. p. 155-160"/22-23 imn., 12: 1.4392. The main fract'ion was a colourless syrup soluble in water and all the usual organic solvents which showed the pro-perties of a lactone or easily hydrolysable ester. It appeared not, t o be a single substance but was shown to contain dimethyl trimethoxyglutarate since it gave a 20 7; yield of the crystalline diamide (m. 13. 233') when treated with ammonia in methyl alcohol (compare €first and Robertson Zoc. cit.) (0.2 g. dissolved in 2 C.C. of methyl alcohol saturated a t 0" with ammonia gave crystals in 48 hours the final yield of pure material being 0.04 8.). On analysis figures were obtained which support the vien- that the product con-sisted of a mixture of dimethyl trimethoxyglutarate C51-130,(0Me),, and trimethyl arabonolact one C,M,O,( OiCIe),,-presulllahlp the 1 4-form. The results are tabulated below : Calc. for Calc. for CBH,O,( OMe) C,H,O,( OXe )3 Culc. for Found. (A). (B )- 30~/,9+50%B. c 76 40.2 48.0 .>0*5 40.25 OMeYL C.C. of N/lO-sodiwii hydroxide required t o hydrolyse 0.1 g. 6.7 8 5.3 6.6 7.4 7.5 7.4 7.3 36 62 49 55.5 33 %I [uj +25-8* (c = 1.430) in niothyl alcohol; [all +22' (c = 0.820) final value in water. The expenses of this research were in part defrayed by a grant from the Medical Research Council. One of the authors (R. W. R.) desires to thank the Department of Scientific and Industrial Research for a grant which enabled him to participate in the work. PHYSIOLOGY INSTITUTE C-4RDIFF. THE UNIVERSITY MANCHESTER. [Received Decem6er %nd P924.

ISSN:0368-1645    

DOI:10.1039/CT9252700348

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

358 HIRST AND ROBERTSON THE CONSTITUTION OF THE LV1.-The Constitution of the Normal Mono-saccharides. Part 11. Arabinose. By EDMUND LANGLEY HIRST and GEORGE JAMES ROBERTSON. AS the result of recent discoveries concerning the nature of the oxide-ring linking in carbohydrates still greater emphasis must be laid on the necessity of obtaining for each individual sugar independent evidence as to internal structure. Thus for example, an examination of derivatives chosen both from the normal and from the y-type of compounds has revealed the fact that the same 1 5-oxide linking is present in tetramethyl 7-fructose (Haworth and Linnell J. 1923,123 294) and in the normal sugars trimethyl xylose (Hirst and Purves ibid. 1352) and tetramethyl galactose (Pryde ibid. 1808) whilst evidence pointing to a similar structure for normal tetramethyl mannose has also been obtained (Levene and Meyer J.Biol. Chem. 1924,60,167). In the case of galactose, it is of special interest to find that the 7-derivative is of the 1 4-or butylene-oxidic structure (Haworth Ruell and Westgarth, J. 1924 125 2468). These investigations have now been supple-mented by inquiries into the structure of normal and 7-derivatives of the pentose sugar arabinose and the following interesting con-clusions have been drawn. Derivatives of the y-series of arabinose compounds have been found by Baker and Haworth (an account of whose experiments we have been privileged to receive from the authors prior to publication) to contain the 1 4- or butylene-oxidic linking (following paper) and on the other hand normal stable derivatives of arabinose have been shown by us to be definitely of the amylene-oxidic or 1 5-type.As a preliminary to work on the constitution of ara.binose a further study of the methylation of this sugar has been carried out, leading to the discovery of trimethyl p-methylarabinoside (compare Purdie and Rose J. 1906 $9 1204). This compound (m. p. 46-48"} which was prepared by methylating the free sugar with methyl sulphate has the properties of a normal stable glucoside. Polarimetric studies of the hydrolysis of the new compound along with determinations of the equilibrium value of the specific rotation in acid methyl alcohol indicate that the same type of oxide linking is present in this sugar and in Purdie's trimethyl a-methylarabin-oside and that these substances bear to each other the relationship of interconvertible a- and p-varieties of normal trimethyl methyl-arabinoside.The equilibrium value of the specific rotation of the liquid trimethyl methylarabinosides formed simultaneously with this new modification indicates the presence of isomerides containin NORMAL MONOSACCHARIDES. PART 11. ARABIKOSE. 359 a different oxide-ring structure. The behaviour of arabinose is here parallel to that of galactose which under similar conditions of inethylation yields a mixture of methylated products containing respectively the 1 4- and the 1 5-oxide linkings (Pryde E r s t and Humphreys preceding paper). Information concerning the internal structure of the normal derivatives of arabinose has been gained from a study of the oxidation by nitric acid of the f idly methylated trimethyl arabinose (III) derived from the crystalline trimethyl a-methylarabinoside (11).The sole oxidation product which was isolated in almost qimntitative yield was trimethoxyglutaric acid (117). Special precautions were taken to prevent methylation of free hydroxy-groups. It is thus evident that when the normal form of fully met'hylated arabinose is oxidised under the conditions here adopted, it gives rise to a. dibasic acid which still contains a chain of five carbon atoms a i d has been formed without loss of any of the incthoxyl groups present in the original trimethyl arabinose. By arguments similar to those advanced in the previous paper on xylose these observations can be interpreted only as showing that the structure of the normal form of fully methylated arabinose is ot the amylene-oxide type (11).The detailed study of the methyl-ation process as applied to sugars which has been carried out during the past few years goes to show that the oxide linking of a normal methylaldoside remains unaltered during methylation and therefore it follows that the unsubstituted cc- and p-methylarabin-osides from which the fully methylated derivatives are prepared also contain this type of oxide linking. These experiments, although not in thcmselves affording direct evidence concerning the structure of the free sugar may be considered in conjunction with arguments based on a comparison of the optical properties and the general reactions of free arabinose with the corresponding properties of the normal and 7-forms of methylarabinoside.They then lend strong support to the view that the same internal structure is present in the free aldose and in the normal forms of methyl-arabinoside and their methylated derivatives. We therefore consider that the behaviour of arabinose may best be understood at the present ttime 011 the basis of the amylene-oxidic ring structure (I) (compare Mirst and Purves Eoc. cit.). One point-which however does not in any way affect the validit)y of the preceding arguments-requires to be considered in somewhat greater detail. The work described has been carried out with I-arabinose whish has been found to yield a dimethyl trimethoxy-glntarate witjIi marked dextrorotatory powers.It is evident that t Tii ester and the dimethyl trimethoq-glutaratc ohtaind 1, 360 HIRST AND ROBERTSON THE CONSTITUTION OF THE Haworth and Linnell from tetramethyl 7-fructose (a sugar belonging to the d-series) should be optical enantiomorphs but these authors have found (Zoc. cit .) that their product also is dextrorotatory almost to the same degree as our own. The rotations shown by our materials have been confirmed on several occasions with samples of different origin and in these circumstances it was felt that a further examination of the question of optical act>ivity was necessary. The most convenient means of attack appeared to lie in the preparation of arabotrimethoxyglutaric acid by an entirely independent method, and this was accomplished by methylating the lzevorotatory arabotrihydroxyglutaric acid C02H*[CH*OH],*C02H (Kiliani Ber., 1888 21 3007; Fischer Ber. 1891 24 1844). The methylated product was dextrorotatory and identical in every respect with the ester derived from methylated arabinose (V); and further proof of the identity of the two compounds was afforded by the isolation of the same crystalline diamide (VI) (m. p. 233" [.ID + 50") from both. The increase of the specific rotation in the dextro sense occasioned by methylation is here of the same order (+ 70") as that found when d-tartaric acid is converted into dimethyl dimethoxysuccinate (C02Me*[CH*OMe],*C02Me) and such a change would appear to be general in this series of dibasic acids. Con-firmation of the accuracy of our former observations was thus obtained and further experiments are now in progress by which it is hoped to obtain an explanation of the interesting anomaly in the direction of the optical rotation of the two esters.ryH*OH r$JH*OMe ryH*OH 702*H yO,*Me yO*NH2 I CH*OH I yH*OMe I YH-OMe FH*OMe YH-OMe YH-OMe OH*OH-tO (jH*OMe-t0 C;H*OMe+yH*OMe+yH*OMe+(iH*OMe (($XC*OH I YH-OMe I VH*OM e YH-OMe YHOOMe SH*OMe LCH LCH LCH CO,H CO,*Me COoNH, (1.1 (11.) (111.) (IV. 1 (V. 1 (VI.) E X P E R I M E N T A L . Hethylartiun of Arabinose.-Trimethyl u-methyhrabinoside,* pre-pared according to Purdie and Rose (Zoc. cit.) and recrystallised several times had m. p. 4-6"; [.ID + 250" in water (c = 1.200), [uL $. 223" in methyl alcohol (c = 1.320) (compare Purdie and Rose); ng 14432 ng* 1.4450 the readings being for superfused material.Trimethyl p-rnethylarrabinoside was obtained by methylating * We are indebted to M i . R. W. Humphreys of the University College of South Wales Cardiff for a specimen of very pure trimethyl a-methyl-arabinoside NORMAL MONOSACCHARIDES. PART 11. ARABINOSE. 361 arabinose (10 g.) with methyl sulphate (50 c.c.) and sodium hydroxide (40 g. in 85 C.C. of water) in the usual manner (Haworth J. 1915, 107 8). When the operation was conducted slowly the form-ation of coloured by-products was entirely avoided and after one methylation a mobile colourless syrup (9 g.) was obtained; this, subjected once again to the same treatment gave 8.5 g. of a syrup, which was purified by distillation. The main fraction (5.5 g.b. p. 123"/24 mm. nij" 1.44'73) crystallised slowly in long white needles, which were drained on porous tile. The new product was soluble in all the ordinary organic solvents including light petroleum and a suitable medium for recrystallisation could not be found. Puri-fication was effected by the somewhat wasteful method of repeatedly rubbing the crystals with light petroleum and draining rapidly on porous tile until constancy was attained in the m. p. 46-48", and rotations [.ID + 24" in methyl alcohol (c = l . l O O ) [.ID + 46.2" in water (c = 0.865). The crystals showed all the properties of a typical gliicoside and were stable in the presence of neutral or slightly alkaline potassium permanganate solution (Found C = 52-3 ; H = 8-8 ; OMe = 59.8.Required C = 52-4 ; H = 8.74 ; OMe = 60.2%). Interconversion of the a- and p-Forms of Trimethyl Methyhrabin-aside.-The initial specific rotation of the a-compound in methyl alcohol was + 223" (c = 1-563) whilst the final value obtained after heating the solution in a sealed tube with the addition of a trace of dry hydrogen chloride. was + 150". The p-variety on the other hand showed initially in acid methyl alcohol [.ID + 24" ( c = 1-100) increasing to a final steady value + 148". Further evidence concerning the relationship between these two substances was obtained from a study of the hydrolysis of the p-form with hydrochloric acid. In 87; aqueous acid the initial value tollD+ 47.6" (c = 1-572) was observed. On heating the solution a t go", the specific rotation increased regularly to a maximum constant value + 146" (c = 1.469) which is in good agreement with the figure + 1/53' quoted by Yurdie and Rose as the end value in the hydrolysis of pure trimethyl a-methylarabinoside.The value quoted is somewhat higher than those found by these authors during a study of the hydrolysis of mixtures containing both the a- and the p-form and higher also than the figure found for tri-methyl arabinose itself (+ 127") but this discrepancy may be connected with the failure of the syrupy trimethyl arabinose from which Purdie and Rose prepared the mixtures of the a- and p-forms of the fully methylated methylarabinoside to give satisfactory analytical results (Zoc. cit.). It is apparent therefore. t h a t these two crystalline substance 362 HIRST AND ROBERTSON THE CONSTITUTION OF THE are interconvertible a- and p-varieties of the same trimethyl methylarabinoside.On the other hand the initia'l specific rotation, [.ID + 57.4" (c = 3-708) of the analytically pure mixture of crystals and syrup forming the whole of the fully methylated arabinose (material described above as the main fraction) increased in acid methyl alcohol to an equilibrium value + 129" and on hydrolysis the final value was observed to be + 110". These figures are considerably lower than those given by the pure crystalline 01- and p-forms and may be taken as indicating that during the methyl-ation process a quantity of material had been formed differing in internal structure from the normal trimethyl methylarabinoside.Similar observations were made during a study of the methylation of galactose (Pryde Hirst and Humphreys loc. cit.). Simultaneous Hydrolysis and Oxidation of Trimethyl a-dlethyl-arabinoside. Isolation of Methyl Trimethoxyglutccrate (V).-In a typical oxidation experiment a solution of trimethyl a-methyl-arabinoside (1.90 9.) in nitric acid (d 1.2) (45 c.c.) was heated at 90" for 6 hours until the oxidation was complete. The excess of nitric acid having been removed (for details see Hirst and Purves, J. 1923 123 1357) the oxidation product was boiled with 3% methyl-alcoholic hydrogen chloride the acid neutralised with silver carbonate in the cold a quantity of anhydrous sodium sulphate added to take up any water and the solvent distilled from the filtered solution under diminished pressure.The residual syrup was freed from a small quantity of silver nitrate by dis-solution in chloroform and finally a colourless mobile liquid (2.1 g.) was isolated which gave on distillation 1.90 g. b. p. l43"/ 18 mm. ngo 1.4355 (yield 83% of the calculated quantity). A further 0.10 g. b. p. 145-150"/16 mm. ni:" 1.4385 was obtained as a second fraction and the still residue remained uncoloured and weighed less than 0.10 g. The main fraction was methyl arabo-trirnethoxyglutccrate. a colourless refractive moderately mobile, uncrystallisable syrup soluble in water and in all the usual organic solvents (Found C = 48.0 ; H = 7.33 ; OMe = 60.2 ; CO,Me, by quantitative hydrolysis with N/10-NaOH = 48.1. C&fI80, requires C = 48.0 ; OMe = 62.0 ; C0,Me = 47*2y0).In methyl alcohol the ester showed [.ID + 47-3" (c = 1.842) and in water [.ID + 45" (c = 1.462). TrimetTLoxyglu~rdiid~ (VI) .-From a mixture of the ester (0-5 g . ) with 6 C.C. of methyl alcohol (saturated with dry ammonia a t 0") at room temperature short prismatic crystals began to separate after 15 hours; 0.10 g. was collected dter 18 hours and a total of 0-26 g. after 4 days (yield 59%. In other experiments, the yield varied between 50 and 60%). The solution became light H = 7-24 NORMAL MONOSACCHARIDES. PART 11. ARABIXOSE. 363 brown but there was no sign of the very characteristic series of colour changes which accompanied the formation of the correspond-ing amide from methyl xylotrimethoxyglutarate (Hirst and Purves, Zoc.cif.). The compound obtained behaved as an acid amicle and liberated ammonia when heated above its melting point giving a volatile crystalline substance which was probably the imide. No change of colour was observed when the amide was heated in air (compare xylotrim~tlioxyglutardiamide) . It was very slightly soluble in cold et'her and in cold methyl alcohol and could con-veniently be recrystallised from the latter ; it showed a considerably grecttcr solubility in cold water m. 13. 232-233" [E], + 50.0" in water ( c = 0-701) (Found C = 43.7 ; €1 = 7.34; OlIe = 41-1 : N = 13.08. C,H,,O,N requires C = 43.6 ; €1 = 7.27 N = 12.73 ; Oble = 42-3:/,). A parallel to the higher specific rotation of the amide as compared uiith that of the ester is to be found in the dimethyl ester and the diainide of dirnethoxysuccinic acid (Purdie and Irvine J.1901 79 960). Xeth?yZa€ion of ,'l~~botrihydroxyglzctaric Acid.-The acid was prepared by Kiliani's method (Ber. 1888 21 3007) except that, after the oxidation with nitric acid and treatment with excess of calcium carbonate the calcium trihydroxyglutarate was precipitated from the cold filtrate by the addition of a small quantity of alcohol. The yellow amorphous mass thus obtained was washed with a little Ivater and dried on porous tile a t 40". The salt contained 1pi,O whereas Kiliani's product contained 3H,O. The substancc showed the solubilities aiid properties of calcium t,rihydroxy-glutaratc described by previous workers (Found H,O = 7.57 ; Cn = 13.35 for the anhydrous substance.Calc. for CaC5II,O7,H,O, H,O = '7.63 and for C ~ L C I T ~ ~ Ca = 18.35%). Its identity was confirmed by determining the specific rotation of the free acid corresponding to t'he calcium salt which was accomplished by iiieasuring the rotation of the salt when dissolved in a slight excess of hydrocliloric acid [a]L = - 21.2" in water for c = 1.065 (as acid). The value yuotcd by Fischer ( B e y . 1391 24 1844) is - 22.7". The free acid (7 g.) prepared by treating thc calcium salt with the calculated quantity of oxalic acid and evaporating the filtered solution in a vacuum was methylated in methyl alcohol in the iistzal manner with methyl iodide aiid silver oxide external cooling being necessary at first. The product was isolated dissolved in methyl iodide and subjected to two further treatments with rnet,hyl iodide and silver oxide to complete the inethylation.On distilling the product (4.5 g.) froin the third niathylation fractions were obtained I 1.95 Q . b. p. 135"/15 mm. 77yy 1.4353 n!:' 1-4400 364 THE CONSTITUTION OF THE NORMAL MONOSACCHARIDES. PART 11. 11 0-7 g. b. p. 140"/15 mm. nF 1.4373. The former contained methyl oxalate (proved by the formation of oxamide on treatment with methyl-alcoholic ammonia) and a portion of this was redis-tilled when 1.2 g. gave 0.7 g. b. p. 135"/12 mm. n\f 1.4370. This product was added to that forming the second portion of the first distillation and the material was identical with the ester previously identified as methyl trimethoxyglutarate [.ID + 45.5" in methyl alcohol (c = 1.230) (Found C = 47.7 ; H = 7.28 ; OMe = 59-4 ; C0,Me = 474%).Additional proof of identity was given by the isolation in good yield (0.6 g. gave 0.3 g.) of arabotrimethoxy-glutardiamide m. p. 232" alone or mixed with an authentic specimen [.ID + 49-7" (c = 1.150 in water); OMe = 41.3%. No trace of dimethoxysuccinamide could be detected evidence being thus provided that the calcium salt used as starting material in this series of experiments was not contaminated with calcium tartrate. Control Experiments.-The arguments by which the structure of trimethyl arabinose was deduced would be invalid in the event of there being any possibility for methylation of free hydroxy-groups to take place at some stage during the course of the experiments.I n order to prove that no such methylation takes place under the conditions described above experiments were carried out on the preparation of dimethyl tartrate under conditions chosen to conform as exactly as possible to those under which the oxidation product obtained from methylated arabinose was esterified. The ester (isolated in good yield) was the normal dimethyl tartrate (Found : OMe = 32.8%). Treatment of dimethyl tartrate with excess of boiling methyl alcohol containing 8% of nitric acid followed by neutralisation of the acid in boiling solution with freshly-prepared silver oxide gave unchanged dimethyl tartrate (Found OMe = 34.7%). There is therefore no possibility for alkylation to take place under the very much milder conditions of the experiments described earlier in this paper.We desire to express our gratitude to the Trustees of the Carnegie Trust for a grant and for a scholarship which has enabled one of us (G. J. R.) to take part in this work. THE UNIVERSITY ST. ANDREW$. THE UNIVERSITY ~NCHESTER. [Received December lSth 1924. 358 HIRST AND ROBERTSON THE CONSTITUTION OF THE LV1.-The Constitution of the Normal Mono-saccharides. Part 11. Arabinose. By EDMUND LANGLEY HIRST and GEORGE JAMES ROBERTSON. AS the result of recent discoveries concerning the nature of the oxide-ring linking in carbohydrates still greater emphasis must be laid on the necessity of obtaining for each individual sugar independent evidence as to internal structure. Thus for example, an examination of derivatives chosen both from the normal and from the y-type of compounds has revealed the fact that the same 1 5-oxide linking is present in tetramethyl 7-fructose (Haworth and Linnell J.1923,123 294) and in the normal sugars trimethyl xylose (Hirst and Purves ibid. 1352) and tetramethyl galactose (Pryde ibid. 1808) whilst evidence pointing to a similar structure for normal tetramethyl mannose has also been obtained (Levene and Meyer J. Biol. Chem. 1924,60,167). In the case of galactose, it is of special interest to find that the 7-derivative is of the 1 4-or butylene-oxidic structure (Haworth Ruell and Westgarth, J. 1924 125 2468). These investigations have now been supple-mented by inquiries into the structure of normal and 7-derivatives of the pentose sugar arabinose and the following interesting con-clusions have been drawn.Derivatives of the y-series of arabinose compounds have been found by Baker and Haworth (an account of whose experiments we have been privileged to receive from the authors prior to publication) to contain the 1 4- or butylene-oxidic linking (following paper) and on the other hand normal stable derivatives of arabinose have been shown by us to be definitely of the amylene-oxidic or 1 5-type. As a preliminary to work on the constitution of ara.binose a further study of the methylation of this sugar has been carried out, leading to the discovery of trimethyl p-methylarabinoside (compare Purdie and Rose J. 1906 $9 1204). This compound (m. p. 46-48"} which was prepared by methylating the free sugar with methyl sulphate has the properties of a normal stable glucoside.Polarimetric studies of the hydrolysis of the new compound along with determinations of the equilibrium value of the specific rotation in acid methyl alcohol indicate that the same type of oxide linking is present in this sugar and in Purdie's trimethyl a-methylarabin-oside and that these substances bear to each other the relationship of interconvertible a- and p-varieties of normal trimethyl methyl-arabinoside. The equilibrium value of the specific rotation of the liquid trimethyl methylarabinosides formed simultaneously with this new modification indicates the presence of isomerides containin NORMAL MONOSACCHARIDES. PART 11. ARABIKOSE. 359 a different oxide-ring structure. The behaviour of arabinose is here parallel to that of galactose which under similar conditions of inethylation yields a mixture of methylated products containing respectively the 1 4- and the 1 5-oxide linkings (Pryde E r s t and Humphreys preceding paper).Information concerning the internal structure of the normal derivatives of arabinose has been gained from a study of the oxidation by nitric acid of the f idly methylated trimethyl arabinose (III) derived from the crystalline trimethyl a-methylarabinoside (11). The sole oxidation product which was isolated in almost qimntitative yield was trimethoxyglutaric acid (117). Special precautions were taken to prevent methylation of free hydroxy-groups. It is thus evident that when the normal form of fully met'hylated arabinose is oxidised under the conditions here adopted, it gives rise to a.dibasic acid which still contains a chain of five carbon atoms a i d has been formed without loss of any of the incthoxyl groups present in the original trimethyl arabinose. By arguments similar to those advanced in the previous paper on xylose these observations can be interpreted only as showing that the structure of the normal form of fully methylated arabinose is ot the amylene-oxide type (11). The detailed study of the methyl-ation process as applied to sugars which has been carried out during the past few years goes to show that the oxide linking of a normal methylaldoside remains unaltered during methylation and therefore it follows that the unsubstituted cc- and p-methylarabin-osides from which the fully methylated derivatives are prepared also contain this type of oxide linking.These experiments, although not in thcmselves affording direct evidence concerning the structure of the free sugar may be considered in conjunction with arguments based on a comparison of the optical properties and the general reactions of free arabinose with the corresponding properties of the normal and 7-forms of methylarabinoside. They then lend strong support to the view that the same internal structure is present in the free aldose and in the normal forms of methyl-arabinoside and their methylated derivatives. We therefore consider that the behaviour of arabinose may best be understood at the present ttime 011 the basis of the amylene-oxidic ring structure (I) (compare Mirst and Purves Eoc.cit.). One point-which however does not in any way affect the validit)y of the preceding arguments-requires to be considered in somewhat greater detail. The work described has been carried out with I-arabinose whish has been found to yield a dimethyl trimethoxy-glntarate witjIi marked dextrorotatory powers. It is evident that t Tii ester and the dimethyl trimethoq-glutaratc ohtaind 1, 360 HIRST AND ROBERTSON THE CONSTITUTION OF THE Haworth and Linnell from tetramethyl 7-fructose (a sugar belonging to the d-series) should be optical enantiomorphs but these authors have found (Zoc. cit .) that their product also is dextrorotatory almost to the same degree as our own. The rotations shown by our materials have been confirmed on several occasions with samples of different origin and in these circumstances it was felt that a further examination of the question of optical act>ivity was necessary.The most convenient means of attack appeared to lie in the preparation of arabotrimethoxyglutaric acid by an entirely independent method, and this was accomplished by methylating the lzevorotatory arabotrihydroxyglutaric acid C02H*[CH*OH],*C02H (Kiliani Ber. , 1888 21 3007; Fischer Ber. 1891 24 1844). The methylated product was dextrorotatory and identical in every respect with the ester derived from methylated arabinose (V); and further proof of the identity of the two compounds was afforded by the isolation of the same crystalline diamide (VI) (m. p. 233" [.ID + 50") from both.The increase of the specific rotation in the dextro sense occasioned by methylation is here of the same order (+ 70") as that found when d-tartaric acid is converted into dimethyl dimethoxysuccinate (C02Me*[CH*OMe],*C02Me) and such a change would appear to be general in this series of dibasic acids. Con-firmation of the accuracy of our former observations was thus obtained and further experiments are now in progress by which it is hoped to obtain an explanation of the interesting anomaly in the direction of the optical rotation of the two esters. ryH*OH r$JH*OMe ryH*OH 702*H yO,*Me yO*NH2 I CH*OH I yH*OMe I YH-OMe FH*OMe YH-OMe YH-OMe OH*OH-tO (jH*OMe-t0 C;H*OMe+yH*OMe+yH*OMe+(iH*OMe (($XC*OH I YH-OMe I VH*OM e YH-OMe YHOOMe SH*OMe LCH LCH LCH CO,H CO,*Me COoNH, (1.1 (11.) (111.) (IV.1 (V. 1 (VI.) E X P E R I M E N T A L . Hethylartiun of Arabinose.-Trimethyl u-methyhrabinoside,* pre-pared according to Purdie and Rose (Zoc. cit.) and recrystallised several times had m. p. 4-6"; [.ID + 250" in water (c = 1.200), [uL $. 223" in methyl alcohol (c = 1.320) (compare Purdie and Rose); ng 14432 ng* 1.4450 the readings being for superfused material. Trimethyl p-rnethylarrabinoside was obtained by methylating * We are indebted to M i . R. W. Humphreys of the University College of South Wales Cardiff for a specimen of very pure trimethyl a-methyl-arabinoside NORMAL MONOSACCHARIDES. PART 11. ARABINOSE. 361 arabinose (10 g.) with methyl sulphate (50 c.c.) and sodium hydroxide (40 g. in 85 C.C. of water) in the usual manner (Haworth J.1915, 107 8). When the operation was conducted slowly the form-ation of coloured by-products was entirely avoided and after one methylation a mobile colourless syrup (9 g.) was obtained; this, subjected once again to the same treatment gave 8.5 g. of a syrup, which was purified by distillation. The main fraction (5.5 g. b. p. 123"/24 mm. nij" 1.44'73) crystallised slowly in long white needles, which were drained on porous tile. The new product was soluble in all the ordinary organic solvents including light petroleum and a suitable medium for recrystallisation could not be found. Puri-fication was effected by the somewhat wasteful method of repeatedly rubbing the crystals with light petroleum and draining rapidly on porous tile until constancy was attained in the m.p. 46-48", and rotations [.ID + 24" in methyl alcohol (c = l . l O O ) [.ID + 46.2" in water (c = 0.865). The crystals showed all the properties of a typical gliicoside and were stable in the presence of neutral or slightly alkaline potassium permanganate solution (Found C = 52-3 ; H = 8-8 ; OMe = 59.8. Required C = 52-4 ; H = 8.74 ; OMe = 60.2%). Interconversion of the a- and p-Forms of Trimethyl Methyhrabin-aside.-The initial specific rotation of the a-compound in methyl alcohol was + 223" (c = 1-563) whilst the final value obtained after heating the solution in a sealed tube with the addition of a trace of dry hydrogen chloride. was + 150". The p-variety on the other hand showed initially in acid methyl alcohol [.ID + 24" ( c = 1-100) increasing to a final steady value + 148".Further evidence concerning the relationship between these two substances was obtained from a study of the hydrolysis of the p-form with hydrochloric acid. In 87; aqueous acid the initial value tollD+ 47.6" (c = 1-572) was observed. On heating the solution a t go", the specific rotation increased regularly to a maximum constant value + 146" (c = 1.469) which is in good agreement with the figure + 1/53' quoted by Yurdie and Rose as the end value in the hydrolysis of pure trimethyl a-methylarabinoside. The value quoted is somewhat higher than those found by these authors during a study of the hydrolysis of mixtures containing both the a- and the p-form and higher also than the figure found for tri-methyl arabinose itself (+ 127") but this discrepancy may be connected with the failure of the syrupy trimethyl arabinose from which Purdie and Rose prepared the mixtures of the a- and p-forms of the fully methylated methylarabinoside to give satisfactory analytical results (Zoc.cit.). It is apparent therefore. t h a t these two crystalline substance 362 HIRST AND ROBERTSON THE CONSTITUTION OF THE are interconvertible a- and p-varieties of the same trimethyl methylarabinoside. On the other hand the initia'l specific rotation, [.ID + 57.4" (c = 3-708) of the analytically pure mixture of crystals and syrup forming the whole of the fully methylated arabinose (material described above as the main fraction) increased in acid methyl alcohol to an equilibrium value + 129" and on hydrolysis the final value was observed to be + 110".These figures are considerably lower than those given by the pure crystalline 01- and p-forms and may be taken as indicating that during the methyl-ation process a quantity of material had been formed differing in internal structure from the normal trimethyl methylarabinoside. Similar observations were made during a study of the methylation of galactose (Pryde Hirst and Humphreys loc. cit.). Simultaneous Hydrolysis and Oxidation of Trimethyl a-dlethyl-arabinoside. Isolation of Methyl Trimethoxyglutccrate (V).-In a typical oxidation experiment a solution of trimethyl a-methyl-arabinoside (1.90 9.) in nitric acid (d 1.2) (45 c.c.) was heated at 90" for 6 hours until the oxidation was complete. The excess of nitric acid having been removed (for details see Hirst and Purves, J.1923 123 1357) the oxidation product was boiled with 3% methyl-alcoholic hydrogen chloride the acid neutralised with silver carbonate in the cold a quantity of anhydrous sodium sulphate added to take up any water and the solvent distilled from the filtered solution under diminished pressure. The residual syrup was freed from a small quantity of silver nitrate by dis-solution in chloroform and finally a colourless mobile liquid (2.1 g.) was isolated which gave on distillation 1.90 g. b. p. l43"/ 18 mm. ngo 1.4355 (yield 83% of the calculated quantity). A further 0.10 g. b. p. 145-150"/16 mm. ni:" 1.4385 was obtained as a second fraction and the still residue remained uncoloured and weighed less than 0.10 g.The main fraction was methyl arabo-trirnethoxyglutccrate. a colourless refractive moderately mobile, uncrystallisable syrup soluble in water and in all the usual organic solvents (Found C = 48.0 ; H = 7.33 ; OMe = 60.2 ; CO,Me, by quantitative hydrolysis with N/10-NaOH = 48.1. C&fI80, requires C = 48.0 ; OMe = 62.0 ; C0,Me = 47*2y0). In methyl alcohol the ester showed [.ID + 47-3" (c = 1.842) and in water [.ID + 45" (c = 1.462). TrimetTLoxyglu~rdiid~ (VI) .-From a mixture of the ester (0-5 g . ) with 6 C.C. of methyl alcohol (saturated with dry ammonia a t 0") at room temperature short prismatic crystals began to separate after 15 hours; 0.10 g. was collected dter 18 hours and a total of 0-26 g. after 4 days (yield 59%. In other experiments, the yield varied between 50 and 60%).The solution became light H = 7-24 NORMAL MONOSACCHARIDES. PART 11. ARABIXOSE. 363 brown but there was no sign of the very characteristic series of colour changes which accompanied the formation of the correspond-ing amide from methyl xylotrimethoxyglutarate (Hirst and Purves, Zoc. cif.). The compound obtained behaved as an acid amicle and liberated ammonia when heated above its melting point giving a volatile crystalline substance which was probably the imide. No change of colour was observed when the amide was heated in air (compare xylotrim~tlioxyglutardiamide) . It was very slightly soluble in cold et'her and in cold methyl alcohol and could con-veniently be recrystallised from the latter ; it showed a considerably grecttcr solubility in cold water m.13. 232-233" [E], + 50.0" in water ( c = 0-701) (Found C = 43.7 ; €1 = 7.34; OlIe = 41-1 : N = 13.08. C,H,,O,N requires C = 43.6 ; €1 = 7.27 N = 12.73 ; Oble = 42-3:/,). A parallel to the higher specific rotation of the amide as compared uiith that of the ester is to be found in the dimethyl ester and the diainide of dirnethoxysuccinic acid (Purdie and Irvine J. 1901 79 960). Xeth?yZa€ion of ,'l~~botrihydroxyglzctaric Acid.-The acid was prepared by Kiliani's method (Ber. 1888 21 3007) except that, after the oxidation with nitric acid and treatment with excess of calcium carbonate the calcium trihydroxyglutarate was precipitated from the cold filtrate by the addition of a small quantity of alcohol. The yellow amorphous mass thus obtained was washed with a little Ivater and dried on porous tile a t 40".The salt contained 1pi,O whereas Kiliani's product contained 3H,O. The substancc showed the solubilities aiid properties of calcium t,rihydroxy-glutaratc described by previous workers (Found H,O = 7.57 ; Cn = 13.35 for the anhydrous substance. Calc. for CaC5II,O7,H,O, H,O = '7.63 and for C ~ L C I T ~ ~ Ca = 18.35%). Its identity was confirmed by determining the specific rotation of the free acid corresponding to t'he calcium salt which was accomplished by iiieasuring the rotation of the salt when dissolved in a slight excess of hydrocliloric acid [a]L = - 21.2" in water for c = 1.065 (as acid). The value yuotcd by Fischer ( B e y . 1391 24 1844) is - 22.7".The free acid (7 g.) prepared by treating thc calcium salt with the calculated quantity of oxalic acid and evaporating the filtered solution in a vacuum was methylated in methyl alcohol in the iistzal manner with methyl iodide aiid silver oxide external cooling being necessary at first. The product was isolated dissolved in methyl iodide and subjected to two further treatments with rnet,hyl iodide and silver oxide to complete the inethylation. On distilling the product (4.5 g.) froin the third niathylation fractions were obtained I 1.95 Q . b. p. 135"/15 mm. 77yy 1.4353 n!:' 1-4400 364 THE CONSTITUTION OF THE NORMAL MONOSACCHARIDES. PART 11. 11 0-7 g. b. p. 140"/15 mm. nF 1.4373. The former contained methyl oxalate (proved by the formation of oxamide on treatment with methyl-alcoholic ammonia) and a portion of this was redis-tilled when 1.2 g.gave 0.7 g. b. p. 135"/12 mm. n\f 1.4370. This product was added to that forming the second portion of the first distillation and the material was identical with the ester previously identified as methyl trimethoxyglutarate [.ID + 45.5" in methyl alcohol (c = 1.230) (Found C = 47.7 ; H = 7.28 ; OMe = 59-4 ; C0,Me = 474%). Additional proof of identity was given by the isolation in good yield (0.6 g. gave 0.3 g.) of arabotrimethoxy-glutardiamide m. p. 232" alone or mixed with an authentic specimen [.ID + 49-7" (c = 1.150 in water); OMe = 41.3%. No trace of dimethoxysuccinamide could be detected evidence being thus provided that the calcium salt used as starting material in this series of experiments was not contaminated with calcium tartrate.Control Experiments.-The arguments by which the structure of trimethyl arabinose was deduced would be invalid in the event of there being any possibility for methylation of free hydroxy-groups to take place at some stage during the course of the experiments. I n order to prove that no such methylation takes place under the conditions described above experiments were carried out on the preparation of dimethyl tartrate under conditions chosen to conform as exactly as possible to those under which the oxidation product obtained from methylated arabinose was esterified. The ester (isolated in good yield) was the normal dimethyl tartrate (Found : OMe = 32.8%). Treatment of dimethyl tartrate with excess of boiling methyl alcohol containing 8% of nitric acid followed by neutralisation of the acid in boiling solution with freshly-prepared silver oxide gave unchanged dimethyl tartrate (Found OMe = 34.7%). There is therefore no possibility for alkylation to take place under the very much milder conditions of the experiments described earlier in this paper. We desire to express our gratitude to the Trustees of the Carnegie Trust for a grant and for a scholarship which has enabled one of us (G. J. R.) to take part in this work. THE UNIVERSITY ST. ANDREW$. THE UNIVERSITY ~NCHESTER. [Received December lSth 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700358

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

SYNTHESIS O F DERIVATIVES O F 7-ARABMOSE. 365 LVI1.-Eynthesis of Derivatives of y-Arabinose. By STANLEY BAKER and WALTER NORMAN HAWORTH. THE derivatives of I-arabinose which have hitherto been prepared are dextrorotatory as indeed is the pentose itself. The authors have now isolated a series of lavorotatory compounds which, although configurationally identical with those already known (Fischer Ber. 1895 28 1156; Purdie and Rose J. 1906 89, 1204) belong to the new group of 7-sugars and have a different oxide-ring structure. The synthesis of these derivatives of 7-arabinose has been achieved by the initial condensation of I-arabinose with methyl-alcoholic hydrogen chloride a t 18" instead of conducting the reaction a t 100" as prescribed by the previous authors. The new compound, y-methylarabinoside (I) is characterised by its existence as a liquid having [aID - 71.3" in methyl alcohol by its remarkable instability in presence of permanganate and by the great ease with which it undergoes hydrolysis with acids of extreme dilution.Fischer's compound differs markedly in each of these respects and is strongly dextrorotatory. On methylation this distinction is maintained, for the new y-methylarabinoside is converted into a mixture of the a- and p-forms of trimethyl y-methylarabinoside (11) which again is laevorotatory (- 55.8" in water). The p-form appears to be capable of selective hydrolysis with 0.0360,/ hydrochloric acid leaving the a-modification largely unchanged but both are readily hydrolysed with 0.2570 acid to trimethgl 7-arabinose (111), a liquid [.ID - 39.5" in water exhibiting in a marked degree instability towards neutral permanganate.In all these respects, this methylated sugar contrasts strongly with the normal trimethyl arabinose investigated by Purdie and Rose (Ioc. cit.) and again by Hirst and Robertson (preceding paper) who have shown that the normal form is capable of hydrolysis only with 5% hydrochloric acid and has a rotation of + 127.2". A determination of the structure of this trimethyl y-arabinose discloses the reason for these differences in properties. Oxidation with nitric acid gives rise to a lactone of a trimethoxyhydroxy-valeric acid (IV) and also to a dimethoxyhydroxyglutaric acid (V). The latter product represents a further stage of oxidation than the former inasmuch as the terminal group of the monobasic acid has undergone conversion into an acid group giving a dibasic acid as the product this secondary reaction being accompanied, however by the elimination of one methoxyl residue.That the secondary product of the oxidation is the acid (V) i 366 BAKER AND HAWORTH : proved by its conversion into the completely methylated ester, dimethyl trimethoxyglutarate (VII) which forms a crystalline acid amide with ammonia. The structure allocated to both these oxidation products is supported by the following considerations. The trimethoxyvalerolactone (IV) is lavorotatory more so apparently, tha,n the acid to which it gives rise on keeping in aqueous solution. Adopting Hudson's rule the oxide ring must be situated on the left of the carbon chain and therefore it can only be a 1 3- or a 1 4-oxide.The possibility of the existence of the 1 5-oxide structure is eliminated since the terminal group 5 remains intact as a methyl-ated carbinol group which in the case of the secondary oxidation product is seen to undergo further oxidation by loss of methoxyl to the corresponding dimethoxyhydroxyglutaric acid (V). The choice between a 1 3- or propylene-oxide ring and that of a 1 4- or butylene-oxide structure for the trimethyl y-arabinose is determined by the consideration that the existence of a propylene-oxide sugar has not hitherto been substantiated whilst the 1 :4-oxides are commonly known. A propylene-oxide structure has been ascribed to trimethyl and tetramethyl 7-glucose by Irvine and Patterson (J.1923 123 898; compare Irvine J. 1922 121, 2146). A reference to the tetramethyl gluconolactone derived from the latter sugar on oxidation shows however that this lactone is dextrorotatory to a greater degree than the acid into which it is partly converted in water. The oxide ring of the latter should therefore be on the right of the carbon chain and on this reasoning tetramethyl 7-glucose must be either a 1 4- or a 1 5-oxide. A 1 3- or propylene-oxide ring would in the configuration of d-glucose, be situated on the left and its lactone would thus be lzvorotatory. If it be assumed that normal glucose is butylene-oxidic then the most probable formula for tetramethyl y-glucose is one having a SPRTi3ESIS OF DERIVATIVES OF 7-ARABIXOSE .367 arnylene-oxide structure (VIII) on the analogy of 7-fructose and it follows that glucose diacetone which is a 7-derivative should be given the formula (IX). r 1 The accompanying paper by E-lirst and Robertson furnishes an interesting corollary to the present investigation. These authors have demonstrated that the normal forms of I-arabinose and its derivatives are 1 5- or amylene-oxides a conclusion which applies also to normal xylose. It thus appears that in the pentose series the y-sugars belong to the butylene-oxide type on the analogy of galactose (Haworth Ruell and Westgarth J. 1924 125. 2468). E x P E R I 111 E N T A L. y-~~ethyZarccbirLoS.ide.-Finely sieved dried I-arabinose (10 g.) was shaken for 17 hours a t room temperature in 200 C.C.of dried methyl alcohol (acetone-free) containing 2 g. of hydrogen chloride. Solution of the solid occurred after 6 hours when the original specific rotation of arabinose (+ 107") had diminished to - 1.0" ; after 17 and 21 hours a minimum value [c(]D - 42~0"~ was attained. After neutralisation with silver carbonate followed by removal of solvent the viscid product was repeatedly extracted with ethyl aceta>te so long as the extracts showed a pronounced levorotation. The combined extracts yielded a clear syrup (8 g.) which gave only a faint reaction with Fehling's solution before distillation : h. p. 173-175"/0-15 mm. "rz = 1.4880 (Found C = 43.6; H = 7-4; OMe = 174. C6H,,0 requires C = 43.9; H = 7.3; ONe = lS*90/,). The maximum lzvorotation recorded for the specimens ivas [RID - 71.3" (c = 0.8) in methyl alcohol changing after 6 months to - 51.9" whilst the value in water was - 46.8".The y-methylarabinoside instantaneously decolorised neutral per-inangana te. Trimethyl y-1Clethykarab2'77oside. - The undistilled y-methyl-arabinoside (20 g.) showing [.ID - 51.5" and prepared from 25 g. of E-arabinose was methylated with methyl sulphate and sodium hydroxide followed by Purdie's reagents. The product 17.5 g., was a colourIess liquid b. p. 85-87"/0*3 iiim. ?zD = 1.4355 [.ID - 55.8" in water ( c = 1.04) (Found C = 52.3; H = 8.9 368 BAKER AND HAWORTH : OMe = 58.0. C,H,,O requires C = 52.4; H = 8.7 ; OMe = 60.2 yo). The compound decolorised neutral permanganate rapidly. Trimethyl 7-Arabinose.-The p-form of the above 7-arabinoside was hydrolysed by digestion a t 100" with N /lOO-hydrochloric acid ; and during 3 hours the value of [or]= changed from - 38-6" to - 58" and then remained constant.At this stage the solution actively reduced Fehling's solution. The or-form required a higher concentration of acid to promote its hydrolysis and by increasing the acid content to N/lO the specific rotation changed from - 58" to a constant value of - 32.2" during 34 to 4 hours. The mixture of a- and p-isomerides of trimethyl y-methylarabin-oside was completely hydrolysed by N /15-hydrochloric acid at 100" after 34 to 4 hours the rotation values recorded being : Time in minutes ... 0 45 60 150 240 [alD .. ................... -3'7.5" -51.8" -51.8' -31.6" -31.6" The initial depression in the laevorotatory direction is followed by a rise to rotation values corresponding with those of the pre-ceding experiments and the form of the curve connecting these data is of the usual type.The product of hydrolysis trimethyl 7-arabinose was isolated in the usual way and distilled as a colourless liquid b. p. 97-99"/ 0.18 mm. n = 1.4503 (Found C = 49.9; H = 8.4; OMe = 49.3. C,H,,O requires C = 50.0; H = 8.3; OMe = 4804%). The sugar showed in water [a], = - 39.5" and reduced Fehling's solution and neutral permanganate instantaneously. Oxi&tion.-A solution of trimethyl 7-arabinose (5 9.) in 100 C.C. of dilute nitric acid (d 1.20) was heated a t 90" until oxidation com-menced and then maintained a t 75" for 10 hours or until the evolution of nitrous fumes had ceased.The solution was diluted with water and the whole of the nitric acid distilled under dimin-ished pressure at M" water being frequently added during this operation. The residual syrup was dried by distilling from it methyl alcohol several times and was finally esterified by methyl-alcoholic hydrogen chloride (3.0%). Thereafter the solution was neutralised by barium carbonate the use of silver carbonate being avoided for the reason that any free hydroxyl group might undergo methylation in the presence of methyl chloride (compare the methylation of malic acid which occurs during ester formation by the action of methyl iodide on silver malate). The esterified. product was a syrupy liquid (4-2 g.) which distilled completely a t 105-1 18"/0.02 mm.and showed refractive indices varying from 1.4388 to 1.4437. These data along with the analytical figures pointed to the non-homogeneity of the product PHENYL BENZYL DIKETONE AND SOME DERlVATIVES. 369 and this conclusion was confirmed by subsequent experiments designed to separate the individual constituents. The esterified oxidation product was hydrolysed by heating a t 80" with 2.0% hydrochloric acid for 2 hours. The mineral acid was neutralised using Congo-red as indicator the' solution evaporated under diminished pressure and the residue extracted from mineral matter and distilled b. p. 00"/0-03 mm. n = 1.4430. This distillate represented 757; of the oxidation product (leaving an undistilled residue which was subsequently examined) and immedi-ately set to a hard mass of crystals; m.p. 29" (after draining on tile); [.ID = - 43.2" in water (changing to - 33.8" after 2 days, and to - 23.9" after 20 days) (Found C = 50.5; H = 7-4: OMe = 46.0. Calc. for C,H,,O, C = 50.5; H = 7.4; OMe = 48.9%). On titration the compound behaved as a trimethoxy-valerolactone ; 0.0906 required on heating 4.87 C.C. of Ar/lO. sodium hydroxide. Calc. for C,H,,O, 4.8 C.C. The undistilled residue (250/ of the total product) was a mixture of dimethoxyhydroxyglutaric acid and its lactone (Found C = 42.37; H = 5.7. Calc. €or C,H,,O, C = 40.4; N = 5.8. Calc. for C,H,,OG C = 44.2; H = 5.3%). After esterification with methyl alcohol the product contained OMe = 53.6y0 and after nuethylation with methyl iodide and silver oxide it gave the follow-ing analytical results C = 47-9; H = 7.1 ; OMe = 60.0.Calc. for CloH150, C = 48.0 ; H = 7.2 OMe = 62.00/,. This specimen of dimethyl trimethoxyglutarate was dissolved in methyl alcohol which had been saturated with ammonia at O" and the corresponding amide m. p. 223" was isolated. The amide the amount of which was small was not recrystallised. I n admixture with a specimen of the diamide of triinethoxyglutaric acid provided by Hirst and Robertson (Zoc. c i f . ) it melted a t 225-227". The authors are indebted to the Department of Scientific and Industrial Research and to the Research Endowment Fund of Armstrong College for grants in aid of t,his work. UNIVERSITY OF DURHAM ARMSTRONG COLLEGE, NEWCASTLE -ON-TYSE. [Received December 15th 1924.SYNTHESIS O F DERIVATIVES O F 7-ARABMOSE. 365 LVI1.-Eynthesis of Derivatives of y-Arabinose. By STANLEY BAKER and WALTER NORMAN HAWORTH. THE derivatives of I-arabinose which have hitherto been prepared are dextrorotatory as indeed is the pentose itself. The authors have now isolated a series of lavorotatory compounds which, although configurationally identical with those already known (Fischer Ber. 1895 28 1156; Purdie and Rose J. 1906 89, 1204) belong to the new group of 7-sugars and have a different oxide-ring structure. The synthesis of these derivatives of 7-arabinose has been achieved by the initial condensation of I-arabinose with methyl-alcoholic hydrogen chloride a t 18" instead of conducting the reaction a t 100" as prescribed by the previous authors.The new compound, y-methylarabinoside (I) is characterised by its existence as a liquid having [aID - 71.3" in methyl alcohol by its remarkable instability in presence of permanganate and by the great ease with which it undergoes hydrolysis with acids of extreme dilution. Fischer's compound differs markedly in each of these respects and is strongly dextrorotatory. On methylation this distinction is maintained, for the new y-methylarabinoside is converted into a mixture of the a- and p-forms of trimethyl y-methylarabinoside (11) which again is laevorotatory (- 55.8" in water). The p-form appears to be capable of selective hydrolysis with 0.0360,/ hydrochloric acid leaving the a-modification largely unchanged but both are readily hydrolysed with 0.2570 acid to trimethgl 7-arabinose (111), a liquid [.ID - 39.5" in water exhibiting in a marked degree instability towards neutral permanganate.In all these respects, this methylated sugar contrasts strongly with the normal trimethyl arabinose investigated by Purdie and Rose (Ioc. cit.) and again by Hirst and Robertson (preceding paper) who have shown that the normal form is capable of hydrolysis only with 5% hydrochloric acid and has a rotation of + 127.2". A determination of the structure of this trimethyl y-arabinose discloses the reason for these differences in properties. Oxidation with nitric acid gives rise to a lactone of a trimethoxyhydroxy-valeric acid (IV) and also to a dimethoxyhydroxyglutaric acid (V). The latter product represents a further stage of oxidation than the former inasmuch as the terminal group of the monobasic acid has undergone conversion into an acid group giving a dibasic acid as the product this secondary reaction being accompanied, however by the elimination of one methoxyl residue.That the secondary product of the oxidation is the acid (V) i 366 BAKER AND HAWORTH : proved by its conversion into the completely methylated ester, dimethyl trimethoxyglutarate (VII) which forms a crystalline acid amide with ammonia. The structure allocated to both these oxidation products is supported by the following considerations. The trimethoxyvalerolactone (IV) is lavorotatory more so apparently, tha,n the acid to which it gives rise on keeping in aqueous solution. Adopting Hudson's rule the oxide ring must be situated on the left of the carbon chain and therefore it can only be a 1 3- or a 1 4-oxide.The possibility of the existence of the 1 5-oxide structure is eliminated since the terminal group 5 remains intact as a methyl-ated carbinol group which in the case of the secondary oxidation product is seen to undergo further oxidation by loss of methoxyl to the corresponding dimethoxyhydroxyglutaric acid (V). The choice between a 1 3- or propylene-oxide ring and that of a 1 4- or butylene-oxide structure for the trimethyl y-arabinose is determined by the consideration that the existence of a propylene-oxide sugar has not hitherto been substantiated whilst the 1 :4-oxides are commonly known. A propylene-oxide structure has been ascribed to trimethyl and tetramethyl 7-glucose by Irvine and Patterson (J.1923 123 898; compare Irvine J. 1922 121, 2146). A reference to the tetramethyl gluconolactone derived from the latter sugar on oxidation shows however that this lactone is dextrorotatory to a greater degree than the acid into which it is partly converted in water. The oxide ring of the latter should therefore be on the right of the carbon chain and on this reasoning tetramethyl 7-glucose must be either a 1 4- or a 1 5-oxide. A 1 3- or propylene-oxide ring would in the configuration of d-glucose, be situated on the left and its lactone would thus be lzvorotatory. If it be assumed that normal glucose is butylene-oxidic then the most probable formula for tetramethyl y-glucose is one having a SPRTi3ESIS OF DERIVATIVES OF 7-ARABIXOSE .367 arnylene-oxide structure (VIII) on the analogy of 7-fructose and it follows that glucose diacetone which is a 7-derivative should be given the formula (IX). r 1 The accompanying paper by E-lirst and Robertson furnishes an interesting corollary to the present investigation. These authors have demonstrated that the normal forms of I-arabinose and its derivatives are 1 5- or amylene-oxides a conclusion which applies also to normal xylose. It thus appears that in the pentose series the y-sugars belong to the butylene-oxide type on the analogy of galactose (Haworth Ruell and Westgarth J. 1924 125. 2468). E x P E R I 111 E N T A L. y-~~ethyZarccbirLoS.ide.-Finely sieved dried I-arabinose (10 g.) was shaken for 17 hours a t room temperature in 200 C.C.of dried methyl alcohol (acetone-free) containing 2 g. of hydrogen chloride. Solution of the solid occurred after 6 hours when the original specific rotation of arabinose (+ 107") had diminished to - 1.0" ; after 17 and 21 hours a minimum value [c(]D - 42~0"~ was attained. After neutralisation with silver carbonate followed by removal of solvent the viscid product was repeatedly extracted with ethyl aceta>te so long as the extracts showed a pronounced levorotation. The combined extracts yielded a clear syrup (8 g.) which gave only a faint reaction with Fehling's solution before distillation : h. p. 173-175"/0-15 mm. "rz = 1.4880 (Found C = 43.6; H = 7-4; OMe = 174. C6H,,0 requires C = 43.9; H = 7.3; ONe = lS*90/,).The maximum lzvorotation recorded for the specimens ivas [RID - 71.3" (c = 0.8) in methyl alcohol changing after 6 months to - 51.9" whilst the value in water was - 46.8". The y-methylarabinoside instantaneously decolorised neutral per-inangana te. Trimethyl y-1Clethykarab2'77oside. - The undistilled y-methyl-arabinoside (20 g.) showing [.ID - 51.5" and prepared from 25 g. of E-arabinose was methylated with methyl sulphate and sodium hydroxide followed by Purdie's reagents. The product 17.5 g., was a colourIess liquid b. p. 85-87"/0*3 iiim. ?zD = 1.4355 [.ID - 55.8" in water ( c = 1.04) (Found C = 52.3; H = 8.9 368 BAKER AND HAWORTH : OMe = 58.0. C,H,,O requires C = 52.4; H = 8.7 ; OMe = 60.2 yo). The compound decolorised neutral permanganate rapidly. Trimethyl 7-Arabinose.-The p-form of the above 7-arabinoside was hydrolysed by digestion a t 100" with N /lOO-hydrochloric acid ; and during 3 hours the value of [or]= changed from - 38-6" to - 58" and then remained constant.At this stage the solution actively reduced Fehling's solution. The or-form required a higher concentration of acid to promote its hydrolysis and by increasing the acid content to N/lO the specific rotation changed from - 58" to a constant value of - 32.2" during 34 to 4 hours. The mixture of a- and p-isomerides of trimethyl y-methylarabin-oside was completely hydrolysed by N /15-hydrochloric acid at 100" after 34 to 4 hours the rotation values recorded being : Time in minutes ... 0 45 60 150 240 [alD .. ................... -3'7.5" -51.8" -51.8' -31.6" -31.6" The initial depression in the laevorotatory direction is followed by a rise to rotation values corresponding with those of the pre-ceding experiments and the form of the curve connecting these data is of the usual type.The product of hydrolysis trimethyl 7-arabinose was isolated in the usual way and distilled as a colourless liquid b. p. 97-99"/ 0.18 mm. n = 1.4503 (Found C = 49.9; H = 8.4; OMe = 49.3. C,H,,O requires C = 50.0; H = 8.3; OMe = 4804%). The sugar showed in water [a], = - 39.5" and reduced Fehling's solution and neutral permanganate instantaneously. Oxi&tion.-A solution of trimethyl 7-arabinose (5 9.) in 100 C.C. of dilute nitric acid (d 1.20) was heated a t 90" until oxidation com-menced and then maintained a t 75" for 10 hours or until the evolution of nitrous fumes had ceased.The solution was diluted with water and the whole of the nitric acid distilled under dimin-ished pressure at M" water being frequently added during this operation. The residual syrup was dried by distilling from it methyl alcohol several times and was finally esterified by methyl-alcoholic hydrogen chloride (3.0%). Thereafter the solution was neutralised by barium carbonate the use of silver carbonate being avoided for the reason that any free hydroxyl group might undergo methylation in the presence of methyl chloride (compare the methylation of malic acid which occurs during ester formation by the action of methyl iodide on silver malate). The esterified. product was a syrupy liquid (4-2 g.) which distilled completely a t 105-1 18"/0.02 mm.and showed refractive indices varying from 1.4388 to 1.4437. These data along with the analytical figures pointed to the non-homogeneity of the product PHENYL BENZYL DIKETONE AND SOME DERlVATIVES. 369 and this conclusion was confirmed by subsequent experiments designed to separate the individual constituents. The esterified oxidation product was hydrolysed by heating a t 80" with 2.0% hydrochloric acid for 2 hours. The mineral acid was neutralised using Congo-red as indicator the' solution evaporated under diminished pressure and the residue extracted from mineral matter and distilled b. p. 00"/0-03 mm. n = 1.4430. This distillate represented 757; of the oxidation product (leaving an undistilled residue which was subsequently examined) and immedi-ately set to a hard mass of crystals; m.p. 29" (after draining on tile); [.ID = - 43.2" in water (changing to - 33.8" after 2 days, and to - 23.9" after 20 days) (Found C = 50.5; H = 7-4: OMe = 46.0. Calc. for C,H,,O, C = 50.5; H = 7.4; OMe = 48.9%). On titration the compound behaved as a trimethoxy-valerolactone ; 0.0906 required on heating 4.87 C.C. of Ar/lO. sodium hydroxide. Calc. for C,H,,O, 4.8 C.C. The undistilled residue (250/ of the total product) was a mixture of dimethoxyhydroxyglutaric acid and its lactone (Found C = 42.37; H = 5.7. Calc. €or C,H,,O, C = 40.4; N = 5.8. Calc. for C,H,,OG C = 44.2; H = 5.3%). After esterification with methyl alcohol the product contained OMe = 53.6y0 and after nuethylation with methyl iodide and silver oxide it gave the follow-ing analytical results C = 47-9; H = 7.1 ; OMe = 60.0. Calc. for CloH150, C = 48.0 ; H = 7.2 OMe = 62.00/,. This specimen of dimethyl trimethoxyglutarate was dissolved in methyl alcohol which had been saturated with ammonia at O" and the corresponding amide m. p. 223" was isolated. The amide the amount of which was small was not recrystallised. I n admixture with a specimen of the diamide of triinethoxyglutaric acid provided by Hirst and Robertson (Zoc. c i f . ) it melted a t 225-227". The authors are indebted to the Department of Scientific and Industrial Research and to the Research Endowment Fund of Armstrong College for grants in aid of t,his work. UNIVERSITY OF DURHAM ARMSTRONG COLLEGE, NEWCASTLE -ON-TYSE. [Received December 15th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700365

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

PHENYL BENZYL DIKETONE AND SOME DERlVATIVES. 369 LVII1.-Phenyl Benxyl Dilcetone and some Derivatives. By THOMAS MALKIN and ROBERT ROBISSON. TIIAT the methylene group in a-alkyloxy-ketones of the type of cu-methoxyacetophenone is characterised by considerable reactivity is clear from the use which has been made of these substances in VOL. CXXVII. 370 MALKIN AND ROBINSON: the synthesis of the anthocyanidins and the work now to be described was instituted with the object of taking further advantage of this property. An experiment (p. 377) in which o-methoxy-acetophenone and phenyl propyl ketone were put in competition for salicylaldehyde in boiling methyl-alcoholic potassium hydroxide solution showed that the former ketone exhibited the greater reactivity. The effect of the oxygen of the methoxyl group is doubtless to produce a general drift of electrons in the molecule towards it and this facilitates the acquirement of a negative charge by the carbon atom of the methylene group in the activated phase which determines the occurrence of the reaction.In the accom-panying scheme the curved arrows show the covalency changes OH G f-x -C=CH-OMe during activation of the enolic form of t8he ketone and the straight arrow represents the general drift due to the oxygen of the methoxy-group. Here the effects are in the same direction and result in enhanced reactivity whilst in phenyl propyl ketone the hydrogen atoms produce an electron drift in the opposite sense and the reactivity due fo the part'icular conjugation represented is diminished.Very numerous applications of this conception of the interaction of the electronic changes due to conjugation and the general polar or electrostatic induction effect can be made and one example in connexion with orientation is the explanation afforded of the frequent occurrence of substitution in the position situated between an o-p-directive group and a m-directive group themselves in the rn-position to one another. A case in point is the application of the Skraup reaction to m-nitroaniline. The two possible activations by conjugation are shown in (A) and (B) and the latter is assisted by the general electron drift due to the nit'roxyl. The chief product -+ of the reaction is in fact 5-nitroquinoline. When the nitro-group is replaced by methyl the direction of the general drift will be * The curved arrows in (A) and (B) imply that free electrons of the N atom become covalency electrons of N and Ca in the nucleus and that C, in order t o preserve its total covalency unaltered abandons correspondingly Ca - Cg covalency electrons to the sole use of Cp PHENYL BENZYL DIKETONE AND SOi\lE DERIVATIVES.371 reversed (C) and accordingly m-toluidine is converted in the Xkraup reaction into 7-mcthylquinoline. We have investigated some of the transformations of the arylidene-o -metlioxyacetophenones . Phenyl fhnetho.rystyryZ ketone PhCO*C( OMe):CHPh forms a colourless crystalline dibromide the stability of which although riot of a high order was unexpected. The failure of the group Ph-CQ*c (0Me)Br to lose methyl bromide spontaneously is no doubt related to the unusual stability of the hydrate Ph*CO*CH(OH),.By reduction nith hydrogen in presence of palladium tbe un-saturated ketone is changed to a tetrahydro-derivative, Ph*CU (OH )*CH (O;\le)-CN,Ph. When subjected to somewhat vigorous hydrolysis by acids the arj*lidene-ctl-methoxyacetophenones yield a-diketones isomeric with the diaroylmethanes. Thus phenyl p-methoxystyryl ketone is changed by nieans of a hot solution of sulphuric acid in acetic acid into phenyl benzyl diketone PhCOCO*CH,Ph a substance which can be readily prepared in this manner. Whilst our work was proceeding Dufraisse and Moureu placed on record a descrip-tion of the compound which was obtained by a different process (@om@. rend. 1924 178 6 573).The diketone is almost certainly a tautomeric substance ; it is yellow oxidisable soluble in aqueous sodium hydroxid-e and gives a ferric chloride reaction. The facile condensation with o-phenylenediamine leads to phenylbenzyl-quinoxaline . The most characteristic property of this diketone is however, the remarkable ease with which i t undergoes the benzil-benzilic acid type of transformation. It is rapidly converted by hot dilute aqueous sodium hydroxide into sodium a-benzylmandelate. This rearrangement could be represented as due to the migration of either the phenyl or the benzyl group but as it occurs more smoothly than in the case of benzil itself the latter assumption seems the more natural : Ph*CO*CO*CH,Ph + H,O + Ph*C(OH)(CO,H)*CH,Ph. + I This interpretation is in harmony with the conclusions which Tiffeneau and Ordkhov (compare An?zuaZ Reports 1923 115) have drawn from their experiments on intramolecular rearrangements of the pinacol-pinacolin type and also with the results of Claisen (2.angezu. Chem. 1923 36 478) on the alkylation of the phenols. I n these and other cases the high aptitude for migration possessed by the benzyl group has been emphasised. Corresponding un-saturated ket,ones a-cliketones and their transformation products have been obtained in three other series. 0 372 MATXIN AND ROBINSON: E X P E R I M E N T A L . AlethoxyacetonitriZe.-This intermediate in the preparation of some w-methoxyacetophenones (Slater and Stephen J. 1920 117, 314; Pratt and Robinson J. 1923 123 748) is best obtained by the following modification of Polstorff and Meyer's method (Ber., 1912 45 1911).Aqueous formaldehyde solution (reputed 40%, 35 c.c.) is gradually added with cooling in ice-water to sodium cyanide (19 g.) dissolved in water (38 c.c.). Powdered sodium cyanide (19 9.) is then introduced and when solution is complete a further quantity of aqueous formaldehyde (35 c.c.) is added with careful cooling. The mixture is kept at a low temperature for 9 hour and the thick oily liquid or soft paste is then treated with methyl sulphate (80 c.c.) which is added in portions of 10 to 15 C.C. The mixture is thoroughly shaken and not cooled until the tem-perature rises to 35". After cooling for a few minutes in ice-water, the mixture is again allowed to warm to 35"; then it is cooled and the next portion of methyl sulphate is added only when there is no further heat of reaction.The product is taken up in ether, and the separated extract dried with sodium sulphate and dis-tilled. After separation from methyl sulphate by a preliminary fractionation under slightly reduced pressure 39 g. (yield 70 yo), b. p. 119-120" distilled at the ordinary pressure. Phenyl p -2Methox yst yryl Ketone PhCO*C( 0Me):CHPh .-Aqueous sodium hydroxide (20%) (5 c.c.) was added to a solution of w-meth-oxyacetophenone (5 g.) and benzaldehyde (3.5 g.) in ethyl alcohol (30 c.c.). After 12 hours the greater part of the alcohol was distilled from the st,eam-bath and the residue diluted with water and extracted with ether. The ethereal solution was dried over sodium sulphate and distilled under diminished pressure ; 2.4 g.of a mixture of benzaldehyde and o-methoxyacetophenone were recovered and 4-8 g. of a pale yellow oil b. p. 202-204"/13 mm., which solidified on cooling were obtained. The substance is readily soluble in most organic solvents but may be crystallised by cooling a saturated solution in ethyl alcohol or light petroleum to 0". The rectangular plates m. p. 35" are almost colourless (Found C = 80-9 ; H = 5.8. C,,H,,O requires C = 80-7 ; H = 5.9 %). The citron-yellow solution in sulphuric acid becomes yellowish-green and finally deep violet on heating. Phenyl aB-Dibromo-a-methoxy-p-phenylethyl Ketone, PhCO*CBr(OMe)*CHBrPh . -Phenyl p-methoxystyryl ketone (6 g.) dissolved in ether (10 c.c.), was gradually treated at 0" with bromine (4 g.).The dibromide (4.7 g . ) crystallised in a few minutes and a further quantit PIIENYL BENZYL DIKETONE AND SOME DERIVATIVES. 373 (4-5 g.) of somewhat less pure product was obtained on evapor-ation of the solution. The substance crystallises from benzene in colourless needles m. p. 103" (Found C = 48.5; H = 3.6. C,,HI,O,Br requires C = 48.2; H = 3.5%). I n the course of a few days red specks appear in the crystals. but attempts to obtain definite products of decomposition have not yet been successful. This is probably due to the circumstance that the substance tends to lose the elements of methyl bromide as well as of h?-drogen bromide. It was shown by titration that when boiled with water the dibromide yields a molecular proportion of hydrogen bromide but the resulting yellow oil could not be satisfactorily purified.A Zeisel determination (Found Me0 = 5.5. C,5H,,0Br*OMe re-quires Me0 = 9.8%) showed that hydrolysis at the methoxyl group must occur to some extent. Boiling aqueous sodium hydr-oxide attacks the dibromide with formation of sodium bromide (2 mols.). The final ethereal mother-liquor from the preparatisn deposited yellow crystals. m. 1). 59" but the quantity obtained ~vas insufficient for further investigation. Phenyl BenxyZ Diketone .-A solution of phenyl p-luethosystyryl ketone (2 g.) in acetic acid (9 c.c.) and concentrated sulphuric acid (1 c.c.) was heated over a free flame until the yellow solution became deep brownish-red. Prolonged heating is disadvantageous and the time necessary to bring the liquid to the boiling point usually suffices.After dilution with water and extraction with ether the ethereal layer was washed with water and then with successive small portions of loo/ aqueous sodium hyciroside. These deep orange alkaline washings were expeditiously acidified with hydro-chloric acid in presence of ice and the diketone was again taken up in ether. The extract was dried over sodium sulphate the greater part of the solvent removed by distillation and the remainder by evaporation in a vacuum leaving 1.7 g. of a yellow crystalline solid. The substance crystallises from methj.1 alcohol or ether in pale yellow prisms m. 11. 65" (Dufraisse and Moureu Zoc. cit. 67-68") (Found C = 80.6; H = 5.7.Calc. C = 80.4; H = 54°/o). This diketone is readily soluble in most organic solvents; the crystals rapidly become oily on exposure. In alcoholic solution, a purplish-brown coloration is developed on the addition of ferric chloride . 3-PheizyZ-3-bcnxylqz~i~~o~uZ~ne.-A solution of phenyl benzyl diketone (1.2 g.) and o-phenylenediamine (0.6 g.) in ethyl alcohol (3 c.c.) was gently heated on the steam-bath for 20 minutes. The coinpact yellow crystals (0.7 g.) that separated on cooling crystal-lisecl from ethyl alcohol in almost colourless lustrous needles 374 MALKIN AND ROBINSON : m. p. 97" (Found C = 83.1; H = 5.7; N = 9.6. C,,H,GN, requires C = 83.1 ; H = 5-4 ; N = 9.5%). The orange solution in concentrated sulphuric acid becomes colourless on dilution with water.Phenyl p 4-Dirnethoxptyryl Ketone Ph*CO*C( OMe):CH*C,H,*OMe. -Aqueous sodium hydroxide (5 C.C. of 20%) was added to a solu-tion of oJ-met,hoxyacetophenone (5 g .) and anisaldehyde (4.5 g.) in ethyl alcohol (30 c.c.). Next day 3-5 g. of product had crystal-lised and a further portion (1 g.) separated on cooling the solution in ice. The mother-liquor was treated as in the preparation of phenyl p-methoxystyryl ketone and unchanged material (2.5 g .) and the unsaturated ketone (1 g.) were SO obtained. The total yield was therefore 5.5 g. The substance crystallises from alcohol, in which it is moderately readily soluble in hard pale yellow, rectangular prisms m. p. 75" b. p. 238-242"/14 mm. (Found: C = 76.3; H = 5.8. C1,H1,03 requires C = 76.1 ; H = 6-Oy0).The orange solution in sulphuric acid becomes deep yellowish-brown on heating. Attempts to prepare a crystalline dibromide were unsuccessful. Phenyl 4-Methoxybenxyl Diketone Ph=CO*CO*CH,*C,H4*OIe.-The hydrolysis of the foregoing substance by means of sulphuric acid in acetic acid solution gave unsatisfactory yields (30y0) but the use of hydrobromic acid effected a considerable improvement. The anisylidene derivative (2 g.) was dissolved in acetic acid (10 c.c.), concentrated aqueous hydrobromic acid (4 c.c.) added and the orange liquid heated over a free flame until there was a rather sudden change of colour to a dirty red. The remaining procedure followed exactly that described in the case of phenyl benzyl ketone and there resulted 1.7 g.of a yellow crystalline mass. The sub-stance is not very stable and crystallises best from methyl alcohol, separating in pale yellow prismatic needles m. p. 68" (Found : C = 75.2; H = 5.6. ClGHl4O3 requires C = 75.6; H = 5.5%). In alcoholic solution the substmce gives a purplish-brown color-ation with ferric chloride and on condensation with o-phenylene-diarnine in alcoholic solution it readily yields 2-phenyl-3-p-methoxy-benxylquinoxaline which crystallises from ethyl alcohol in colourless needles m. p. 119' (Found C = 80.9; H = 5.7. C,,Hl,ON, requires C = 81-0; I3 = 5.5y0) and gives a brown solution in sulphuric acid. When the alkaline solution of the diketoiie was agitated with methyl sulphate phenyl p 4-dimethoxystyryl ketone was regener-ated in good yield.The crystallised substance m. p. 75" exhibited an unaltered melting point when mixed with an authentic specimen PHENYL BENZYL DIKETONE AND SOME DERIVATIVES. 37.5 4-Jfethoxyphenyl p - Methoxystyryl Ketone, MeO-C,H,*CO*C( 0Me):CBPh. -This substance was prepared in the same way as phenyl p-methoxy-styryl ketone (above). w 4-Dimethoxyacetophenone (4 g.) and benzaldehyde (2.4 g.) yielded 3.3 g. of a yellow oil b. p. 240-250"/33 mm. which crystallised and 2 g. of recovered material, whilst the residue in the flask gave 0.5 g. of the eondensation pro-duct by crystallismtion from alcohol. The substance is readily soliible in most organic solvents and crystallises from ethyl alcohol in colourless rectangular prisins m. p. 74" (Found C = 76.1 ; H = 6.0.CZ7H1603 requires C = 76.1; I3 = G.OO/,). The deep yellow solution in sulphuric acid becomes intensely orange-red on warming and crimson on heating more strongly. 4-Methoxyphenyl be?axyl diketone ~leO*C,H,*CO.CO*CN,Bh ob-tained froin the foregoing unsaturated ketone by the same method and in the same yield as described above in the case of an isomeride, crystallises from ether or alcohol in yellow plates m. p. $2" (Found : C = 75.6; M = 5.7. C1,H,,O requires C = 75-6; H = 5.5%). The properties of the substance closely resemble those of phenyl benzyl diketone. Condensation with o-phenylenediamine leads to 2-p-metl~ox~phenyl-3-benzylqui~zoxaline which crystallises from alco-hol in colourless silky needles m. p. 141" (Found C = 80.8; H = 5.7. C,,H,,ON requires C = 81.0; H = 55y0).The solu-tion in siilphuric acid is Bordeaux red. 4-Methoxyphenyl p 4-Dimethoxyslyryl Ketone, MeO*C,H,*CO*C( QMe):@H*C,H,*O~ile. -The condensation of anisaldehyde and w 4-climethoxyaceto-phenone was carried out in the manner prescribed for the pre-paration of phenyl p-methosystyryl ketone except that after the removal of unchanged materials by distillation under diminished pressure the residue was stirred with alcohol and so induced t0 crystallise. The substance crystallises from alcohol in faintly yellow rectangular plates m. p. 72.5" (Pound C = 72-5 ; H = 6-2. C,8H1,0 requires C = 72.5 ; H = 6.0%). The orange-red solution in sulphuric acid becomes rich crimson on heating. Comparison of the colour of the derivatives of benzylideneacetophenone now described shows that a methoxy-group in the p-position in the benzylidene nucleus has auxochromic character whilst a similar substitution in the acetophenone nucleus has a feeble bathochrornic influence.On hydrolysis with hydrobromic acid in acetic acid solution this trimethoxybenzylideneacetophenone yields 4-methoxyphenyl 4-meth-oxybeszzyl diketone MeO*C,PI,*CO*CO*CH,*C,II,.OMe in almost theoretical amount. This substance closely resembles pheny 376 MALEIN AND ROBINSON: benzyl diketone and crystallises from ethyl alcohol in yellow prisms, m. p. 92" (Found C = 71.7; H = 5.8. Cl,H1,O requires C = 71-8 ; H = 5.6%). 2-p-Methoxyphenyl-3-p-methoxybenzylquin-oxaline crystallises from alcohol in colourless silky needles m. p. 123" (Found C = 77.5 ; H = 5.7.C,,H,O,N requires C = 77.5; H = 5.6%). This base dissolves in concentrated hydrochloric acid to an orange-yellow solution but the salt is dissociated on dilution with water. The solution in sulphuric acid is Bordeaux red. None of the quinoxalines now described exhibits fluorescence in acid or neutral solution. a- Benzylmndelic Acid and Derivatives.-When solutions of phenyl benzyl diketone or its derivatives in aqueous sodium hydroxide of any convenient concentration are boiled the deep orange colour rapidly fades to pale yellow and acidification of the cooled liquid with hydrochloric acid precipitates colourless crystals of the corre-sponding hydroxy-acid (yield nearly theoretical). These acids are sparingly soluble in hot water and very readily soluble in alcohol; they can best be crystallised from benzene.a-Benzylmctndelic acid occurs in colourless needles m. p. 164" (Found C = 74.7 ; H = 6.1. C15H1403 requires C = 74.4 ; H = 5.8%). The substance is oxidised by chromic acid in acetic acid solution with formation of benzil whilst the action of bromine on a solution in aqueous sodium carbonate produces a neutral com-pound which contains bromine and crystallises from alcohol in colourless flakes m. p. 54". This is probably desyl bromide, m. p. 55". On distillation under ordinary pressure the acid (0.7 g.) yielded a-phenylcinnamic acid (0.5 g.) m. p. 170° identified by the method of mixed melting point and a small amount of stilbene, m. p. 124". The acid C15H1403 m. p 160-161" which Bogdanowska (Ber., 1892 25 1276) obtained by the action of 1% aqueous potassium hydroxide on dibenzyl ketone is doubtless identical with a-benzyl-mandelic acid.It may be that dibenzyl ketone suffers auto-condensation followed by oxidation and production of phenyl benzyl diketone and in its turn benzylmandelic acid. a-4-Methoxybenxylmandelic acid OH*CPh(CO,H)*CH,*C,H,*OMe, crystallises from benzene in prismatic needles m.~ p. 193" (Found C = 70.7 ; H = 6.1. C1,Hl,O4 requires C = 70.6 ; H = The isomeric 4 -methox y- a- benzylmandelic acid, 5.9 yo). MeO*C,H,*C( OH) (C0,H) *CH,Ph, crystallises in colourless needles m. p 181" (Found C = 70.6 ; H = 6.170) PHEKYL BENZYL DIKETONE AND SOME DERIVATIVES. 377 4 4'-Dimethoxy-cr-benxylmndelic acid, MeO*C,H,.C( OH) ( C02H)oCH2*C,H4*OMe, crystallises from benzene in colourless prismatic needles m.p. 170" (Found C = 67.6 ; H = 6.1. C,,H,,O requires C = 67.6 ; H = 6.0 yo). m-Hydroxy- p-methoxy- cry-diphenylpropane, Ph*CH(OH)-CH( OMe)*CH,Ph. -The reduction of phenyl p-methoxystyryl ketone by means of hydrogen in presence of palladium in acetic acid solution was unsuccessful. The ketone (4.5 g.) dissolved in ethyl alcohol (100 c.c.) was reduced during 3.5 hours by agitation with hydrogen, 15 C.O. of a solution of palladous chloride (06%) and gum arabic (06%) having been added. Absorption of hydrogen was still occurring so the process was continued for a further 2.5 hours, when absorption of gas ceased. The filtered solution was distilled to remove alcohol and the oil remaining was isolated with the aid of ether and distilled 3.6 g.b. p. 197'115 mm. being obtained [Found C = 79.1 ; H = 7.4; Me0 = 11.9 11.8 (first expt.), 12.6 (second expt.). C1,H1,O requires C = 79.3 ; H = 7.4 ; Me0 = 12+3y0]. The readily soluble colourless oil does not yield a semicarbazone. It dissolves in sulphuric acid to a crimson solution which on gently heating becomes nearly colourless with simultaneous deposition of a deep bluish-grey solid. Relative Reactivity of w-Methoxyacetophenone and Phenyl Propyl Ketone.-w-Methoxyacetophenone (7.5 g. ; 1 mol.) b. p. 115-116'115 mm. phenyl propyl ketone (7.4 g.; 1 mol.) b. p. 118-l20'/16 mm. salicylaldehyde (7.6 g. ; 1.25 mols.) and potassium hydroxide (4 g.) were dissolved in methyl alcohol (100 c.c.) and the mixture boiled for 24 hours.The oil insoluble in alkali was then isolated by means of ether and distilled 10.5 g. b. p. 115-122" being obtained (Found Me0 = 5.2y0) and from this result it may be calculated that the whole of the phenyl propyl ketone was recovered unchanged whilst about 5 g. of the w-methoxy-acetophenone had been converted into the salicylidene derivative. The authors wish to thank the Chemical Society for a grant THE UNIVERSITY MANCHESTNR. which covered a part of the cost of the investigation, [Received December 29th 1924. PHENYL BENZYL DIKETONE AND SOME DERlVATIVES. 369 LVII1.-Phenyl Benxyl Dilcetone and some Derivatives. By THOMAS MALKIN and ROBERT ROBISSON. TIIAT the methylene group in a-alkyloxy-ketones of the type of cu-methoxyacetophenone is characterised by considerable reactivity is clear from the use which has been made of these substances in VOL.CXXVII. 370 MALKIN AND ROBINSON: the synthesis of the anthocyanidins and the work now to be described was instituted with the object of taking further advantage of this property. An experiment (p. 377) in which o-methoxy-acetophenone and phenyl propyl ketone were put in competition for salicylaldehyde in boiling methyl-alcoholic potassium hydroxide solution showed that the former ketone exhibited the greater reactivity. The effect of the oxygen of the methoxyl group is doubtless to produce a general drift of electrons in the molecule towards it and this facilitates the acquirement of a negative charge by the carbon atom of the methylene group in the activated phase which determines the occurrence of the reaction.In the accom-panying scheme the curved arrows show the covalency changes OH G f-x -C=CH-OMe during activation of the enolic form of t8he ketone and the straight arrow represents the general drift due to the oxygen of the methoxy-group. Here the effects are in the same direction and result in enhanced reactivity whilst in phenyl propyl ketone the hydrogen atoms produce an electron drift in the opposite sense and the reactivity due fo the part'icular conjugation represented is diminished. Very numerous applications of this conception of the interaction of the electronic changes due to conjugation and the general polar or electrostatic induction effect can be made and one example in connexion with orientation is the explanation afforded of the frequent occurrence of substitution in the position situated between an o-p-directive group and a m-directive group themselves in the rn-position to one another.A case in point is the application of the Skraup reaction to m-nitroaniline. The two possible activations by conjugation are shown in (A) and (B) and the latter is assisted by the general electron drift due to the nit'roxyl. The chief product -+ of the reaction is in fact 5-nitroquinoline. When the nitro-group is replaced by methyl the direction of the general drift will be * The curved arrows in (A) and (B) imply that free electrons of the N atom become covalency electrons of N and Ca in the nucleus and that C, in order t o preserve its total covalency unaltered abandons correspondingly Ca - Cg covalency electrons to the sole use of Cp PHENYL BENZYL DIKETONE AND SOi\lE DERIVATIVES.371 reversed (C) and accordingly m-toluidine is converted in the Xkraup reaction into 7-mcthylquinoline. We have investigated some of the transformations of the arylidene-o -metlioxyacetophenones . Phenyl fhnetho.rystyryZ ketone PhCO*C( OMe):CHPh forms a colourless crystalline dibromide the stability of which although riot of a high order was unexpected. The failure of the group Ph-CQ*c (0Me)Br to lose methyl bromide spontaneously is no doubt related to the unusual stability of the hydrate Ph*CO*CH(OH),. By reduction nith hydrogen in presence of palladium tbe un-saturated ketone is changed to a tetrahydro-derivative, Ph*CU (OH )*CH (O;\le)-CN,Ph.When subjected to somewhat vigorous hydrolysis by acids the arj*lidene-ctl-methoxyacetophenones yield a-diketones isomeric with the diaroylmethanes. Thus phenyl p-methoxystyryl ketone is changed by nieans of a hot solution of sulphuric acid in acetic acid into phenyl benzyl diketone PhCOCO*CH,Ph a substance which can be readily prepared in this manner. Whilst our work was proceeding Dufraisse and Moureu placed on record a descrip-tion of the compound which was obtained by a different process (@om@. rend. 1924 178 6 573). The diketone is almost certainly a tautomeric substance ; it is yellow oxidisable soluble in aqueous sodium hydroxid-e and gives a ferric chloride reaction. The facile condensation with o-phenylenediamine leads to phenylbenzyl-quinoxaline .The most characteristic property of this diketone is however, the remarkable ease with which i t undergoes the benzil-benzilic acid type of transformation. It is rapidly converted by hot dilute aqueous sodium hydroxide into sodium a-benzylmandelate. This rearrangement could be represented as due to the migration of either the phenyl or the benzyl group but as it occurs more smoothly than in the case of benzil itself the latter assumption seems the more natural : Ph*CO*CO*CH,Ph + H,O + Ph*C(OH)(CO,H)*CH,Ph. + I This interpretation is in harmony with the conclusions which Tiffeneau and Ordkhov (compare An?zuaZ Reports 1923 115) have drawn from their experiments on intramolecular rearrangements of the pinacol-pinacolin type and also with the results of Claisen (2.angezu. Chem. 1923 36 478) on the alkylation of the phenols. I n these and other cases the high aptitude for migration possessed by the benzyl group has been emphasised. Corresponding un-saturated ket,ones a-cliketones and their transformation products have been obtained in three other series. 0 372 MATXIN AND ROBINSON: E X P E R I M E N T A L . AlethoxyacetonitriZe.-This intermediate in the preparation of some w-methoxyacetophenones (Slater and Stephen J. 1920 117, 314; Pratt and Robinson J. 1923 123 748) is best obtained by the following modification of Polstorff and Meyer's method (Ber., 1912 45 1911). Aqueous formaldehyde solution (reputed 40%, 35 c.c.) is gradually added with cooling in ice-water to sodium cyanide (19 g.) dissolved in water (38 c.c.).Powdered sodium cyanide (19 9.) is then introduced and when solution is complete a further quantity of aqueous formaldehyde (35 c.c.) is added with careful cooling. The mixture is kept at a low temperature for 9 hour and the thick oily liquid or soft paste is then treated with methyl sulphate (80 c.c.) which is added in portions of 10 to 15 C.C. The mixture is thoroughly shaken and not cooled until the tem-perature rises to 35". After cooling for a few minutes in ice-water, the mixture is again allowed to warm to 35"; then it is cooled and the next portion of methyl sulphate is added only when there is no further heat of reaction. The product is taken up in ether, and the separated extract dried with sodium sulphate and dis-tilled.After separation from methyl sulphate by a preliminary fractionation under slightly reduced pressure 39 g. (yield 70 yo), b. p. 119-120" distilled at the ordinary pressure. Phenyl p -2Methox yst yryl Ketone PhCO*C( 0Me):CHPh .-Aqueous sodium hydroxide (20%) (5 c.c.) was added to a solution of w-meth-oxyacetophenone (5 g.) and benzaldehyde (3.5 g.) in ethyl alcohol (30 c.c.). After 12 hours the greater part of the alcohol was distilled from the st,eam-bath and the residue diluted with water and extracted with ether. The ethereal solution was dried over sodium sulphate and distilled under diminished pressure ; 2.4 g. of a mixture of benzaldehyde and o-methoxyacetophenone were recovered and 4-8 g. of a pale yellow oil b. p. 202-204"/13 mm., which solidified on cooling were obtained.The substance is readily soluble in most organic solvents but may be crystallised by cooling a saturated solution in ethyl alcohol or light petroleum to 0". The rectangular plates m. p. 35" are almost colourless (Found C = 80-9 ; H = 5.8. C,,H,,O requires C = 80-7 ; H = 5.9 %). The citron-yellow solution in sulphuric acid becomes yellowish-green and finally deep violet on heating. Phenyl aB-Dibromo-a-methoxy-p-phenylethyl Ketone, PhCO*CBr(OMe)*CHBrPh . -Phenyl p-methoxystyryl ketone (6 g.) dissolved in ether (10 c.c.), was gradually treated at 0" with bromine (4 g.). The dibromide (4.7 g . ) crystallised in a few minutes and a further quantit PIIENYL BENZYL DIKETONE AND SOME DERIVATIVES. 373 (4-5 g.) of somewhat less pure product was obtained on evapor-ation of the solution.The substance crystallises from benzene in colourless needles m. p. 103" (Found C = 48.5; H = 3.6. C,,HI,O,Br requires C = 48.2; H = 3.5%). I n the course of a few days red specks appear in the crystals. but attempts to obtain definite products of decomposition have not yet been successful. This is probably due to the circumstance that the substance tends to lose the elements of methyl bromide as well as of h?-drogen bromide. It was shown by titration that when boiled with water the dibromide yields a molecular proportion of hydrogen bromide but the resulting yellow oil could not be satisfactorily purified. A Zeisel determination (Found Me0 = 5.5. C,5H,,0Br*OMe re-quires Me0 = 9.8%) showed that hydrolysis at the methoxyl group must occur to some extent.Boiling aqueous sodium hydr-oxide attacks the dibromide with formation of sodium bromide (2 mols.). The final ethereal mother-liquor from the preparatisn deposited yellow crystals. m. 1). 59" but the quantity obtained ~vas insufficient for further investigation. Phenyl BenxyZ Diketone .-A solution of phenyl p-luethosystyryl ketone (2 g.) in acetic acid (9 c.c.) and concentrated sulphuric acid (1 c.c.) was heated over a free flame until the yellow solution became deep brownish-red. Prolonged heating is disadvantageous and the time necessary to bring the liquid to the boiling point usually suffices. After dilution with water and extraction with ether the ethereal layer was washed with water and then with successive small portions of loo/ aqueous sodium hyciroside.These deep orange alkaline washings were expeditiously acidified with hydro-chloric acid in presence of ice and the diketone was again taken up in ether. The extract was dried over sodium sulphate the greater part of the solvent removed by distillation and the remainder by evaporation in a vacuum leaving 1.7 g. of a yellow crystalline solid. The substance crystallises from methj.1 alcohol or ether in pale yellow prisms m. 11. 65" (Dufraisse and Moureu Zoc. cit. 67-68") (Found C = 80.6; H = 5.7. Calc. C = 80.4; H = 54°/o). This diketone is readily soluble in most organic solvents; the crystals rapidly become oily on exposure. In alcoholic solution, a purplish-brown coloration is developed on the addition of ferric chloride .3-PheizyZ-3-bcnxylqz~i~~o~uZ~ne.-A solution of phenyl benzyl diketone (1.2 g.) and o-phenylenediamine (0.6 g.) in ethyl alcohol (3 c.c.) was gently heated on the steam-bath for 20 minutes. The coinpact yellow crystals (0.7 g.) that separated on cooling crystal-lisecl from ethyl alcohol in almost colourless lustrous needles 374 MALKIN AND ROBINSON : m. p. 97" (Found C = 83.1; H = 5.7; N = 9.6. C,,H,GN, requires C = 83.1 ; H = 5-4 ; N = 9.5%). The orange solution in concentrated sulphuric acid becomes colourless on dilution with water. Phenyl p 4-Dirnethoxptyryl Ketone Ph*CO*C( OMe):CH*C,H,*OMe. -Aqueous sodium hydroxide (5 C.C. of 20%) was added to a solu-tion of oJ-met,hoxyacetophenone (5 g .) and anisaldehyde (4.5 g.) in ethyl alcohol (30 c.c.).Next day 3-5 g. of product had crystal-lised and a further portion (1 g.) separated on cooling the solution in ice. The mother-liquor was treated as in the preparation of phenyl p-methoxystyryl ketone and unchanged material (2.5 g .) and the unsaturated ketone (1 g.) were SO obtained. The total yield was therefore 5.5 g. The substance crystallises from alcohol, in which it is moderately readily soluble in hard pale yellow, rectangular prisms m. p. 75" b. p. 238-242"/14 mm. (Found: C = 76.3; H = 5.8. C1,H1,03 requires C = 76.1 ; H = 6-Oy0). The orange solution in sulphuric acid becomes deep yellowish-brown on heating. Attempts to prepare a crystalline dibromide were unsuccessful. Phenyl 4-Methoxybenxyl Diketone Ph=CO*CO*CH,*C,H4*OIe.-The hydrolysis of the foregoing substance by means of sulphuric acid in acetic acid solution gave unsatisfactory yields (30y0) but the use of hydrobromic acid effected a considerable improvement.The anisylidene derivative (2 g.) was dissolved in acetic acid (10 c.c.), concentrated aqueous hydrobromic acid (4 c.c.) added and the orange liquid heated over a free flame until there was a rather sudden change of colour to a dirty red. The remaining procedure followed exactly that described in the case of phenyl benzyl ketone and there resulted 1.7 g. of a yellow crystalline mass. The sub-stance is not very stable and crystallises best from methyl alcohol, separating in pale yellow prismatic needles m. p. 68" (Found : C = 75.2; H = 5.6. ClGHl4O3 requires C = 75.6; H = 5.5%).In alcoholic solution the substmce gives a purplish-brown color-ation with ferric chloride and on condensation with o-phenylene-diarnine in alcoholic solution it readily yields 2-phenyl-3-p-methoxy-benxylquinoxaline which crystallises from ethyl alcohol in colourless needles m. p. 119' (Found C = 80.9; H = 5.7. C,,Hl,ON, requires C = 81-0; I3 = 5.5y0) and gives a brown solution in sulphuric acid. When the alkaline solution of the diketoiie was agitated with methyl sulphate phenyl p 4-dimethoxystyryl ketone was regener-ated in good yield. The crystallised substance m. p. 75" exhibited an unaltered melting point when mixed with an authentic specimen PHENYL BENZYL DIKETONE AND SOME DERIVATIVES. 37.5 4-Jfethoxyphenyl p - Methoxystyryl Ketone, MeO-C,H,*CO*C( 0Me):CBPh.-This substance was prepared in the same way as phenyl p-methoxy-styryl ketone (above). w 4-Dimethoxyacetophenone (4 g.) and benzaldehyde (2.4 g.) yielded 3.3 g. of a yellow oil b. p. 240-250"/33 mm. which crystallised and 2 g. of recovered material, whilst the residue in the flask gave 0.5 g. of the eondensation pro-duct by crystallismtion from alcohol. The substance is readily soliible in most organic solvents and crystallises from ethyl alcohol in colourless rectangular prisins m. p. 74" (Found C = 76.1 ; H = 6.0. CZ7H1603 requires C = 76.1; I3 = G.OO/,). The deep yellow solution in sulphuric acid becomes intensely orange-red on warming and crimson on heating more strongly. 4-Methoxyphenyl be?axyl diketone ~leO*C,H,*CO.CO*CN,Bh ob-tained froin the foregoing unsaturated ketone by the same method and in the same yield as described above in the case of an isomeride, crystallises from ether or alcohol in yellow plates m.p. $2" (Found : C = 75.6; M = 5.7. C1,H,,O requires C = 75-6; H = 5.5%). The properties of the substance closely resemble those of phenyl benzyl diketone. Condensation with o-phenylenediamine leads to 2-p-metl~ox~phenyl-3-benzylqui~zoxaline which crystallises from alco-hol in colourless silky needles m. p. 141" (Found C = 80.8; H = 5.7. C,,H,,ON requires C = 81.0; H = 55y0). The solu-tion in siilphuric acid is Bordeaux red. 4-Methoxyphenyl p 4-Dimethoxyslyryl Ketone, MeO*C,H,*CO*C( QMe):@H*C,H,*O~ile. -The condensation of anisaldehyde and w 4-climethoxyaceto-phenone was carried out in the manner prescribed for the pre-paration of phenyl p-methosystyryl ketone except that after the removal of unchanged materials by distillation under diminished pressure the residue was stirred with alcohol and so induced t0 crystallise.The substance crystallises from alcohol in faintly yellow rectangular plates m. p. 72.5" (Pound C = 72-5 ; H = 6-2. C,8H1,0 requires C = 72.5 ; H = 6.0%). The orange-red solution in sulphuric acid becomes rich crimson on heating. Comparison of the colour of the derivatives of benzylideneacetophenone now described shows that a methoxy-group in the p-position in the benzylidene nucleus has auxochromic character whilst a similar substitution in the acetophenone nucleus has a feeble bathochrornic influence.On hydrolysis with hydrobromic acid in acetic acid solution this trimethoxybenzylideneacetophenone yields 4-methoxyphenyl 4-meth-oxybeszzyl diketone MeO*C,PI,*CO*CO*CH,*C,II,.OMe in almost theoretical amount. This substance closely resembles pheny 376 MALEIN AND ROBINSON: benzyl diketone and crystallises from ethyl alcohol in yellow prisms, m. p. 92" (Found C = 71.7; H = 5.8. Cl,H1,O requires C = 71-8 ; H = 5.6%). 2-p-Methoxyphenyl-3-p-methoxybenzylquin-oxaline crystallises from alcohol in colourless silky needles m. p. 123" (Found C = 77.5 ; H = 5.7. C,,H,O,N requires C = 77.5; H = 5.6%). This base dissolves in concentrated hydrochloric acid to an orange-yellow solution but the salt is dissociated on dilution with water. The solution in sulphuric acid is Bordeaux red.None of the quinoxalines now described exhibits fluorescence in acid or neutral solution. a- Benzylmndelic Acid and Derivatives.-When solutions of phenyl benzyl diketone or its derivatives in aqueous sodium hydroxide of any convenient concentration are boiled the deep orange colour rapidly fades to pale yellow and acidification of the cooled liquid with hydrochloric acid precipitates colourless crystals of the corre-sponding hydroxy-acid (yield nearly theoretical). These acids are sparingly soluble in hot water and very readily soluble in alcohol; they can best be crystallised from benzene. a-Benzylmctndelic acid occurs in colourless needles m. p. 164" (Found C = 74.7 ; H = 6.1. C15H1403 requires C = 74.4 ; H = 5.8%). The substance is oxidised by chromic acid in acetic acid solution with formation of benzil whilst the action of bromine on a solution in aqueous sodium carbonate produces a neutral com-pound which contains bromine and crystallises from alcohol in colourless flakes m.p. 54". This is probably desyl bromide, m. p. 55". On distillation under ordinary pressure the acid (0.7 g.) yielded a-phenylcinnamic acid (0.5 g.) m. p. 170° identified by the method of mixed melting point and a small amount of stilbene, m. p. 124". The acid C15H1403 m. p 160-161" which Bogdanowska (Ber., 1892 25 1276) obtained by the action of 1% aqueous potassium hydroxide on dibenzyl ketone is doubtless identical with a-benzyl-mandelic acid. It may be that dibenzyl ketone suffers auto-condensation followed by oxidation and production of phenyl benzyl diketone and in its turn benzylmandelic acid.a-4-Methoxybenxylmandelic acid OH*CPh(CO,H)*CH,*C,H,*OMe, crystallises from benzene in prismatic needles m.~ p. 193" (Found C = 70.7 ; H = 6.1. C1,Hl,O4 requires C = 70.6 ; H = The isomeric 4 -methox y- a- benzylmandelic acid, 5.9 yo). MeO*C,H,*C( OH) (C0,H) *CH,Ph, crystallises in colourless needles m. p 181" (Found C = 70.6 ; H = 6.170) PHEKYL BENZYL DIKETONE AND SOME DERIVATIVES. 377 4 4'-Dimethoxy-cr-benxylmndelic acid, MeO*C,H,.C( OH) ( C02H)oCH2*C,H4*OMe, crystallises from benzene in colourless prismatic needles m. p. 170" (Found C = 67.6 ; H = 6.1. C,,H,,O requires C = 67.6 ; H = 6.0 yo). m-Hydroxy- p-methoxy- cry-diphenylpropane, Ph*CH(OH)-CH( OMe)*CH,Ph.-The reduction of phenyl p-methoxystyryl ketone by means of hydrogen in presence of palladium in acetic acid solution was unsuccessful. The ketone (4.5 g.) dissolved in ethyl alcohol (100 c.c.) was reduced during 3.5 hours by agitation with hydrogen, 15 C.O. of a solution of palladous chloride (06%) and gum arabic (06%) having been added. Absorption of hydrogen was still occurring so the process was continued for a further 2.5 hours, when absorption of gas ceased. The filtered solution was distilled to remove alcohol and the oil remaining was isolated with the aid of ether and distilled 3.6 g. b. p. 197'115 mm. being obtained [Found C = 79.1 ; H = 7.4; Me0 = 11.9 11.8 (first expt.), 12.6 (second expt.). C1,H1,O requires C = 79.3 ; H = 7.4 ; Me0 = 12+3y0]. The readily soluble colourless oil does not yield a semicarbazone. It dissolves in sulphuric acid to a crimson solution which on gently heating becomes nearly colourless with simultaneous deposition of a deep bluish-grey solid. Relative Reactivity of w-Methoxyacetophenone and Phenyl Propyl Ketone.-w-Methoxyacetophenone (7.5 g. ; 1 mol.) b. p. 115-116'115 mm. phenyl propyl ketone (7.4 g.; 1 mol.) b. p. 118-l20'/16 mm. salicylaldehyde (7.6 g. ; 1.25 mols.) and potassium hydroxide (4 g.) were dissolved in methyl alcohol (100 c.c.) and the mixture boiled for 24 hours. The oil insoluble in alkali was then isolated by means of ether and distilled 10.5 g. b. p. 115-122" being obtained (Found Me0 = 5.2y0) and from this result it may be calculated that the whole of the phenyl propyl ketone was recovered unchanged whilst about 5 g. of the w-methoxy-acetophenone had been converted into the salicylidene derivative. The authors wish to thank the Chemical Society for a grant THE UNIVERSITY MANCHESTNR. which covered a part of the cost of the investigation, [Received December 29th 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700369

出版商:RSC    

年代:1925

数据来源: RSC

摘要:

378 INGOLD AND WEAVER THE ADDITIVE L1X.-The Additive Formation of Four-membered Rings. Part VI. The Addition of Axo-compounds to Ethylene8 and some Transformations of the Dirnethylene-l 2-di-imine Ring. By CHRISTOPHER KELK INGOLD and STANLEY DOUGLAS WEAVER. THE experiments described in this paper were made with the object of ascertaining the tendency of the groups N=N and C=C to undergo additive union with each other to form a ring and of increasing our knowledge of the somewhat obscure heterocyclic types which can be produced in this way. The azo-group in azobenzene possesses a very small additive power and this may be ascribed to the engagement by the phenyl groups of the residual affinity of the unsaturated residue : Ph-NZN-Ph. When however the phenyl groups are replaced by other groups such as carbethoxyl which have a much smaller affiity demand structures are produced such as Ph-NxN-CO,Et and C02Et-N=N-C02Et possessing free residual affinity and hence greater additive power.These azo-esters were theref ore chosen as representative compounds for the purpose of studying the additive reactions of the azo-group. The ethylene derivatives were selected in accordance with the principle which emerged during the earlier parts of this research, that substitution especially by a large gem-grouping like the gem-diphenyl group favours the production of stable four-membered rings. Styrene as-diphenylethylene and diphenylketen were the examples chosen. Phenylazocarboxylic ester combines with great ease with diphenylketen forming a f our-membered ring-compound * (I).This compound which belongs to a heterocyclic family very few members of which are at present known undergoes a number of interesting changes. ,_--.. /--. ,--.. --. ,~-NPh:N*CO,Et 4- CPh&O The action of hot aqueous-alcoholic sodium hydroxide leads to an acidic substance having an additional H,O in its composition. On dehydrating this with acetic anhydride the original substance * The direction of this addition conforms to the theory of alternate polarities d i k e many of the cases previously discussed (compare for instance Ingold and Weaver J. 1924 125 1456) FORMATION OF FOUR-MENBERED RIKGS. PART V1. 379 is regenerated. Since the constitution assigned to the original substance is analogous to that of a p-lactam these reactions may legitimately be compared with those of the lactam (111) which as Staudinger Klever and Kobner showed (Annalen 1911 374 13), is converted by potassium hydroxide into an acid (IV) from which the lactam can be regenerated by the agency of acetyl chloride : PhHF-y.CH,Ph 2% PhHy-NH*CH,Ph (Iv.) (111.) t- Me&-C 0 Acci Me,C-CO,H The closeness of the analogy leaves little doubt but that alkali opens the ring in (I) in the manner shown and that formula (11) may be ascribed.to the acid produced.A remarkable ring-transformation takes place when compound (I) is boiled with mineral acids. The product of the reaction is isomeric with the original substance but possesses very different properties. The key to the nature of this isomeric change is given by the fact that whereas the original four-membered ring compound does not of course form an acetyl derivative its transformation product is readily acetylated giving a monoacetyl compound ; this can be explained only on the assumption that a hydrogen atom has passed from one of the phenyl groups to nitrogen.Formula (I) represents a ditertiary hydrazine RIR1lN*NR1l'R1v in which two of the groups such as R1' and RIII together participate in a ring. Now the ditertiary hydrazines are known to be especially addicted to transformations of the ortho-semidine type. Thus tetraphenylhydrazine (V) although its constitution admits of any of the four rearrangements to which aromatic hydrazines are liable (the ortho- and para-semidine and the ortho- and para-benzidine changes) actually isomerises exclusively to the base (VI) (Weland Annalen 1911 381 200) : The structure of the cyclic hgdrazine (I) admits of an ortho- or para-semidine change but not a benzidine change since only one of the nitrogen atoms carries a phenyl group.On the grounds of analogy therefore it is highly probable that the observed trans-formation is of the ortho-semidine type and may be formulated as in the preceding case 380 INOOLD AWD WEAVER THE ADDITIVE and this probability amounts to a practical certainty when it is reflected that the only possible alternative a para-semidine rearrangement is in this case intrinsically unlikely since the product would have formula (VIII) which is quite out of keeping with its ea'se of formation and stability.Formula (VII) on the other hand is in complete harmony with the properties of the substance. -N(CO,Et)*CO I (VIII.) CPh, 0 V N H -One other transformation is of sufficient interest to be mentioned here. The compound (VII) does not react in the cold with phosphorus pentachloride but if heated with this reagent it loses ethyl chloride giving an acid chloride (IX) which by the inter-action of its acyl chloride residue with the basic imino-group yields the trioyclic compound (X) : (IX. 1 (X.) This substance belongs to the type represented by the formula N-b-N (XI) where a b and c denote three different groups, one of these (at least) being unsymmetrical with respect to the two nitrogen atoms. The space model of (X) lies in three planes (like that of camphor) and the compound should therefore be capable of optical activity depending on the asymmetry of its two tervalent nitrogen atoms (Moore P.1914 182). Moore and Doubleday (J. 1921,119,1170) recently prepared some asymmetric, tervalent nitrogen compounds of a similar type but these contained methylene groups in place of the carbonyl groups in (X) and exhibited certain changes of colour and molecular weight in solution. It was hoped that the introduction of the cyclic -CO-N-linking in place of the -CH,-N- linking might confer greater stability and the opportunity of completing the synthesis of a stable substance of type (XI) was therefore followed up in the manner described. The compound (X) is in fact remarkably stable and is colourless in the solid state and in solution.No special proof is offered here regarding its constitution but the method of formation appears to place this beyond any reasonable doubt. /a\ \C / FORMATION OF FOUR-MEMBERED RINGS. PART VI. 381 Amongst the additive ring syntheses an account of which will be found in the experimental portion are t'he addition reactions between styrene and as-diphenylethylene on the one hand and azodicarboxylic ester on the other. The products belong to an almost unknown f amily of six-membered rings the hesahydro-27-tetrazines which to judge by the examples described (XI1 and YIII) possess unexpected st'ability. N*CO,Et N-CO,Et :XII.) Ph€€(f\y*CO,Et Ph,t"\~*CO,Et (sIII.) €I& ,N*CO,Et H,C,, ,N*CO,Et N*C02Et N*CO,Et E x P E R I 31 E N T A L.I3thyZ nzodicurbo-i.ylate was prepared by a modification c d Diels's method (Ber. 1911 44 3020). Rydraziiie sulphate (130 g.) was dissolved in a minimum of water and the base liberated by potassium hydroxide (112 g. in a little water). The precipitation of potassium sulphate was furthered by adding alcohol and the filtered solution treated with a mixture of '10 C.C. of ethyl chloroformate and 300 C.C. of ethyl alcohol. -4fter heating for one hour on the water-bath, the precipitated hydrazine hydrochloride was collected the filtrate evaporated a t the ordinary temperature and the product crystttllised from boiling water. The hydrazo-ester (m. p. 131" yield almost theoretical) was dissolved in concentrated nitric acid (5 parts) contained in a separating funnel and the mixture ailowed to warm slightly (this occurs spontaneously with the forma tion of nitrogeii peroxide the liquid becoming green).When the mixture became turbid and an oil separated on the surface the lower layer w;,2s run off and cooled somewhat by a freezing mixture whilst the oil, dissolved in ether was washed once with water to prevent further oxidation by the excess of nitric acid contained in it. The acid layer was then replaced in the fuiiiiel allowed to warm again and the process repeated until no more oil could be obtained. The combined ethereal solutions were washed about 15 times with lo?/ sodium carbonate solution then with water dried over sodium sulphate, and the ether removed. The residual oil was purified by distillation a i d the ethyl azodicarboxylate collected a t l21-lZi0/l6 mm.Ethyl hy drnzotr ica yboxy Zat e CO,E t *NH*N ( C 0,E t ) a 11 y - pr odu c t in the above preparation was collected in the fraction b. 1). 199-203Oj22 mm. which on re-distillation yielded a neutral colourless oil, 1). p. 200-201"/23 mm. (Found C = 42-95; H = 647 ; N = 11-3; -11 in freezing benzene = 276 258. C',M,,O,N require;. 6' = 43.5 ; H = 6.4; N = 11*3°(1 ; X = 248) 382 WGOLD AND WEAVER THE ADDPTIVE Ethyl benxemzouzrboxylate was prepared by a modified form of Heller and Widman's methods (Annalen 1891 263 287; Ber., 1895 28 1927). Ethyl chloroformate (50 g.) was added gradually and with vigorous stirring to an ice-cold solution of 100 g. of phenylhydrazine in 600 C.C. of dry ether. The red oil which remained when the ether was evaporated from the filtered solution, was dissolved in benzene and ligroin (b.p. GO-80°) added to bring about the separation of the hydrazo-ester in nearly colourless needles m. p. 80-82" (yield 60%). Forty grams of this dissolved in cold glacial acetic acid were treated gradually with an aqueous solution of 12 g. of potassium permangsnate. After the excess of the permanganate had been destroyed with hydrogen peroxide t'he mixture was poured into water and the oil extracted with ether and washed several times with sodium carbonate and then with water. The extract was dried with calcium chloride and evaporated and the azo-ester freed from the last traces of ether by the passage of a current of dry air a t 40" (yield 9O"/b). Addition of Ethyl Axodicarboxylate to Diphenylketen Forrnation Y tion containing ethyl azodicarboxylate (7.5 g.) and diphenylketen (8.6 g.) was kept for 24 hours out of contact with air and moisture.The crystals which had separated were recrystallised several times from ethyl alcohol colourless needles m. p. 129-131" being obtained (Found C = 72.61 ; H = 5.30; N = 5.03. C,,H,,O,N requires C = 72-44 ; H = 5-34 ; N = 4.98%). The compound gives no colour with ferric chloride and is stable to permanganate in the cold ; it is however fairly sensitive to hydrolysing agents. Hydrolytic Fission Anhydro- a-diphen ykcetyl- u( or p)-carboq-p(or a)-carbethoxyhydrazine- p-diphenylacetic Acid, ~Pb2-~*N(CQ2Et)*CO-CHPh2 or ~Ph,*N(CO2Et)*~*CO*CHPli,. CO=O* c 0 co-0-co -The pyridazine (4 g.) was boiled with concentrated hydrochloric acid (15 c.c.) and alcohol (70 c.c.) until crystals began to separate.After cooling the product was collected and crystallised from a mixture of alcohol and ethyl acetate from which colourless needles separated m. p. 155-156" (yield 3.4 9.) (Found C = 71-57; * This y-diketopyridazine formula is ascribed in preference t o the &diketo. pyridazine formula Co'N(Co~Et)~~*Co2Et owing to the close analogy with the y-diketopiperidines of Staudinger which unlike the isomeric &diketo-piperidines are readily split by hydrolytic agents (compare Anmlen 1911, bPh,-CPh,-CO 374 11) FORMATION OF FOUR-MEMBERED RINGS. PART VI. 383 H = 5-19 ; N = 5-06. C32H2806N2 requires C = 71.63 ; H = 5.22 ; N = 5.22%).The compound is stable towards permanganate and gives no colour with ferric chloride. Addition of Eayl Benzeneazocurboxylate to Diphenylketen Form-ation of Ethyl 4-Keto-2 3 ; 3-trip~nyldimethene-1 2-di-imine-1-carboxylate (I).-The azo-ester (5.1 g,) was added to a solution of 5.6 g. of the keten in 150 C.C. of light petroleum and the mixture kept for 24 hours out of contact with air and moisture. The crystals were then collected drained and crystallised from ether, alcohol dilute acetic acid or chloroform-ligroin from any of which colourless prisms separated m. p. 132-133" (yield 70%) (Bound C = 74.30 ; H = 5.50 ; N = 7.61. C,,H,,O3N requires C = 74.20; H = 5.38; N = 7.53%). The compound gives no colour with alcoholic ferric chloride and does not reduce perman-ganate in the cold; nor can it be reduced by zinc in boiling acetic acid.It yields no acetyl derivative and is for example unchanged by prolonged boiling with acetic anhydride. On distillation under reduced pressure an operation in which so many four-membered ring compounds are broken down into unsaturated substances (" thermal division ") this compound passes over unchanged. It is however sensitive to hot mineral acids and alkalis. Ring Fission by Alkaline Hydrolysis P-Phenyl- cr-carbethoxy-hydraxine- P-diphen $acetic Acid (II).-A solution of the ring-compound (3.4 9.) in 35 C.C. of alcohol was boiled with 10 C.C. of 10% aqueous sodium hydroxide for about 5 minutes cooled and acidified with hydrochloric acid. The precipitated oil was extracted with chloroform and recovered by evaporation of the solvent after drying with calcium chloride.It readily solidified on rubbing with ether and was then crystallised from chlorof orm-ligroin from which slender colourless needles m. p. 157-158" were obtained. Yield 3.5 g. (Found C = 70.38 ; H = 5434 ; N = 7.16. C,,H,,O,N, requires C = 70.76; H = 5-64; N = 7.18%). It is a weak acid, soluble in dilute sodium hydroxide solution but only slowly soluble in sodium hydrogen carbonate. Closure of the Ring by Dehydration with Acetic Anhydride.-The acid (0.3 g.) was boiled for about 3 minutes with 2 C.C. of acetic anhydride and the product warmed with water to remove the excess of the latter. The oily precipitate was extracted with chloroform and the extract washed with water dried mith calcium chloride and evaporated.The residue on rubbing with ether, solidified and was crystallised from alcohol from which the ring-compound (I) separated (yield 0.25 g.). It was identified by m. p. (132-133") and mixed m. p. and by analysis (Found C = 73.7 ; H = 5.4%) 384 INGOLD AND WEAVER THE ADDITIVE Conversioib of a 4-Membered Ring into a 6-Membered Ring by o-Semidine Change Ethyl 3- Keto-2 2-diphenyltetrahydroquinoxaline-4-carboxykate (VII).-A solution of 5 g. of the ring-compound (I) in 40 C.C. of alcohol was boiled with 20 C.C. of concentrated hydro-chloric acid until crystallisation commenced. The solid product was collected from the cooled solution and crystallised from chloro-form-ligroin dilute alcohol or dilute acetic acid from any of which it separated in bunches of colourless needles m.p. 165-166" (yield almost theoretical). Although this product melted fairly sharply close examination revealed the presence of about 10% of an impurity which could not be removed by fractional crystallisation. After many trials the following process was adopted. The substance (3 g.) was dissolved in 15 C.C. of alcohol and boiled with 30 C.C. of 10% sodium hydroxide. The small quantity of solid which separated was collected after cooling (0-3 g.). After crystallisation from ligroin-chloroform it yielded slender colourless needles m. p. 180-181" (Found : C = 75.97 ; H = 5.12 ; N = 9.17. C,,H,,O,N requires C = 75.85 ; H = 5.06; N = 8436%). This substance is apparently a keto-triphenyloxadiazole but the quantity obtained was too small for investigation.The mother-liquors from this substance deposited the quinoxaline, which could be washed with dilute acid and crystallised ; but a more convenient process was to add hydrochloric acid and extract the oily precipitate with chloroform. The product recovered in this way soon solidified and after crystallisation from dilute acetic acid melted a t 168" (Found C = 74.47 ; H = 5.44; N = 7.44. C,,H,,O,N requires C = 74-20; H = 5-38; N = 7.53%). This substance is extremely stable towards most reagents. It is not attacked by concentrated mineral acids or alkalis and is only slowly oxidised by hot acid permanganate. It is not reduced by zinc dust in boiling acetic acid solution. The acetyl derivative was obtained when the quinoxaline (0-4 g .) was boiled with acetic anhydride (5 c.c.) for about 15 minutes. The product was boiled with water t o remove excess of the anhydride and sufficient glacial acetic acid was added to produce a clear solution which on cooling deposited colourless needles, m. p. 190-191" (yield 0.4 g.) (Found C = 72.33; H = 5.31; N = 8-87. C,,H,,O,N requires C = 72.46; H = 5.31 ; N = 6.76%). This substance is readily hydrolysed to the parent quinoxaline (VII) by boiling for a few minutes with aqueous-alcoholic hydrochloric acid or aqueous-alcoholic sodium hydroxide. Action of Phosphorus Pentachloride on the Quinoxaline (VII) : Formation of 1 ; 4-endo-Keto-2-keto-3 3-diphenyltetrahydroquinosa FORMATIOS O F FOUR-MEMBERED RISOS. PART VI. 385 line (X) and other Products.-No very trustworthy process could be discovered for producing the endo-keto-compound ; although it could be obtained in a variety of ways the yield was always small and the results were somewhat uncertain.The reason for this is partly that the cornpouiid is attacked by tlhe reagent (phosphorus pentachloride) used in its formation as is shown by the production of the dichloro-compound (below) and partly that from the commeiicement of the reaction changes occur which cannot lead to the desired coinpound this is proved by the evolut'ion of carbonyl chloride and by the formation of the monochloro-com-pound (below). The most trustworthy method was the following. The eiido-Keto-co,iz~o2~~~rl (X).-A mixture of the quinosaliiie with an equal weight of phosphorus pentachloride was treated with sufficieiit phosphorus osychloride to produce a clear solution a t 190".The mixture was then boiled gently for about 20 minutes cooled, anit filtered from the small prccipitate produced during the boiling. The chlorides of phosphorus were decomposed with water and the solid prodnct was collected dried and quickly extracted with warm absolute alcohol. The solid which separated from the filtered solution consisted essentially of the eizclo-keto-compouiId, uhich a t this degree of purity (m. p. 305-31Q0) is only sparingly soluble in alcohol. (Hence arises the necessity for extracting quickly ; otherwise the compound does not pass into solution with its impurities and is not crystallised thus rendering further purification dii'ficult.) Repeated crystallisation from nitrobenzene raises t'he m.p. to 333" (yield 67;) (Found C = 77-26 H == 4-59 ; N = 8.67. CZ1H14OZNZ requires C = 77-30 ; H = 4-29 ; X = 8.59%). -1 dichloro-compound probably 2 2-dichloro-l 4-emlo-keto-3 3-diphenyltetrahydroquinosaline (annexed for-/'d 1 \CPh mula) was obtained in the course of the above I I y o ' experiments. In the presence of the impurities which accompany it it is readily soluble in alcohol, from which after slight dilution with water it slowly crystallises. Rspeatcd crystallisation from a mixture of nitrobenzene and ligroin (b. p. 100-120") yields the pure compound as a micro-crystalliiie powder m. p. 246" (decomp.) (Found C = GG-24; H = 3.90; C1= 18-46. C,1H140N2C12 requires C = 66-14 ; H = 3.67 N = l8.M.,b).-1 moizochloro-compound. probably 3-chloro-2 2-diphenyl- 1 2 -tlihy~roquinoxaliiie (annexed formula) was isolated in the course of ;L series of experiments in which 'f'?P1i2 benzene was used as a solvent instead of phosphorus \/\/"' osychloride. It was separated from the product x obtaiaed after decomposing with water by extraction with ether in a Sorhlet's apparatus and fractional crystallisation N \/\N/CC12 NH 386 THE ADDITIVE FORMATION OF FOUR-MENBERED RINGS. PART VI. from benzene and from nitrobenzene-ligroin. It accumulated in the more soluble fractions and was ultimately obtained as minute prisms m. p. 204" (Found C = 75-07 ; H = 4.87; C1= 11.22. C,oHI,N,C1 requires C = 75.35; H = 4.71 ; C1 = 11015%). Addition of Ethyl Axodicarboxylate to as-Diphenylethylene : Formation of Ethyl 6 6-Diphenylhexahydro-1 2 3 4-tetraxine-1 2 3 4-tetrmarboxylate (XIII).-Equimolecular quantities of as-diphenylethylene and the azo-compound were mixed and kept for about 4 days a t the ordinary temperature when the colour of the azo-compound disappeared and the liquid became extremely viscous.On rubbing with ether a solid was obtained which separated from chloroform-ligroin in colourless prisms m. p. 1 6 4 -166" (Found C = 58-25; H = 6.1s ; N = 10.4. C&&&gN4 requires C = 59.10 ; H = 6-06 ; N = 10.6y0). The ether washings yielded unchanged diphenylethylene (about 0-5 mol.) but no other reaction product. The tetrazine derivative is unattacked by cold potassium permanganate and by boiling acetyl chloride.Attempts to hydrolyse it were not successful deep-seated de-composition taking place no definite product of which could be recognised. Formtion of Bthyl 6-Phenylhexahydro-1 2 3 4-tetraxine-1 2 3 4tetracarb-oxylate (XII).-This reaction was carried out like the preceding one, the colourless glassy mass partly solidifying on trituration with ether and styrene (about 0.5 mol.) being recovered from the ether solution after removal of the solid. The substance separated from chloroform-ligroin in colourless prisms m. p. 133-134" and had properties similar to those of the preceding compound (Found : C = 52.81 ; H = 6.15; N = 12.4; 2M = 466. C,oH,,08N, requires C = 53.10 ; H = 6.19 ; N = 12.4% ; M = 452). Supplementary Note Addition of Benxylidene-p-nitrobenz?/larnirLe to Dipheny1Eeten.-A solution of the azomethine (666 9.) in ether was mixed with a ligroin solution containing 5.55 g.of the keten. The mixture was kept for 24 hours out of contact with air and moisture and the crystals which had separated were then collected and crystallised from ether and from dilute alcohol from which large colourless prisms separated m. p. 133-134" (Found c = 77-39 ; H = 5.22 ; N = 6.42. C,,H,,O,N requires c = 77.41 ; H = 5-07; N = 6.45%). The compound is moderately stable to heat and is non-basic and is therefore probably 2-keto-3 3 4-tri-phenyl- 1 - p-nitrobenx yltrimeth yleneimine (the lactam of p -p- xitro-benxylamino- uu p-triphen ylpropionic acid), Addition of Ethyl Axodicarboxylate to Styrene : CPh,<C~ph>~*cH,'c,H~'No~ co- (in) FORMATION OF UNSATURATED AND CYCLIC COMPOUNDS ETC.387 The authors desire to record their thanks t o the Royal Society for a grant which has defrayed part of the cost of this investiga-t ion. THE UNIVERSITY LEEDS. IMPERIAL COLLEUE SOUTH KENSINGTON. [Received December llth 1924. 378 INGOLD AND WEAVER THE ADDITIVE L1X.-The Additive Formation of Four-membered Rings. Part VI. The Addition of Axo-compounds to Ethylene8 and some Transformations of the Dirnethylene-l 2-di-imine Ring. By CHRISTOPHER KELK INGOLD and STANLEY DOUGLAS WEAVER. THE experiments described in this paper were made with the object of ascertaining the tendency of the groups N=N and C=C to undergo additive union with each other to form a ring and of increasing our knowledge of the somewhat obscure heterocyclic types which can be produced in this way.The azo-group in azobenzene possesses a very small additive power and this may be ascribed to the engagement by the phenyl groups of the residual affinity of the unsaturated residue : Ph-NZN-Ph. When however the phenyl groups are replaced by other groups such as carbethoxyl which have a much smaller affiity demand structures are produced such as Ph-NxN-CO,Et and C02Et-N=N-C02Et possessing free residual affinity and hence greater additive power. These azo-esters were theref ore chosen as representative compounds for the purpose of studying the additive reactions of the azo-group. The ethylene derivatives were selected in accordance with the principle which emerged during the earlier parts of this research, that substitution especially by a large gem-grouping like the gem-diphenyl group favours the production of stable four-membered rings.Styrene as-diphenylethylene and diphenylketen were the examples chosen. Phenylazocarboxylic ester combines with great ease with diphenylketen forming a f our-membered ring-compound * (I). This compound which belongs to a heterocyclic family very few members of which are at present known undergoes a number of interesting changes. ,_--.. /--. ,--.. --. ,~-NPh:N*CO,Et 4- CPh&O The action of hot aqueous-alcoholic sodium hydroxide leads to an acidic substance having an additional H,O in its composition. On dehydrating this with acetic anhydride the original substance * The direction of this addition conforms to the theory of alternate polarities d i k e many of the cases previously discussed (compare for instance Ingold and Weaver J.1924 125 1456) FORMATION OF FOUR-MENBERED RIKGS. PART V1. 379 is regenerated. Since the constitution assigned to the original substance is analogous to that of a p-lactam these reactions may legitimately be compared with those of the lactam (111) which as Staudinger Klever and Kobner showed (Annalen 1911 374 13), is converted by potassium hydroxide into an acid (IV) from which the lactam can be regenerated by the agency of acetyl chloride : PhHF-y.CH,Ph 2% PhHy-NH*CH,Ph (Iv.) (111.) t- Me&-C 0 Acci Me,C-CO,H The closeness of the analogy leaves little doubt but that alkali opens the ring in (I) in the manner shown and that formula (11) may be ascribed.to the acid produced.A remarkable ring-transformation takes place when compound (I) is boiled with mineral acids. The product of the reaction is isomeric with the original substance but possesses very different properties. The key to the nature of this isomeric change is given by the fact that whereas the original four-membered ring compound does not of course form an acetyl derivative its transformation product is readily acetylated giving a monoacetyl compound ; this can be explained only on the assumption that a hydrogen atom has passed from one of the phenyl groups to nitrogen. Formula (I) represents a ditertiary hydrazine RIR1lN*NR1l'R1v in which two of the groups such as R1' and RIII together participate in a ring.Now the ditertiary hydrazines are known to be especially addicted to transformations of the ortho-semidine type. Thus tetraphenylhydrazine (V) although its constitution admits of any of the four rearrangements to which aromatic hydrazines are liable (the ortho- and para-semidine and the ortho- and para-benzidine changes) actually isomerises exclusively to the base (VI) (Weland Annalen 1911 381 200) : The structure of the cyclic hgdrazine (I) admits of an ortho- or para-semidine change but not a benzidine change since only one of the nitrogen atoms carries a phenyl group. On the grounds of analogy therefore it is highly probable that the observed trans-formation is of the ortho-semidine type and may be formulated as in the preceding case 380 INOOLD AWD WEAVER THE ADDITIVE and this probability amounts to a practical certainty when it is reflected that the only possible alternative a para-semidine rearrangement is in this case intrinsically unlikely since the product would have formula (VIII) which is quite out of keeping with its ea'se of formation and stability.Formula (VII) on the other hand is in complete harmony with the properties of the substance. -N(CO,Et)*CO I (VIII.) CPh, 0 V N H -One other transformation is of sufficient interest to be mentioned here. The compound (VII) does not react in the cold with phosphorus pentachloride but if heated with this reagent it loses ethyl chloride giving an acid chloride (IX) which by the inter-action of its acyl chloride residue with the basic imino-group yields the trioyclic compound (X) : (IX.1 (X.) This substance belongs to the type represented by the formula N-b-N (XI) where a b and c denote three different groups, one of these (at least) being unsymmetrical with respect to the two nitrogen atoms. The space model of (X) lies in three planes (like that of camphor) and the compound should therefore be capable of optical activity depending on the asymmetry of its two tervalent nitrogen atoms (Moore P. 1914 182). Moore and Doubleday (J. 1921,119,1170) recently prepared some asymmetric, tervalent nitrogen compounds of a similar type but these contained methylene groups in place of the carbonyl groups in (X) and exhibited certain changes of colour and molecular weight in solution.It was hoped that the introduction of the cyclic -CO-N-linking in place of the -CH,-N- linking might confer greater stability and the opportunity of completing the synthesis of a stable substance of type (XI) was therefore followed up in the manner described. The compound (X) is in fact remarkably stable and is colourless in the solid state and in solution. No special proof is offered here regarding its constitution but the method of formation appears to place this beyond any reasonable doubt. /a\ \C / FORMATION OF FOUR-MEMBERED RINGS. PART VI. 381 Amongst the additive ring syntheses an account of which will be found in the experimental portion are t'he addition reactions between styrene and as-diphenylethylene on the one hand and azodicarboxylic ester on the other.The products belong to an almost unknown f amily of six-membered rings the hesahydro-27-tetrazines which to judge by the examples described (XI1 and YIII) possess unexpected st'ability. N*CO,Et N-CO,Et :XII.) Ph€€(f\y*CO,Et Ph,t"\~*CO,Et (sIII.) €I& ,N*CO,Et H,C,, ,N*CO,Et N*C02Et N*CO,Et E x P E R I 31 E N T A L. I3thyZ nzodicurbo-i.ylate was prepared by a modification c d Diels's method (Ber. 1911 44 3020). Rydraziiie sulphate (130 g.) was dissolved in a minimum of water and the base liberated by potassium hydroxide (112 g. in a little water). The precipitation of potassium sulphate was furthered by adding alcohol and the filtered solution treated with a mixture of '10 C.C. of ethyl chloroformate and 300 C.C. of ethyl alcohol.-4fter heating for one hour on the water-bath, the precipitated hydrazine hydrochloride was collected the filtrate evaporated a t the ordinary temperature and the product crystttllised from boiling water. The hydrazo-ester (m. p. 131" yield almost theoretical) was dissolved in concentrated nitric acid (5 parts) contained in a separating funnel and the mixture ailowed to warm slightly (this occurs spontaneously with the forma tion of nitrogeii peroxide the liquid becoming green). When the mixture became turbid and an oil separated on the surface the lower layer w;,2s run off and cooled somewhat by a freezing mixture whilst the oil, dissolved in ether was washed once with water to prevent further oxidation by the excess of nitric acid contained in it.The acid layer was then replaced in the fuiiiiel allowed to warm again and the process repeated until no more oil could be obtained. The combined ethereal solutions were washed about 15 times with lo?/ sodium carbonate solution then with water dried over sodium sulphate, and the ether removed. The residual oil was purified by distillation a i d the ethyl azodicarboxylate collected a t l21-lZi0/l6 mm. Ethyl hy drnzotr ica yboxy Zat e CO,E t *NH*N ( C 0,E t ) a 11 y - pr odu c t in the above preparation was collected in the fraction b. 1). 199-203Oj22 mm. which on re-distillation yielded a neutral colourless oil, 1). p. 200-201"/23 mm. (Found C = 42-95; H = 647 ; N = 11-3; -11 in freezing benzene = 276 258. C',M,,O,N require;. 6' = 43.5 ; H = 6.4; N = 11*3°(1 ; X = 248) 382 WGOLD AND WEAVER THE ADDPTIVE Ethyl benxemzouzrboxylate was prepared by a modified form of Heller and Widman's methods (Annalen 1891 263 287; Ber., 1895 28 1927).Ethyl chloroformate (50 g.) was added gradually and with vigorous stirring to an ice-cold solution of 100 g. of phenylhydrazine in 600 C.C. of dry ether. The red oil which remained when the ether was evaporated from the filtered solution, was dissolved in benzene and ligroin (b. p. GO-80°) added to bring about the separation of the hydrazo-ester in nearly colourless needles m. p. 80-82" (yield 60%). Forty grams of this dissolved in cold glacial acetic acid were treated gradually with an aqueous solution of 12 g. of potassium permangsnate. After the excess of the permanganate had been destroyed with hydrogen peroxide t'he mixture was poured into water and the oil extracted with ether and washed several times with sodium carbonate and then with water.The extract was dried with calcium chloride and evaporated and the azo-ester freed from the last traces of ether by the passage of a current of dry air a t 40" (yield 9O"/b). Addition of Ethyl Axodicarboxylate to Diphenylketen Forrnation Y tion containing ethyl azodicarboxylate (7.5 g.) and diphenylketen (8.6 g.) was kept for 24 hours out of contact with air and moisture. The crystals which had separated were recrystallised several times from ethyl alcohol colourless needles m. p. 129-131" being obtained (Found C = 72.61 ; H = 5.30; N = 5.03. C,,H,,O,N requires C = 72-44 ; H = 5-34 ; N = 4.98%).The compound gives no colour with ferric chloride and is stable to permanganate in the cold ; it is however fairly sensitive to hydrolysing agents. Hydrolytic Fission Anhydro- a-diphen ykcetyl- u( or p)-carboq-p(or a)-carbethoxyhydrazine- p-diphenylacetic Acid, ~Pb2-~*N(CQ2Et)*CO-CHPh2 or ~Ph,*N(CO2Et)*~*CO*CHPli,. CO=O* c 0 co-0-co -The pyridazine (4 g.) was boiled with concentrated hydrochloric acid (15 c.c.) and alcohol (70 c.c.) until crystals began to separate. After cooling the product was collected and crystallised from a mixture of alcohol and ethyl acetate from which colourless needles separated m. p. 155-156" (yield 3.4 9.) (Found C = 71-57; * This y-diketopyridazine formula is ascribed in preference t o the &diketo. pyridazine formula Co'N(Co~Et)~~*Co2Et owing to the close analogy with the y-diketopiperidines of Staudinger which unlike the isomeric &diketo-piperidines are readily split by hydrolytic agents (compare Anmlen 1911, bPh,-CPh,-CO 374 11) FORMATION OF FOUR-MEMBERED RINGS.PART VI. 383 H = 5-19 ; N = 5-06. C32H2806N2 requires C = 71.63 ; H = 5.22 ; N = 5.22%). The compound is stable towards permanganate and gives no colour with ferric chloride. Addition of Eayl Benzeneazocurboxylate to Diphenylketen Form-ation of Ethyl 4-Keto-2 3 ; 3-trip~nyldimethene-1 2-di-imine-1-carboxylate (I).-The azo-ester (5.1 g,) was added to a solution of 5.6 g. of the keten in 150 C.C. of light petroleum and the mixture kept for 24 hours out of contact with air and moisture. The crystals were then collected drained and crystallised from ether, alcohol dilute acetic acid or chloroform-ligroin from any of which colourless prisms separated m.p. 132-133" (yield 70%) (Bound C = 74.30 ; H = 5.50 ; N = 7.61. C,,H,,O3N requires C = 74.20; H = 5.38; N = 7.53%). The compound gives no colour with alcoholic ferric chloride and does not reduce perman-ganate in the cold; nor can it be reduced by zinc in boiling acetic acid. It yields no acetyl derivative and is for example unchanged by prolonged boiling with acetic anhydride. On distillation under reduced pressure an operation in which so many four-membered ring compounds are broken down into unsaturated substances (" thermal division ") this compound passes over unchanged. It is however sensitive to hot mineral acids and alkalis.Ring Fission by Alkaline Hydrolysis P-Phenyl- cr-carbethoxy-hydraxine- P-diphen $acetic Acid (II).-A solution of the ring-compound (3.4 9.) in 35 C.C. of alcohol was boiled with 10 C.C. of 10% aqueous sodium hydroxide for about 5 minutes cooled and acidified with hydrochloric acid. The precipitated oil was extracted with chloroform and recovered by evaporation of the solvent after drying with calcium chloride. It readily solidified on rubbing with ether and was then crystallised from chlorof orm-ligroin from which slender colourless needles m. p. 157-158" were obtained. Yield 3.5 g. (Found C = 70.38 ; H = 5434 ; N = 7.16. C,,H,,O,N, requires C = 70.76; H = 5-64; N = 7.18%). It is a weak acid, soluble in dilute sodium hydroxide solution but only slowly soluble in sodium hydrogen carbonate.Closure of the Ring by Dehydration with Acetic Anhydride.-The acid (0.3 g.) was boiled for about 3 minutes with 2 C.C. of acetic anhydride and the product warmed with water to remove the excess of the latter. The oily precipitate was extracted with chloroform and the extract washed with water dried mith calcium chloride and evaporated. The residue on rubbing with ether, solidified and was crystallised from alcohol from which the ring-compound (I) separated (yield 0.25 g.). It was identified by m. p. (132-133") and mixed m. p. and by analysis (Found C = 73.7 ; H = 5.4%) 384 INGOLD AND WEAVER THE ADDITIVE Conversioib of a 4-Membered Ring into a 6-Membered Ring by o-Semidine Change Ethyl 3- Keto-2 2-diphenyltetrahydroquinoxaline-4-carboxykate (VII).-A solution of 5 g.of the ring-compound (I) in 40 C.C. of alcohol was boiled with 20 C.C. of concentrated hydro-chloric acid until crystallisation commenced. The solid product was collected from the cooled solution and crystallised from chloro-form-ligroin dilute alcohol or dilute acetic acid from any of which it separated in bunches of colourless needles m. p. 165-166" (yield almost theoretical). Although this product melted fairly sharply close examination revealed the presence of about 10% of an impurity which could not be removed by fractional crystallisation. After many trials the following process was adopted. The substance (3 g.) was dissolved in 15 C.C. of alcohol and boiled with 30 C.C. of 10% sodium hydroxide.The small quantity of solid which separated was collected after cooling (0-3 g.). After crystallisation from ligroin-chloroform it yielded slender colourless needles m. p. 180-181" (Found : C = 75.97 ; H = 5.12 ; N = 9.17. C,,H,,O,N requires C = 75.85 ; H = 5.06; N = 8436%). This substance is apparently a keto-triphenyloxadiazole but the quantity obtained was too small for investigation. The mother-liquors from this substance deposited the quinoxaline, which could be washed with dilute acid and crystallised ; but a more convenient process was to add hydrochloric acid and extract the oily precipitate with chloroform. The product recovered in this way soon solidified and after crystallisation from dilute acetic acid melted a t 168" (Found C = 74.47 ; H = 5.44; N = 7.44.C,,H,,O,N requires C = 74-20; H = 5-38; N = 7.53%). This substance is extremely stable towards most reagents. It is not attacked by concentrated mineral acids or alkalis and is only slowly oxidised by hot acid permanganate. It is not reduced by zinc dust in boiling acetic acid solution. The acetyl derivative was obtained when the quinoxaline (0-4 g . ) was boiled with acetic anhydride (5 c.c.) for about 15 minutes. The product was boiled with water t o remove excess of the anhydride and sufficient glacial acetic acid was added to produce a clear solution which on cooling deposited colourless needles, m. p. 190-191" (yield 0.4 g.) (Found C = 72.33; H = 5.31; N = 8-87. C,,H,,O,N requires C = 72.46; H = 5.31 ; N = 6.76%). This substance is readily hydrolysed to the parent quinoxaline (VII) by boiling for a few minutes with aqueous-alcoholic hydrochloric acid or aqueous-alcoholic sodium hydroxide.Action of Phosphorus Pentachloride on the Quinoxaline (VII) : Formation of 1 ; 4-endo-Keto-2-keto-3 3-diphenyltetrahydroquinosa FORMATIOS O F FOUR-MEMBERED RISOS. PART VI. 385 line (X) and other Products.-No very trustworthy process could be discovered for producing the endo-keto-compound ; although it could be obtained in a variety of ways the yield was always small and the results were somewhat uncertain. The reason for this is partly that the cornpouiid is attacked by tlhe reagent (phosphorus pentachloride) used in its formation as is shown by the production of the dichloro-compound (below) and partly that from the commeiicement of the reaction changes occur which cannot lead to the desired coinpound this is proved by the evolut'ion of carbonyl chloride and by the formation of the monochloro-com-pound (below).The most trustworthy method was the following. The eiido-Keto-co,iz~o2~~~rl (X).-A mixture of the quinosaliiie with an equal weight of phosphorus pentachloride was treated with sufficieiit phosphorus osychloride to produce a clear solution a t 190". The mixture was then boiled gently for about 20 minutes cooled, anit filtered from the small prccipitate produced during the boiling. The chlorides of phosphorus were decomposed with water and the solid prodnct was collected dried and quickly extracted with warm absolute alcohol. The solid which separated from the filtered solution consisted essentially of the eizclo-keto-compouiId, uhich a t this degree of purity (m.p. 305-31Q0) is only sparingly soluble in alcohol. (Hence arises the necessity for extracting quickly ; otherwise the compound does not pass into solution with its impurities and is not crystallised thus rendering further purification dii'ficult.) Repeated crystallisation from nitrobenzene raises t'he m. p. to 333" (yield 67;) (Found C = 77-26 H == 4-59 ; N = 8.67. CZ1H14OZNZ requires C = 77-30 ; H = 4-29 ; X = 8.59%). -1 dichloro-compound probably 2 2-dichloro-l 4-emlo-keto-3 3-diphenyltetrahydroquinosaline (annexed for-/'d 1 \CPh mula) was obtained in the course of the above I I y o ' experiments. In the presence of the impurities which accompany it it is readily soluble in alcohol, from which after slight dilution with water it slowly crystallises.Rspeatcd crystallisation from a mixture of nitrobenzene and ligroin (b. p. 100-120") yields the pure compound as a micro-crystalliiie powder m. p. 246" (decomp.) (Found C = GG-24; H = 3.90; C1= 18-46. C,1H140N2C12 requires C = 66-14 ; H = 3.67 N = l8.M.,b). -1 moizochloro-compound. probably 3-chloro-2 2-diphenyl- 1 2 -tlihy~roquinoxaliiie (annexed formula) was isolated in the course of ;L series of experiments in which 'f'?P1i2 benzene was used as a solvent instead of phosphorus \/\/"' osychloride. It was separated from the product x obtaiaed after decomposing with water by extraction with ether in a Sorhlet's apparatus and fractional crystallisation N \/\N/CC12 NH 386 THE ADDITIVE FORMATION OF FOUR-MENBERED RINGS.PART VI. from benzene and from nitrobenzene-ligroin. It accumulated in the more soluble fractions and was ultimately obtained as minute prisms m. p. 204" (Found C = 75-07 ; H = 4.87; C1= 11.22. C,oHI,N,C1 requires C = 75.35; H = 4.71 ; C1 = 11015%). Addition of Ethyl Axodicarboxylate to as-Diphenylethylene : Formation of Ethyl 6 6-Diphenylhexahydro-1 2 3 4-tetraxine-1 2 3 4-tetrmarboxylate (XIII).-Equimolecular quantities of as-diphenylethylene and the azo-compound were mixed and kept for about 4 days a t the ordinary temperature when the colour of the azo-compound disappeared and the liquid became extremely viscous. On rubbing with ether a solid was obtained which separated from chloroform-ligroin in colourless prisms m.p. 1 6 4 -166" (Found C = 58-25; H = 6.1s ; N = 10.4. C&&&gN4 requires C = 59.10 ; H = 6-06 ; N = 10.6y0). The ether washings yielded unchanged diphenylethylene (about 0-5 mol.) but no other reaction product. The tetrazine derivative is unattacked by cold potassium permanganate and by boiling acetyl chloride. Attempts to hydrolyse it were not successful deep-seated de-composition taking place no definite product of which could be recognised. Formtion of Bthyl 6-Phenylhexahydro-1 2 3 4-tetraxine-1 2 3 4tetracarb-oxylate (XII).-This reaction was carried out like the preceding one, the colourless glassy mass partly solidifying on trituration with ether and styrene (about 0.5 mol.) being recovered from the ether solution after removal of the solid.The substance separated from chloroform-ligroin in colourless prisms m. p. 133-134" and had properties similar to those of the preceding compound (Found : C = 52.81 ; H = 6.15; N = 12.4; 2M = 466. C,oH,,08N, requires C = 53.10 ; H = 6.19 ; N = 12.4% ; M = 452). Supplementary Note Addition of Benxylidene-p-nitrobenz?/larnirLe to Dipheny1Eeten.-A solution of the azomethine (666 9.) in ether was mixed with a ligroin solution containing 5.55 g. of the keten. The mixture was kept for 24 hours out of contact with air and moisture and the crystals which had separated were then collected and crystallised from ether and from dilute alcohol from which large colourless prisms separated m. p. 133-134" (Found c = 77-39 ; H = 5.22 ; N = 6.42. C,,H,,O,N requires c = 77.41 ; H = 5-07; N = 6.45%). The compound is moderately stable to heat and is non-basic and is therefore probably 2-keto-3 3 4-tri-phenyl- 1 - p-nitrobenx yltrimeth yleneimine (the lactam of p -p- xitro-benxylamino- uu p-triphen ylpropionic acid), Addition of Ethyl Axodicarboxylate to Styrene : CPh,<C~ph>~*cH,'c,H~'No~ co- (in) FORMATION OF UNSATURATED AND CYCLIC COMPOUNDS ETC. 387 The authors desire to record their thanks t o the Royal Society for a grant which has defrayed part of the cost of this investiga-t ion. THE UNIVERSITY LEEDS. IMPERIAL COLLEUE SOUTH KENSINGTON. [Received December llth 1924.

ISSN:0368-1645    

DOI:10.1039/CT9252700378

出版商:RSC    

年代:1925

数据来源: RSC