摘要:

108 FORSTER : INFRACAMPHOLENIC ACID, AN ISOMERIDE OF X.-Infracampholenic Acid, an Isomeride of Cam- pholytic and isoLauronolic Acids. By MARTIN ONSLOW FORSTER. EIGHTEEN months ago I described the unsaturated nitrile, C9H13N, produced on eliminating hydrogen bromide and carbon monoxide from the anhydride of bromonitrocamphane (Trans., 1899, 75, 1141). At that time it seemed highly probable that the nitrile, and the amideCAMPHOLYTIC AND ISOLAURONOLIC ACIDS. 109 obtained from it on hydrolysis, were derivatives of Walker's cam- pholytic acid, because the amide, although distinct from isolauronol- amide, was converted into that substance by dilute mineral acids. The investigation of the acid derived from the amide is still incom- plete, but the recent appearance of a posthumous paper by Tiemann, in association with Kerschbaum and Tigges, on the two campholytic acids (Ber., 1900, 33, 2935), closely following a communication on the same subject by G.Blanc (Bull. Soc. Chim., 1900, [ iii 3, 23, 695), obliges me to describe briefly the progress which has been made i n the examination of the substance. The nitrile has to be heated with alcoholic potash continuously for several weeks before ammonia ceases to be evolved; there is then obtained the potassium salt of a liquid acid, C,H,,O,, which closely resembles Walker's campholytic acid, forming a viscous oil which boils a t 145' and 239' under pressures of 24 mm. and 758 mm. respectively. &loreover, the substance is optically inactive, and treatment with dilute mineral acids transforms it into isolauronolic acid, differing in no respect from the acid, obtained by the action of aluminium chloride on camphoric anhydride.Here, however, the resemblance to campholytic acid ceases. According t o Walker (Trans., 1893, 63, 498), that substance absorbs a molecular proportion of bromine, yielding the dibromide C,H,,O,Br,, which melts and blackens a t 106-107'. When, however, the new acid is treated with bromine under the conditiofis specified by Walker, two molecular proportions of the halogen are engaged, hydrogen bromide is elimi- nated, and the solid product consists of a tribromocarboxylic acid, C,Hl,0,Br3, which melts to a colourless liquid, and evolves gas, a t 182'. Moreover, the dibromide of the new acid, which can be obtained when bromine is slowly added in quantity scarcely sufficient t o con- vert all the substance into the compound C,H,,O,Br,, is quite distinct from the isomeric dibromide of campholytic acid, because it melts at 125' without blackening.Furthermore, whilst campholytic acid is converted by hydrobromic acid into the hydrobromide, C,Hl,OBr, several attempts, under varying conditions, to obtain a corresponding derivative from the new acid have resulted i n the production of isolauronolic acid. It has now been shown that the new substance is the lower homo- logue of a-campholenic acid, and I propose therefore to call it infracampholenic acid, the prefix '' infra " representing in this sense the converse of '' homo.'' Some months after the discovery of tribromodih y droinfracampholenic acid, and the consequent recognition of the fact that infracampholenic and campholytic acids are distinct, the paper by G.Blanc (Zoc. cit.) was published without any previous intimation that he proposed to110 FORSTER : INFRACAMPHOLENIC ACID, AN ISOMERIDE OF investigate the nitrile with which I was working. On reducing that substance with sodium i n absolute alcohol, Blanc obtained the amine which a-campholenamide yields when oxidised with sodium hypobromite, namely, a-aminocampholene, first described by Blaise and Blanc (BUZZ. Soc. Chim., 1899, [ iii], 21, 976) ; assuming that the nitrile is indeed the nitrile of campholytic acid, this result appeared to confirm the view that campholytic acid is the lower homologue of a-campholenic acid, and Blanc would have expressed its constitution by the formula C1H2* $JH*CO,H CH,* C : CH, I p e 2 7 but for the appearance oT Walker's latest paper on the subject (Trans., 1900, "7, 374).In consequence of this publication, Blanc agreed that campholytic acid is a stereoisomeride of isolauronolic acid, CH,* g*CO,H CH,*CMe2 I yMe 7 and adopting Bouveault's formula for a-campholenic acid, I, repre- sented the constitution of infracampholenic acid by the expression I1 : CH,-$J'H* CH,-CO,H CH,* VH*CO,H CH,*C:CH, CH,*C:CH, Working with Noyes' active campholytic acid, that is t o say, with the acid obtained by the action of nitrous acid on dihydroamino- campholytic acid, Tiemann (Zoc. cit.) arrived a t aa-dimethyltricarb- allylic acid by oxidation with dilute nitric acid, and therefore represents the constitution of campholytic acid by the formula I11 : UH,* yH*CO,H CH =CMe I.I ?Me, - 11. I ?Me, 111. I ?Me, This view is now endorsed by Blanc (Compt. rend., 1900, 131, S03), who has oxidised inactive campholytic acid, derived on this occasion from isolauronolic acid by Walker's process, obtaining also aa-dimethyl- t ricarball y lic acid. In giving expression to this change of view, Blanc does not refer to the result of his experiment with the nitrile of infracampholenic acid, which showed that this acid is the lower homologue of a-campholenic acid ; the formula 111, which, in agreement with Tiemann, he ascribes to campholytic acid, represents the latter substance as the lowerCAMPHOLYTIC AND ISOLAUROKOLIC ACIDS. 111 homologue of a-campholenic acid, the constitution of which is best expressed by Tiemann’s formula, 1H2* QH* CH,*CO,H CH,*FH*CO,H 7% 4 I ?Me, .HXMe CHZCMe In view of the fact, established in this paper, that campholytic and infracampholenic acids are distinct, one of three things follows : Tiemann’s formula for a-campholenic acid is incorrect, Blanc’s re- duction of infracampholenonitrile to a-aminocampholene is misleading, or the expression I11 does not truly represent the structure of campho- lytic acid. Now Tiemann’s formula for a-campholenic acid is based on the production of isoketocamphoric acid, COMe*CMe,*CH(CH,*CO,H),, on oxidation, and appears therefore to be well founded. There is likewise no reason to mistake the conclusion to be drawn from Blanc’s experiment showing that a-campholenic acid is the homo-derivative of infracampholenic acid.There remains, therefore, the third possibility, namely, the invalidity of the formula for campholytic acid advocated by Tiemann and by Blanc. While discussing the constitution of that substance, the last-named investigators do not allude t o the alternative formula, CH= F C0,H CH,*CHMe IV. I ?Me, , from which, by oxidation, aa-dimethyltricarballylic acid might be obtained. Perhaps the drawback which presented itself to them was the conversion of the complex *CMe2*CHMe* into the grouping -CMe,*UH(CO,H)*, a change which is certainly unusual. In view of the present difficulty, however, this formula deserves consideration because the structure of infracampholenic acid would then be re- presented by the expression 111.The following arguments may be brought forward in support of this suggestion. 1, The formula IV, with the qualification already mentioned, accounts for the production of aa-dimethyltricarballylic acid, CH=S-CO,H CO,H vO,H I ?Me2 YMe2 . 2. It represents campholytic acid as an up-unsaturated acid, in 3. It reconciles the facts that infracampholenic acid is distinct from CH,*CHMe - ~H,--CII.CO,H accordance with the results of Walker’s experiments.1 12 FORSTER : INFRACAMPHOLENIC ACID, AN ISOMERIDE OF campholytic acid, and is nevertheless a lower homologue of a-cam- pholenic acid. 4. The representation of infracampholenic acid by the formula 111 explains the production of a tribromo-derivative by direct action of bromine, the a-carbon atom being hydrogenised, and therefore sus- ceptible to the action of bromine.5. The formula IV is more consistent with the behaviour of campho- lytic acid towards bromine than the representation which is given by Tiemann and by Blanc, because dihydroisolauronolic acid, CH,*QH*CO,H CH,*CMe, I p M e 9 can be brominated in the a-position (Perkin, Trans., 1898, 73, 838), and tetramethylenecarboxylic acid, QH,*QH*CO,H CH,*CH, ? readily undergoes the same change (Perkin and Sinclair, Trans., 1892, 61, 42); if therefore, cRmpholytic acid has the structure 111, it might be expected to behave like infracampholenic acid, and give a tribromo- derivative instead of a dibromide. 6. On the lines of Lapworth’s proposal, according to which the production of isolauronolic acid from camphoric acid involves the migration of a methyl group (Trans., 1900, 77, 1057), the conversion of campholytic acid into isolauronolic acid can be explained as follows : CH=C*CO,H Me CH,*CHl!de this scheme is no less plausible than that adopted by Blanc (Compt.rend., 1900, 131, 805 ; Abstr., 2901, 80, i, 11) for the same purpose. Against the propositions made in this paper will be urged the fact that aminodihydrocampholytic acid, CH,*v H-CO,H CH,*CMe*NH, I ?Me2 9 under the influence OF nitrous acid, is more likely to yield a substance having the formula I11 than the alternative compound, IV. This is, prim$ facie, true, but it must be borne in mind that the substituentsCAMPHOLYTIC AND TSOLAURONOLIC ACIDS. 113 in this complex display great mobility, which is shared by the hydrogen atoms.I n the hope of settling definitely the constitution of infracam- pholenic acid, a study of its products of oxidation is being made, and I expect to gain evidence of its structure also by examining the alcohol obtained from aminoinfracampholene, C8H13*NH2, by the action of nitrous acid; the base itself is described in this paper, being readily furnished by inf racampholenamide when treated with sodium hypo- bromite. Before proceeding to the experimental details, I think it is desirable to draw attention to the nomenclature for campholytic and isolauronolic acids adopted by Tiemann’s collaborators in the paper first mentioned (Ber., 1900, 33, 2935). They distinguish these substances, which are perfectly well recognised under the original names, as a- and /3-campho- lytic acids respectively.This distinction seems to be somewhat unfor- tunate. I n the first place, the substance which they propose to call a-campholytic acid, is derived from P-camphoramic acid, whilst a-camphor- amic acid yields, not /3-campholytic acid, but. lauronolic acid. Secondly, it is claimed that the use of these letters illustrates the relationship of the acids to a- and P-campholenic acids ; no evidence is adduced in the paper, however, to shorn that such a relation holds good, and although Blanc’s investigations suggest that /3-campholenic acid is the homo- derivative of isolauronolic acid, the same author has shown that a-campholenic acid is not connected with campholytic acid in a similar manner. I n these circumstances, confusion will be avoided by adher- ence to the original names for campholytic and isolauronolic acids.EXPERINENTAL. Infracmpholenic Acid, C,H,,O,. The readiness with which the amide, C,Hl,* 00 *NH,, is converted into isolauronolamide under the influence of dilute hydrochloric acid renders this agent useless for the purpose of hydrolysis. Attempts have been made under varied conditions to transform the amide into the acid by means of nitrous acid, but on each occasion the unchanged substance was recovered. The only alternative was to use alcoholio potash, and although the action is extremely slow, and involves heating the liquid during several weeks, this method was ultimately adopted. Twenty grams of the purified amide were dissolved in 100 C.C. of alcohol, and heated with 25 grams (3; mols.) of potassium hydroxide dissolved in the minimum quantity of water, until no further evolution of ammonia took place.Hydrolysis was complete after 200 hours, The liquid was then evaporated on the water-bath, and the viscous residue washed two or three times with ether, dissolved in water, and VOL. LXXIX. I114 FORSTER : INFRACAMPHOLENIC ACID, AN ISOMERIDE OF just acidified with cold, dilute, hydrochloric acid, which precipitated a pale brown, viscous oil. This was dissolved at once in ether, washed with water, redissolved in sodium carbonate, and then extracted with ether in order to remove any non-carboxylic impurities. The solution of the sodium salt was exactly neutralised with dilute sulphuric acid, and on removing the precipitated oil with ether, drying the extract with fused sodium sulphate, and afterwards evaporating the solvent on a water-bath, 19 grams of the acid were obtained.The product, which was pale brown and very viscous, mas then distilled under reduced pressure ; various specimens boiled a t 145q 170°, 180°, and 239' under pressures of 24 mm., 60 mm., 105 mm., and 758 mm. respectively, yielding a colourless, or very pale yellow, viscous oil, having a faint, somewhat disagreeable odour. 0*2000 gave 05122 GO, and 0.1630 H,O. C,H,,O, requires C = 70.13 ; H = 9.09 per cent. A 20 per cent. solution in ether is optically inactive, and a 10 per cent. solution of the amide in absolute alcohol is also devoid of activity. The acid has a sp. gr. 1.0146 a t 1 6 O , and a refractive index pNa 1.4660 at 1 9 O .When infracampholenic acid is warmed with dilute sulphuric acid it soon solidifies, yielding isolauronolic acid, which was compared with a specimen obtained from camphoric anhydride; it melts a t the same temperature, and like the acid from this source, is optically inactive. A neutral solution of the ammonium salt gives no precipitate with magnesium sulphate, calcium chloride, or barium chloride, but the mercuric salt forms minute white needles, sparingly soluble in cold water. The copper salt separates immediately as a dark green, crystalline pre- cipitate, whicb dissolves readily in hot alcohol, forming a deep green solution j this deposits nodular aggregates of minute green needles. The lead salt forms a white, flocculent precipitate, soluble in boiling water, from which it crystallises in small, transparent, six-sided plates.The silver salt is soluble in hot water, separating in colour- less crystals which are affected only slowly by light. C = 69.85 ; H = 9-05, Certain salts of infracsmpholenic acid are well defined. Tri6romodihydroinfraca~p~o~~nic Acid, CgH1,O,Br,. I n the first attempts to prepare a dibromide, the conditions pre- scribed by Walker (Zoc. cit.) were observed. Seven grams of bromine dissolved in 20 C.C. of dried carbon disulphide were placed in a wide- mouthed bottle through the stopper of which passed a tap-funnel and a tube containing calcium chloride ; the bottle mas immersed in melt- ing ice in a large, blackened beaker. Five grams of infracampholenicCAMPHOLYTIC AND ISOLAURONOLIC ACIDS.115 acid dissolved in 20 C.C. of dried carbon disulphide were then added slowly through the tap-funnel, the solut?ion of bromine being shaken continuously during the process, and the operation being carried out in a darkened room. Colourless crystals were soon deposited in the bottle, and hydrogen bromide escaped through the calcium chloride tube. After remaining 12 hours in the dark, the solution was de- canted, and the crystals washed with light petroleum; the crude material obtained in this may amounted to 4.5 grams, a further quan- tity being obtained from the mother liquor. The freshly precipitated substance melted a t 178'. It was recrystalIised from hot ethyl acet- ate, in which it dissolves readily, being deposited in aggregates of small, hard needles, which melt to a colourless liquid, evolving gas, a t 182'; the melting point is dependent on the rate a t which the tem- perature rises, and has been observed as high as 187".0.2164 gave 0.2174 CO, and 0,0649 H,O. 0,1725 ,, 0-2465 AgBr. Br=60*80. The operation just described has been repeated many times, and the same result mas obtained in each case. Even when the halogen solution was cooled by a freezing mixture, and the acid added as slowly as possible, in a dark room, hydrogen bromide was evolved after a very short interval, and crystals wore deposited in the bottle when only a small proportion of the material had been added. Increasing the quantity of bromine does not improve the yield of the substance, which rarely exceeded 65 per cent, of the theoretical amount.The tribromide of infracampholenic acid dissolves readily in alcohol, and the cold solution immediately develops with silver nitrate a turbidity which rapidly intensifies to a copious precipitate. It dissolves in aqueous sodium carbonate with liberation of carbon dioxide, form- ing a bromohydrocarbon and an unsaturated acid; if the alkali is added in small quantities amounting in all to one molecular proportion only, nearly two-thirds of the substance remains unchanged. The following experiment was therefore performed. Twenty grams of the finely powdered tribromide were suspended in water, and treated with a cold solution of 21 grams (4 mols.) OF anhydrous sodium carbonate. The substance dissolved almost imme- diately without liberating carbon dioxide, as this was absorbed by the excess of alkali.The turbid solution, after 24 hours, had deposited a heavy, colourless oil, which was removed by means of ether, washed twice with water, and freed from ether on the water-bath; on passing a current of steam through the residue, a bromohydrocarbon was obtained having an agreeable odour. C= 27-40 ; H=3*33. C9H1,0,Br, requires C = 27.48 ; H = 3.33 ; Br = 61.07 per cent. 1 211 6 FORSTER : INFRACAMPHOLENIC ACID, AN ISOMERIDE OF 0.1908 gave 0.1781 AgBr. Br = 39.71. 0.1818 ,, 0.1702 AgBr. Br = 39.83. C,H,,Br requires Br = 42.78 per cent, It is probable that this substance does not represent the initial pro- duct arising from the tribromide by the elimination of carbon dioxide and hydrogen bromide according to the equation : C,H,,O,Br,Na L= C,H,,Br + NaBr + HBr + GO,.Most likely the.hydrocarbon dibromide, C8HI2Br2, is first produced, and undergoes resolution into the bromo-derivative, C,HllBr, and hydrogen bromide during the process of isolation, because the sub- stance extracted by ether is colourless, becoming pale yellow when distilled in steam ; the aqueous residue in the distilling flask contains a considerable amount of hydrobromic acid, and holds some dark brown, non-volatile, tarry matter in suspension. It will be interesting to ascertain the nature of the acid produced along with the hydrocarbon, and steps are being taken in this direc- tion, but unfortunately the substance is resinous, and the only infor- mation concerning it which has been gained so far is the fact that it is unsaturated and contains bromine. Four grams of infracampholenic acid were dissolved in 100 C.C.of dry chloroform, and to the solution, immersed in a good freezing mix- ture, rather less than 4 grams of bromine, dissolved in 50 C.C. of cold chloroform, were slowly added. Owing to the readiness with . which one atom of hydrogen in infracampholenic acid is replaced by bromine, great care was taken to keep the solution in a state of agitation, and the solution of bromine was admitted drop by drop; liberation of hydrogen bromide was thus reduced to a minimum, and only towards the end of the operation did the gas make its appear- ance. Without removing the vessel from the freezing mixture, a current of dry air was aspirated through the pale yellow liquid during one hour, after which interval the solution was allowed to acquire the temperature of the atmosphere.When the chloroform had com- pletely evaporated, a white, butter-like mass remained ; this was drained on porous earthenware, and washed several times with cold petroleum, The snow-white, micro-crystalline powder obtained in this way melts at 117" to a colourless liquid evolving gas ; it dissolves very readily in alcohol and in cold ethyl acetate, but is rather sparingly soluble in boiling petroleum, which deposits it in minute rectangular plates; these melt and evolve gas at 125'.CAMPHOLYTIC AND ISOLAURONOLIC ACIDS. 117 0.2152 gave 0.2653 CO, and 0.0853 H,O. 0*1599 ,, 0,1940 AgBr. Br = 51-62. C = 33-62 ; H = 4.40. C,H,,O,Br, requires C = 34.14 ; H = 4-46 ; Br = 50.95 per cent.The dibromide dissolves immediately in aqueous sodium carbonate, and the turbid solution deposits a bromohydrocarbon on standing. The Arnide of Infraaampholenic Acid. When the extraordinary indifference of inf racampholenamide towards alkaline hydrolytic agents was first observed, an attempt was made to st'udy the oxidation products of the acid by oxidising the amide and hydrolysing the product. Oxidation of Infracampholenamide.--Ten grams of the amide were dissolved in 5000 C.C. of boiling water and rapidly cooled, the temper- ature of the solution being finally reduced to about Oo by immersion in melting ice. Three hundred C.C. of a 2 per cent. solution of potass- ium permanganate were added in small quantities, the colour of the solution being immediately destroyed.The liquid was then treated with 15 grams of potassium carbonate, boiled, filtered, and evaporated to small bulk, when a dark yellow oil separated, and solidified on cooling, After being drained on porous earthenware, washed with a small quantity of cold water, and again drained, the colourless pro duct weighed 8.5 grams. Under these conditions, the amide is oxidised to a dihydroxy-deriva- tive. The substance dissolves very readily in water, forming a solution which is neutral to litmus. Alcohol also dissolves it freely, and ethyl acetate is the most convenient solvent from which to crystallise it, depositing the derivative in prisms containing lH20. A specimen dried in the desiccator was analysed, with the following result : 0.1775 gave 0.3492 CO, and 0.1534 H,O.C =53.65 ; H= 9.60. C,H,lO,N,H,O requires C = 52.68 ; H = 9.27 per cent. In the hydrated condition the substance has no definite melting point, but liquefies at about llOo, when water is liberated. If the crystals deposited by ethyl acetate are powdered finely and dried at 90' until no further loss of water takes place, the substance melts at 170°, without evolving gas, 0.1816 gave 0.3861 CO, and 0.1500 H,O. C=57*99 ; H= 9-17. 0.2218 ,, 14.2 C.C. of nitrogen a t 16.5' and 779 mm. N = 7-63. C,H,,O,N requires C = 57-76 ; H = 9.09 ; N = 7.48 per cent. The oxidised amide is hydrolysed by alcoholic potash much more 0.2073 ,, 0.4415 CO, ,, 0.1694 H,O. C=58*08 ; H=9*08.118 FORSTER : INFRACAMPIIOLENIC ACID, AN ISOMERIDE OF readily than infracampholenamide, but the acid obtained in this way takes the form of a resin, Hydrobromide of Infracampholenamide, C,H,,ONBr.-The amide of infracampholenic acid was dissolved in 48 per cent. hydrobromic acid, and allowed to remain in the desiccator. After some days, clusters of flat, transparent, rhomboidal plates separated. Cold alcohol dis- solves the substance very readily, and it is also soluble in cold water, forming an acid solution ; when potassium permanganate is added to this liquid, the colour is destroyed and bromine set free. The hydro- bromide is insoluble in petroleum, and very sparingly soluble in cold ethyl acetate, but it dissolves readily in the boiling liquid, which deposits it in transparent plates melting a t 144', with vigorous dis- engagement of gas.0.2165 gave 0.1603 AgBr. Br= 31-50. C,HI6ONBr requires Br = 34.1 8 per cent. C9HlGONBr,H',O ,, Br = 31.74 ,, An attempt t o prepare the hydrobromide by dissolving the amide in more concentrated acid (sp. gr. 1.83) resulted in the production of bolauronolamide. The clear solution in the acid deposited lustrous, colourless crystals melting indefinitely between 70' and SO', and yielding isolauronolamide and hydrobromic acid on treatment with water, which first converts the crystals into an oil ; isolauronolamide itself yields similar crystals under the influence of the concentrated acid, the product consisting most likely of an unstable salt. Dibromide of Infrc6ccamphole~ccmicEe, C,HI,ONBr,.-Ten grams of the amide were dissolved in dried chloroform, cooled in a freezing mixture, and treated with 10 grams of bromine (1 mol.) in the same solvent, the halogen being added in small quantities at a time ; the bromine was immediately decolorised, and no hydrogen bromide was liberated.On evaporating the chloroform, colourless crystals were deposited, and the product was filtered from a small quantity of oil, washed with chloroform, and recrystallised from boiling ethyl acetate, which deposited it in white needles melting at 114'. 0.2148 gave 0.2435 AgBr. Br = 48.33. 0.2660 ,, 0.3017 AgBr. Br = 48.26. 0.3321 ,, 13.1 C.C. of nitrogen at 20' and 762 mm. N=447. C,H,,ONBr, requires Br = 51.12 ; N = 4.60 per cent. C9H,50NBr2,H20 ,, Br = 48-34 ; N = 4.23 ,, The dibromide is insoluble in petroleum, but dissolves readily in alcohol, and is very freely soluble in water, forming a neutral solution from which it crystallises in white prisms; the aqueous liquid pre- cipitates silver bromide from the nitrate, but does not liberate iodineCAMPHOLYTIC AND ISOLAURONOLIC ACIDS, 119 from potassium iodide, even when acidified with dilute sulphuric acid.It is indifferent towards a neutral solution of potassium perman- ganate, but in presence of dilute sulphuric acid bromine is liberated, and the permanganate decolorised. Arninoin fi.acamnphoZene, C,H1,*N H,. Ten grams of purified infracampholenamide were finely powdered and suspended in 25 C.C. of water; 10 grams of bromine were then dissolved in 100 C.C. of water containing 10 grams of caustic soda, and added to the amide.On gently warming the liquid, a basic odour became perceptible in a few minutes, and an oil rose to the surface. After about an hour, during which period the liquid was agitated, and at intervals gently heated, the base was extracted with ether, washed several times with water, and after removing the ether on a mater- bath, distilled in an atmosphere of steam. The colourless oil obtained in this manner was collected by ether, dried with solid potash, and freed from ether on the water-bath. The yield amounted to 4 grams, and might possibly be augmented by manipulating smaller quantities of the amide at one time, because an experiment in which 25 grams of material were employed yielded only 9 grams of base. Aminoinfracampholene is a colourless, limpid oil having a pungent, somewhat pleasant odour, and boils a t 158-160' under 754 mm.pressure ; it has a sp. gr. 0.8'770 a t 14", and refractive index pNn 1.4748 at 19". The base absorbs carbon dioxide readily from the air, forming a crystalline carbonate. The hydrochloride is readily soluble in cold water, and crystallises in lustrous leaflets melting a t 213'. The plutinicldoride separates immediately in pale red crystals on adding aqueous platinic chloride to a solution of the hydrochloride in water, It dissolves very freely in hot alcohol, and crystallises in beautiful, lustrous, pale red leaflets. 0.1528 gave 0*0450 Pt. Pt=29*45. (C,H,,N),, H,PtCI, requires P t = 29.48 per cent. The salt darkens at about 200°, and melts to a charred mass The picrate crystallises in clusters of sulphur-yellow needles on 0.2452 gave 33.8 C.C. of nitrogen at 18' and 752 mm. It melts at 2 1 3 O to a deep brown liquid which soon begins to The benxoyl derivative is very readily soluble in ethyl acetate at 238-240O. adding to the base a hot solution of picric acid in alcohol, N = 15.75. C,H,,N,C,H,O,N, requires N = 15-82 per cent. evolve gas.3 20 EASTERFIELD AND ASTON: TUTU. PART I. and in alcohol, crystallising from the latter in rosettes of long, slender prisms melting a t 105' ; it is sparingly soluble in boiling petroleum, from which it separates in lustrous, silky needles which melt also at 105O. 0.1672 gave 0.4631 00, and 0.1225 H,O. C1,HIQON requires C = 75.31 ; H = 7.95 per cent. The carbamide derivative is not precipitated immediately on mix- ing moderately concentrated solutions of the hydrochloride and potassium cyanate, but soon crystallises when the liqyid is heated on the water-bath; i t forms lustrous, white needles melting a t 182'. 0.1658 gave 24-5 C.C. of nitrogen at 1705~ and 756 mm. N = 17.01. C,H,,ON, requires N = 16-66 per cent, The phenykarbamide derivative separates in aggregates of flat, lustrous needles on adding a solution of phenylcarbimide in a mix- ture of ether with petroleum to a solution of the base (1 mol.) i n ether. C=75*54; H=8*14. 0.1831 gave 0-4920 CO, and 0.1357 H,O. The substance crystallises from alcohol in very long, flat, trans- C = 73.28 ; H = 8.23. Cl,H,,0N2 requires C = 73-77 ; H = 8.19 per cent. parent needles and melts a t 180O. ROYAL COLLEQE OF SCIENCE, LONDON, SOUTH KLNSINGTON, S. W.

ISSN:0368-1645    

DOI:10.1039/CT9017900108

出版商:RSC    

年代:1901

数据来源: RSC

摘要:

3 20 EASTERFIELD AND ASTON: TUTU. PART I. XI.-Tutu. Part I. Tutin and Coriamyrtin. By THOMAS HILL EASTERFIELD, Professor of Chemistry, Victoria Col- lege, Wellington, N.Z., and BERNARD CRACROFT ASTON, Chemist to the New Zealand Department of Agriculture. THE monotypic natural order, Cwiarice, is represented in New Zealand by three species, which are known collectively as Tutu or toot. Coriaria ruscifolia, L. (C. Sarmentosa, Forst ; C. ar6orea, and C. Tutu, Lindsay ; Tutu, pohou, and tupakihi of the Maori) is commonly known as the tree-toot ; it is a handsome shrub with glossy, acuminate leaves, and grows to a height of 20-26 feet. C. thymifolia, Humb. and Bonp. (Tutu-pa.pa or tutu-heu-heu of the Maori), seldom exceeds three feet in height, and is known as the ground-toot. C.angustissima, Hook. f., is of comparatively rare occurrence. It is a small, herbaceous upland annual with a characteristic fern-like appearance.TUTIN AND CORIAMY RTIN. 121 A peculiar interest-attaches to these plants in that they are all known to be highly toxic. The animals brought by Captain Cook in both his voyages died in what was to him an unaccountable manner, but as Lauder Lindsay ( B . and F. Med. and Chir. Rev., July, 1865, 153 ; October, 1868, 465 ; also B.A. Report, 1863, 98) has pointed out, the general description of the symptoms leaves little doubt that they died of tutu poisoning. Many instances are upon record in which upwards of 50 per cent. of a large herd of cattle has been lost in a single night from toot poisoning. The plants are very succulent and attractive t o cattle, so that stock can only be driven through a tutu country at considerable risk.Cattle living in these districts appear to eat the plant with impunity, but if starved or overdrivea, the apparent toleration disappears, partly, no doubt, from the fact that under these circumstances the plant is eaten in excessive quantity. Cattle suffering from tutu poison, popularly said to be tooted, rush madly about, then stagger and fall, convulsions are of frequent occur- rence, large volumes of gas appear in the stomach, and the animal eventually dies in a comatose condition. Tutu berries are of luscious appearance and taste, and are consumed in quantity by the Maoris ; the seeds are, however, poisonous, and deaths from swallowing them are not uncommon, particularly amongst children.It is said that birds are not poisoned by the seeds, but cases have come under the notice of the authors in which domestic fowls bave been poisoned by eating the berries, the symptoms being typical of tutu poisoning. Human beings who have recovered from toot poisoning nearly always suffer for a time from impaired memory, and permanent physical distortion sometimes accompanies severe cmes. Bleeding is the usual remedy adopted by the natives and settlers, and the beneficial effect is remarkably rapid. It is somewhat remarkable that the poisonous constituent of tutu has remained hitherto unisolated. Skey (Trans. N.Z. Inst., 1869, 153, 399, 400) has shown that ether removes from the seeds a highly poisonous green oil, which, he remarks, is or contains the poison.Hughes (Trans. N.Z. Inst., 1870, 237) showed that C. s w c i - folia contained crystalline constituents soluble in alcohol or water, but did not identify them. H e found that boiling with slaked lime destroyed the poisonous action of thq drug. Christie (N.Z. Med. JO'UTN., July and October, 1890) has examined the physiological effect of decoctions of the plant, and denies that lime destroys the poison. The present paper contains an account of the investigation of the three species of New Zealand Coriaria. It is shown that the plants all contain a highly poisonous, non-nitrogenous glucoside, C,7H,,0,, for which the name tutin is proposed. C. thyrngolia also contains quercetin122 EASTERFIELD AND ASTON: TUTU. PAIlT I , and some half-dozen well-known acids, and C.angustissinza has yielded a volatile acid, C,H,O,, which has not been identified. EXPERIMENTAL. (1). Coriaria thymifoZicc.--Eleven kilograms of the air-dried plant (root excluded) gathered at Dunedin at the time of flowering (January) were put through a chaff -cutter and boiled with successive quantities of water. The concentrated infusion was treated with a large volume of alcohol which precipitated inorganic salts, ellagic acid, and a large quantity of black, tarry matter, The residue remaining after distilling off the alcohol from the supernatant liquid was extracted with ether. When the ether was distilled off, the residue containing the character- istic glucoside tutin set to a semi-solid, crystalline mass with a pungent odour.Prom the distillate a silver salt was prepared, which, after a single recrystal- lisation, gave Ag = 64.3 per cent. Calculated for C2H,02Ag, Ag = 64.7 per cent. Gallic acid remained in quantity when the solution, which had been distilled with steam, was evaporated to the crystallising point and the residue extracted with chloroform, It gave the usual colour reactions. After recrystallisation from water, it was dried at 150' and gave : Acetic acid was recognised by distilling the mass with steam. C = 49.4 ; H = 3.5 per cent. Quercetin, or some isomeric compound, was present in the crude gallic acid. After purification by repeated recrystallisation from water, it showed the usual colour reactions and dyeing properties, lost 2 mols. of water at 160°, and, on analysis, gave : C,H,O, requires C = 49.0 ; H = 3 -5 per cent.C = 69.2 ; H= 3.6 per cent. Quercetin has been definitely shown by Perkin to exist in C. m y t i - folia (Trans., 1900, "7, 429). The chloroform solution separated from the gallic acid was evaporated and the product dissolved in ether, the remaining acids were then removed by sodium carbonate. It was recog- nised by qualitative reactions, melting point, and analysis of the silver salt. C,,H,,O, requires C = 59.6 ; H = 3.2 per cent. Succinic acid was identified in the alkaline solution. C = 14.3 ; H = 1.25 ; Ag = 64.8 per cent. 8eeds.-A kilogram and a half of the seeds of C.-tlhym;foZia were pul- C,H,O,Ag, requires C = 14.4 ; H = 1.2 ; Ag = 65.0 per cent.TUTIN AND CORIAMYRTIN. 123 verised and exhausted by carbon disulphide which removed 2206 per cent.of a green, drying oil. The seeds, freed from oil, yielded to water a small quantity of tutin which was extracted with ether, and after recrystallisa- tion melted at 208-209O. The oil upon saponification yielded a liquid acid which was probably linoleic acid, since its calcium and barium salts were readily soluble in ether. (2). C. ruscifoZia.-In the examination of this plant, the juice ex- pressed from the succulent, asparagus-like shoots (gathered at Wellington early in October) was employed. It contained the same acids as the extracts of C. thymifolia. The yield of tutin was 0.03 per cent. Samples of the plant gathered later in the year from the same hill-side, contained a smaller percentage of the poison.The dried seeds of C. ruscifolicc, on extraction with carbon disulphide, yielded 22.8 per cent. of oil which was very faintly toxic. 0.18 gram administered to a small kitten prodyced only very mild symptoms of tutu poisoning. From the extracted seeds, water removed a few crystals of a substance which gave the characteristic bitter taste and colour reaction of tutin. (3). C. angustissima.-Only 1 kilogram of the dried plant was obtainable. It was collected at Dunedin early in January. Tutin was obtained from it and identified by its melting point. This species contains an acid which was not detected in the other two; when the aqueous extract of the plant was repeatedly shaken up with ether, the later extractions contained the acid in a comparatively pure condition.It crystallised from chloroform in silky, yellowish needles which were finally sublimed at 125O under diminished pressure. It was thus oh- tained in colourless, iridescent plates, very readily soluble in water, alcohol, or ether, The acid has a characteristic smell, gives a transient violet colour with ferric chloride, and melts at 130’ (uncorr.). On analysis : 0,1214 gave 0.2537 CO, and 0.0545 H,O. C = 56.99 ; H = 4.99. C8H,0, requires C = 57.10 ; H = 4.76 per cent. The ethereal solution, from which all the acids had been removed, was evaporated and yielded almost colourless crystals which were repeatedly recrystallised from water and from alcohol. From water, the substance separates in characteristic acicular forms, from alcohol, in oblique ended prisms.The compound is perceptibly volatile, may be slowly sublimed at 120-130°, melts at 208--209° (uncorr.), and has an intensely bitter taste. It contains no nitrogen, and after hydrolysis by dilute acids reduces Fehling’s solution, and with phenylhydrazine gives an amorphous precipitate which is not phenylglucosazone.124 EASTERFIELD AND ASTON: TUTU. PART I. Strong sulphuric acid added to a few drops of a saturated aqueous solution of tutin gives a blood-red coloration. Examination by Zeisel's method for methoxyl groups gave nega- tive results. When evaporated to dryiiess with slaked lime, solutions of tutin yield amorphous compounds amongst which tutin can no longer be detected even when the residue has been acidified. Some preliminary experiments upon the toxic effect of tutin were carried out by Mr.J. A. Gilruth, Chief Government Veterinary Surgeon. A dose of 0.129 gram killed a kitten weighing 1 kilogram in 40 minutes; 0*001 gram given to a cat weighing 2 kilograms caused a fit in 3 hours and illness for the next 24 hours. The same cat subsequently succumbed to a dose of 0.003 gram. A dose of about a milligram produced nausea, vomiting, and in- capacity for work extending over 24 hours in a healthy, full-grown man. Three preparations were analysed, i and ii from G. tAymvoZia and iii from C. ~ ~ s c i f o l i a : i. 0,1299, dried at 120-130', gave 0.2899 CO, and 0.0691 H20. ii. 0.1255, dried in desiccator, gave 0.2793 CO, and 0*0710 H,O. iii. 0.1264, dried a t 120-130°, gave O92S35 CO, and 0.0658 H,O. Cl7H2,O, requires C = 60.71 ; H = 5.95 per cent.Molecular Feight Determinations.-Calculated for C,71€,,07. M = 336. 0.403 gram depressed the m. p. of 10 grams of acetic acid 0.47'. M = 332. The compound is very poisonous. C = 60.78 ; H = 5.91. C = 60.70 ; H = 6.20. C = 60.95 ; H == 5.78. 0,319 ,, 9 , 9 9 ?I ,, 0.38'. M=325. 0.2448 ,, 9 9 ,, 8 ), phenol 066'. M=333. 1 ,1173 grams raised the b.p. of 11 *65 ,, alcohol 0.35'. M = 320. SoZubiZities.-One hundred grams of water at lo', of ether at lo', and of alcohol at 16" dissolve 1.9, 1.5, and 8.2 grams of tutin respec- tively. It is very soluble in acetone, but dissolves only sparingly in chloroform, and is insoluble in benzene or carbon disulphide. The optical activity has been determined by Professor C. R. Mar- shall, of University College, Dundee, who reports as follows : aD = + 0.37' ; I = 2 dcm.; d = 0-8 ; c = 2.5 per cent. in alcohol ; whence Note on the Pharmacology of Tutim-Professor Marshall has under- taken the pharmacology of tutin, and furnishes the following pre- liminary note : (6 Tutin, pharmacologically, is closely allied to coriamyrtin, and [a]'D9'"= + 9.25.TUTIN AND CORIAMYRlIN. 125 belongs to what is known as the picrotoxin group of substances. After preliminary depression, it induces salivation, a fall in the fre- quency of the pulse, and increased respiratory activity, followed by convulsions, for the most part clonic and limited in the earlier stages to the fore part of the body. The effect is apparently due to an action on the medulla oblongata and basal ganglia of the brain.' I It differs from coriamyrtin in being less toxic and slower in its action. On this account, the preliminary depression is more marked. Its connection with this substance, however, is close. Experiments suggest that it is broken up in the body into some substance, possibly coriamyrtin, which is the active convulsant factor. "It ought to be stated that the coriamyrtin employed by me was obtained from Merck. After boiling for a short time with dilute hydrochloric acid (2 per cent.), it did not reduce copper sulphate solution. It melted at 224' (uncorr.), and its solubility in physi- ological saline solution (0.6 per cent. NaCl) was less than 0.1 per cent. Riban's coriamyrtin melted a t 220°, and was soluble in water to the extent of 1.44 per cent.at 22O." CoTiamy rtin. The physiological action of the New Zealand species of Coriaria and of the European species (C. mprtifolia) is so similar that a direct comparison of tutin with coriamyrtin, the glucoside isolated by Riban (Bull. SOC. Chirn., 1864, [ii], 1, S7 ; 1867, [ii], '7, 79), seemed desirable. A gram of coriamyrtin was obtained from Merck, of Darm- stadt; the specimen melted at 225' (uncorr.),* and the melting point was not altered by recrystallisation from alcohol. Like tutin, the compound is somewhat volatile, sublimation commencing a t about 150'. Analysis of the compound before and after crystallis- ation gave numbers agreeing closely with those obtained by Riban : C = 64.56 ; H = 6.57. 0.1389 gave 0-3288 CO, and 0.0823 H,O. 0.1263 ,, 0.2976 CO, ,, 0.0734 H,O.C= 64.25 ; H= 6.45. Riban found (mean of three analyses) C = 64.07 ; H = 6.57. C,,H,,O,, (Riban) requires C = 64.75 ; H = 6.47 per cent. C2,H,07 requires C = 64.61 ; I€ = 6.66 per cent. If the latter formula were correct, coriamyrtin would differ from tutin by C,H, only, and its higher melting point, lower volatility, and solubility suggest strongly that i t is a higher member of the series to which tutin belongs. Molecular weight detcrminations, how- ever, indicate that the true formula is smaller than either of the above, being probably half that assigned to tutin by Riban. * Riban gives 220" ; Merck (Chern. Ccntr., 1899, i, 706) gives 229".126 MELLOR : SOME U-ALKYL SUBSTITUTIOW PRODUCTS 0.2478 gram raised the b. p. of 3-76 grams of acetone 0.46'.0.1732 ,, depressed them, p. of 8 ,, phenol 0.62'. 0.3196 ,, ?? 6.4 ,? ,? 0.33'. 0.2226 ?) ? I 9 9 8 * ? ,, 0.80'. OF M = 255. M = 265. M = 250. M = 250. Calculated for C,,HI,O,, M = 278 ; and for C2,H2,07, M = 390. The conclusion that the real formula is C,,H,,O, harmonises with the fact that, by tho action of bromine, Riban obtained a crystalline derivative in which 1/18th of the hydrogen was replaced by the halogen. If, however, the compound is a glucoside, as its reactions suggest, the sugar which it yields upon hydrolysis cannot contain more than four atoms of oxygen, and the formula is remarkable in that it contains fewer oxygen atoms than that of any glncoside hitherto described. Tho appended table shows the chief differences between tutin and coriamyrtin : Solubility in 100 parts of water ... Solubilityin 100 parts of alcohol .. 8.2 at 16' 2.00 a t 22' ,, Coriamyrtin, C15H1805 (E. and A ). 1.44 at 22' (Riban) Tutin, Cl,H,07. 1.8 at 10' } Nil. Reaction with hydriodic acid, followed by potash ............ Magenta" ,, With concentrated sulphuric acid., Blood red Dirty yellow Initial temperature of sublimation About 120" About 150' * The authors desire, in conclusion, to express their thanks to Mr. J. D. Ritchie, and the other officers of the New Zealand Department of Agriculture, for their kindness in securing the raw material employed n this investigation of tutu.

ISSN:0368-1645    

DOI:10.1039/CT9017900120

出版商:RSC    

年代:1901

数据来源: RSC

摘要:

126 MELLOR : SOME U-ALKYL SUBSTITUTIOW PRODUCTS OF XIL- Some ct-AlkyE Substitution Products o f Glutaric, Adipic, and Pimelic Acids. By J. W. MELLOR. THE a-alkyl substitution products of glutaric, adipic, and pimelic acids have been comparatively little studied, and, as it was thought that it would be interesting to prepare some of these derivatives and deter- mine their dissociation constants, I undertook the following work at the suggestion of Professor W. H. Perkin, jun. The a-methyl- and a-ethyl-glutaric acids have been prepared by Auwers and Titherly (Anncden, 1896, 292, 209-21 3). I n preparing derivatives of adipic acid, I have employed a modification * Reaction verified by the authors.GLUTARIC, ADIPIC, AND PIMELIC ACIDS, 127 of the process described by Montemartini (Bey., 1895,28,985).Monte- martini first prepared ethyl butanetricarboxylate by the interaction of the sodium compound of ethyl malonate with ethyl y-chlorobutyrate : (CO,Et),CHNa + CH2C1*CH,*CH,*C0,Et = ( C0,Et),CH*CH,*CH,*CH,*C02Et + NaCl. This ester, by hydrolysis and subsequent decomposition of the result- ing tricarboxylic acid by heat, yields adipic acid. Montemartini also showed that a-substituted derivatives of adipic acid may be obtained by using homologues of ethyl malonate in this synthesis, and in this way he prepared a-methyl- and a-ethyl-adipic acids. Since, however, the ethyl 7-chlorobutyrate required for these es- periments had to be prepared by the hydrolysis of y-chlorobutyro- nitrile, OH,Cl*CH,*CH,*CN, by a troublesome operation conducted in sealed tubes, I have simplified the process by carrying out the synthesis with the nitrile instead of with the ester.The prepara- tion of adipic acid, for example, may be readily accomplished as follows : The sodium compound of ethyl malonate is treated with y-chloro- butyronitrile, when the following decomposition takes place : (CO,Et),CHNa + CH,Cl*CH,*CH,*CN = NaCI + (CO,Et),CH~CH,*CH,*CH,*CN. It is now only necessary to boil the ethyl w-cyanobutane-aa-dicarb- oxylate thus formed with dilute sulphuric acid, when hydrolysis and elimination of carbon dioxide simultaneously occur, and adipic acid is formed. If instead of ethyl malonate the substitution products of ethyl malonate are employed in the above synthesis, it is an easy matter to prepare any a-substitution product of adipic acid.However, in the examples given in the paper, the y-chlorobutyronitrile was converted into ethyl y-chlorobutyrate, CH,Cl*CH,-CH,*CO,Et, acd this was digested with the sodium compound of the ethyl alkylmalonate. The ester thus obtained gave, on hydrolysis, the desired substituted acid, with elimination of carbon dioxide. The simplification in the process above-mentioned was suggested to me by Professor Perkin after the three alkyl-adipic acids had been prepared. I n the preparation of the substituted pimelic acids, the process em- ployed was essentially that of Crossley and Perkin (Trans,, 1894, 65, 989). The sodium compound of a substitution product of ethyl malonate is first treated with trimethylene chlorobromide, when the following reaction takes place : (CO,Et),CRNa + CH,Br*UH,*CH,C1 = (C0,Et)2CR*CH,*CH2*CH,Cl + NaBr.1-28 MELLOit : SOME a-ALKYL SUBSTITUTION PRODUCTS OF The chloro-ester so prepared is then allowed to react with the sodium compound of ethyl malonate, thus : (C02Et),CH*CH,*CH2*CH,CI + NaCH(CO,Et), = (C0,Et)2CH*CH,*CH,*CH2*CH(C02Et)2 + NaCl.The tetracarboxglic ester so produced is digested with hydrochloric acid, when hydrolysis and elimination of carbon dioxide takes place, and the a-substituted pimelic acid is prepared. U-A LKYL-GILUTARIC ACIDS. a- Methylglutaric Acid, CO,H* CH( CH,)*CH,*CH2*C02H.-In pre- parisg this acid, sodium (1 at.) is dissolved ;in absolute alcohol and mixed with ethyl propanetricarboxylate, (CO,Et),CH*CH,*CH,*CO,E t (1 mol.). A slight excess of methyl iodide (1 mol.) is then added, and after heating for 2 hours on the water-bath, the product is diluted with water and the oily ester extracted with ether in the usual way. After drying over calcium chloride and fractionation, the ethyl methyl- propanetricarboxylate, (CO,Et),*C(CH,)*CH,*CH,*CO,Et, which distils at 165' under 20 mm.pressure, is digested with concentrated hydro- chloric acid for about 6 hours. After evaporation to dryness, a viscid mass remains which soon solidifies. The product crystallises from water in a vacuum, melts at 77-78', and consists of pure a-meth ylgl utaric acid. This acid has been prepared in a variety of ways, but the above appears to be the best method. The dissociation constants were as follows : V. Pv- m. x. 85 22-66 0-0642 0.0052 170 32.23 0.0913 54 340 45-18 0.1280 55 680 6 1 -42 0.1 740 54 Temp.24.4' ; pm = 352 ; K = 0*0054. Bethmann (vide iafra) gives 0.0054 ; Walden (wide i..fra) 0.0052. a-Ethy Zg Zu t ark A cid, C0,H * CH( C,H,) CH, CH, C0,H.-Th is acid has lately been prepared by Auwers and Titherly (Zoc. cit.) by the hydrolysis of ethyl a-ethylpropanetricarboxylate, (CO,Et),*C(C,H,)*CH,*CH,* C0,Et. I used the same process, and found the boiling point of this ester to be 175-179' (30 mm.), and the melting point of the acid to be 60-61' (Auwers and Titherly give 60.5'). The dissociation constants were as follows :GLUTARZC, ADII'IC', AND PIM ELIC ACIDS. I29 1'. PtI. 112. h7. 44.6 16.86 0.0479 0.0054 89-2 23.99 0.0685 56 178-2 34.04 0.0967 55 356.8 47.03 0.1 336 57 $13 6 63.15 0.1 795 55 Temp.24.2" ; ,urn = 358 ; I<= 0.0056. Pfaff (An9aaZoz, 1S96, 292, 214) gives I<= 0-0058. a-Pro~$gZuta~*ic Acid, CH,* CH,* C: 13,. CH( CO,H) C'H,*C H,* CO,H. - This ncicl, which does not appear to li,zvo been previously described, was obtained in .z similar way to the a-ethyl acid just mentioned. Eth y I a-propylpopc~iae t ricccrboxy Zccte, ( C0,Et),C(C,H7)*C:H,* CH,*CO,Et, was first prepared by treating the sodium compound of ethyl propane- tricarboxylnte with propyl iodide, and the ester, which distils a t 180-1 85" under 38 mm. pressure, was hydrolysed by boiling with hydrochloric acid. a-Propylglutsric acid crystallises by evaporation of the aqueous solution in n vacuum, and melts at 66-68'. On nnalysiq: C,FI,,O, requires C = 55-2 ; H = S.1 per cent.0*1093 gave 0,2234 CO, and 0.0826 H,O. 'I'he dissociation constants were as follows : C== 55.7 ; H = 8.4. 2'. Pll. 772. AT. 62-51 30.20 0.05 75 0.0058 125 .08 28.67 0.0116 58 250.16 40.75 0.1161 61 500.32 55.36 0.1577 59 1000.64 76.07 0,2167 59 Temp. 24.4' ; pm = 35 ; K = 0.00586. a-lsoivro~~~ZyZutca.ic Acid, (C H,),C H*C H( CO,H) CH,*CH,*CO, H.- The acid employed in the following determination was the specimen prepared by Perkin (Trans., 1896, 69, 1495). The dissociation constants mere as follows : It melted at 94". V. P V. ?i2. K. 36.5 15.30 0,0436 0.00548 73 21.85 0.0623 567 146 30.19 0.0860 555 292 41.59 0.1 185 541 584 57.88 0.1649 559 1168 79.25 0.2258 563 Temp., 24.4' ; p a = 351 ; K = 0*00555. VOL, LXXIX. K1.30 MELLOR : SOME a-ALKTL SUBSTITUTION PIiODUC'TS OF ADIPIC ACID AND THE ~-ALKYL-ADJPIC ACIDS.Adipic Acid, CO,H* CH,* CH,* CH,* CH,* CO,H. -According to Markomnikoff (Anncclen, 1898, 302, 34) and Aschan (Ber., 1899, 32, 1771), adipic acid is readily prepared by the oxidation of Russian light petroleum, boiling a t 80-82O, with nitric acid, but it is dificult to obtain Russian light petroleum in this country. The next best way of preparing adipic acid appears to be the following. Trimethylene chlorobromide, CH,Cl*CH,* CH2Sr, is treated with potassium cyanide, and the product converted into y-chlorobntyro- nitrile, CH2C1* CH,* CH,-CN, as described by Gabriel (Ber., 1890, 23, 1771 ; compare Henry, Compt. rend., 1885, 101, 358). This nitrile is then digested with the calculated quantity of the sodium compound of ethyl malonate in the usual way, and the ethyl cyano~roiuylnadonate, CN* CH,* CH,* CH,* CH(CO,Et),, boiling between 170" and 175" under 40 mm.pressure, thus obtained is boiled with dilute sulphuric acid (1 : 2) for 5 hours, and the adipic acid produced is extracted with ebher, and purified by recrystallising once from water. This process not only gives a good yield, but the acid is a t once obtained in a state of purity. a-Methyhdipic Acid, CO,H* CH(C H,)*CH,* CH,* CH2* C0,H.-This acid was first prepared by Bone and Perkin (Trans., 1895, 65, 115), and subsequently by Montemartini (Gaxx., 1896, 26, ii, 278). The acid used in the following determinations was prepared in the following way. Ethyl y-chlorobutyrate, obtained from y-chlorobutyronitrile by the method described by Henry (BdZ.Xoc. Chim., 1885, [ii], 45, 341), was digested with the calculated quantity of the sodium compound of ethyl methylmalonate for 2 hours. After adding water and extracting with ether, an oil was obtained which distilled constantly at 175-178' under 33 mm. pressure, and evidently consisted of ethyl a-methyl- butanetricarboxylate. This, on hydrolysis with concentrated hydro- chloric acid, yielded a-methyladipic acid melting at 63' (Perkin and Bone give the melting point as 64'). The dissociation constants were as follows : V. PV. ,In. k. 54-31 15.84 0.0450 0.0039 108.62 22-46 0.0638 40 217.24 31.72 0.0901 41 434.48 44.86 0.1275 43 868.96 62.56 0.1780 44 Temp. 24.4' ; pa, = 352 ; K = 0,0041. a-Etlt,?/Zudipic Acid, CO,H* CH(C,H,).CH,-CH,*CH,*CO,H.-ThisGLUTARIC, ADIPIC, AND PIMELIC ACIDS, 131 acid has already been obtained by Lean and Lees (Trans., 1897, 71, 1067), and by Montemartini (Be).., 1896, 29, 11 15). The specimen used in thofollowjng experiments wmpreparedfrom ethyl a-ethylbutanetricarboxyla te, (CO,Et),C( C,H,) *CH;CH;CH;CO,Et, boiling a t 180-183' under 28 mm. pressure, by hydrolysis with boiling hg'drochloric acid and elimination of carbon dioxide. a-Ethyl- adipic acid melts at 48". The dissociation constants were ns follows : .a. PiJ. 112. lz. 47 O2 15 *08 0,0429 0-0041 9 4.4 20.66 0,0589 39 188.8 30 20 0.0866 43 377.6 40.63 0.1158 40 755.2 57.57 0.1640 43 Temp. 24.2"; pa = 351 j K = 0.00415. a-Propy Zcdipic Acid, CO,H* CH( C,H7) CH,. CH,* CH,* C0,H.-This acid, which has not been previously described, was prepared in a similar way to the corresponding a-ethyl acid, namely, by the hydro- lysis of ethyl a-pro~yZbutaizet,,icccl.bo~~Zate and elimination of carbon dioxide.The last-named ester boils a t 200-205' under 30 mm. pressure. The acid, which melted not quite sharply a t 55-59", was analysed with the following results : 0.1293 gave 0.2736 CO, and 0.1005 H,O. The dissociation constants were as follows : C = 57.6 ; H = 8.6. C,HI,O, requires C = 57.4 ; H = 8.5 per cent. v. PS. .,n . K. 38.51 13.31 0.0380 0-0039 77.03 19.12 0.0546 41 154.04 37.35 0.0810 43 305.08 38.07 0.1 088 43 601.16 52.53 0,1501 43 Temp. 24.4'; pa =350; K=0.0042. WALKYL-PIMELIU ACIDS. a-MethyZpimeZic Acid, CO,H*CH(CH,) [CH,],*CH2*C0,H.-This acid has already been prepared by Zelinsky and Generowsow (Bey., 1896, 29, 729), and by Einhorn (Annalen, 1897, 295, 175).It melts at 57 -58". The determinations of the dissociation constant by Zelinsky and Generowsow gave the value K= 0.00315. a-EtJqZpimeZk Acid, C0,H*CH(C,H,)*[CH,],*CH2*C0,H.-This acid has already been obtained by Crosslcy and Perkin (Zoc. cit.), and is described by them as an oil. 1 have somewhat modified their132 MELLOR : SOME a-ALKYL SUBSTlTUTION PRODUCTS OF method of preparation in the hope of obtaining the acid in a crys- talline condition, but without success. If 1 gram-molecule of trimethylene chlorobromide is treated with 1 gram-molecule of the sodium compound of ethyl rnalonate in the usual way, R 22 per cent. yield of ethyl o-chloropropylethylmnlonate is produced (Crossley and Perkin, Zoc.cit., 991), distilling at 145" under 18 mm. pressure. When this chloro-ester is heated with a large excess of concentrated hydrochloric acid ,(sp. gr. 1-16) for 6 hours on a sand-bath, and the product extracted with ether in the usual way, 6-chlorovaleric acid, CH,C1*CH,*CH,*CH,*C02H, is obtained as an oil. This, on esterification with alcohol and hydrogen chloride, yields ethyl S-chZoi.ovuZerate, C H,Cl*CH,*CH,*CH,*CO,Et, as a colour- less oil, boiling a t 120-125' under 40 mm. pressure. This ester was analysed with the following result : 0.1846 gave 0.1627 AgC1. Cl= 21.8. C7Hl,0,C1 requires C1= 21 5 per cent. The chloro-ester was digested in alcoholic solution with the calcu- lated quantity of the sodium compound of ethyl ethylmalonate, water was then added, and the oily product extracted with ether, the etherettl solution washed with water, dried over calcium chloride, and evaporated, The residual oil was purified by fractional distilla- tion under reduced pressure.I n this way, e t l q l etlql'pentanzetricarh- oxglcbte, (C0,Et)2C(C2H,)*[CH,],*CH,*C0,Et, was obtained as a colour- less oil boiling at 189-191' under 20 mm. pressure. On analysis : 0.2055 gave 0.4528 CO, and 0.1658 H,O. Cl,H,80, requires C = 60.8 ; H = 8.8 per cent;. On hydrolysing this ester with hydrochloric acid in the usual way, a-ethylpimelic acid was obtained as a thick oil which even on stand- ing for 3 months in a vacuum over sulphuric acid showed no signs of cry stallisation. No determinations of the dissociation constants were made, since the acid was not considered pure enough for the purpose. C = 60.1 ; H = 8.9.THE DISSOCIATION CONSTANTS. T. have collected, in the table on p. 133, the known dissociation constants for the a-alkyl-succinic, -glutaric, -adipic, and -pimelic acids. The numbers for the succinic acids are from Bethmann's (Zed. phys- ikaZ. Chew,., 1890, 5, 413), and Wslden's (ibid., 1892, 8, 433) papers, those for glutaric acid and adipic acid from Ostwald's paper (ibid., 1889, 3, 170, 241, 369). The value for pirnelic acid is the mean of those prepared by different methods given in Walden's paper, and isGLUTARIC, ADIPIC, AND PIMELIC ACIDS. 133 Adipic acid. a-Alkyl radicle. Pirnelic acid. ~~ Parent acid.. ...................Methyl ........................ Ethyl ........................... Propyl .......................... dsoPropy1.. ...................... isoButyl ........................ Ally1 ........................... (Benzoyl) ..................... 0.0037 09041 0’00415 0.00423 - Succinic acid. 0.0068 0.0085 0.0086 0.0089 0.0075 0.0088 0.0109 0.0091 0.0035 0‘0031 - - - Glutaric acid. 0’0047 0’0054 0’0056 0.0059 0.0055 - - - I identical for that of synthetical pimelic acid prepared by Perkin’s process (Trans., 1887, 51, 241). The chief point of interest lies in the fact that, although the avidity of succinic, glutaric, and adipic acids increases when hydrogen is replaced by an a-alkyl group, yet the effect with pimelic acid appears fo be the converse of this. For example, the differences between the values of this constant for these acids and their respective a-methyl derivatives are as follows :- Methylsuccinic acid - succinic acid ...........+ 0*0017 + 0*0007 Methyladipic acid - adipic acid.. ................ + 0.0004 - 0.0004 Methylglutaric acid - glutaric acid ............ Methylpimelic acid - pimelic acid.. ............. 30 40 50 60 70 80 Dissociation constant, K x lo4. The effect of the substitution thus appears to become less marked as the distance between the carboxyl groups increases. These facts may be shown graphically by plotting the number of carbon atoms VOL. LXXIX. 1,134 CHAPMAN : SANTALENIC ACID. in the introduced methyl, ethyl, or propyl group, against the value of R X 104. The curves on page 133 indicate : (1) The effect of the substitution is greater the heavier the alkyl group introduced, (2) With succinic, adipic, and pimelic acids the effect of the substitution is less marked the further the carboxyl groups are apart, as is evident from the gradual flattening of the curves from succinic t o adipic acid. (3) The reversal in the direction of the slope of the curve in the case of pimelic acid and its methyl derivative seems to indicate that in the suberic, azelaic, and sebacic series a still greater reversal will be observed when the dissociation constants of the a-alkyl substitu- tion products of these acids have been determined.

ISSN:0368-1645    

DOI:10.1039/CT9017900126

出版商:RSC    

年代:1901

数据来源: RSC

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134 CHAPMAN : SANTALENIC ACID. XI1 I. -San talenic Acid. By ALFRED C. CHAPMAN, F.T.C. A FEW years ago, in conjunction with Mr. H. E. Burgess, I undertook an examination of the hydrocarbon obtained by distilling santalol with phosphoric oxide, chiefly for the purpose of comparing its properties with those of cedrene. In the preliminary note in which the results of this investigation were given (Proc., 1896, 12, 140), reference was incidentally made to the Formation of a crystalline acid by the action of oxidising agents on oil of sandal-wood, for which we suggested the name sccntalenic acid. At that time circumstances compelled me to discontinue the work, but recently I have been able to make a f u r - ther study of the properties of this acid and its salts, as well as of the conditions under which it is most readily formed, with the results detailed in this paper.In my earlier experiments, that fraction of the sandal-wood oil which boiled at 301--306' (corr.) was used, but I soon found that it was much simpler and more economical to work with the oil itself. Of the samples of oil used, which were all of undoubted genuineness, three were specially distilled for me. As the result of numerous experiments made with the object of ascertaining the conditions under which the best yield was obtained, the following procedure was finally adopted. To 20 C.C. of the oil in a large flask an aqueous solution of potassium permanganate containing 50 grams per litre is added in successive quantities of about 20 C.C.CHAPMAN : SANTALENIC ACID.135 a t a time, thecontents of the flask being thoroughly shaken after each addition. At first, the permanganate is rapidly reduced with the de- velopment of a considerable amount of heat, but when about two- thirds of the solution has been used the oxidation proceeds more slowly. After the whole has thus been added, and the reduction is complete, the oxides of manganese are filtered off, and the filtrate is acidified with sulphuric acid. The precipitated santalenic acid, after having been allowed t o stand for a short time, is filtered off, thoroughly washed with cold water, and dried on a porous tile. Working in this manner, an average yield of 20 per cent. was obtained, but it was found that this depended to some extent on the origin of the oil used, as well as on the rate at which the oxidation was allowed to proceed, The air-dried acid is then dissolved i n alcohol, and water added until the point at which precipitation of the acid occurs is nearly reached.On allowing this solution to stand in a cool place for some hours, the santalenic acid crystallises out in large, transparent plates, and may be further purified by a second crystallisation. After drying in a vacuum over sulphuric acid, two different preparations were analysed, with the following results : 0.2010 gave 0.5540 CO, and 0.1695 H,O. C= 75.17 ; H = 9.36. 0.2105 ,, 0.5810 GO, ,, 0.1800 H,O. C=75*28 ; H=9.50. Cl3Hz0O2 requires C = 75.00 ; H = 9.61 per cent. Titration of ths Acid with Xodcb.-Sodium hydroxide (prepared from sodium) containing 0*00506 gram Na per C.C.was run into a solution of the acid in dilute alcohol, phenolphthalein being used as indicator. 0.494 gram of the acid required for neutralisation 11.4 C.C. of soda solution (= 0.0576 gram Na). For a monobasic acid of the formula C13H2002, 0.0546 gram Na would be required. Molecular Weight.-Two determinations by the freezing point method, using acetic acid as solvent, gave the following results : Depression of Weight of acid. Weight of solvent. freezing point. Mol. weight. 0.185 gram. 8.807 grams. 0-41 9' 194 0.388 ,, 8.430 ,, 1*030° 173 These numbers are in fair accordance with the molecular weight corresponding with the formula C,H,,O,, namely, 208. Using benzene as a solvent, much higher numbers were obtained, but it is well known that many organic acids give abnormal results in benzene solution.Santalenic acid crystallises in thin, colourless plates having a bril- liant pearly lustre, is insoluble in water, but dissolves readily in all the ordinary organic solvents. It melts at 76O, boils without decom- position at 189O (corr.) under a pressure of 25 mm., and can be distilled L 2136 CHAPMAN : SANTALENIC ACID. with steam. Santalenic acid is dextrorotatory. A determination of its specific rotatory power in solution in 90 per cent. alcohol gave the following numbers : c = 10 ; l = 2 dcm. ; a, = 3'37' ; t = 20' ; whence [.ID = + 18.05O. The above number is the mean of two closely agreeing observations, working with different specimens of the acid. When solutions of the metallic salts indicated below were added to an aqueous solution of sodium santalenate, the following results were observed : Gopper sulphate ............Nickel sulphate ............ Magnesium sulphate ...... Zinc sulphate ............... Silver nitrate ............... Mercuric chloride ......... Mercurous nitrate ......... Ferric chloride.. ............. A pale blue precipitate. A pale green precipitate. No reaction. A white precipitate. A white, curdy precipitate. A white precipitate. A white, granular precipitate. A buff-coloured, granular precipitate. Sodium Salt.-This salt was prepared by neutralising a solution of the acid in dilute alcohol with caustic soda, and is soluble both in alcohol and in water. 0,649 gave 0.198 Na,SO,. Na = 9.88. C,,H1,02Na requires Na= 10.00 per cent. Potassium 8alt.-Prepared in a similar manner to the sodium salt.It forms a roughly crystalline, deliquescent mass, soluble in alcohol and in water. 0,332 gave 0.117 K2S04. C,,H,,O,K requires K = 15.86 per cent. Ammonium Salt.-The acid dissolves in dilute aqueous ammonia, but on evaporating the solution ammonia is given off and a residue of the acid left. Silver SccZt.-On adding silver nitrate to solutions of any of the fore- going salts, a white, curdy precipitate is formed which is but slightly soluble in water and not greatly affected by light. After being dried i n a vacuum over sulphuric acid, it was analysed with the following result : K = 15.81. 0-208'7 gave 0.0725 Ag. C,,H,,O,Ag requires Ag = 34.29 per cent. Barium Salt.-This salt may be obtained either by adding barium chloride to a strong solution of the sodium or potassium salt, or by Ag= 34-74.CHAPMAN : SANTALENIC ACID.13'7 neutralising a solution of the acid in dilute alcohol with baryta. is very appreciably Roluble in water. It 0,098 gave 0.042 BaSO,. Ba= 25.20. (C,,H,,O,),Ba requires Ba = 24.86 per cent. Strontium 8ccZt.-Prepared in a similar manner to the barium salt. It is more soluble in water and more distinctly crystalline than the latter. 0*101 gave 0.037 SrSO,. Sr= 17.46. (C1,Hl,O,),Sr requires 8r = 17.39 per cent. The calcium, lead, and copper salts were also prepared and analysed (C,,H,,O,),Ca requires Ca= 8.81. (C,,H,,0,)2Pb ?, P b = 33.33. ,, P b = 33.70 ), (C13Hl902) 2cu 9 9 Cu=13*29. ,? C~=13*36 ,, with the following results : Found Ca = 9-10 per cent.Nethyl Ester, C,,H190,*CH,.--Dry hydrogen chloride was passed into a well-cooled solution of the acid in about six times its weight of methyl alcohol. When the gas ceased to be absorbed, the contents of the retort wera poured into water and the excess of hydrochloric acid carefully neutralised with soda. The precipitated methyl santalenate was then extracted with ether, the ethereal solution dried over calcium chloride, and the ether separated by distillation. The methyl ester then remaining was purified by distillation under reduced pressure, almost the whole of it boiling a t 232-234' under 35 mm. It is a colourless, oily liquid, possessing a faint but agreeable smell, and has a sp. gr. 1.0132 at 1 5 O / 1 5 O . It is lsvorotatory, producing a rotation of - 18"13' in a 100 mm.tube at 20'. On analysis, the following results were obtained : 0.166 gave 0.460 CO, and 0.144 H,O. C,,H2,0, requires C = 75.67 ; H = 9.91 per cent. Bromine Derivative.-Santalenic acid was heated with an excess of bromine in chloroform solution for two days under a reflux condenser, hydrogen bromide being liberated in considerable quantity. On dis- tilling off the chloroform, an oily residue was left, which on standing solidified to a crystalline mass. Very great difficulty was experienced in purifying this by crystallisation, owing to its great solubility in almost all the ordinary organic solvents, and to its marked tendency to separate as an oil. From a mixture of benzene and light petroleum, however, small needle-shaped crystals were obtained, but they were undoubtedly still contaminated with some of the bye-products of the bromination process, and attempts to further purify them faiIed. These C = 75-6 ; H = 9.63.138 CROSSLEY : THE INTERACTION OF crystals melted a t 114--115O, and contained Br=40*8 per cent., a dibromosantalenic acid of the formula CI3Hl8O2Br2 requiring BF = 43.7 1 per cent. In the oxidation experiments above described, the filtrates from the santalenic acid on extraction by ether yielded an oily acid liquid having a peculiar and characteristic odour. The silver salt prepared from this, darkened rapidly on exposure to light, and was much more soluble in water than silver santalenate. This acid is now being studied. Acetic acid and carbon dioxide were also produced in small quantities. It seems not improbable that a further study of the derivatives and decomposition products of santalenic acid may throw some light upon the constitution of the so-called santalols which form the chief con- stituents of the oil.

ISSN:0368-1645    

DOI:10.1039/CT9017900134

出版商:RSC    

年代:1901

数据来源: RSC

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138 CROSSLEY : THE INTERACTION OF XIV.-The Interaction of Ethyl Xodiomethylmalonate and Mesityl Oxide. By ARTHUR WILLIAM CBOSSLEY. EXPERIMENTS undertaken with the object of synthesising dihydrocam- phoric acid (Trans., 1898, 73, 5, 23) have already been described by the author (Trans., 1899,75, 771). Although non-success has attended further efforts to prepare this acid, several new and interesting sub- stances have been encountered, and are described in the present com- munication (compare Proc., 1900, 16, go), of which the main object was the preparation of a ketonic acid of the formula CH,*CO* CH,*C(CH,),*CH( CH,)*CO,H. It was then intended to add on the elements of hydrogen cyanide to the ketonic group, ultimately obtaining a substituted adipic acid. Vorlander (Annalen, 1897,294, 317) has shown that several of the substituted dihydroresorcinols undergo hydrolysis, with rupture of the ring, when treated with either barium hydroxide or dilute mineral acids.For example, phenyldihydroresorcinol gives rise to P-phenyl- y-acetobutyric acid when treated in this manner : It seemed possible, therefore, that the ketonic acid just mentioned might be obtained by hydrolysis of trimethyldihydroresorcinol (2 : 6- diketo-3 : 4 : 4-trimethylhexamethylene) :ETHYL SODIOMETHYLMALONATE AND MESITYL OXIDE. 139 This substance may be readily prepared in large quantities by hydrolysing the compound formed by the condensation of ethyl sodio- rnethylmalonate and mesityl oxide : That this substance, I, has the constitution ascribed to it, is proved, not only by its method of formation, but also by the facts that it gives the characteristic reactions of substituted resorcinols, and is converted on oxidat ion with sodium hypo bromit e into up@ trime t h ylglut aric acid : Up to the present, however, it has not been possible to hydrolyse this substance and produce the desired ketonic acid by splitting the ring.It may, for example, be recovered quantitatively after boiling for 16 hours with excess of barium hydroxide. On boiling with dilute sulphuric acid, it appears to suffer some change, and the question of its hydrolysis is still being investigated. Like the dihydroresorcinols already described (Merling, Annalen, 1894, 278, 20 ; Vorlander, ibid., 1897, 294, 309), 2 : 6-diketo-3 : 4 : 4- trimethylhexamethylene behaves in some respects as a diketone, giving, for example, a well-defined dioxime : It may also react as AG-6-hydroxy-2-keto-3 : 4 : 4-trimethyl~exccmethyI- ewe (and this appears to be its most usual form) : when, for example, it yields a silver salt, and this on treatment with ethyl iodide gives an ethyl ether : Towards phosphorus pentachloride, however, it behaves as A2t6-2 : 6-140 CROSSLEY : THE INTERACTION OF dihydroxy-3 : 4 : 4-t~imethyZdihy~~oresorcilnol (formula I), giving rise to h2*'-2 : 6-dichZ0*0-3 : 4 : 4-trimethyldihydrobenxel.Le (formula 11), where both oxygen atoms have been removed as hydroxyl groups. This ' hehaviour is peculiar, as apparently no derivatives of dihydro- resorcinol or substituted dihydroresorcinols have been described in which these compounds react as though they contained two hydroxyl groups.Dihydroresorcinol gives a monoacetyl derivative, but Merling states (Zoc. cit., 23) that he was unable to obtain a diacetyl derivative. On this account, the action of the phosphorus haloids and other reagents towards subs tit u t ed dih ydroresorcinols is being thoroughly investigated. The unsaturated nature of diketotrimethylhexamethylene (hydroxy- ketonic form) is shown by its behaviour towards bromine, when it takes up two atomic proportions forming dibromohydroxyketotrimethyl- hexametiiykne (formula 111.). This is a highly unstable compound, readily losing hydrogen bromide to form l-b9-omo-2 : 6-diketo-3 : 4 : 4-tri- methyMexamethylene (formula IV), from which, conversely, it may be prepared by the direct addition of the elements of hydrogen bromide.CH(CH )-CO (CH3)2C<CH2. asr (OH)>CHBr? 111. When treated with an insufficient amount of sodium hypobromite for complete oxidation, diketotrimethylhexamethylene is converted into a dibromo-derivative t o which the following constitution is assigned : because when treated with potash alone it is converted into app-tri- methylglutaric acid and monobromodiketotrimethylhexamethylene (formula IV), and when oxidised with sodium hypobromite is quanti- tatively changed into aPP-trirnethylglutaric acid and bromoform.ETHYL SODIOMETHYLMALONATE AND MESITYL OXIDE. 141 Ex P E R I YE NTA L. Ethyl 2 : 6-Diketo-3 ; 4 : 4-trimethylhexamethylene-3-carboxyZate, Ethyl methylmalonate was first prepared by pouring ethyl malonate into a solution of 5 per cent.more than the theoretical quantity of sodium in absolute alcohol, cooling the whole, and then gradually add- ing a slight excess of methyl iodide. After working up in the usual manner, the liquid was submitted to careful fractionation, and the portion boiling between 198-200" used in these experiments. As the context shows (see page 142), however, this liquid must have contained considerable quantities of unaltered ethyl malonate. Twenty-three grams of sodium were dissolved in 275 C.C. of absolute alcohol, 185 grams of ethyl methylmalonate added, and after cooling, 98 grams of mesityl oxide. The mixture, which turned a light reddish- brown and became warm, was heated on the water-bath for 10 hours, when water was added, the alcohol evaporated, and the alkaline liquid extracted* twice with ether.On distilling off the ether, 30 grams of a dark red-brown liquid, A, smelling of peppermint were obtained. The whole was then acidified with dilute sulphuric acid, and again extracted with ether, the ethereal solution washed with water, dried over calcium chloride, and the ether evaporated. The residual clear yellow oil (207 grams) set almost immediately to a semi-solid mass which was spread on a porous plate. After drying, it weighed 120 grams, B, and on extracting the porous plate with ether 65 grams of a dark brown, oily liquid, C, were obtained. A. This material has not yet been fully investigated, but, most probably, it consists of condensation products of mesityl oxide.Claisen and Ehrhardt (BeT., 1889,21, 1013) have shown that sodium ethoxide acts on mesityl oxide with production of several complicated condensa- tion products. Probably these compounds are formed during the course of the above reaction, despite the fact that excess of ethyl malonate was always employed for the express purpose of avoiding the presence of free sodium ethoxide. B. This substance was purified by rapid crystallisation from a mix- ture of chloroform and light petroleum (b. p. 40-60°), when it was obtained as a microcrystalline powder melting at 935-94.5' (uncorr.). C,,H1,O, requires C = 63.71 ; H = 7.96 per cent. 0.1172 gave 0.2730 CO, and 0,0842 H20. Unless the alkaline liquid is treated in this manner, the final products are C = 63.53 ; H = 7.98.difficult to obtain in a pure crystalline condition.242 CROSSLEY: THE INTERACTION OF Ethyl diketotrimethylhexamethylenecarboxylate dissolves only slightly in hot water or light petroleum, but is readily soluble in other ordinary organic solvents. When slowly crystallised from a mixture of chloroform and light petroleum, it comes down in large, six-sided prisms, but is most readily obtained pure as described above. The yield (53 per cent. of the theoretical) cannot well be compared with that of the ester obtained by condensing ethyl malonate and mesityl oxide, for it is impossible to say how much unchanged ethyl malona t e was contained in the ethyl methylmalonate employed. The ester may be distilled under diminished pressure with but very slight decomposition, and boils a t 190' under 31 mm.Its aqueous solution is coloured violet-red by addition of ferric chloride. When treated in alcoholic solution with an acetic acid solution of semicarbazide, it yields a semkcw6axone separating from dilute ethyl alcohol in crystalline nodules, melting a t 206' with decomposition and evolution of gas. 0.1594 gave 204 C.C. moist nitrogen a t 14Oand 760 mm. N = 15.06. C1,H,,O,N, requires N = 14-84 per cent. G . This thick, dark-coloured oil showed no signs of solidifying after standing in a vacuum for many weeks, so it was hydrolysed with alcoholic potash, acidified with sulphuric acid, extracted with ether, a,nd the residue left after evaporation of the ether distilled in a vacuum. Two main fractions were obtained, boiling respectively a t 140-1 50' and 170-175O uuder 41 mm.pressure, and a considerable residue re- mained which, on cooling, set to a red resin (compare Trans., 1899, The fracGon boiling at 140-150' under 41 mm. pressure smelt strongly of fatty acids, and on distilling in air separated into two portions, boiling about 118' and 140" respectively and although not further investigated, evidently consisted of acetic and propionic acids, produced by the hydrolysis of unaltered ethyl malonate and ethyl methylmalonate. The fraction 6oiZing at 170-175O under 41 mm. pressure solidified completely, and by repeated crystallisation from a mixture of chloro- form and light petroleum two compounds were isolated melting at 148O (with production of a red film) and 100'. These are the melting points respectively of 2 : 6-diketo-4 : 4-dimethylhexamethylene (di- methyldihydrorssorcinol) and 2 : 6-diketo-3 : 4 : 4-trimethylhexamethylene (see page 1433, the occurrence of the former being due to the preeence of ethyl malonate in the ethyl methylmalonate employed in the conden- sation experiment.as, 773).ETHYL SODIOMETHYLMALONATE AND MESITYL OXIDE. 143 3 ; 6-Diketo-3 : 4 : 4-trimethylhexa~ethylene (2 ; 6-Dihydroxy-3 : 4 : 4-tri- methyldihydroresorcinol), ( CH,),C<CH, CO>CH2. CH(CH,)*CO Onehundredandfifteengramsof ethyl 2 : 6-diketo-3 :4 :4-trimethylhexa- methylene-3-carboxylate were hydrolysed by heating for 12 hours with 170 grams of pure potassium hydroxide dissolved in alcohol. Water was then added, the alcohol evaporated, and the whole acidified with dilute sulphuric acid.A small amount of material separated, which was insoluble in water or ether, but on boiling with water, carbon dioxide was evolved, and diketotrimethylhexamethylene remained, so the substance probably consisted of diketoti*imetl~yZl~examethylenec~rboxyZic acid. The acidified solution was then extracted with ether, &c., when 75 grams (calculated 78) of a solid were obtained, which was purified by crystallisation from a mixture of chloroform and light petroleum (b. p. 40-60°) and analysed : 0.1172 gave 0.3012 CO, and 0.0970 H,O. C=70*08 ; H=9*19. CgH,,O2 requires C = 70.13 ; H = 9-09 per cent. Diketotrimethylhexamethylene is sparingly soluble in water or light petroleum, but dissolves readily in the ordinary organic solvents.It crystallises from the above mixture in radiating clusters of needles melting at 995-100O. When heated in a capillary tube above its melting point, i t does not give rise to a red film like the dimethyl derivative, but at 200-210° evolves gas, becomes light brown in colour, and does not resolidify on cooling. Its aqueous solution has an intensely acid reaction, effervesces with sodium hydrogen carbonate, and gives a violet-red coloration with ferric chloride. The silver salt, C,H,,O,Ag, prepared in the usual manner, is a white, flocculent precipitate almost insoluble in water, 0.2402 gave, on ignition, 0.0990 Ag. The dioxime, C,H,,O,N,, was obtained by adding the calculated quantities of hydroxylamine hydrochloride and sodium hydroxide, dissolved in the smallest possible quantity of water, to an alcoholic solution of the ketone, On standing, the solution became violet and gradually deposited crystals, which were filtered off, treated with animal charcoal, and recrystallised from dilute ethyl alcohol, from which solvent they separate in colourless, four-sided pyramids melting at 167O. It is insoluble in chloroform or benzene, but readily soluble in msthyl or ethyl alcohol on warming.Ag=41.21. C,E,,O,Ag requires Ag = 41 -38 per cent. 0.1994 gave 27 C.C. moist nitrogen at 1 7 O and 760 mm. N= 15.71, C9H,,0,N, requires N = 15.22 per cent.144 CROSSLEY: THE INTERACTION OF heating the dry silver salt suspended in dry ether with the calculated amount of ethyl iodide in a reflux apparatus for 3 hours. The oil obtained by evaporating the filtered ethereal solution did not solidify even after long standing.It was therefore purified by distillation and analysed : 0.1182 gave 0.3127 CO, and 0.1036 H20. The ether is a faintly yellow, thick, oily liquid boiling at 265' under 750 mm. pressure. It is insoluble in cold sodium carbonate solution, and when hydrolysed with alc~holic potassium hydroxide is quantita- tively reconverted into diketotrimethylhexamethylene. C= 72.16 ; H = 9.74. C1,H1,02 requires C = 72.52 ; H = 9-90 per cent. Action of Phosph0ru.v Pentuchloride on. A2le-2 : 6-Dihydvoxy-3 : 4 : 4- trimeth yldih ydroresorcimol, Five grams of the resorcinol were mixed with 14 grams of phosphorus pentachloride. A moderate action at once set in with formation of a yellow solution, which was heated on a water-bath for half an hour to complete the reaction, during which time remarkable colour changes took place.The yellow solution first changed to olive-green, and then successively to brown, green, indigo-blue, nearly black, and finally reddish-brown. The whole was then slowly poured into water and extracted with ether, the ethereal solution washed with water, dried over calcium chloride, and the ether evaporated, when a thick brown liquid was obtained which rapidly deposited crystals. These were drained off,* purified by crystallisation from methyl alcohol, and analysed : 0-1400 gave 0.2914 CO, and 0.0740 H,O. C=56*77; H=5*90. 0.1504 ,, 0.2260 AgC1. C1= 37*17. C,H,,CI, requires C = 56.54 ; H = 6.28 ; C1= 37.17 per cent. A2,6-2 ; 6-Dichloro-3 : 4 : 4-trimethyZdihydro6enze~e, ( CH,),C<g2HAz$XH, thus obtained, is insoluble in water, but very soluble in the cold in benzene, light petroleum, or acetone, and in methyl or ethyl alcohol on warming.From the last-named solvent it crystallises in beautiful, long, flattened, glistening needles melting at 77'. pressure, but its properties have not yet been further examined. * The filtrate from thcse crystals boils undecomposed a t 120-125" under 31 mm.ETHYL SODIOMETEYL~bLONATE AN D MESITYL OXIDE. 145 Act ion of By0 m in e on Dike t ot rime th y lh e xcc meth y h e . To a solution of diketotrimethylhexamethylene in dry chloroform, a solution of bromine in dry chloroform was added in the dark, until the colour of 'the bromine was no longer destroyed, when hydrogen bromide was freely evolved.The whole was placed in a vacuum over potassium hydroxide, when it slowly solidified. After purification by spreading on porous plates and crystallisation from benzene, the sub- stance was analysed : 0.2366 gave 0.1899 AgBr. I-Brorno-2 : 6-diketo-3 ; 4 ; 4-trimet~Lylhexamethylerte, Br = 34.15. C,H,,O,Br requires Br = 34.33 per cent, is insoluble in light petroleum; moderately soluble in hot water or benzene, and very soluble in alcohol, acetone, or ethyl acetate. It crgstallises from benzene in stellar aggregates of colourless, trans- parent, glistening plates melting at 151.5" with decomposition and evolution of gas. When dissolved in dilute aqueous potassium hydr- oxide and treated with sodium amalgam, it is quantitatively reconverted into diketotrimethylhexamethylene melting at looo, and when oxidised with sodium hypobromite it is converted into app trimethylglutaric acid (see p.147). If during the addition of bromine the whole is cooled in ice, comparatively little hydrogen bromide is evolved, and after stand- ing for some time a white, crystalline powder is deposited, which on exposure to air rapidly evolves hydrogen bromide. It mas therefore filtered off by the aid of a pump, washed with light petroleum, dried as rapidly as possible, and the bromine determined : 0.1986 gave 0.2450 AgBr. C9H,,02Br2 requires Br = 50.95 per cent. Additional bromine determinations in separate preparations gave : Br=53-34, 52.21, and 52.95 per cent. The amount of hydrogen bromide evolved on keeping the substance in a vacuum over potassium hydroxide was also determined, but was always in excess of that calculated : 1.8530 lost 0.5266 HBr.HBr = 28.42. 1.8304 ,, 0.5225 HBr. :HBr=28.54. Although the numbers obtained do not agree either with the calcu- Br = 52.41. Calculated loss of HBr = 25-80 per cent.146 ETHYL SODIOMETHYLMALONATE AND MESITYL OXIDE, latsd amount or with one another, they are sufficiently close to point to the fact that this substance is a dibromide formed by the direct addition of two atomic proportions of bromine to the hexamethylene derivative, 1 : 6-Dibromo-6-hpdroxy-2-keto-3 ; 4 ; 4-trimet?~yZhexarnetl~yZene, is a white, crystalline powder melting sharply a t 87-88’. It cannot be obtained pure because it only separates from a solution containing excess of hydrogen bromide, and on attempting to crystallise it from any solvent, hydrogen bromide is evolved, and the above described monobromo-derivative melting at 151 -5’ separates out.It seemed probable, therefore, that this dibromide would be formed by the direct addition of hydrogen bromide t o monobromodiketotrimethylhexa- methylene, which proved to be the case, for if the latter is dissolved in dry chloroform and the solution after cooling in ice is saturated with hydrogen bromide, on standing a crystalline powder separates melting at 87-88O and having identical properties with the above dibromo- derivative. Action, of Sodium Hypobrornite on 2 : 6-Diketo-3 : 4 ; 4-trimethylhexa- met h y lene. Fifty grams of bromine were poured into 300 C.C.of water cooled to O”, and a strong solution of sodium hydroxide was then slowly added until the colour of the bromine had disappeared. A solu- tion of 12 grams of diketotrimethylhexamethylene in sodium hydroxide (14 grams NaOH in 80 C.C. of water) was then poured in and the whole allowed to stand for 24 hours. The solution, after separation from carbon tetrabromide and bromoform, was acidified with hydro- chloric acid, when a copious white precipitate (10 grams) was formed which was collected (filtrate = A), purified by crystallisation from alcohol, and analysed ; 0.1560 gave 0*1883 AgBr. Br = 51.34. 0.1554 ,, 0.1868 AgBr. Br=51*15. 1 ; 1-Dibomo-2 ; 6-diketo-3 ; 4 ; 4-trimethyZhexamethyZene, C9H,,0,Br, requires Br = 51.28 per cent, is readily soluble in cold chloroform, acetone, or ethyl acetate, but less so in hot alcohol, light petroleum, or water.It crystallises from alcohol in well-formed white needles melting a t 112.5’ without any sign of decomposition, and resolidifies at 110’. When boiled with aqueous potassium hydroxide, it dissolves and bromoform separates,THE ATOMlC WEIGHT OF NITROGEN. 147 On acidifying the filtered solution with hydrochloric acid, a white solid separates which was collected (filtrate = B) and purified by crystallisation from benzene, when it was found to melt at 1 5 1 - 5 O with decomposition and evolution of gas, and had properties identical with rnonobromodiketotrimethylhexamethylene (see page 145). A portion of the dibromo-derivative (m. p. 151.5') was then further treated with sodium hypobromite. The res ulting liquid, separated from bromoform, gave no precipitate on acidification with hydrochloric acid, b u t after evaporation and extraction with ether, &c., app-tri- methglglutaric acid melting at 87' was obtained. The filtrates A and B, on evaporation and extraction with ether, gave further quantities of the same glutaric acid. I f when treating the hexamethylene derivative with sodium hypo- bromite the above quantities are slightly varied (the proportions which give the best results are : 80 grams of bromine in 1000 C.C. of water, decolorised with sodium hydroxide ; and 20 grams of diketotrimethyl- hexamethylene in a solution of 30 grams of sodium hydroxide in 150 C.C. of water), then on acidifying with hydrochloric acid no solid separates. On evaporation and extraction with ether, &c., a solid substance is obtained which dissolves completely in water with a very acid reaction, and on saturating the solution with hydrogen chloride, crystallises out in beautiful leaflets melting a t 87-88'. 0.1 109 gave 0.2231 CO, and 0.0802 H,O. C = 54.86 ; H = 8.03. I n order to further compare this substance with the ~Pp-t~ri- wthylglutaric acid described by Perkin and Thorp (Trans., 1899, 75, 65), it was converted into the anhydride and this into the anilic acid, which crystallised from dilute methyl alcohol in stout needle- shaped crystals melting at 150'. C8H,,0, requires C = 55.17 ; H = 8.04 per cent. CHEMICALABORATORY, ST. THOMAS'S HOSPITAL.

ISSN:0368-1645    

DOI:10.1039/CT9017900138

出版商:RSC    

年代:1901

数据来源: RSC

摘要:

THE ATOMlC WEIGHT OF NITROGEN. 147 XV,-Amrnonium Bromide and the Atomic Weight of Nit?-ogen. By ALEXANDER SCOTT. ALTHOUGH the whole of the recent work on the ratio of the atomic weights of hydrogen and oxygen relatively to one another seems to establish that ratio as 1 : 15.88 or 1.0075 : 16, 1 thought it would be not only of great interest, but of the highest importance if this ratio148 SCOTT: AMMONIUM BROMIDE AND TEE could be determined in some manner totally different from any that had been previously attempted and depending in no way on determin- ations of the composition of water. The ideal method was to find some atom or group of atoms which unites with hydrogen and with oxygen to produce compounds of suffi- cient stability for their equivalent weights to be accurately deter- mined.We seem to have this in the three bases-hydrazine, ammonia, and hydroxylamine, which for this purpose may be regarded as having the formula? NH,, NH,, NH,O, hydrazine having one hydrogen atom less and hydroxylamine one oxygen atom more than ammonia. The hydrobromides of these bases seem from their general properties admirably adapted for comparison with one another by determining in each case the equivalent amount of pure silver. Although the preparation and purification of the substances and the necessary careful study of their adaptability for the end in view has occupied rather more than two years, it was not anticipated that any serious difficulty would occur in the case of the central member of the group, ammonium bromide. Nevertheless, such is the case, and the explanation of the discrepancies which exist between the classical work of Stas and my own i? by no means easy.Stas (G%wes, 1,812) gives the ratio of ammonium bromide to silver as 98.032: 107.93, whereas I find only 97.995 : 107.93 ; the corresponding values for ammonium are 18.0’77 and 18-040, and for the atomic weight of nitrogen 14.047 and 14.010. Stas deduced the value above stated from seven experiments on samples of ammonium bromide prepared in different ways and ap- parently always against the same sample of silver. He states (Zoc. cit.,p. 790) “On le sait,le bromure d’ammonium peut Btre volatilis4 sans ddcomposition dans un courant de gaz ammoniac sec. Dans le but de me procurer ce sel B 1’6tat compacte e t partant facile ii peser e t B manier, j’ai essay6 d’avoir recours & cette volatilisation, mais aprhs plusieurs tentatives infructueuses, j’ai dtb oblige d’y re- noncer.Bn effet, & une tempdrature trh-peu supdrieure A sa volatili- sation, il se dissocie, du brome mbme devient parfois libre. On con- state aisbment la presence de ce corps par la coloration de la vapeur du bromure, et par la colorcction enjaune du sel condens:, qui a produit des fumbes lorsqu’on l’a chauffe dans de l’ammoniaque seche.” He further remarks that his bromide, which was brilliantly white and remained so indefinitely at the ordinary temperature under a bell jar over potash, lost its white- ness and became greyish (gi*isdtre) when heated in air at temperatures above looo, that this greyness increased as the salt was heated from 115’ to 180’’ and that the whiteness was only partially restored by heating it in a current of ammonia.The italics are those of Stas himself.ATOMIC WEIGHT O F XITROGEN. 149 All my samples were also brilliantly white and showed no greyness when heated in air t o 180°, although they lost their sparkling white- ness; this was due, however, to a change in the surface of the crystals owing t o the slight sublimation which takes place when the salt, imperfectly dried, is heated to that temperature. No difficulty was experienced in subliming the salt either in a vacuum, in a mixture of ammonia and hydrogen, or in pure ammonia itself, and no trace of yellow coloration was observed in any instance, the condensed .salt being a somewhat horny, translucent mass. The silver employed was prepared from the pure silver of commerce by dissolving it in nitric acid, evaporating the solution to dryness, and fusing the salt for twenty minutes, the fused mass was then dissolved in water, filtered and ,kept gently boiling for several hours with 10 to 15 grams of freshly precipitated silver oxide, the oxides of lead, copper, and iron being thus precipitated and apparently completely removed.After filtration, the solution of silver nitrate thus purified was added in small quantities at a time to a solution of equivalent quantities of ammonium formate and acetate sufficient t o reduce rather more than the total silver nitrate added. The solution of ammonium formate and acetate was made by distilling pure formic and pure acetic acids into a solution of ammonia (which had been prepared by passing well washed ammonia into pure redistilled water in a porcelain beaker) until the solution was strongly acid ; everything of a nature not very easily volatile was thus completely excluded from the reducing agent.It was suitably diluted and raised to the boiling point i n a flask of special non-attackable glass and the silver nifrate solution added. The reaction which takes place is : HCO,NH, + 2AgN0, = NH,NO, + HNO, + 2Ag + CO, = NH,NO, + CH,*CO,H, the use of the ammonium acetate being merely to exchange the liberated nitric for acetic acid. After being thoroughly washed and dried, the silver was fused with a little pure sodium and potassium carbonates along with a little nitre, granulated, and the above process repeated, the reprecipitated and thoroughly washed silver being raised t o a low red heat in a muffle and kept in the easily divided form thus obtained.Only two or three milligrams of ferric oxide were separated by the second treatment from a kilogram of silver. This silver was notably better than a sample prepared with the utmost care by the cuprous ammonium sulphite method so much employed for the purification of silver. The hydrobromic acid employed was made in two ways : (1) by dis- tilling potassium bromide with somewhat diluted sulphuric acid and frequent redistillation (Squibb’s process), and (2) by the reduction of and CH,*CO,NH, + HNO, VOL. LXXIX. M150 SCOTT : AMMONIUM BROMIDE AND THE bromine to hydrobromic acid by means of sulphurous acid, as IZ have described (Trans., 1900, 77, 649).The ammonia was also from two soiirces : (1) from ammonium sul- phnte drastically treated with nitric and sulphuric acids, and (2) from potassium nitrite reduced by means of zinc which had been fused with lead oxide. In both cases, all the precautions given by Stas were rigorously adhered to and in some cases even exceeded. The balance chiefly employed in the weighings was an excellent one by Bunge and the weights were of platinium-iridium made by Messrs. Johnson, Matthey & Co. and adjusted with great accuracy by Oertling. The silver, after being heated over a spirit burner in pure hydrogen and weighed, was dissolved in a carefully stoppered bottle in pure nitric acid (sp. gr. 1-42), the bottle standing on the water-bath for an hour.After complete cooling, the pressure inside the bottle was almost always considerably less than that of the atmosphere, so that water could be drawn in when the stopper was carefully removed and all possible loss of silver thus avoided, The silver nitrate solution was then diluted and kept on the water- bath until both the solution and the atmosphere above it were quite colourless. The ammonium bromide, heated in almost every case to 180' for some hours in a current of hydrogen which had been bubbled through pure ammonia solution and dried by passing over solid soda and metallic sodium, was weighed after being cooled in a vacuum, then dissolved and added to the silver solution in a room lit with red light only, the whole vigorously shaken, and this shaking frequently repeated, The excess of silver or bromide remaining in solution was determined (usually after two days) by means of standard solutions (which were in all cases weighed).I n the following summary all the weights given are reduced to vacuum weighings, and corrected for all errors in the face values of the weights. To test the effect of sublimation on the salt, the third crop of crystals obtained by evaporating to dryness the mother liquors from the am- monium bromide used in series IV and V below was employed. Obtained in this way, it was likely t o be abnormally acid, and there- fore would tend to give a low equivalent. The atomic weight of silver is taken as 107.93. (a). Not sublimed, dried in hydrogen and ammonia at 180'.4.89631 NH,Br = 5.39380 Ag .*. NH,Br = 97.975. (b). Sublimed once in Sprengel vacuum, but not dried or treated further. 2,45925 NH,Br = 2.70914 Ag :. NH,Br = 97,972.ATOMIC WEIGHT OF NITROGEN. 151 (c), Sublimed twice in Bprengel vacuum, and dried in hydrogen and ammonia a t 180'. 3.29478 NH,Br = 3.62928 Ag .*. NH,Br = 97.982, (d). Sublimed in hydrogen and ammonia and heated in the same a t 180° for some hours. 4.46957 NH,Br = 4,92273 Ag :. NH,Br = 97.994. (a), (b), and ( c ) show by their low equivalents that they were dis- tinctly acid, which acidity was only overcome by sublimation in a strongly ammoniacal atmosphere. The other samples of aiumonium bromide were crystallised from alkaline solutions. The solutions of the dried bromide, like those of Stas, were all strongly acid to litmus.Hydrobromic acid from potassium bromide. I. Ammonia from ammonium sulyhate. Silver reduced by formate. (a). 4.20661 NH,Br = 4.63303 Ag .*. NH,Br = 97.996. (b). 4.23664 NH,Br = 4.66644 Ag :. NH,Br = 97-989. Silver reduced by formate. (a), 4.31464 NH,Br = 4.75175 Ag .*. NH,Br = 98.001. (b). 6.19233 NH,Br = 6.82047 Ag .'. NH,Br = 97.990. 11. Ammonia from potassium nitrite. Hydrobromic acid from potassium bromide. 111. Same ammonium bromide as in I. Silver reduced by cuprous ammonium sulphite. 8,77664 NH,Br = 9,66788 Ag .*. NH,Br = 97,981. This silver was found to contain 0.0018 gram of ferric oxide, hence the true equivalent weights are : 8.77664 NH,Br = 9.66608 Ag .*. NH,Br = 97.999. IV. Ammonia from ammonium sulphate. Hydrobromic acid from pure bromine.First crop of crystals. Silver reduced by formate unfilsad. (8). 10.47233 NH,Br = 11.53416 Ag ... NH,Br = 97.994. Same, but the silver fused on pure calcium phosphate cupel. (b). 4.91997 NH,Br = 5.41834 Ag .*. NH,Br = 98.0028. V. Ammonia from ammonium sulphate. Hydrobromic acid from pure bromine, Second crop of crystals. Silver reduced by formate. The ammonium bromide was sublimed in a current of pure ammonia, and allowed to cool for 4 hours in it at the atmospheric pressure, then left in a vacuum for 36 hours over sulphuric acid. It was then divided M 2152 SCOTT: AMMONIUM BROMIDE AND THE into two portions, one of which was left 54 hours longer over suIphuric acid in a vacuum, when (a). 5.00442 NH,Br = 5.51164 Ag .*.NH,Br = 97.997. The other portion was dried as usual in hydrogen and ammonia a t 1 SOo, when (b). 5.17914 NH,Br = 5.70390 Ag :. NH,Br = 98.000. VI. In order to test in the severest manner possible the quality of the silver employed, at the suggestion of Professor Dewar I reduced the silver bromide obtained in series IT (a) by pure hydrogen ; one part of this was fused on a pure calcium phosphate cupel by means of a mouth blow-pipe of glass fed by pure hydrogen, and cooled in hydrogen, then thoroughly cleaned by treatment first with pure hydrochloric acid and then with ammonia, and heated for some time in hydrogen. When compared with the ammonium bromide of series IV, it was found : (a). 4.84099 NH4Br = 5.33177 Ag .'. NH,Br = 97.995. The other portion was fused on a cupel of pure lime made as Richards recommends by igniting a mixture of 3 parts of pure lime and 1 part of pure calcium nitrate, and treated as above.It was weighed and then heated for nearly an hour in a Sprengel vacuum at the boiling point of sulphur, and afterwards to as high a temperature as the combustion tube would stand, and cooled in the vacuum. Its weight was unchanged, and no gas was extracted from it. (b). 5.10677 NH4Br = 5-62515 Ag .*. NH,Br = 97.984. This seems to corroborate the statement of Stas that the silver fused on calcium phosphate is purer than that fused on pure calcium oxide. It also looked more brillimt, although the dulness of that fused on the lime was due partly to a small quantity of lime dust floating on the surface. The silver bromide precipitated was collected after several of tho titrations, in order to detei.mine whether the silver and the brorniae were strictly comparable with those of Stas.To ensure the whole of the silver being precipitated, a few drops of pure hydrobromic acid were always added. The silver bromide was collected in a porcelain Gooch crucible on a filter of the finest asbestos, which had been very care- fully purified by means of sulphuric and nitric acids. It was then heated to lSOo, and after an hour or so at this temperature was dried perfectly, even with the largest quantities collected. Fusion of the bromide resulted in the loss of a few tenths of a milligram only, which by blank experiments was shown to be due to the asbestosATOMIC WEIGHT OF NITROGEN.153 filter. No difficulty was encountered in getting both the crucible and filter, and these together with the silver bromide and chloride, to give weights constant to one-tenth of a milligram. The whole of the filtrate was evaporated to dryness in each case to see if any foreign matter could be detected, or if any silver bromide had passed through. In only one case was anything weighable found, and that was in the case of the silver reduced by means of cuprous ammonium sulphite (series 111) when 0*0018 gram of ferric oxide was obtained. The weights of silver bromide are obviously more likely to be too low than too high from experimental errors. 11. (b) 6,82315 Ag gave 11.87733 AgBr. :. 100 Ag = 174,074 AgBr. Stas found 174.080. 111. 9,66809 Ag gave 16.132816 AgBr.corr. for Fe,O, 174.090. :. 100 Ag = 174.059 AgBr. (b) 5.41906 Ag gave 9.43315 AgBr. .*. 100 Ag = 174-0735 AgBr. (a) 5.51258 Ag gave 9.59596 AgBr. :. 100 Ag = 174.074 AgBr. (b) 5.70686 Ag gave 9.93346 AgBr. :. 100 Ag = 174.062 AgBr. (a) 5.33191 Ag gave 9.28093 AgBr. :. 100 Ag = 174.064 AgBr. (b) 5.62572 Ag gave 9-79254 AgBr. .*. 100 Ag = 174.067 AgBr. IV. V. VI. A further interesting corroboration of the value found above for ammonium bromide as it involves different samples of ammonia, hydrobromic acid, and silver, as well as personal equation, is that in August, 1882, Mr. C. T. Heycock and the author prepared ammonium bromide which was titrated as above against silver prepared by the cuprous ammonium sulphite method, the titration being done by Mr. Heycock.The mean of two experiments in each of which over 7 grams were used was 97.993. As Mr. Heycock was working at the time on the atomic weight of rubidium, and along with Professor Dewar I was working at the atomic weight of manganese, our object in then preparing ammonium bromide was to have a salt which we thought could be prepared easily at any time and used as a standard substance to determine the purity of any sample either of hydrobromic acid or of silver, but as our154 THE ATOMIC WEIGHT OF NITROGEN, value differed from that of Stas, only these two determinations were made, and the salt condemned as unsuitable for our purpose. Two determinations mere made with ammonium chloride ; the ammonia was from the purified ammonium sulphnte used in the ex- periments on the bromide, and the hydrochloric acid was the pure acid of commerce diluted till just under constant boiling point strength and boiled gently for some hours, a few crystals of potassium chlorate being added a t intervals, all chlorine and chlorine oxides were then expelled by boiling, and the acid distilled first through a glass and then through a platinum condenser.(a). 4.78257 NH,CI = 9-64484 Ag .'. NH,CI = 530519. (b). 5,51744 NH,Cl = 11.12810 Ag :. NH,CI = 53.513, The silver chloride was collected from (a) when with the standard ammonium chloride solution added, it was found that 4.7850 NH,Cl gave 12.82048 AgCI. which is the mean of the two titration values. Stas is 53.532. If AgCl = 143.387 then NH,Cl = 5305165, The value given by The situation may be thus summed up : The values obtained by Stas for the equivalents of ammonium bromide and chloride are 98.032 and 53532, whereas mine are 97.995 and 53,516 respectively.That is to say, my results are in the first case 1/2650, and in the second 1/3350 lower than those of Stas, so that if I admit 113000 impurity in my silver this would explain the discrepancy, especially as the value for ammonium and therefore for the atomic weight of nitrogen deduced by Stas from the bromide and from the chloride agree so well : (1 8.075 from the chloride), (18.077 ,, bromide), whilst my values for ammonium do not, but are 18.040 from the bromide and 18.059 from the chloride. But my silver and my bromine agree exactly with those of Stas as shown by the weight of silver bromide produced from a given weight of silver.Moreover, the ammonium bromide of Stas seems to have contained some foreign matter, most probably platinum, in vessels of which he largely made his preparations. I found that I could use platinum vessels for hydrochloric acid and chlorides but not for hgdro- bromio acid, as the latter attacks platinum when warmed in presence of air in vessels of this material. The value for ammonium chloride calculated from the data given by Marigaac (Bibl. Crniv. Geneve, 1843, 46, 367) is 53.486, but I haveTHE NITRATION OF THE TEREE TOLUENEAZOPHENOLS. 155 been unable to find how he purified his silver ; but i t is obvious that it must have been very pure, as he found that 100 parts of silver were equivalent to 110,343 of potassium bromide, whilst Stas found (as the mean of 14 experiments) 110.345. A further proof of the purity of my silver is given in the paper on the preparation of pure hydrobromic acid above referred to, where my value for this ratio is shown to be 110.349. I gave some of my silver t o Sir W. Crookes when I had no reasons for suspecting any impurity, and he informed me that it was the purest silver he had ever tested spectroscopically, giving fewer lines than a specimen which he had until then regarded as pure, but which on comparison with mine was shown t o contain traces of copper. Every titration performed has been given above as well as every gravimetric determination with the exception of two in which some of the precipitated silver salt was unfortunately lost during transference from the bottle to the filter, these being the silver bromide in IV (a) and the silver chloride in (b). No two determinations were made in exactly the same way throughout, even with those in the same series, but the extreme values differ very little and in no case has any value approached that of Stas. It is obvious that further determinations of ammonium chloride and also some of ammonium iodide must be made in order to clear up the discrepancies indicated above. Until this has been done it would be premature to discuss the value for the atomic weight of nitrogen as deduced from the equivalent weights of ammonium haloid salts. DAVY FARADAY RESEARCH L-4BORATORY OF THE ROYAL INSTITUTION.

ISSN:0368-1645    

DOI:10.1039/CT9017900147

出版商:RSC    

年代:1901

数据来源: RSC

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THE NITRATION OF THE TEREE TOLUENEAZOPHENOLS. 155 XVL-The Nitration o,f the Three Tolueneaxophenols. By JOHN THEODORE HEWITT and JAMES HENRY LINDFIELD. EXPERIMENTS which have been made on the nitration of benzeneazo- phenol with dilute nitric acid (Hewitt, Trans., 1900, 77, 49) and with the strong acid in sulphuric acid solution (Noelting, Ber., 1887, 20, 2997) lead to the conclusion that in the former case the substance reacts a6 a phenolic compound, whereas under the latter conditions its behaviour coincides with that which might be expected from a phenyl- hydrazone of quinone. More recently it has been shown that benzene- azosalicglic acid is quite analogous in its interactions with nitric acid, benzeneazo-o-nitrosalicylic acid being obtained on nitration with warm156 HEWITT AND LINDFIELD : THE NITRATION OF THE dilute nitric acid, and p-nitrobenzeneazosalicylic acid on nitration with a mixture of concentrated nitric and sulphuric acids (Hewitt and Fox, Trans., 1901, 79, 49).I n order to obtain further evidence of the generality of this reaction, the three isomeric tolueneazophenols have been nitrated with dilute acid and compared with the substances obtained by coupling toluene- diazonium salts with nitrophenol. I n each case, identical products were obtained, but as in the case of benzeneazo-o-nitrophenol, far better yields were obtained by nitrating the oxyazo-compounds than by coupling the diazotised bases with o-nitrophenol. o-5!'oZzleneaxo-o-nnitrophenoZ, CH,* C,H,*N:N*C,H3( NO,)*OK [CH, : N,: NO, : OH=2' : 1 : 3 : 41. -A.solution of 10.7 grams of o-toluidine in 30 gritrrs of concentrated hydrochloric acid and 30 grams of water mas thoroughly cooled ex- ternally with ice and salt and diazotised with 7.1 grams of sodium nitrite (97 per cent.) dissolved in 15 C.C. of water. The diazotised solution was added to 13.9 grams cjf o-nitrophenol in 100 C.C. of well- cooled methylated spirit containing 27 grams of powdered crystallised sodium acetate. The mixture was allowed to stand overnight and then the alcohol and unattacked o-nitrophenol were removed in a current of steam. The azonitrophenol was extracted from the tarry residue by ammonia, precipitated by hydrochloric acid and recrys- tallised from glacial acetic acid. The same substance was also obtained in good yield by gently warm- ing 10 grams of finely-powdered o-tolueneazophenol with a mixture of 20 C.C.of nitric acid (sp. gr. 1-36) and 60 C.C. of water. The reaction set in at about 40°, the thermometer then rapidly rising to 50'; water was added to reduce the temperature to below 40' and the mixture left for half an hour. The precipitate was collected, washed, and twice recrystallised from glacial acetic acid. The corrected melting point of the substance is 146O; a mixture of the two preparations showed no depression of melting point. 0.2560 gave 36.4 C.C. moist nitrogen at 1 5 O and 765 mm. N = 16.7. C13H,,0,N3 requires N = 16.3 per cent. The substance is very soluble in acetone or chloroform, fairly SO in acetic acid, benzene, carbon disulphide, or ethyl acetate, but only sparingly so in alcohol or light petroleum.The ace@ derivative, obtained by heating the azophenol (1 part) with fused sodium acetate (1 part) and acetic anhydride (24 parts) on the water-bath, forms golden-yellow needles after it has been recrys- tallised from acetic acid. N= 13.6. The yield was extremely small. 0.1380 gave 17.1 C.C. moist nitrogen at 26' and 754 mm. C1,H,,O,N, requires N = 14.1 per cent.THREE TOLUENEAZOPHENOLS. 157 The substance melts a t 108" and dissolves very easily in non- hydroxylic solvents with the exception of light petroleum. The benxoyl derivative, obtained by boiling the substance gently with an equal weight of benzoyl chloride for 1 hour, forms red, prismatic crystals on recrystallisation from benzene. It melted a t 1 18', soften- ing having previously taken place at about 105'.0.1300 gave 13.8 C.C. moist nitrogen at 22' and 760 mm. I n non-hydroxylic solvents, except light petrolenm, the substance dissolves easily although to a less extent than the acetate. The ethyl ether is obtained in very poor yield by the usual means. An idea of the incompleteness of the ethylation is furnished by the details of the following experiment. 0.15 gram of sodium was dis- solved in 10 c . ~ . of 98 per cent. ethyl alcohol, 1.7 gram of o-tolueneazo- o-nitrophenol was then added, and after allowing the mixture to stand for several hours to ensure complete conversion into the sodium salt, an excess (2 grams) of ethyl bromide was added. The tube was heated for 3 hours at 100-llO", and, after cooling, the contents were poured into dilute sodium hydroxide solution and the ethyl ether collected, well washed, and recrystallised from spirit.Only 0.17 gram was obtained, and the unattacked azophenol was easily recovered from the alkaline soIution by acidification.* Particular attention has been called to this resistance to alkylation, since the m- and p-tolueneazo-o-nitro- phenols give good yields of the ethyl ethers under similar conditions, N = 15.3. C,,H,,O,N, requires N = 14.7 per cent. N = 12.0. C,oH150,N, requires N = 12.06 per cent. 0.0962 gave 12.9 C.C. moist nitrogen at 21' and 764 mm. The ethyl ether forms orange needles, which melt at 83' ; it is fairly soluble in hot ethyl alcohol. m-5?oZueneaxo-o-nitrophenoZ [CH, : N, : NO, : OH = 3' : 1 : 3 : 41 was obtained by both methods, the two preparations individually and when mixed showing the same melting point.It is very necessary to have the m-tolueneazophenol in a state of purity before nitration, otherwise tarry mixtures are obtained from which the isolation of a pure sub- stance is dificult, although a fair separation may be effected by dissolving the crude preparation in hot dilute ammonia solution, allowing to cool, filtering, and precipitating the azonitrophenol from the filtrate by means of hydrochloric acid. After several recrystal- lisations, the substance separates from glacial acetic acid in nearly black, prismatic crystals melting at 12'7". By recrystallisation from light petroleum to which a little ethyl acetate has been added to increase the solubility, i t can be obtained, however, in fine, yellow * I n the particular experiment described above, 1.1 gram was thus recovered.158 HEWITT AND LINDFIELD: THE NITRATION OF THE needles melting at 128*5O. This alteration of melting point when a different solvent is used is not great, but shows that the removal of the last traces of impurity is no simple matter. 0.1926 gave 26.0 C.C.moist nitrogen at 15O and 760 mm. N = 16.0. Cl3H,,O,N, requires N = 16.3 per cent. Attempts which were made to introduce acetyl or benzoyl groups in place of the hydrogen of the phenolic hydroxyl group proved abortive, although the 0- and p-isomerides acetylate and benzoylate easily and normally. By long-continued boiling with acetic anhydride and fused sodium acetate, or with benzoyl chloride, oily products were obtained which dissolved in alkali.Even when the azophenol was boiled for 10 minutes with four times its weight of benzoyl chloride, and then allowed to stand in the cold for 3 days, it was found that the crystals which had been deposited from the solution consisted of unaltered szophenol. The great resistance to ncylation is remarkable and de- serves further attention ; perhaps future work may give some clue to the cause. Alkylation by means of sodium ethoxide and ethyl bromide is, how- ever, readily effected. The ethyl ether was prepared similarly to that of o-tolueneazo-o-nitro- phenol, and a good yield obtained ; it separates from alcohol in small, brown crystals which melt at 92'. 0.1065 gave 13-4 C.C. moist nitrogen at 17" and 764 mm.N = 14.7. C,,H,,O,N, requires N = 14.7 per cent. p-17oZueneazo.o-nitrophsnol [CH, : N, : NO, : OH = 4' : 1 : 3 : 41 is pro- duced by nitration a t about 40°, and, with care, very nearly theoretical yields may be obtained. In one case, 20 grams of ptolueneazophenol yielded 23 grams of dried, crude nitro-compound, which, after recrys- tallisation from glacial acetic acid, furnished 19 grams of substance melting at 147'. In this case, the constitution of the substacce was also settIed by comparison with a spocimen obtained by coupling benzenediazonium chloride with o-nitrophenol. The substance, which forms brown leaflets, is very soluble in benzene, chloroform, or carbon disulphide, and fairly so in acetic acid, acetone, ethyl alcohol, ether, or ethyl acetate, but almost insoluble in light petroleum.0.1360 gave 0.3035 CO, and 090640 H,O. 0.1248 ,, .17*3 C.C. moist nitrogen a t 15' and 768 mm. N= 16.4. The acetyl derivative, which was obtained in the usual way, crystal- lises from acetic acid in small, brown prisms melting at 94'. 0.1173 gave 14.0 C.C. moist nitrogen at 15' and 7'72 mm. N = 14% C = 60.2 ; H = 5.2. C,,H,,O,N, requires C = 60.6 ; H = 4.3 ; N = 16.3 per cent. C,,Hl,O4N3 requires N = 14.1 per cent.THREE TOLUENEAZOPHENOLS. 159 Benzeneazo-o-nitrophenol . . o-Tolueneazo-o-nitrophenol. p-Tolueneazo-o-nitrophenol. m-Tolueneazo-o-nitrophenol The benxoyl derivative was prepared by boiling the azophenol with three times its weightfof benzoylpchloride for 1 hour. After recrystalli- sation from a large quantity of spirit, the corrected melting point was found to be 129O.0.0829 gave 8.9 C.C. moist nitrogen at 29' and 756 mm. N = 11.6. C20H1,04N3 requires N = 12.06 per cent. The substance, which forms small, yellow plates, is easily soluble in. solvents of non-hydroxylic character, with the usual exception of light petroleum; it is fairly soluble in acetic acid, but, on the other hand, is only sparingly dissolved by alcohols. The ethyl ether was obtained by the usual method; it separated from alcohol as brownish needles melting at 1lSO.j 0.1405 gave 18.2 C.C. moist nitrogen a t 16' and 766 mm. N= 15.1. C,,HI,O,N, requires N = 14.7 per cent. Benxeneaeo-o-nityophenyl ethyl ethey was prepared for purposes of comparison by heating benzeneazo-o-nitrophenol with sodium ethoxide and ethyl bromide. After the usual purification and recrystallisation from spirit, small, brownish needles (frequently arranged in radiating groups) melting a t 93' were obtained ; the yield was good. 0,1168 gave 16.0 C.C. moist nitrogen at 24Oand 753 mm. N = 15%. Cl4HI3O3N3 requires N = 15.5 per cent. The substance dissolves sparingly in cold ethyl alcohol, fairly easily in benzene or carbon disulphide, and readily in acetone. The melting points of the substances described in this paper, and also those of the corresponding derivatives of benzeneazo-o-nitrophenol, are given in the following table : 93" 120.5" 132" ::68 "" 1 83 1 108 118 128 -5 92 1 - 129 147 1 116 - I 94 I Phenol. 1 Ethyl ether. 1 Acetate. 1 Benzoate. I-! I I EAST LONDON TECHNICAL COLLEGE.

ISSN:0368-1645    

DOI:10.1039/CT9017900155

出版商:RSC    

年代:1901

数据来源: RSC

摘要:

160 HEWITT AND PHILLIPS: THE BROMINATION OF XV 11. -The Bromination of o-Uxyazo-compounds and its bearing, on their Constitution, By .JOHN THEODORE HEWITT and HENRY ABLETT PHILLIPS, THE constitution of the o-oxyazo-compounds has for some years been a matter of considerable discussion. These, as well as the p-deriva- tives, were a t the time of their discovery looked upon as hydroxylic compounds, this view being first of all disputed by Liebermann (Bey., 1883, 16, 2929). Zincke and Bindewald’s discovery that phenylhydr- azine reacts with a-naphthaquinone with production of benzeneazo-a- naphthol(Ber., 1884,17,3026), whilst withp-naphthaquinoneasubstance strongly resembling, although not identical with, benzeneazo-/I-naphthol is obtained (Zoc. cit. 3029), led the two latter chemists to look upon p-oxyazo-compounds as true azophenols, but upon the o-oxyazo-com- pounds, however, as hydrazones.The possibility then arose that all the substances hitherto regarded as hydroxyl derivatives of azo- compounds might perhaps be hydrazones of quinones. Reduction of alkyl and acyl derivatives has led to somewhat conflicting state- ments, although, speaking generally, the alkyl derivatives may be regarded as of the true azo-type, that is, they are oxygen ethers both in the ortho- and the para-series (Compare Meldola and Morgan, Trans., 1889,55, 608, 609 ; Witt and Schmidt, Ber., 1892, 25, 1013 ; Jacobson, Annalen, 1895, 287, 97, &c.). Experiments with acyl derivatives have not given such definite results, for whilst in certain cases the scission of these derivatives seems to have been complete and primary amines obtained, from which the conclusion might be drawn that acylation had not taken place with respect to the nitrogen atom, in others acylated amines and aminophenols have been isolated as sole products of the reduc- tion ; for example, the acetyl derivative of benzeneazo-p-cresol yields only acetanilide and amin0.p-cresol (Goldschmidt and Bru- bacher, Ber., 1891, 24, 2301 ; compare Meldola, Phil.Mag,, 1888, 26, 403 ; Meldola and Morgan, Trans., 1889,55 114 ; Meldola and Forster, Trans., 1891, 59, 710 ; Meldola, Hawkins, and Burls, Trans,, 1893, 63, 923 ; Meldola and Hanes, Trans., 1894, 65, 834). Goldschmidt mas indeed inclined to regard the oxyazo-compounds as in all cases quinonehydrazones acylating with respect to a nitrogen atom.The incorrectness of this view was proved by McPherson, who found that as-benzoylphenylhydrazine condenses with benzoquinone to form an isomeride of the benzoyl derivative of benzeneazophenol (Bey., 1895, 28, 2414; Amer. Chem. J., 1899, 22, 364). Since McPherson’s Many attempts have been made to settle this question.0-OXPAZO-COMPOUNDS. 161 compound must be acylated with regard to nitrogen, the substance obtained by the benzoylation of benzeneazophenol must have the constitution C6H5*N : N*C6H4*0 CO*C,H,. The balance of evidence mould seem to be in favour of the acyl as well as the alkyl derivatives being oxygen ethers. Quite recently, however, Mohlau has shown that benzeneazotetramethyldiaminobenz- hydryl-a-naphthol, reacts towards acetic anhydride as if i t were a quinonehydrazone of the constitution its acetyl derivative giving a practically quantitative yield of acet- anilide on reduction (Bey., 1900, 33, 2858).From this fact and the further observation that other p-oxyazo-compounds react readily with tetramethyldiaminobenzhydrol, Mohlau draws the conclusion that the p-derivatives must be represented as quinonehydrazones. In so many instances do compounds undergo change in constitution on alkylation or acylation, that any conclusions drawn from the structure of derivatives must of necessity be doubtful ; oxyazo-com- pounds so easily unite with acids to form additive products of the quinonehydrazone type that the production of a nitrogen ether from an oxyazo-compound might easily take place according to the scheme : NR: N*C,,H,- OH - C6H5'C0>NHR*N: C,,H,:O - c1 C6H,* CO*NR*N:C,,H,:O.On the contrary, the acylation of a quinonehydrazone with regard to oxygen would not be surprising, in fact, it would closely correspond to the conversion of a quinone- hydrazone salt into the azophenol through the intermediate stage of the '' pseudohydrate " (to use Hantzsch's nomenclature), which in the case of pethoxybenzeneazophenol, for instance, can he represented in the following manner (compare Auwers, Ber., 1900, 33, 1302) : C2H50'C6H4>NH2=N:C6H,:0 c1 - C2H50*C6H4*NH*N:CgH4(OH)2 - C2H,0*C,H4*N N*C,H,*OH. It might be expected that physical measurements would give the162 HEWITT AND PElLLIPS: THE BROMINATION OF most trustworthy results in a case of this sort, and Auwers and Orton’s method (Zeit.physikd. Chem., 1896, 21, 355) of determining the molecular weight in non-hydroxylic solvents seemed to give a definite solution to the problem of the constitution of the oxyazo-compounds. Broadly speaking, hydroxylic compounds exhibit association in solu- tions in benzene and naphthalene, hydrazones, on the contrary, do not ; and corresponding to this difference of behaviour, the p-oxyazo-corn- pounds give abnormal, whilst the o-oxyazo-compounds give normal, values when their molecular weights are determined. The conclusion that the ortho-compounds are quinonehydrazones and the para-com- pounds true azophenols agrees well with the insolubility of the former and the ready solubility of the latter in cold dilute alkalis.To obtain chemical evidence in favour of this view, both Auwers and Hewitt (Auwers, Ber., 1900, 33, 1302 ; Hewitt, Trans., 1900, 77, 99 ; Hewitt and Aston, ibid., 712, 810; Hewitt and Fox, this vol., 49 ; Hewitt and Lindfield, ibid., 155) have instituted experiments on the behaviour of oxyazo-compounds with bromine and dilute nitric acid, the conditions chosen being such as to preclude salt formation. I n the case of the poxyazo-compounds, the results obtained were such as were to be expected for true hydroxyl derivatives, and it may be pointed out that in such substitution experiments the group to be detected is not directly attacked but only used to influence the course of substi- tution ; a hydroxyl derivative of azobenzene should be substituted in the phenol nucleus, a quinonephenylhydrazone, on the other hand, in &he benzene nucleus of the phenylhydrazine residue.The results obtained for the p-oxyazo-compounds have been fully in accordance with Auwers’ view that these substances are true hydroxylic compounds in the free state, and it seemed to be an interesting problem to continue the study of the substitution of oxyazo-corn- pounds in the ortho-series. Using benzeneazo-p-cresol as material, it was confidently expected that either the p- or the o-bromobenaene- azo-p-cresol would be obtained on brorninating in glacial acetic acid solution in the presence of sodium acetate. On carrying out an experiment it was found that a monobromo-derivative was indeed produced, which, however, on comparison, immediately proved not to be p-bromobenzeneazo-p-cresol ; on synthesising the corresponding ~-b~~ornobenzeneazo-p-cresol, a substance was obtained which differed from the direct bromination product of the azocresol in no very marked degree with regard to -melting point.As the purity of any 0-bromobenzeneazo-compound must depend on the purity of the 0-bromoaniline diazotised, considerable care must be exercised in the purification of this base. A pure sample of o-bromoaniline having been obtained by a process which will be subsequently described, it mas diazotised and coupled with alkaline p-cresol. A beautiful azo-corn- .0-OXYAZO-COMPOUNDS. 163 pound was obtained which in appearance showed a close resemblance to the product of the bromin;ltion of benzeneazo-p-cresol, but whereas the latter melts at 123O, o-bromobenzeneazo-pcresol melts con- stantly a t 1 1 6 O , and a mixture of the two substances indefinitely atl about 90'.Finally, benzeneazobromo-p-cresol of the constitution C1,H,*N:N*CsH,Br(OH)*C~H, [N, : OH : Br : CH, = 1 : 2 : 3 : 51 was prepared by the coupling of diazotised aniline with o-bromo-p- cresol and found to be identical with the product we had obtained by the action of bromine on the oxyazo-compound. Hence benzeneazo-p-cresol brominates as if it were a true hydroxylic compound, a result which is at variance with the physical results of Auwers and scarcely agrees with the insolubility of the o-oxyazo- compounds in alkalis. Of such behnviour only three explanations seem possible : 1. That the o-oxyaxo-compounds are true hydroxylic derivatives.2. That the o-oxyazo-compounds behave in solution in hydrocarbon solvents as quinonehydrazones, but in acetic acid solution on the contrary are hydroxyl derivatives of azo-compounds. 3. That in solution the two forms are in equilibrium, but the oxyazo-form is so milch more reactive than the quinonehydrazone that only the derivatives of the first form are obtained in appreciable yield. EXPERIMENTAL. Brominatioiz of Benxeneaxo-p-cresol. 5.3 grams of benzeneazo-p-crasol and 5 grams of fused sodium acetate are dissolved in 150 C.C. of glacial acetic acid, and 4 grams of bromine dissolved in 5 C.C. of glacial acetic acid are added gradually from a dropping funnel, the temperature being kept below 12'. The brominated compound separates out, being less soluble than the benzeneazocresol.On warming, the substance passed into solution and separated on cooling in long red needles; these were collected, washed, and dried; the corrected melting point is 123'. If the substance is fractionally crystallised, the separations have the same melting point, showing that only one substance results in any appreciable quantity on the bromination of this o-oxyazo-compound. Synthesis from dicczotised Aniline and 0- Bromo-p-cresol.--l2-5 grams of o-bromo-p-cresol were dissolved in 8 grams of sodium hydroxide and about 100 C.C. of water. 6.2 grams of aniline were dissolved in 14 C.C. of strong hydrochloric acid and about 100 C.C. of water. The latter solution was treated with 4.8 grams of sodium nitrite dissolved in a little water, the solution of the diazonium salt then being added to that of the bromocresol.Coupling took place with considerably greater164 HEWITT AND PHILLIPS: THE BROMINATION OF readiness than has been noticed in the case of o-dibromophenol and o-nitrophenol. After being allowed to stand for 2 hours, the precipitated oxyazo-compound was collected, mashed, and extracted with alcohol. The alcoholic solution was allowed to slowlyevaporate to dryness; a tarry mass, in which groups of crystals mere distributed, was thus obtained. On washing this with cold glacial acetic acid, the tar was dissolved, the crystals being to a certain extent undissolved. The crystals were collected and recrystallised from ether ; the substance was then found to melt at 121'.By dissolving i t in ether with an equal quantity of the substance obtained by the bromination of benzeneazop-creso1, and allowing the solution to gradually cry stallise, brilliant red needles melting sharply at 1 2 3 O were obtained. Hence there is no doubt that the two substances are identical, and that in the bromination of benzeneazo-p-cresol bromine takes up the ortho-position to the hydroxyl group. Benzeneazo-o-bromo-p-cresol is very sparingly soluble in dilute alkalis ; it is very soluble in ether, benzene, or hot glacial acetic acid, and fairly so in alcohol, acetone, or light petroleum. 0*2078 gave 0.1362 AgBr. Br=27*9. CI,H,,0N2Br requires Br = 27.5 per cent. The acetyl derivative, obtained by boiling this compound with three times its weight of acetic anhydride for 2 hours, forms brilliant orange- red needles after recrystallisation from alcohol.0.1572 gave 11.9 C.C. moist nitrogen at 2 3 O and 750 mm. N=8*6. C15Hl,0,N2Br requires N = 8.4 per cent. The substance is very soluble in acetone or benzene, and is taken up fairly readily by alcohol, acetic acid, or light petroleixm. It melts at 8 3 O . The benxoyl derivative was prepared by boiling with an excess of benzoyl chloride. After destruction of the excess of the acid chloride with cold spirit, the substance was collected and recrystallised frcm boiling spirit, from which it separates in small, yellowish-orange needles. 0.1133 gave 6.8 C.C. moist nitrogen at Z O O and 766 mm. N=6*9. C,oH,,02N,Br requires N = 7.1 per cent. This compound, which melts at l l O o , is very soluble in acetone or benzene, fairly so in acetic acid or ether, but only sparingly so in alcohol or light petroleum.0-OXYAZO-COMPOUNDS 165 o-Bromo benzeneaxo-p-cresol.As has been explained in the introductory part of the paper, it was at one time thought that this substance was identical with that ob- tained by the bromination of benzeneazo-p-cresol. The first preparation was made with an ordinary specimen of o-bromoaniline, and separated as minute, orange crystals melting at 113'. Since the substance yielded unsatisfactory acetyl and benzoyl derivatives, it was concluded that the o-bromoaniline used was contaminated with the para-isomeride, and that the o-bromooxyazo-compound was likewise mixed with a small quantity of p-bromo benzeneazo-p-cresol.This supposition proved to be correct, although even when o-bromobenzeneazo-pcresol is obtained in a state of purity it does not melt higher than 116'. As o-bromonitrobenzene is never obtained pure commercially, and as o-bromoaniline is usually somewhat impure, the following process, which furnishes a pure base, has been devised. Commercial o-nitro- bromobenzene is reduced in the usual way with tin and hydrochloric acid, and the base driven over with steam after the solution has been rendered alkaline. The crude o-bromoaniline is collected, and slightly more than a molecular proportion of acetic anhydride added ; the mixture becomes warm, and on dilution with water the acetobromo- anilide is precipitated. This is recrystnllised from alcohol until it shows a constant melting point (99') ; it is then hydrolysed by boiling with aqueous caustic potash, and distilled over in a current of steam.On distillation, the base passes over with a constant boiling point. If this pure base is dissolved in acid, diazotised, and then coupled with alkaline p-cresol, an oxyazo-compound is obtained which crystal- lises from hot acetic acid in the form of brilliant, dark-red needles melting sharply at 116'. A mixture of this substance with about an equal weight of benzeneazo-o-bromoy-cresol melted a t about 90'. 0.1606 gave 14 C.C. moist nitrogen a t 20' and 768 mm. N = 9.9. C13H,,0N2Br requires N = 9.6 per cent. o-Bromobenzeneazo-p-cresol dissolves moderately in ether, benzene, acetone, or acetic acid, but is sparingly soluble in alcohol or light petroleum. The acetyl derivative.-When the pure o-bromobenzeneazo-p-cresol is boiled with acetic anhydride, a well defined compound is obtained, which crystallises in flat, orange-brown needles and melts sharply at 859 0.2959 gave 22.8 C.C.moist nitrogen a t 20' and 762 mm. VOL. LXXIX. N N = 8.8. C,5H,,0,N2Br requires N = 8.4 per cent.166 THE BROMINATION OF 0-OXYAZO-COMPOUNDS. This substance is very soluble in acetone, benzene, or ether, but less so in acetic acid, light petroleum, or alcohol. The benxoyl derivative also crystallises well in small orange plates when prepared from the pure oxyazo-compound ; its solubilities re- semble those of the acetyl derivative. The substance melts a t 106.5'. 0.1166 gave 6.6 C.C. moist nitrogen at 12' and 768 ,mm.N= 6.75. C,,,H,,O2N,Br requires N = 7.1 per cent. m-Bromo benaerteaxo-p-cresol. I t forms small, orange-brown needles which melt at 112' and dissolve readily in acetone or benzene, moderately in acetic acid, ether or light petroleum, and only sparingly in cold alcohol. 0.1482 gave 0.2948 GO, and 0.0506 H,O. C= 54-25 ; H= 3.8. 0.1949 ,,. 0.1248 AgBr. Br= 27.3. C1,IIIION,Br requires C = 53.6 ; H = 3.8 ; Br = 27.5 per cent. These compounds usually give very high values for carbon on analy- sis, no doubt owing to the presence both of halogen and nitrogen. The acetyl derivative forms small, dark reddish-brown crystals melting at 61-62' which are easily soluble in benzene or ether, and moderately so in other solvents. m-Bromobenxeneaxo-p-cresol was prepared in the usual manner. 0.2085 gave 15.8 C.C. moist nitrogen at 20' and 762 mm. N = 8.7. Cl,H130,N2Br requires N = 8.4 per cent. The benxoyl derivative melts at 94' and forms very small, yellow crystals. It dissolves easily in acetone or benzene, moderately in acetic acid or ether, but only sparingly,in alcohol or light petroleum. 0-1220 gave 0,2755 CO, and 0.0406 H20. C= 61.5 ; H=4.0. C,,H,,O,N,Br requires C = 60-6 ; H = 4.0 per cent. p-Bromobenzeneaxop-cresol. This substance forms small, orange leaflets melting at 147'. 0.1894 gave 16.4 C.C. moist nitrogen a t 20'and 766 mm. The acetyl derivative forms small, bright orange crystals melting at It is very soluble in acetone or benzene, and is taken up fairly It dis- solves fairly in most solvents, but only sparingly in light petroleum. N= 9.9. CI,Hl,0N2Br requires N = 9.6 per cent. 1 2 3 O . readily by most other solvents with the exception of light petroleum. N= 8.4. C1,H,,02E2Br requires N = 8.4 per cent. 0.2052 gave 15.2 C.C. moist nitrogen at 20° and 762 mm.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 167 The benneoyl derivative melts at 11 2 O and separates from solution in 0.1585 gave 10.0 C.C. moist nitrogen at 23' and '753 mm. Its solubilities, although less than, resemble those of the acetyl very small crystals. N = 7*2. C,oH,,O,N,Br requires N = 7.1 per cent. derivative. EAST LONDON TECHNICAL COLLEGE.

ISSN:0368-1645    

DOI:10.1039/CT9017900160

出版商:RSC    

年代:1901

数据来源: RSC

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ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 167 XVTII.--The Influence o f Solvents on the Rotation of Optically Active Compounds. I. Influence of Wates., Methyl Alcohol, Ethyl Alcohol, n-Propyl Alcohol, and Glycerol on the Rotation of Ethyl Tartrate. By T. S. PATTERSON. ALTHOUGH a t the present time the results of a considerable number of investigations relative to the influence of solvents on the rotation of optically active compounds are available, they seem insufficient t o allow of the deduction of any satisfactory generalisations. A few theories have been suggested attributing the phenomena observed, for instance, to difference of solubility of the active substance in the various solvents used or to the formation of chemical combinations of active substance and solution, but no one of these can be said to have met with much success.The work already done appears to be neither sufficiently extensive nor sufficiently systematic. Only in the case of the application of the electrolytic dissociation theory to explain the simi- larity of the rotations of dilute aqueous solutions of different salts of the same optically active acid or base, do facts and theory correspond, and this, however satisfactory the correspondence may be, is merely a verification of the dissociation theory; it does not help us at all to understand the general effect of solvents on the rotation of optically active substances. For, supposing that the active ion could be obtained free in two different solvents, it would in all probability not have the same rotation in each.Different solvents would presumably have different effects on active ions just as they have on undissociatedcom- pounds, and it seems also impossible to explain the behaviour of solu- tions of optically active substances by assuming varying degrees of electrolytic dissociation in each. This property of causing electro- lytic dissociation to any considerable extent is only possessed by a few liquids ; in the rest, the physical molecular weight of the solute is the N Z168 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE same as the chemical molecular weight, or it is greater, The question whether the existence of the solute as associated, simple, or dissoci- ated molecules in solution merely depends on some one property of solvents which is developed to a different degree in each, does not yet seem to admit of answer.However that may be, the theory which asserts that variation of rotation and varying degree of association are causally connected with each other has received a certain amount of credence. I n the case of homogeneous compounds, P. F. Frankland (Trans., 1899, 75, 347) has been able to trace a very interesting connection between the abnormal (that is, B priori unexpected) rotations often shown by the lower mem- bers of homologous series of active compounds and their association factor as calculated by I. Traube's method, and several investiga- tions have been undertaken with the object of ascertaining whether a direct connection could be proved between the rotation and associa- tion factors of an optically active substance in solution.The evidence which has thus been collected is unsatisfactory ; i t perhaps does not abso- lutely disprove the possibility of the connection sought for, but i t leaves plenty of room for doubt as to its probability. The whole question of rotation in solution is one still requiring much careful investigation, and it is the object of this paper, as it will be OF succeeding ones, to add at least something to the data on the subject. As the possible connec- tion of association and rotation arises naturally in discussing the ex- periments detailed below, the short criticism of existing work which is necessary is introduced further on (p. 184). Ethyl tartrate has been chosen for investigation for the present, since it can be obtained pure without much difficulty, has a sufficiently high rotation to allow of fairly accurate measurement, and is miscible in all proportions with many organic solvents, so that it is possible t o draw, complete concentration curves, and, finally, has a simple con- stitution which is fairly well understood.The ethyl tartrate used in this investigation was prepared by boiling tartaric acid with ethyl alcohol (in the proportion of 1 molecule to 4) for some hours. The solution was then cooled and saturated with hydrogen chloride at a low temperature. After an interval of about 12 hours, the gas was removed as f a r as possible in a vacuum and further expelled, along with excess of alcohol, by heating on a water-bath at a low pressure. A weight of alcohol equal t o that previously used was then added and the solution again saturated with hydrogen chloride, which was driven off as before.The residual ethyl tartrate was carefully fractionated several times under about 15 mm. pressure until two successive fractions had identical rotations. The observed rotation of the product thus prepared was, from the figures given on p. 198, + 9.244' in II 100 mm. tube, and the specific rota-ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 169 tion, therefore, +7.67". This value agrees well with that found by other investigators who have prepared the est-er in the same manner, as the following figures show : t. UD Perkin" (Trans., 1887, 51, 363) ........................ 20 9-65 Frankland and Patterson (Trans., 1898,73, 188) ... 20 9.31 Frankland and McCrae (Trans., 1898, 73, 310) ......20 9.323 Pictet (Jahresber., 1882, 356) ........................... 20' +9*236O Rodger and Brame (Trans., 1898, '73, 304) ............ 20.1 9.37 The optical behaviour of ethyl tartrate in water, methyl alcohol and ethyl alcohol has already been studied by Landolt (Annslen, 1877, 189, 311), who, however, in his experiments used an ester having a specific rotation of + 8.31' at Z O O and a density 1.1989. That these values do not agree with those of other investigators he assumes to be due to admixture with some inactive impurity, probably alcohol. The following investigation is somewhat more extensive than his, especially with regard to temperature, it being possible from the figures and curves given t o deduce the rotation of ethyl tartrate in each of the solvents dealt with, at any temperature within the limits of the experiments and at! any concentration whatever, with fair accuracy.The instrument used was a Laurent half-shadow polarimeter reading direct to one minute. I t is fitted with a large jacket which for use at higher temperatures is filled with hot water and allowed to cool down slowly, observations being made at intervals as the desired temperatures are reached. For readings at loo", steam is passed through the jacket until the rotation is constant. The liquids t o be examined are contained in tubes differing only slightly from the ordinary form. Fig. 1 shows a t A and B two different forms for the ends. I n A , a short piece of indiarubber tubing is drawn past the end of the tube so as to project a little beyond the disc, over mhich it folds t o some extent.It is then squeezed against the disc by the brass ring, which is screwed to a corresponding metal collar fitting against the glass flange a t the end of the tube. B shows the end of a tube of different form, which was made by Messrs. Schmidt and Haensch, Berlin. The end is flanged as before, but is then ground out so that the disc fits closely into position and flush with the face of the tube. A rubber washer, which has only a very small annular space to cover, is held in position by brass end * Perkin, in the course of his preparation, dissolved the ester in ether, and treated the solution with anhydrous potassiuni carbonate, which seems to have effected some slight purification beyond that accomplished by simple distillation.170 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE pieces.This is a very suitable form but much more troublesome to make than the other. The tubes are also fitted with a lateral tube, C , for filling and to allow of expansion of the liquid on heating. This is constricted a t the distal end, which is ground flat so as to be about 2 inch in dia- meter. When the tube has been filled so that no air bubble can be seen on looking through it, the open end of the side piece is closed with a small microscope cover-glass held in position by a rubber band. A small rubber balloon is then slipped over the side piece. This arrangement is found to prevent evaporation very satisfactorily, the density of the solution and the rotation, as will be observed from the figures given, being, in most cases, almost identical before and after the observations at higher temperatures had been made, even when the heating had been carried up to within ten or fifteen degrees of the boiling point of the solvent.FIG. 1. The rotations are recorded in the order in which they were observed, so that a comparison of the first and last figures will show to what extent evaporation of the solution has affected the experiments. The densities, which are all relative to that of water a t 4O, were determined by means of Ostwald pyknometers of about 8 C.C. capacity. The error of a determination is probably not more than about three or four units in the fourth place. Percentage composition throughout this paper is understood to mean grams of active substance per 100 grams of solution.The expression ‘‘ after experiment ” attached to some of the density data means that the determination was made with the solution taken from the polarimeter tube after the rotation had been observed. The observed rotations are generally given to three places of deci- mals, since two successive determinations, each the mean of ten settings of the instrument, agree usually to within a few units in the thirdROTATION OF OPTICALLY ACTIVE COMPOUNDS. I, 171 place. The specific rotation is, however, only given to two places of decimals, and in many cases the probable error of a figure for specific rotation may be fairly large, although seldom more than 0*1', even with dilute solutions. Nearly all the experimental data in this paper are represented by the curves shown in the different figures, and since these give a corn- prehensive idea of the results very much more quickly and clearly than the numbers themselves, the latter have been collected and placed at the end of the paper, where reference can easily be made to them when necessary.The rotation of ethyl tartrate is known to be very sensitive to change of temperature, but although observations have been recorded a t 100' and at 20' by various observers and between 12' and 20' by Perkin (Trans., 1887, 51, 368), the rotation does not appear to have been examined at temperatures between 20' and looo. The rotation of pure ethyl tartrate a t various temperatures was therefore first determined. The figures obtained will be found on p.198 and the curve obtained from them is shown in Figs. 2,3,4, 5, and 6 (the fiducial points being only introduced, however, in Fig. 2), in order that the rotation of the free substance and its solutions may be easily compared. EthyE Turtrute in Water. Solutions of percentage composition 1, 2.5, 4.999, 9.994, 24.954, 49.993, 74.99, were made up and examined a t various temperatures. The figures obtained will be found onpp. 199-201, and the results are plotted in Fig. 2 as curves which show clearly the behaviour of the rotations of aqueous solutions of ethyl tartrate with regard both to temperature and to concentration, the former being, however, the more obvious. It will be noticed that the curves show a slight amount of irregularity, which is due to the fact that the solutions were heated up first to a comparatively low temperature and the rotation observed, then allowed to cool, and another observation made in order to see whether the heating had produced any permanent effect on the rota- tion of the solution.The heating was then again carried to a higher temperature than before, another observation made, the solution allowed to cool again, and so on. The results show that ethyl tartrate is rather more stable in aqueous solution than might have been expected. A 50 per cent. solution may be hested up to 75', and kept a t that temperature for some time without showing, on cooling, any noticeable change in rotation, and this applies to other solutions as well. Only a very slight decrease is noticeable in the rotation of a 5 per cent.solution even after standing172 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE for fifteen days, although a 10 per cent. solution showed a greater change after standing a shorter time, It is apparent from the curves shown in Fig. 2 that the specific rotation of ethyl tartrate is profoundly modified by solution in water, as was indeed already known from the experiments of Landolt, and from the evidence adduced later on (p. 181) there seems no reason whatever to ascribe this to chemical action of the solvent on the ester. FIG. 2.-Speci$c rotation of aqueous solutions of ethyl tartrate. + 27" + 25 + 23 + 21 +19 2 +17 R 5 +15 + 13 3 u & + 11 + 9 I + 7 * + 5 10" 20" 30" 40" 50" 60" 70" 80" 96" 100" Temperature.The curve for a solution of p = 75 lies considerably above that for the free ester, the specific rotation of the solution a t all temperatures for which the curve holds is greater than that of the pure tartrate, and a t the same time, i t should be carefully noticed, the influence of tempera- ture upon the rotation becomes less marked ; the curve for the solution is flatter than that for the ester. Both these influences are more evident in a p = 50 solution ; the specific rotation is again increased,ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 173 the observed rotation for this solution being actually greater than that caused by the same tube filled with pure ethyl tartrate, and the specific rotation of the solution instead of increasing with increase of tempera- ture, exhibits just the opposite behaviour, diminishing slightly.The specific rotation gradually increases with further dilution up to a com- position of p = 10, when the maximum influence of the solvent appears to be reached, since the value of [a]: is almost identical for solutions of p = 10, 5, 2.5, and 1. A 10 per cent. solution may, apparently, SO far as rotation is concerned, he regarded as one infinitely dilute, and this maximum influence which the water can exert on the ethyl tar- trate molecules dissolved in it, not only increases the rotation of the latter t o between three and four times its original value, but pro- duces such a condition in them that increase of temperature causes a diminution in their rotation t o nearly the same extent that it produces a rise in the rotation of the free ester, the latter effect being quite a s remarkable and interesting as the former.Landolt's experiments seem t o show that the rotation of a solution of ethyl tartrate in water is a linear function of the concentration. This, however, is not borne out by my results, as will be seen by reference to Fig. 8, where, amongst others, the concentration rotation curve for aqueous solutions is shown. The curve is not a straight line, even between p = 25 and p= 100, but is at first concave to the concen- tration axis and then convex to it, having a point of inflection at about p=50. Ethyl Tartrate in Methyl AZcohol. The figures obtained in the examination of solutions of ethyl tar- trate in methyl alcohol for which p = 5,10, 25.01, 56, and 75 will be found on pp.202-204. They are represented graphically in Fig. 3,which shows the variation in specific rotation with change of temperature. The general appearance of the curves is in all eases similar, but they possibly tend to approach one another somewhat a t higher tempera- tures, although only very slightly, and they preserve also practically the same form as that of the homogeneous ester a t any rate up to about 60'. On mixing ethyl tartrate, then, with methyl alcohol, the rotation of the dissolved molecules slowly increases, the influence of the alcohol seeming to reach its maximum when the dilution has been carried to about p = 10, since the curve for a p = 5 solution coincides almost exactly with that of one for which p = 10, though perhaps it is just a little higher." This variation of rotation with concentration can be seen from Fig.8. As the dilution increases the rotation also increases * The ciirve fororp=5 is not shown in the figure, since the fiducial points are apt t o be coufused with those for ap=lO solution.174 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE fo a maximum of about + 1 l o 2 5 O , the influence of methyl alcoh'ol being therefore much less than that of water, but in this case, what- ever change takes place in the molecule on solution, increase of tempera- fure has the same effect as on the free ester, the rotation increases, whilst in water it diminishes. Ethyl Tartmte in Ethyl Alcohol. The solutions examined in the cases of this solvent were of 5, 10.94, The experimental figures will be found 20, 40, and 60-01 per cent.FIG. 3.-Ethyl tartrate in, methyl alcohol. + 14" + 13 + 12 + 11 rz' -$ 2 3 +10 3 & + 9 u +8 + 7 + 6 I 10" 20" 30" 40" 50" 60" Temperature. on pp. 204-206, and are represented graphically in the accompanying diagram, Fig. 4. It is obvious from the curves obtained that the general behaviour of ethyl tartrate in ethyl alcohol is much the same as in methyl alcohol, although the latter has a markedly greater effect. The specific rotation of dilute solutions is slightly higher than that of the homogeneous substance, but as will be seen from the concentra- tion-rotation curve (Fig. S ) , the effect of increasing dilution in thisROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 175 and the previous case is different.Addition of methyl alcohol to ethyl tartrate causes at first a fairly rapid increase in rotation, which be- comes gradually less and less as the dilution increases. Addition of ethyl alcohol, however, causes little or no change in specific rotation until the percentage composition of the solution is about 60. Further addition of alcohol then causes increase of specik rotation, the rate of increase being greater the more dilute the solution becomes. The FIG. 4.-EthyE tartrate in. ethyl alcohol. + 15' I- 14 + 13 -t- 12 z4 s g & s 4-11 s i-10 @ + 9 + 8 +7 + 6 10" 20" 30" 40" 50" 60" 70 80" 90 l'emperattcre. curve obtained is therefore convex to the concentration axis, the maximum effect of the ethyl alcohol being only reached in infinitelr dilute solution.It may be noticed, too, from Fig, 4 that, although the effect of in- crease of temperature on the ethyl alcoholic solutions and on ethyl tartrate is much the same up to about 50°, it appears to be somewhat different at higher temperatures when the influence of increasing temperature has less effect on the pure ester than on its solutions.176 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE Ethyl Tartrate in n-Propyl Alcohol. The n-propyl alcohol which was used in this investigation, although bought as pure, proved to be laxorotatory, but only to so slight an extent that the influence of the impurity is probably completely eliminated by the introduction of a small correction in calculating the specific rotation from the data obtained (see p. 207).2.5, 5, 7.71, FIG. &-Ethyl tartrate in n-propyl alcohol. + 14' + 13 + 12 + 11 i .$ +10 E u u $ 9 & + 8 +7 +6 + 5 10 2G" 30" 40" 50" 60" 70" 80" 90" Temperature. 10, 17.5, 25, 37.51, 49.83, and '74.99 per cent. solutions were examined. The experimental numbers will be found on pp. 208-210, and are repre- sented graphica.lly by the curves in Fig. 5. The curves for four of these solutions are, however, omitted in the diagram, as their intro- duction only tended to cause confusion. The influence of the other solvents examined is t o increase the specific rotation of the dissolved ethyl tartrate, but this effect of the solvent becomes less in passing from water to methyl alcohol and ethylROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 177 alcohol, and in n-propyl alcohol becomes such that at low temperatures fhe rotation is depressed below that of the free ester.The specific rotation of a p = 75 solution is at 20" about, 1.l0 lower than that of pure ethyl tartrate, the addition of alcohol to give a, solution of p = 49.S3 diminishing the specific rotation still more. With further dilution, however, the specific rotation gradually rises again, the curve for p = 25 lying above those for the concentrations just mentioned, so that when p = 5, the specific rotation of the solution is almost as high FIG. 6.--Ei%yl tartrate in glycerol. 4- 14' + 13 + 11 + 10 + G + 5 Temperature. as that of the free ethyl tartrate. The specific rotation of a solution, however, never seems to quite equal that of the pure ester, and at 20" appears to be constant for any concentration less than p = 10, which is apparent from the curve marked "propyl alcohol" in Fig.8. No solution, therefore, of ethyl tartrate in propyl alcohol below 30' has a rotation as great as that of the pure ester; but it should be noticed that since the rate of variation of specific rotation with variation of temperature is distinctly greater in the solutions, and especially in the178 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE more dilute ones, than in the free ester, this does not hold at tempera- tures above about 36O. Another interesting fact to which attention may be drawn i s the existence, for any temperature within the limits of these experiments, of a concentration of minimum rotation. Only a few similar cases are known, and in this one the phenomenon is very distinctly marked.As will be seen from Fig. 8, the minimum value of the specific rotation (+ 6.4') occurs (at 20°) when p=57. For other tempera- tures, the concentration at which it occurs is different, being greater the higher the temperature. Ethyl TuTtruts in Glycerol. The curves in Fig 6 represent the results obtained in the examination of solutions containing 5 , 9.9, 23.45, 48-12, 69-93, and 89.98 per cent. of ethyl tartrate. The curves do not always pass exactly through the experimental points," the irregularity being due to the fact that these experiments were carried out before the others and with apparatus less suitable than was obtained later. It will be noticed in the first place that the specific rotation of ethyl tartrate may suffer considerable variation by mixture of the ester with glycerol, being either greater or less than, or equal to, that of the free ester, according t o the composition and temperature of the solution.The phenomena observed are somewhat similar to those due t o the action of n-propyl alcohol. The addition of about 10 per cent. of glycerol lowers the specific rotation of the ethyl tartrate at 20' by 1.5') another 20 per cent. of glycerol causes a further diminution, after which, however, a rapid increase in rotation takes place with increasing dilution, but the effect of glycerol is different in two respects from that of n-propyl alcohol. Firstly, the specific rotation of dilute solutions is much higher at low temperatures than that of the ester itself, and secondly, owing to the fact that the temperature coeffi- cient is less for dilute solutions than for the pure ester, the tendency is for the specific rotation of all solutions t o sink below that of the free active substance at higher temperatures.It is obvious that here again we meet with a very good example of solutions of minimum rotation, the phenomenon being perhaps more marked in this than in any case previously observed. A number of concentration-rotation curves for different; temperatures are shown in Fig 7, from which it will be seen that the occurrence of the minimum rotation is more pronounced at low temperatures than at higher ones. * This is particularly the case for a p = 5 solution at higher temperatures, and is more obvious in the concentration-rotation curves.The data for these solutions will be found on pp. 211-213.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. x. 179 The difference between the maximum and minimum rotations at 10' is about 6*2O, whilst at 100' it is only 2*5O, so that with increasing temperature the concentration-rotation curve becomes flatter. The position of the minimum, too, seems to shift to a less concentration with rise of temperature. Thus at 10' the minimum specific rotation FIG, 7. --Ethyl tartrate in glycerol. Concentmtion-rotat$on curves. 10 20 30 40 50 60 70 80 90 100 Percentage composition of solution in gram of ethy,? tartrate per 100 grams of solution. is found at p = 70, a t 25' it lies at p = 65, at 50' a t p = 60, a t 75' about p = 55, and at 100' at p = 53.Discwss~oon of Results. Passing now to a general discussion of these results, since water, methyl alcohol, ethyl alcohol, and n-propyl alcohol form part of a homo- logous series, it is natural to seek, in the first place, for some effect on180 PATTERSON: THE INFLUENCE OF SOLVENTS ON TEIE the rotation of ethyl tartrate due to their influence and varying in a gradual manner from one solvent to another. It is only in dilute solution that the maximum influence of the solvent can be exerted, and FIG. 8.-Relationship of specdjic rotation and concentration, and of mo2ecular- solution-volume and Concentration at 20". 10 20 30 40 50 60 70 80 90 100 Concentration. in such-for which p = 10 or less-a gradual variation may be noticed : (1) 1% the value of the speciJc rotation, which decreases as the molecular weight of the solvent increases.ROTATION OF OPTICALLY ACTIVE COMPOUNDS.I. 181 (2j 17% the fawn of the concentration curves, which gradually changes from the concave for water and methyl alcohol to the slightly convex for ethyl alcohol-with the possibility of a concentration of minimum rotation-and the still more convex curve for n-propyl alcohol with a distinct minimum, and, if we include glycerol, to its still more marked minimum and convexity. This is apparent from the curves in Fig. 8. (3) In, the efect of increase of tenzperatuve upon corresponding solutions. In water, the coefficient is negative, in methyl alcohol it is positive, but perhaps a little less than for the pure ester, i n ethyl alcohol it is the same as for the pure ester and for m-propyl alcohol distinctly greater, as is apparent from an examination of Figs.2, 3, 4, and 5. These three regularities then in the behaviour of sollitions of ethyl tartrate in the above solvents may be distinguished ; it remains t o correlate, if possible, the variation in rotation with some other similarly variable physical property of the dissolved substance, the solvent or the solution. The results obtained may first be discussed with regard to existing ideas, the most important of which, as already stated, attributes varia- tion of rotation to varying degrees of association of the molecules of the active substance in the different solutions, The variations of the rotation of ethyl tartrate described above are so considerable that if they be really due to this cause one might expect to trace the con- nection experimentally, and it is noticeable that the rotations stand in the same order as the dissociating power of the solvents used.That the behaviour of aqueous solutions of ethyl tartrate is remark- able is obvious from the description of it on p. 172 ; it shows peculiari- ties which easily suggest the possibility of an exceptional character for such solutions, notably in the remarkably high specific rotation and in the influence of temperature change. It is possible that in aqueous solution ethyl tartrate suffers hydrolysis to ethyl hydrogen tartrate which also has a high rotation (for c=2*252 [aID =21.8 [Fayollat, Compt. rend., 1893, 11'7, 630]), but this is improbable on account of the fact that no permanent change seems to take place in the solutions on heating ; the rotation returns to its original value when the solution cools.The fact that the molecular rotation of a 10 per cent. aqueous solu- tion of ethyl tartrate is +53*82' whilst that of similar solutions of the neutral tartrates is about + 60' suggests the possibility of electro- lytic dissociation in the former as in the latter, and this, could it be proved to occur in ethyl tartrate solutions, might explain, not only their high rotation, but possibly also the anomalous influence of change of temperature as well. If the rotation of dilute aqueous solutions of ethyl tartrate and the neutral tartrates depends on the same thing, VOL. LXXIX. 0182 PATTERSON: THE INFLUEWE OF SOLVENTS ON THE Constant 18'6 0.2594 0.3304 0.5467 0.5940 0.8928 namely, the existence of the free tartaryl ion in solution, both ought to behave alike with regard to change of temperature, and this appears to afford a means of determining whether the two solutions are similarly constituted.I n order to apply this criterion, a p = 13.68 solution of Rochelle salt (equivalent to a p = 10 solution of ethyl tartrate) was made up and examined in the polarimeter at various temperatures. The experi- mental figures will be found on p. 214 and are represented by the curve in Fig 2 marked '(Rochelle salt," It will be seen that the specific rotation of the Rochelle salt, instead of diminishing, increases somewhat* with rise of temperature, the rate of increase, however, becoming less and less at higher temperatures, so that between 60' and 100" it is almost independent of temperature and it must be con- cluded that the conditions in the solutions of this salt and ethyl tartrate are not similar.There remains, however, the possibility of varying degrees of association of the ethyl tartrate in the different solvents used, so in order to ascertain if the complexity of the active substance varies sufficiently with the solvent to account for the rotations observed, the following molecular weight determinations were made. In water, the cryoscopic method was used with these results : 9.0578 11-2638 10 '29 06 10 '4460 9.7404 Calc. mol. wt. = 206. Weight of Weight of substance solvent taken, 1 used. Percentage composition of solution, Grams per 100 grams solution.2-78 2 -85 5 *05 5 -38 8 '40 I 0.265" 0.280 0.495 0,535 0.835 Mean ..... M. 201 194.8 199.5 197.2 204'2 199-3 The molecular weight determinations in methyl, ethyl, and a-propyl alcohol were made ebullioscopically. An apparatus similar (except that it was not graduated for volume measurement) to that recently described by H. N. McCoy (Amer. Chem. J., 1900, 23, 353) with a thermometer reading direct to twentieths of a degree was used. As a preliminary experiment, the molecular weight of thiocarbanilide was determined in methyl alcohol in which 231.7 instead of the calculated value, 228, was found. * This had already been shown by Hadrich.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 183 No. The following are the results : Weight of ethyl tar- trate.I I1 I11 IV v Weight of solvent. 1,1972 1.0654 1'1972 1'7844 i m 4 Percentage composition of solution. Grams sub- stauce per 100 grams solution. I I1 111 IV I I I 1,5225 33-58 ! 2'0650 32.72 ' 2.0650 1-5225 y; 1 Methyl alcohol. Constant 8-8 : I I1 111 IV V VI 1.3161 1.7504 1'6126 1'8143 1.5560 1.7504 33'24 24.37 25.18 25'02 17'16 28-544 22'750 19.808 22'060 17.064 16'060 3-48 4.17 4 *54 6 '66 9 '42 4.34 5'94 6.61 9 '57 4'41 7'14 7 -53 7 -60 8 -36 9 *83 At. 0.144" 0.175 0.168 0.300 0-385 Mean., . 0-245 0'360 0-365 0.555 Mean., , 0.401 0'630 0'660 0'605 0.650 0.755 Mean.. , Mol. wt. 22 0 -1 219'8 249.0 209.2 237.7 227.2 - 216.5 205.1 226.6 223'1 217'8 182.8 194 196.1 216 221 *6 229 -5 206.6 The distillates from the methyl alcohol determinations mere collected and examined in the polarimeter.No rotation could be detected, so that there was probably no volatilisation of ethyl tartrate. It would appear from the above results that, under the conditions of the experiments, ethyl tartrate exists in these solutions in simple molecules, but obviously any comparison of rotations must be made a t the same temperature; it would have little meaning t o compare the rotation of ethyl tartrate in water a t 0" with those in methyl, ethyl, and propyl alcohols at their respective boiling points, and there- fore the question arises whether we may assume that ethyl tartrate in these last three solvents exists in simple molecules at a temperature of, say, 20" as well as at the boiling points, This is, of course, diffi- cult to answer.I n some cases it does appear that the molecular weight of a given substance determined at the freezing point in a par- ficular solvent is greater than that obtained in the same solvent at 0 2184 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE I. Propyl dipropionyltartrate the boiling point, but if at all, is only slightly greater, and therefore the small amount of association which might be assumed to occur in the above cases a t the ordinary temperature scarcely seems to be a suffi- cient cause to which to attribute the great variation in rotation. The experimental evidence which has previously been collected on this subject is somewhat unsatisfactory. It is difficult to review it briefly, but a few figures may be given which seem to show the in- sufficiency of the hypothesis that variation of the rotation of an active substance in different solvents is due t o corresponding variation of association.Freundler (Ann. Chim. Phys., 1895, [vii], 4, 256) has found that, in a number of substances examined by him, when the molecular weight is normal, the rotation is the same or very similar in the free state and in solution, whilst in other cases where the molecular weight is not normal the rotation differs in solution from that of the free active compound. He gives, amongst others, the following examples : Ethylene bromide 346 ~ Active substance, 11. Propyl diacetyltartrate ... y , diphenacetyltartrate 111. Methyl tartrate .............. ,, ............... 2 9 >t Propyl , , ............... Y9 I .Calc.I Benzene Nitrobenzene Acetic acid Benzene Ethylene bromide 9 , 318 470 470 178 234 234 Founc 342 277 378 377 411 306 326 - lolution. +5.4" + 1.2 + 14.6 + 27 -2 - 8.8 + 20.1 - 0.6 Free. + 5 3 " +13'4 + 20.9 + 20-9 +2'14 + 12-44 + 1244 From these figures, Freundler has deduced two '' laws," against which, however, it is not difficult t o bring objections. It should be noticed, for instance, that propyl diphenacetyltartrate is dissociated t o exactly the same extent in nitrobenzene and acetic acid, but whilst in the former solvent the rotation is depressed, in the latter it is raised. Again, propyl tartrate is associated in benzene and in ethyl- ene bromide, the association being accompanied in the former solvent by an increase in rotation of about 60 per cent., and in the latter by a decrease in rotation of over 100 per cent.on that of the free sub- stance. Surely it may be expected that if these variations in mole- cular weight and rotation are connected with each other, the effects of association or dissociation should be, at any rate, consistent. It should be noticed that of the three possibilities, (1) simultaneous normality or abnormality of molecular weight and rotation ; (2) ab- normal molecular weight with normal rotation ; (3) normal molecularROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 185 weight with abnormal rotation ; the last is much the most important. Of these, (1) may indicate, but does not necessarily prove, a causal con- nection between variation of rotation and variation of association ; (2) does not necessarily disprove such a connection ; but (3) if it can be shown that any active substance has normal molecular weight in several different solvents and at the same time very different values for the specific rotation in these solvents, then unless some very good reason can be given to account for this unexpected behaviour, the association hypothesis must be considered disproved. The conditions numbered (3) seem to be met with in the case of ethyl tartrate detailed above, and the following figures taken from a paper by Frankland and Picknrd (Trans,, 1896, 69, 131) appear to furnish another example.Methyl dibenxoylglycerate [ a]1,5" + 26*899 M = 328. ~ ~~~~~ Molecular weight. I Percentage com- position of solution. Solvent : Nitrobenzene. 3 '9 5.3 6.7 7.8 Solvent : Acetic acid.2.0 3.4 5 '1 5.6 7 *7 16'2 327.1 317.8 315.8 322.5 327.9 304'9 306.4 327-6 324-9 323.7 Rotation. Percentage com- position of solution. 5.5 17.4 4.7 13-6 20.62 21'72 33.27 32-61 Thus the molecular weights are in both cases undoubtedly normal, Finally, a case cited by Walden (Zed. physikal. Chem., 1895, 17, whilst there is a very considerable difference in the rotations. 705) may be mentioned. Ethyl mandelate [ a ] , - 123 *lo. I n acetone. I n carbon diszclphide. Molecular weight normal Molecular weight normal [UID - goo, [a]D -180'.186 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE If, therefore, variation of rotation does really depend on variation of association, it will be necessary to attribute a greater influence t o an undetectable degree of association than even the constitution of the active substance itself can have. Of the chemists who seem inclined to adopt this hypothesis, Pope and Peachey (Trans,, 1899, 75, 1111) have perhaps pro- nounced themselves most strongly in its favour, but owing to the fact that they give no direct experimental evidence whatever in support of their views, judgment a s to the correctneEs of their con- clusions must be suspended.I n the paper in question, these authors seek t o base:a method of discriminating betweenracemicandnon-racemic liquids, which consists in ascertaining whether the value of the rotation of one of the forms of an optically active substance changes when dissolved in an inactive mixture of both forms. If the externally compensated substance be racemic, then, according t o these authors, the molecular condition of the active formwill alterwhen dissolved in it, this being the case ‘‘ since an optically active substance necessarily * has different rotation constants according as it is associated t o different degrees,” and therefore, although the evidence is ‘( rather meagre,” ‘‘ we must expect to find that the specific rotatory power of substances having high association factors in the pure liquid state varies considerably with change of solvent and of concentration, whilst those substances having in the pure liquid state association factors approximating to unity would in solution have specific rotatory powers but slightly dependent on the solvent and the concentration.” The authors assume that the association factor of E-tetrahydroquin- aldine is about 1.5-which may or may not be the case-and then show (p.1116) that when dissolved in different media this substance gives various values for [a]= lying between -45.9O and - 97.6O ; ‘( the specific rotatory power of the base in piperidine solution is less than one-half of what it is in carbon tetrachloride solution. These large variations in specific rotatory power with change of solvent can only be attributed to differences in the degree of association of the base in the various solutions.” Considering that molecular weight determinations could have been carried out in at least seven of the nine solvents (excluding acetic acid) used, it does not seem necessary to resort to the indirect (( corro- borative evidence” which the authors addme, namely, that the specific rotation of I-tetrahydroquinaldine is the.same in the free state and when dissolved in its lower homologue, tetrahydroquinoline, this being the case (p. 1117) ‘‘ because the association factor remains almost unchanged.” * In this and the other passages quoted, the italics do not occur in the original.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 187 I-Tetrahydroquinaldine was then dissolved in the externally com- pensated base, If, in the latter, ic the two antipodes are not quite mutually indifferent, the association factor would change on admixture and lzevotetrahydroquinaldine could not have the same specific rotatory power when dissolved in the externally compensated base as solvent as when solvent-free,” The rotation in these two conditions, it appears, is identical, and this proves ‘( in the most conclusive manner possible,” that the externally compensated base is not racemic.On the other hand, ‘ I the determinations of the densities and refraction constants of lzevo- and externally compensated tetrahydroquinaldine indicate with great probability that the association factor is the same in both.” Is not this evidence quite as conclusive as, or even more conclu- sive than, that derived from the rotation data, involving as it does fewer purely arbitrary assumptions? It will be seen a t once that Pope and Peachey’s statements do not rest on any solid foundation, and their paper has been referred to here because the results of the experiments detailed in the present communication seem to be absolutely a t variance with the fundamental assumptions of the authors.If, as they assume, substances which from their nature should have high association factors exhibit very different rotatory powers as the solvent is changed, then it follows, as they admit (p. 1112), that ‘‘ those which should be nearly monomolecular [must] vary but slightly in specific rotatory power in like circumstances.” Pope and Peachey depend for evidence as to the association of tetrahydroquinaldine on some data given by Traube regarding aniline, pyridine, quinoline, and piperidine. Now according to Traube’s method of calculation, ethyl tartrate is a unimolecular substance. Its molecular volume at 15’ (170.1) agrees closely with the cal- culated value (171.3 [Frankland, Trans., 1899, 75, 349]), and therefore the value of its specific rotation in different solvents should be very similar.As a matter of fact, however, the specific rotation of a 5 per cent. aqueous solution (+ 26’) is just three and a half times as great as that of a 5 per cent. n-propyl alcohol solution (+ 7.4”), whilst there is no reason to suppose that any marked difference in degree of association exists in the two solvents. Although, therefore, it may be still premature to deny the connec- tion between association and rotation, that hypothesis can scarcely be considered strong enough to discourage an attempt t o trace the phenomena of rotation in solution to some other cause, to some physical property of solvents which, apriori, might be expected to exercise a marked influence on any substance dissolved in them.188 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE The Relationship between the Rotation of Active Xubstances in XoZution and the Intemccl Pressure of the Solvent.Are we acquainted with such a property of solvents as this? The (1). There must be some reasonable probability of its connection (2). It must be capable of approximate or relative measurement. (3). I n order to account for the very considerable changes which occur in the rotation, it must vary in different solvents between wide limits. These requirements seem to be met by that property of liquids known as the (( internal pressure,” which often assumes enormous proportions and which varies very greatly in different liquids, It was in the hope OF connecting this pressure with rotation that the present investigation was commenced, but the idea appears to have been originally suggested by Tammann, and is attributed to him by Siertsema (compare Abstr., 1900, 78, ii, 329).The latter author has determined the influence of external pressure on the rotation of solutions of sucrose, and if external pressure is capable of influencing rotation, the fact is an encouragement to the investigation of the effect of internal pressure in this direction. The values given by the various authorities for the internal pressure of any given liquid are often very different. According to Tammann, its value in water a t Oo is about 22,000 atmospheres, whilst in ether at the boiling point it is nearly 2,500 atmospheres; according to Ostwald, the values are about half the above, the figures of other investigators being again different, but the relation amongst themselves of the figures of one authority for a number of liquids is generally much the same as that of the figures given by another.I n order to see how this pressure* would act, we can suppose a molecule of ethyl tartrate taken from amongst a large number of similar molecules and placed amongst a large number of water mole- cules, The pressure on the molecule changes then from the value which it has in ethyl tartrate to that which i t has in water. The first effect which we are accustomed to associate with change of pressure is change of volume. The volume of the ethyl tartrate molecule will change, and although, according to Tammann (Zeit.physikal. Chem., 1896, 21, 529) this change of volume is the sum of several changes, we may assume as a first approximation that in dilute * Although the word pressure is used throughout for the sake of clearness, it is without any intention of instituting a too strict analogy between this property and ordinary hydrostatic pressure. few necessary conditions which i t must fulfil are these : with rotation,ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 189 solution the change in volume is suffered entirely by the dissolved substance. Traube, in his recent work on molecular solution volume, assumes that it is suffered by the solvent, but his grounds for doing so are not completely convincing. It seems somewhat unwarrantable t o suppose that when one molecule of ethyl tartrate is dissolved in, say, one hundred molecules of water, the latter should be altered and not the former.A t any rate, a volume change does take place on solution, which we seem at liberty to attribute to the ethyl tartrate, and which we may regard in the meantime as a measure of the change of internal pressure. If now the molecule of ethyl tartrate were quite regular, this change of pressure would probably produce no corresponding change in rotation. It is, however, assumed to be asymmetric, and conse- quently when the volume alters so also will the shape. But it is the shape, or something corresponding to the shape, of the molecule that conditions the value of the rotation, and therefore with altera- tion of volume a corresponding alteration of rotation may be expected.A mechanical conception of the process is not difficult to form, but the simplest illustration (suggested by Dr. Shroud) is afforded by a figure (say a cube) cut out of a substance whose elasticities are dif- ferent along the three axes. Such a figure, subjected to hydrostatic pressure, would alter, not only in volume, but in shape as well. This change in asymmetry of an active molecule will bear some proportion t o the change in rotstion, and it should also bear a relationship to the change in volume, and we may therefore expect to find a connection between the rotation of a substance dissolved in various media and its volume in the same media. The data for calculating the change in volume of ethyl tartrate when dissolved in several solvents are given by the density determinations, so without troubling in the meantime about its cause, we may turn t o a comparison of the change in volume with that in specific rotation.The volume of a gram-molecule of a compound in solution may be calculated from the following formula which has recently been used by Traube : M + S s M.S. V. (molecular-solution-volume) = - - - d 6 ' X= weight of solvent associated with 1 gram-molecule of d = density of solution. 8 = density of solvent. Where N = molecular weight of dissolved substance. dissolved substance. If the solution is one of percentage composition p , then M grams of sub-190 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE stance are associated with M(loo - p ) grams solvent, that is, P a= w o o -P) P and, substituting this value of S in the above equation, we find M.S.K=--( M 100 7-6 100--p 1.P The figures which have been calculated by means of this formula will be found on pp. 214-215, and in Fig. 8 these values of molecular- solution-volume at 20° are plotted relatively to concentration, and below the corresponding concentration-rotation curves for the same temperature. It is evident, in the first place, that the values obtained for molecular-solution-volume in dilute solutions are somew hat uncer- tain, this being due to the difficulty of carrying out the density deter- minations with sufficient accuracy, the effect of a slight error being great in dilute solutions, as is apparent from an examination of the formula used in the calculation, It is therefore rather difficult t o determine how the most probable curve should be drawn in each case from the experimental data.The curves for water and methyl alcohol are not very satisfactory for p < 10, whilst that for ethyl alcohol is the least satisfactory of all; i t has been drawn, however, as nearly as possible between the values for p = 5 and p = 10.94. The ethyl tartrate molecule evidently undergoes a very considerable change in volume on solution in a large quantity of water. At infinite dilution, the molecular-solution-volume seems to be about 157.5 c,c. at 20°, that of the free ester being 170.9 C.C. In methyl alcohol, the change in volume is also considerable but not so great as in the case of water, the value at infinite dilution being about 159.3 C.C.In ethyl alcohol, the volume is 164 C.C. whilst in It-propyl alcohol it is 167.7 C.C. If now the corresponding concentration-rotation curves are examined, it will be noticed that the values of the rotations at infinite dilution stand in the inverse order, and although the rotations do not seem to be quantitatively related to the values of the molecular- solution-volume, there may be a qualitative relationship. There can be little doubt that the order of the values of molecular- solution-volume at isfinite dilution in the above four cases is correct, although the values themselves are a little uncertain, but it is more difficult to say whether the rotation of ethyl tartrate in glycerol can be similarly explained by the value of its molecular-solution-volume in that solvent.As has already been remarked, the accurate deter- mination of molecular-solution-volume becomes more and more difticult as the dilution of the solution increases, and it may be that tbe curveROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 191 11.S.V. (infinite dilution). Solvent. drawn in Fig. 8 for glycerol is not correct and that the molecular-solution- volume a t infinite dilution is greater than that of ethyl tartrate in ethyl alcohol. Nevertheless, the curve obtained from the experi-- mental figures is so regular as to be some guarantee of its accuracy, and assuming it to be correct the molecular-solution-volume of ethyl. tartrate in glycerol at infinite dilution has a value between those found in ethyl alcohol and methyl alcohol, namely, 163.3, and, in agree- ment with this, the rotation of glycerol is greater than in ethyl alcohol and less than in methyl alcohol.At infinite dilution, therefore, the order of the rotations and molecular-solution-volumes correspond inversely, a small volume being associated with a high rotation, as is. apparent from the following table : [alD (infinite dilntion). ........................... 157.7 .............. 159.3 ........................ 163.3 ................ 164 Water Methyl alcohol Glycerol Ethyl alcohol.. n-Propyl alcohol ............ 1 167'5 I 26-15' 11.50 10.57 9'13 7 '40 Change in aD due to solution. 18.49" 3-84 2'91 1'47 - 0.26 The parallelism of these figures is, as a first approximation and in a qualitative sense, fairly satisfactory, but if this relationship is not merely accidental, that is, if variation in molecular-solution-volume does really determine variation in specific rotation, then me may expect to find a connection, not only at infinite dilution, but under ail circum- stances.That is to' say, the curves for rotation should correspond throughout with the true curve for molecular-solution-volume. Now it will be seen in Fig, 8 that the molecular-solution-volume curves for ethyl tartrate in water, methyl alcohol, ethyl alcohol, and n-propyl alcohol are all, in fact, of much the same form, they show a gradation of a similar order to that found in the rotation curves, and this connection between rotation and volume becomes much more striking when glycerol is also taken into account, because its behaviour differs markedly from that of the other solvents ; it presents something of the character of an exception, and if an exceptional variation in rotation is accompanied by exceptional variation in molecular-solution- volume, the suggested correlation of these two phenomena becomes more probable. The concentration-rotation curve for this last solvent is, as has already been mentioned, a remarkable one.At 20°, the rotation a t infinite dilution is + 10~6~. As the concentration increases, the rotation diminishes much more rapidly than in the three other alcohols, and corresponding with this the volume increases much more192 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE rapidly between p = 0 and p = 20, and in the meantime this qualitative relationship is sufficient, It can scarcely be expected that the molecu- lar-solution-volume curves should cut one another at exactly the same concentrations as those at which the corresponding rotation curves intersect.It might be possible to trace this close connection if the trwe curves for molecular-solution-volume were known ; the curves drawn are, however, only approximations, and in all probability not very satis- factory ones. All the contraction on solution has been assumed to take place in the ethyl tartrate. Probably even in a p = 5 solution the error thus committed is considerable, and in a p = 20 solution it must certainly be great. I n the diagrams, however, this volume change is assumed to take place, for all concentrations, in the ethyl tartrate only, which is certainly incorrect.I n reality, the total volume change consists of at least two changes, one in the solute and one in the solvent, but, what is of the greatest importance here, it is not possible to separate it into these two or more simple changes. The curves on the lower part of Fig. 8 are there- fore not correct, although they can probably still give some indication as to the actual behaviour of the substances examined. This (the merely approximate nature of the curves) explains why solutions having the same specific rotation need not necessarily show the same molecular-solution-volume for the dissolved ethyl tartrate. The volume of the tartrate may really be the same in two different solu- tions whilst the volume change in the solvents is not the same.For instance, a p = 25 solution in glycerol has the same rotation ( + 7.6") as a p = 55 solution in ethyl alcohol, although the corresponding volumes are not the same, being for the former 169 C.C. and for the latter 16'7.5 C.C. It is evident that in this case a greater volume change is likely to have taken place in the ethyl alcohol of the latter solution than in the glycerol of the former, both of these changes, however, from the method of calculation, being ascribed to the ethyl tartrate alone. Such a connection as this between molecuIar-solution-volume and rotation appears to render possible a rational explanation of that very interesting phenomenon, the occurrence of a minimum rotation of ethyl tartrate dissolved in glycerol or a-propyl alcohol. For if rotation is really dependent on molecular-solution-volume and in glycerol solution at 20° the minimum rotation occurs when p = 65, then it follows that the molecular-solution-volume for the same temperature should be a maximum at that concentration.Now the molecular- solution-volume curve for glycerol rises rapidly with increasing con- crntration up to about p = 25, after which the increase is much more gradual ; but at about p = 25 it is probable that the glycerol also suffers considerable change in volume and if this be contraction it willROTATION OF OPTICALLY ACTIVE COMPOUSDS. I. 193 counteract the effect of expansion in the ethyl tartrate. That is t o say, the ethyl tartrate ma-yreally continue to expand with increasing con- centration, the state of affairs not being represented by the full line in the figure but rather by the broken one, until a t about p = 65 a maximum volume of about 173 C.C.is reached, the volume then again diminishing rapidly to 171 C.C. when p=lOO. This assumes the possibility of a. value greater than normal for ethyl tartrate in solution, which is, however, surely as possible as one less than the normal. So far it would seem that the assumption of a relationship between molecular-solution-volume and rotation is at least worthy of considera- tion, but there are considerable difficulties to be overcome before the connection can be regarded as proved. One of these is met with in the fact that in n-propyl alcohol, although the molecular-solution- volume at infinite dilution is only 167.1, the rotation is lower than that of the pure ester by 0.26' instead of being higher.The dis- crepancy is not very great, and an explanation can scarcely be expected until more data have been obtained. Another difficulty occurs when the influence of temperature change upon the rotation of these solutions is considered. Except in one case-solution in water-increase of temperature causes increase of rotation. But increase of temperature also causes increase of mole- cular-solution-volume and therefore ought to be attended by decrease of rotation. We have here a direct contradiction, but the following consideration will show that i t is not inexplicable. Let us take the case of free ethyl tartrate, whose rotation, as is well known, increases rapidly with rise of temperature.Imagine one particular molecule, A, in the liquid kept a t a definite temperature, T, whilst all the others are heated to a higher temperature. The pressure on the molecule A will decrease, its volume will increase, and its rotation should also decrease ; that is to say, the molecule becomes less asymmetric. Now let the molecule A be also heated to the higher temperature. The effect will be expansion of the molecule A against a certain pressure-certain forces-resulting in another increase of volume. I n this second case, however, the proximate cause of change of volume is not the same as before-the effort comes from within the molecule, the change is not due to variation in the properties of surrounding molecules-and now the expansion may take place in such a way that the molecule becomes more asymmetric again, and since we know in general that a slight change in the temperature of a liquid or solid will produce a much greater alteration of volume than an enormous chauge of pressure can bring about, the second of the operations just mentioned will probably have a greater effect than the first on the rota- tionof the molecule A, so that the net result is an increased rotation.194 PA4TTERSON: THE INFLUENCE OF SOLVENTS ON THE The same volume might be arrived at either by heating or by diminution of pressure alone, but the shape, that is, the asymmetry, of the molecule would not be similar in each case.The asymmetry of the molecule then depends on temperature and pressure-or some- thing analogous to pressure-but it is only constant for definite values of both variables; the asymmetry is not so simply conditioned as the volume.If this is admitted, then the simultaneous increase of rotation and volume presents no difficulty either in the case of solution in the alcohols or in water, although in the latter case the rotation in dilute solutions (anything less than p = 55) decreases with increase of temperature. I n dilute aqueous solution, where the internal pressure is great, the asymmetry of the ethyl tartrate molecule has become such that the effect of increasing temperature is to produce a less .asymmetric molecule. Under a low pressure (solutions in the alcohols) effort from within the molecule produces greater asymmetry ; under a high pressure,* it produces a less asymmetry, and consequently between these extremes there may be a pressure under which the molecule of ethyl tartrate has an asymmetry practically unaltered by heating, increase of temperature causing expansion of the molecule certainly, the shape, however, remaining always the same.This particular case appears to be found in an aqueous solution for which p=55. The rotation of such a solution is practically insensitive to Semperature. I n this connection, it should also be noticed that the ethyl tartrate molecule appears to be most sensitive t o temperature in those solvents in which its molecular-solution-volume is greatest, which fact is in agreement with the above considerations. In dilute glycerol solutions, the sensitiveness of ethyl tartrate is probably slightly less than that of the free ester, whilst in methyl and ethyl alcohols it is practically the same as that of the free ester.I n m-propyl alcohol, however, it is rather greater. This corresponds with what has been suggested above; the greatest sensitiveness is shown in that solvent in which molecular-solution-volume is high, that is, in n-propyl alcohol. It is obvious, however, that here again we meet with difficulties, for the molecular-solution-volume of the ethyl tartrate in an insensitive aqueous solution (that is, of p=55) is about 163 c.c., which is higher than the volume in infinitely dilute methyl alcoholic solution (159.3 c.c.), and therefore the rotation of dilute solutions in the latter solvent ought also to decrease with increasing temperature, which, of course, is not the case.We must remember, however, that it is not possible to tell what the true molecular-solution-volume of ethyl tartrate in 55 * Always in this particular case of ethyl tartrate, of course. With some other molecule of different asymmetry, the phmomena might be reversed.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 195 per cent aqueous solution reaIIg is, and consequently must be content in the meantime with the indications already pointed out. This relationship of rotation and molecular-solution-volume has been first discussed because the figures necessary for the calculation of both these quantities may be directly obtained from the data collected in this investigation. As already remarked, however, the volume change accompanying solution is probably more complicated than has been assumed, and it is worth while to try to trace the cause of variation in rotation still further back, namely, to that property of liquids which has been supposed to be the cause of variation in voluiiie, the internal pressure.It may be that the variations in volume due to solution are not directly proportional to variation of internal pressure whilst the variations of rotation are, and that therefore there may be a closer and more obvious connection in the latter case than in the former. Barmwater (Zeit. physikal. Chem., 1899, 28, 124) has calculated this quantity for a number of substances, and Traube has suggested a method of calculation based on his work on molecular-solution-volume, whilst others have been proposed by van der Waals, Stefan and Tammann.The choice of a particular set of figures would involve a critical discussion of the various methods of calculation, and this we may avoid by considering, instead of the pressure, that which Briihl (Zeit. physikal. Chem., 1899, 30, 43) calls the medial energy or heat of disgregation of a liquid, because it is from this quantity that Stefan and Tammann both derive-although by slightly different reasoning- their figures for internal pressure. The heat of disgregation is calculated from the formula liquid, E = mechanical where M= mol. wt. of where D = heat of disgregation, IZ = heat of vaporisation, p = vapour pressure, P=volume of 1 gram of vapour, Pl=volume of 1 gram of equivalent, which, since we may set RF p ( P - V1)= - M ’ substance, reduces to The heat of disgregation therefore represents the amount of energy necessary to overcome the internal forces of a liquid, and to separate its particles from each other at any particular temperature and pressure.196 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE 575 '9 272.1 2234 By calculation from the above formula, the following figures are obtained.303.8 48*7 Solvent (t = 0"). 274.5 q7.G 26'4 Water .......................... Methyl alcohol.. .............. Ethyl alcohol .................. +24' (~'10) 9.9 14.1 (p=lO) 12.3 @ = l o ) o.5 11'8 ( p = 5 ) D. 1 A. Water ........................... Methyl alcohol ................ Ethyl alcohol.. ................ n-Propyl alcohol.. ............ 523'1 248'6 201 -6 175'2 t-26.5" ( p = l O ) 9'5 ($?=lo) 6'2 (p=5) A.17.0 3 -3 It will be noticed that here the differences in rotation and heat of disgregation are nearly proportional to each other. By making the calculations for a higher temperature, n-propyl alcohol may also be included in the table. Its heat of vaporisation has only been determined at the boiling point, and has been found to be 166' (cal.). By assuming that it varies in the same manner with temperature as those OF methyl and ethyl alcohols, the value a t 60' can be approximately obtained. From the number thus deduced, the heat of disgregation in the following table has been calculated : I D. Solvent (t= 60'). I These figures are also in fairly close agreement with each other ; the rotation in the different solvents appears to decrease in much the same proportion as the heat of disgregation.Such an agreement may -of course, be merely accidental, and the examination of several other series of solvents will be required to determine the point, but the figures are certainly striking. Plotted on a system of coordinates, the one property is seen to vary almost linearly with the other. It is not necessary, however, to enter into any further discussion regarding this relationship, for nearly everything that could have been said here has been said for molecular-solution-volume, and applies almost equally to both. It would appear, then, that molecular-solution-volume, heat of dis- gregation and rotation have some connection with each other, and in the paper already mentioned Briihl shows that the heat of disgregation and the dielectric constant of a substance are also related phenomenaROTATION OF OPTICALLY ACTIVE COMPOUNDS.I. 197 Association factor of solvent. the latter again varying in an analogous manner with dissociating power, as Nernst has pointed out, and thus we are led back again to a problem which was discussed earlier in this paper-the relationship of dissociation and rotation, As has already been shown, no definite connection can be deduced from the various researches which have been carried out on the subject, but it is nevertheless possible that although the dissociating power of a liquid-a term usually applied to a solvent with regard only to its behaviour towards electrolytes- does not cause actual dissociation in substances other than electrolytes dissolved in that liquid, it may nevertheless modify them.Thus a substance such as ethyl tartrate dissolved in two different liquids may exist in simple molecules in both, but still the force which we call dissociating power is acting t o a different extent in each case, and although unable to cause any decomposition of the molecule into ions, may yet exert some other influence on it which will be evident as change of rotation, for instance. As a summary of the relationships discussed in this paper, the following table may be added. The heat of disgregation is given for 60°, whilst the other figures are for lower temperatures. The association factors of the solvents have been introduced, as it is of interest to compare their values with the other figures given.M. S. V. of ethyl Traube, 15". Ramsay and Shields. tartrate. Infinite dilution, 20". Water , . . . . . . . . . . . Methyl alcohol. Glycerol . .. . , . . . Ethyl alcohol .. n-Propylalcohol f 26 '2" 1 '644" (20") 11.5 2*32* (20") 10 -6 9-1 1*65* (20O) 7'4 2'25 § (46'3" 2-3-f 1.798 1-90? 1-67? 1.667 Heat of disgrega- tion of solvent, 60". 523.1 248.6 201 '6 175-2 157'7 159.3 163.3 164 167'5 Dielectric constant of solvent. From this table, and from what has already been said, i t appears that a relationship, satisfactory in a qualitative sense, can be * Proc. Roy. Soc., 1894, 56, 180. t These numbers are not quoted by Traube?, but are calculated according to his 2 Nernst, Theor. Chemie, 3rd edition, p. 305. 11 Thwing, Zeit. physikal. Chem., 1894, 141, 293.l T Traube, Ueber den Raum der Atome, Ahrsns Sammlung, pp. 32 and 41. VOL. LXXIX. P direotions. Trans., 1893, 63, 1102.198 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE established between variation of rotation in solution and variation of molecular-solution-volume-at least so far as this series of solvents is concerned-and when these phenomena of rotation are traced further back to what may with reason be regarded as the cause of variation of molecular-solution-volume, namely, differences of internal pressure, or what is probably the same thing, of heat of disgregation, very similar regularities are observed, which seems to show that the original assumptions, dependence of volume on internal pressure and rotation on both, are justified. Finally, it may be pointed out that if the idea developed here be correct, greater account must be taken, when considering the rotation of homogeneous active substances, of their own internal forces ; the molecular rotation is not that of a free molecule of the compound.The molecular rotation of a homogeneous liquid is the rotation of the molecule subjected to the internal forces of that liquid. Rotation of ethyl tartrate. Temperature. 10 -8" 37 -6 33.7 29.9 20.1 89 '4 84.4 77 '1 67'2 55 -1 46.1 25 -1 16 11.3 100 an (100 mm.). + 8.047" 11'354 10'842 10-392 9'244 15.129 14'725 14510 14.110 13.600 12-792 12.067 9'900 8.719 8.089 Density. 2.2144 1.1913 1.1952 1.2051 1,1230 1.1349 1'1399 1 *1472 1.1576 1.1697 1.1789 1'2000 1 '2094 1,2140 I -1873 Densities determined : Temperature. 16.8" 37'2" 46.8" 58'3" 68.1" Density ......1.2087 1.1878 1.1783 1'1665 1'1566 + 6-63" 9 -56 9 -10 8 -70 7.67 13.47 12.97 12.73 12-30 11.75 10-94 10.24 8 -25 7-21 6.66 76'2" 99.4" 1 *1484 1.1248 Ethyl Twtrate in Watev. The distilled water used in these experiments was well boiled before use.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 199 Temperature. a, (400 mm.). Density. r a I$ + 26.06" 25-01 25.67 26.30 20" 50.8 27-2 22 -3 1.043 0.995 1 -026 1 -052 1 '0006 0'9945 0.9990 1*0001 Densities determined ; 26'2" 0.9993 Temperature ............ Density .................. 15.8" 1.0017 p = 2-5. Temperature. aD (400 mm.). Density. [alf. 14.7" 50.3 27'3 14.6 + 2,612" 2'450 2.572 2'593 1.0053 0.9940 1'0023 1'0053 -1- 25 *98" 24-65 25.66 25-80 55" Densities determined : Temperature......... 14.6" 26%" 41 '6" Density ............... 1 *0053 1.0024 0.9971 It 0*9912* * Although the water used in making up this solution had been boiled, it was found difficult to carry out the density determinations a t these higher tempera- tures owing to the separation of air-bubbles. These two figures are probably therefore too low. p = 4.999. Temperature. a, (400 mm.). Density. 15.3" 30 -8 16.6 (after standing 14 days) + 5 '304" 5'199 5.289 1 *0110 1,0077 1'0108 + 26 -23" 25.80 26-16 Densities determined : After standing 16 days. 36.1" 14.4" 1.0066 1'0113 Temperature ......... 17 '6" Density ............... 1*0106 P 2200 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE p = 9.994. Temperature. 21'3" 14'8 29.4 18'6 20 -7 (after standing 5 days) a, (400 inm.).+ 10.598" 10-701 10.415 10-650 10.490 Density. 1'0211 1.0231 1'0184 1.0220 1 '021 3 + 25.95" 26.17 2557 26.05 25.69 Densities determined : After standing 5 davs. Temperature ...... 19'2" 13" Density.. . ... . . . . . . 1.0220 1 -0237 27.5" 34-4" 14 *lo 18 - 6 O 1.0192 1.0164 1'0235 1.0220 p = 24.954. Temperature. 15" 32 '5 25 20.6 15 44.9 15 a,, (249 '6 mm.). Densities determined : + 15.725" 14.867 15.314 15'505 15.747 14.249 15-714 Density. 1.0597 1.0511 1,0549 1.0571 1.0597 1-0457 1.0597 4- 23.83" 22'71 23-31 23.55 23-85 21 -88 23-81 After heating After heating to 33'3". to 44'9". Temperature . . .. 16" 23" 33.3" 15'8" 15.2" Density ......... 1,0594 1'0562 1'0509 1.0595 1'0598ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 201 a, (100 mm.). p = 49,993.Density. [ 41;. Temperature. 14.7" 34-2 26 -8 19-9 15.1 46 15 Twelve hours later : 15'3 52.6 14.5 66 -2 56 -1 15.9 17 aD (100 mm.). + 9'759" 9.379 9.529 9,670 9.742 9.197 9'727 9.739 9'112 9.750 8-894 9 '065 9'704 9 '689 Density. 1'1193 1.1052 1.1102 1.1153 1.1190 1'0973 1.1190 1.1188 1.0927 1.1194 1.0835 1 -0903 1'1184 1'1175 r41:. + 17-44" 16.97 17.17 17'34 17.41 16-76 17'39 17.41 16.68 17-42 16'42 16'63 17-35 17.34 Densities determined : After experiment. Temperature.. ..... 15.7' 22'3' 353" 63.8" 70.3" 16.8" Density ............ 1.1186 1.1137 1'1046 1.0807 1 *0752 1.1180 p = 74.99. Temperature. 16.2' 49 -1 45*0 30.6 19.5 16 67'2 53'4 18 Densities determined 1 + 10'069" 11'100 11*000 10'587 10'210 10.049 11'497 11'194 10.144 Temperature.. ....... 18 *3" Density .............. 1 *1690 1.1707 1.1408 1'1446 1,1579 1.1679 1.1709 1 -1248 1-1369 1.1691 + 11-47" 12.97 12-82 12.19 11 '66 11.44 13.63 13.13 11'57 After experiment, 58" 18.2' 1.1323 1.1691 Ethyl Turtrate in Methyl AZcohol.The methyl alcohol used was Kahlbaum's best quality and was redistilled from some sodium which had been carefully freed from petroleum.202 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE Temperature. The density of the methyl alcohol was determined at various tem- peratures, the following numbers being obtained : Temperature.. 16' 2 9' 3s-4' 48' Density . . , . . , 0.7953 0-7830 0.7741 0-7646 From these figures, by extrapolation, we find that the density at 0' is 0-8105, whilst, according to Dittmar and Fawsit, the density of pure methyl alcohol a t 0' is 0-81015. uD (400 mm.).p - 5 . 14'8" 13'2 49 '2 40 '2 32.5 24-3 12.2 + 1,845" 1 *773 2.121 2'081 1.993 I 1'913 I 1.750 Density. 0.8120 0.8137 0.7796 0.7860 0'7949 0.8029 0,8147 Densities determined : Temperature.. . . . , 20.2" 33.8" 46.7" Density .... ..... ... 0.8068 0'7939 0.7815 +11*36" 10.92 13.60 13.24 12-54 11.91 10'74 After experiment. 18.3" 0'8068 p=10. Temperature. 18'9" 12.8 16.7 53 46.7 42'6 35.5 27 16 '2 13 a, (400 mm.). + 3'744" 3.545 3.715 4.368 4.320 4.238 4.138 3.946 3-695 3.615 Density. 0'8240 0.8300 0'8288 0.7905 0 *79 70 0.8010 0.8080 0,8162 0.8268 0'8306 + 11'36" 10.68 11.21 13-81 13-55 13'23 12.81 12.09 11-17 10'88 After experiment. Temperature ... ... 22" 30.6" 39.6" 45'8" 14.2' Density .. . . , . . .. 0.8210 0 ,8128 0.8040 0'7980 0.8286ROTATION OF OPTICALLY ACTIVE COMPOUNDS.I. 203 p = 25.01. ~~ Temperature. 18.3" 20 13.2 48'1 45 -6 42.8 39-4 33'4 25 19'2 18.9 aD (249'6 mm.). + 6.044" 6.110 5.810 7.068 6.997 6'913 6'813 6.627 6'328 6'074 6'065 Densities deteerrnined : Temperature ... . . . 14 *lo Density. 0.8757 0.8741 0.8807 0.8468 0 '849 2 0.8518 0.8553 0'8610 0'8693 0.8750 0-8751 27'3" 36" Dens'ty ......... 0,8799 0.8671 0.8585 [a15 -t- 11 '06" 11.20 10-57 13'37 13'20 13 '00 12.76 12-33 11.66 11.12 11-10 43.2" o-a515 p = 50000. Temperature. 13" 16 53.8 46 -9 43.2 38.2 24.9 17 13'2 14'7 34.8 a, (100 mm.). + 4.781" 4.891 6.088 5'968 5.863 5-711 5-616 5.281 4.966 4.820 4.908 Density. 0.9762 0.9743 0.9366 0.9435 0'9471 0.9521 0.9555 0.9655 0.9733 0.9770 0-9755 Temperature ...,.. 19.8" 34.4" 44.6" Density ......... 0.9707 0.9561 0-9460 +9*80" 10.04 13-00 12-65 12.00 11.76 10-94 10.21 9-87 10.06 12-38 51" 0,9395204 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE p = 75. Temperature. 14'9" 12.5 51 '1 45.6 40'8 33.7 24-7 17.1 a, (100 mm.). + 7'012' 6-839 9.380 9.014 8-792 8.374 7.767 7'207 Dmsities determined : ~ Density. 1.0879 1 -0901 1 -0504 1.0564 1.0610 1.0685 1'0778 1.0853 [ a 15 Temperature ...... 18'3" 32'8" 39.7' 53.2" Density . . , . . . ... . . , 1.0842 1.0692 1'0626 1 -0488 + 8-59" 8-24 11-91 11'38 11 -05 10.43 9.61 8 -85 After experim.ent. 17 '6" 1 *0853 Ethyl Tartrate in Ethyl Alcohol. The ethyl alcohol used was carefully distilled over sodium. Its density was determined with the following results : Temperature 17.6' 30.4O 4 1 0 6 ~ 58 *2O Density ......0.7932 0.7822 0.7723 0.7575 This gives, by extrapolation, the number 0-8090 at Oo, whilst Mendeldef found 0.80625 (Landolt-Bornstein). p = 5a0013. ~~ Temperature. 18.8' 17 11 13'7 15-9 51 -8 42.9 37'2 31 -1 21.7 30.3 23 uD (400 mm.). + 1,419" 1 '370 1'262 1'304 1 '350 1'840 1.729 1'660 1,565 1 *417 1.551 1.459 Density, 0.8072 0.8090 0'8143 0'8119 0.8099 0-7779 0.7858 0.7908 0.7961 0-8046 0-7970 0.8035 + 8-79' 8.47 7-75 8-03 8 '33 11.81 11'01 10-49 9.83 8.80 9-73 9.08 After experiment. Temperature .... , ,. , ... 20-5" 30.6" 38" 54'4" 16" Density ........... ,... 0'8056 0'7969 0'7900 0.7754 0.8097ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 205 p = 10.94. Temperature. 18.6" 7 '1 59.1 52 '8 41 23 '6 6.6 a, (400 mm.). Demsitier determined : + 3.023" 2.553 4-220 4'067 3.772 3'243 2-542 Density.0-8251 0'8353 0-7893 0.7950 0.8052 0.8208 0'8359 I: 4:. + 8 '37' 6-98 12-22 11-69 10.71 9.03 6 '95 After experiment. Temperature .. ... ...... 17.4" 38.4" 55.8" 65.8' 20'2" Density ...... ......... ... 0.8263 0.8079 0'7922 0.7826 0'8240 p = 20°003. Temperature. 16.2" 8.7 64.4 59.7 54 45-6 37.9 23.6 9-5 (249-6 mm.). + 3.348" 2.965 5.078 4.945 4'803 4.551 4.296 3.756 3,076 Density. 0.8569 0-8639 0.8119 0'8161 0'8215 0.8293 0.8367 0.8499 0.8632 + 7-82" 6-87 12'53 12.14 11 *71 10.99 10-28 8.85 7-14 Densities determined : After experiment. Temperature 131' 18.9" 33O 35*2" 39" 46.4" 69" 15%" Density .... 0.8595 0.8544 0.8418 0,8397 0'8362 0.8294 0.8074 0.8577206 PATTERSON: THE INFLUEX'CE OF SOLVENTS ON THE p = 40.002.Temperature. 19-7" 10 *2 60.3 55 51 -2 44 '9 40 -1 36.7 25 12.4 I Density. aD (249 '6 mm. ). + 7 *260" 6'263 10.335 10'058 9'831 9-368 9'063 8.788 7.785 6 *528 0.9244 0.9334 0.8857 0.8907 0'8944 0.9004 0.9050 0'9083 0.9194 0'9312 + 797" 6 -72 11'69 11'31 11.01 10.42 10-03 9'69 8 '48 7.02 After experiment. Temperature ........... 16.7" 33.3" 43'8" 62'8" 19" Density ............... 0.9272 0.9114 0.9017 0.8833 0.9258 p = 60.01. Temperature. 1 aD (100 mm. ). 1 1 l- 21.3" 11.1 14 56.7 48.2 39 34 22 + 4.667" 3'987 4.140 6.480 6'122 5'662 5'389 4.732 Density. 1.0040 1.0141 1.0113 0'9690 0.9774 0.9865 0,9914 1'0030 + 7-75" 6.55 6-82 11-24 10-44 9-56 9-06 7 '86 Densities determined : Temperature ............ 17.5" 28 '9" 47.8' 59 *lo Density ................1.0079 0.9969 0'9780 0'9668 Ethyl Tartrate in n-Propyl Alcohol. The n-propyl alcohol used was of Kahlbaum's best quality and was Its density was determined at various temperatures with the follow- Temperature 20° 2 3 ~ 4 ~ 3 2 O 40° 62*8O 69*6* Density.. .... 0.8039 0*8012 0.7942 0.78'75 0.7682 0.7622 carefully distilled over clean sodium before use. ing results :ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 207 Landolt-Bornstein's tables give d Oo/Oo 0.8205 hence d 0°/4' 0*8204, whilst by extrapolation from the above figures we find d 0°/4' 0%210, so that, judged by the density, the alcohol used seemed almost pure. However, after three solutions had been examined some doubt arose as to whether a portion of one of them had not been returned by mistake to the bottle containing the pure propyl alcohol instead of to that for residues, and to determine this, some of the former liquid was examined polarimetrically and found t o have a slight laevorotation.This might be due to presence of ethyl tartrate (although in that case a positive rotation was to be expected), so the propyl alcohol was redistilled and, on examination, the distillate and the residue left in the flask were found to be laevorotatory to almost exactly the same extent, which although proving that no mistake had been made in the first instance, also showed the propyl alcohol to be somewhat impure. This rotation of the alcohol being only very slight and several experi- ments having already been carried out, it seemed unnecessary to repeat them, since the quantity of impurity present probably did not influence the effect of the propyl alcohol on the rotation of the ethyl tartrate, except by superposition. The rotation of the propyl alcohol was therefore carefully determined : uD - 0.067O at 18.8' in a 400 mm.tube. uD -0994' at 68.5' ,, 99 ;;_Its rotation is thus very small, but becomes of some importance in the case of dilute solutions, and consequently the results of the experiments performed have been approximately corrected for the rotation of the propyl alcohol, the length of the tube and the com- position of the solution examined being taken into account. p = 2.5004. Temperature. (400 mm. ) Corr. I Obs. I I I Densities determined : Temperature . , . . . . . . . 16 *6O Densi ty... ... .... . . ..... , 0.8146 I Density. I [a]:. (400 mm.). I I +0-554" 0-8152 + 6.79" 0.690 1 0.8045 1 8-58 0.574 0 '81 20 7.07 20.9" 32.5" 0.8111 0.8017208 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE Temperature. p= 4.9996. 0b:2i400 Density. 0.8279 0.7970 0.8023 0'8102 0'8191 0.8254 0.8279 0.8826 17'6" 20 68.8 62'3 52'6 45'7 28 '3 18'4 - f 1 -072" 1 *125 1.867 1 *775 1.662 1.572 1 -308 1.108 Corr. + 0.064" 0.066 0.091 0'088 0-082 0.079 0.069 0-065 True aD (400 mm.). + 1-136O 1'191 1.958 1.863 1 '744 1'651 1 *377 1.173 Density. 0'8201 0.8174 0'7763 0.7821 0.7907 0.7970 0'8112 0'8197 + 6'93" 7'29 12.61 11.91 11.03 10-36 8'49 7 *16 Densities determined : After experiment. Temperature 16.7" Density ...... 0'8210 33.2" 44.9" 58" 80.2" 18.8" 0.8075 0,7977 0.7863 0.7661 0.8193 p = 7-71 3.Temperature. 18.7" 55-1 48'7 39'5 28'9 21'3 18'5 13 Obs. a, (400 mm.). + 1 -766" 2'751 2.616 2-396 2.082 1'858 1 *76l 1.570 Corr. + 0'062" 0.089 0'084 0-077 0.070 0'064 0'062 0.058 True aD. (400 mm.). + 1 *828" 2.840 2.700 2'473 2.152 1.922 1.823 1.628 ra1;. +7.16" 11.55 10'90 9-89 8 '52 7.55 7-13 6 -34 Densities determined : After experiment. Temperature 23.5' Density ...... 0.8236 34.2" 45-8" 58'4" i9.6" 20'8" 0.8148 0'8050 0.7941 0.7763 0.8268ROTATION OF OPTICALLY ACTIVE COMPOUNDS, I. 209 Density. p = 17*507. I: a 1;. ~~ True a, (249-6 mm.). + 2.082" 2'939 2-705 2.395 I I f 0-011" I- 2.093" 0.9259 + 6-03" 0'014 2.953 0-9080 8 -67 0-013 2-718 0'9122 7 -94 0-012 2-407 0-9194 6 '98 15 '9" 29'7 19.7 + 2'354" + 0'035" 3'010 0.040 2.555 0 037 + 2'389" 3.050 2'592 Densities delermirted ; Temperature............ 18 '9" Density.. ................ 0'8570 0.8596 0.8480 0.8563 28'2" 0.8492 + 6 '36" 8 -23 6 -93 p = 25. Temperature. 18'9" 68'2 63.3 57'9 51.9 42 -3 33'1 18'8 Obs. a, (249'6 mm.). + 30626~ 6.125 5.945 5.756 5,486 5.076 4.496 3-608 ~ Corr. + 0.033" 0.053 G.051 0 -049 0.047 0 *043 0.039 0'033 True an. 249'6 mm.). + 3,659" 6.178 5'996 5.805 5-533 5-119 4.535 3'641 Density. 0.8799 0 '83 58 0.8402 0.8453 0.8509 0.8596 0.8678 0.8800 Dewit& determined : Temperature ...... 17.7" 31 -6" 52.1" 70 -6" Density ............ 0.8810 0.8691 0.8506 0'8334 [a];. + 6 '67" 11.84 11.44 11.01 10'42 9 '54 8.37 6.63 After experiment. 19" 0,8802 p = 37-51. Temperature. 15.9" 36 31 23 '2 Ob8' an (loo I Corr. 1 True uD (loo I Density.1 [a]:. mm.). mm.). Densities determined : Temperature ............ 17'8" 35-6" Density ................. 0 '9242 0.9082210 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE p = 49.834. Temperature. 19" 71 -2 63.6 58 '2 52.4 41-2 28 19 Obs. aD (100 mm.). + 3.046" 5 '305 5 -021 4.830 4-613 4,150 3.525 3-031 Densities determined : Temperature ......... Density ............... - ~~ Corr. + 0'009" 0,016 0-01 5 0-014 0,014 0.012 0.011 0.009 True aD (100 mm.). -I 3.055" 5 *321 5-036 4-844 4.627 4.162 3.536 3.040 Density. 0.9687 0.9237 0.9262 0.9514 0.9370 0'9479 0.9601 0.9687 [ 42. 4- 6 '33" 11-56 10.91 10-43 9.91 8.81 7.39 6 '30 After experiment. 19.8" 31.20 43.8" 59-40 80.20 i s e 0.9678 0.9571 0.9453 0'9303 0'9099 0.9696 p = 74.99. No correction has been made in this case for the rotation of the propyl alcohol.Temperature. 20' 79 73.6 69.9 60'5 33-3 47.1 17.7 a, (100 mm.). + 5'276" 9'065 8.928 8'791 8-356 6'495 7.605 5-133 Density. 1,0756 1.0169 1 '0221 1 -0259 1 -0350 1.0622 1,0487 1 *on30 c 1:. + 6 '54" 11.89 11 '65 11.43 10.77 8.15 9.67 6 '35 Dernsitk determined : After After experiment. * experiment. * Temperature ...... 21" 38'3" 50.6" 71.2" 18" 20.8" Density ............ 1 *0747 1.0576 1'0448 1 '0248 1.0833 1.0811 In this case, the density after experiment differs more than is usual from the original density.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 2'11 Temperature. Ethyl Tartrate in GZycep*oZ. It boiled between 177O and 1 7 8 O under 20 mm. pressure, the temperature of the bath being 225-235'. Its density was determined at different temperatures with the following results : The glycerol used was carefully redistilled in a vacuum.Temperature 13.2 30' 5 4O 7 5 . 5 O 99*5O Density .,.... 1,2651 1.2552 1.2397 1.2256 1.2097 u,, (200.mm). p = 4-985. Temperature. 1 U, (249'6 mm). 98'2" 17 77.5 47.6 35.7 26'8 + 2'12" 1-52 1-95 1'87 1.77 1 -66 Densitiee determined: Temperature . , , . . . . . , Density. .. .. . .. . . . . . . . ... 17 *lo 1.2620 Density. 1'2080 1.2617 1 *2198 1.2425 1.2500 1.2555 + 14.13" 9'68 12.88 12.10 11 '38 10'63 40" 57" 99" 1.2475 1 '2366 1 *2076 p = 9.906. 99" 17 72.6 85.8 57 52-7 17.2 12.1 7a + 3-11 2 '26 3 -04 3'00 2-94 2.86 2-80 2.25 2.14 Density. 1'2050 1'2600 1'2193 1 '2230 1.2277 1'2340 1.2365 1 *2601 1.2632 I Q 1:. + 13.01" 9-07 12.59 12-28 12.09 11-70 11 '43 9-01 a -55 Temperature.. .. .. 17.3 37' 57" 68.2" 99.5" Density , , . . . . . . , 1-2601 1.2474 1 *2338 1 '2263 1 '2044212 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE p = 23455. Temperature. 15.4" 100 75 68'8 64'9 55 28 '3 25 '8 13 10.5 8 aD (200 mm.). -I- 4.21" 6 '94 6-60 6 *44 6'35 5-99 5.00 4'87 4'18 4.03 3 *89 Density. 1 '2098 1'1944 1'2125 I '21 73 1.2200 1.2271 1'2460 1.2480 1.2566 1 -2580 1.2597 t.1:. + 7-42' 12'39 11-61 11.28 11-10 10-41 8.55 8 -32 7.09 6'83 6.58 Densities determined : Temperature ...... 8.5" 21.4" 45 '2" 60' 100" Density ... . . . ,. . . .. 1.2600 1 *2512 1'2344 1 '2238 1 -1944 p = 48.125. Temperature. 100" 79 70.5 65.8 51 #2 46.5 41.8 39 -1 24 6 *5 aD (200 mm.). Densities determined : +12.97" 12-14 11 -57 11.31 10.49 9 *60 9-12 7 *24 4 '92 a -89 Density.1'1749 1.1920 1'1990 1 '2030 1'2145 1'2187 1 '2222 1 '2243 1'2368 1.2607 rai:. + 11 '47 10.58 10.03 9 -77 8 -98 8 -18 7-76 7 -54 6.08 4 *09 Temperature . . . . . . I 0" 36.3" 55" 7 0" 100" Density . . . . . . . . . . . . 1'2480 1'2269 1'2116 1'1993 1 -1749ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 213 Temperatcre. p = 69.93. C Z ~ (200 mm.). 98.5" 16 78'4 70.7 60-8 48.5 40.6 33 '9 19 Densities determined : + 18.82" 7.91 17-48 16.62 15-37 14.17 13-04 11-87 8 -78 Density. 1-1592 1'2310 1.1763 1.1832 1'1920 1.2028 1'2097 1-2153 1'2287 Temperature ............ 19" 45" 59.5" 80" Density . . . , . . . , , .,. , . , ., , 1.2289 1.2059 1.1932 1'1752 + 11-61" 4.59 10.63 10-03 9 *22 8'42 7-71 6.98 5.11 97" 100" 1'1592 1'1575 p = 89.98. Temperature. 98.5" 15.7 a3 77.8 70'2 66 '1 62.5 49'5 37.9 32.2 13 a, (200 mm.). + 25 *64" 11-72 24'49 24-03 23.01 22 *41 21.83 20.17 17-77 ' 16'73 11-25 ~ Density. 1'1392 1-2190 1.1540 1'1589 1'1665 1.1702 1,1736 1,1865 1.1975 1.2030 1.2212 + 12.50" 5 -34 11-79 11 -52 10.95 10.64 10'34 9 -44 8-25 7 *73 5'12 78" 100 Densities determined : Temperature ..... 8" 17" 35" 53" 72" Density ............ 1.2271 1.2178 1'2004 1.1828 1.1643 1.1582 l.1377 VOL. LXXIX. Q214 PATTERSON: THE INFLUENCE OF SOLVENTS ON THE Ezperirnent with Rochelle Salt, C,H4O,NaK,4H,O. p = 13.686. Temperature. a, (400 mm.). 15.6" 58.9 34 14.8 99'2 14 20" ? S 9 9 9 ) i b , +12-737" 12.834 12.905 12.772 12.482 12.760 5 10 25 50 75 10 Density. 1.0711 1'0521 1.0640 1.0715 1.0273 1-0719 + 21 '72" 22'28 22-15 21.77 22-34 21 '74 Densities determined : Temperature. 15.6" 30.8' 55" 70.1" 14.7" 98.8" Density ...... 1*0710 1'0654 1'0541 1.0457 1,0714 1.0269 Molacular-sol~tion-volume of Ethyl Tartrate in various ,Solvents. M=206. Molecular volume of ethyl tartrate at 20" = 206/1'2053 = 170.91 = +7*67. I t. Water : 20" I 9 9 9 a ? 9 ) ib 2 '5 5 10 24.954 49 '993 74'99 10 ~~~~~ d. 1 -0041 1'0100 1.0216 1.0574 1.1153 1.1673 1.0245 0.8070 0'8229 0.8741 0,9703 1'0824 0'8327 6. M. S. V. 158 '25 159.06 159.44 160.05 163.05 166.50 156.15 159.43 160'68 161'83 164.31 166'97 159'24 ~~ [a]:. + 25-82'" 26-10 26-00 23.60 17.33 11.70 26'30 11 -50 11-48 11.20 10.50 9-12 10'60 * This value is probably rather low.ROTATION OF OPTICALLY ACTIVE COMPOUNDS. I. 215 Molecular-solution-volume of E8hyl Tartrate, &c. (continued). 20" 9 9 9 , 2 1 ib I p. t . 5 10.94 20 40 60.01 10.94 Ethylialcohol : rt-Propyl alcohol : 20" 9 , 9 ) 11 3 , I , 1 , 1 , ib Glycerol : 20" 9 , 1 , 9 , 1 ) ib 15 2 -5 5 7 :713 10 17'507 25 37'51 49.834 74'99 5 4 -98 9.906 23-45 48.125 69-93 89.98 9'906 9'906 d. 0.8061 0 '8240 0.8532 0,9240 1,0054 0.8328 0 '8 11 3" 0-8183 0 '826 1 * 0'8339 0.8561 0.8790 0'7222 0.9677 1-0757 0.8267 1'2600 1 *2581 1-2521 1.2399 1.2277 1.2149 1.2649 1.2614 6. 0,7912 9 , 1 1 1 1 o - ~ b o o 0.8043 0*%55t 0.8043 1 J 1 ) $ 9 9 , 0*&27 1 '2608 1 7 9 1 9 1 9 1.6365 1 '2638 M. S. v. 163.57 165.89 165'93 166730 167.90 164.74 167.30 168.10 168-27 168-51 167.80 169-01 168.76 169.56 169.95 167-27 165.44 166'99 168.84 169.17 169-84 170-24 164.91 166.33 8.82 8 -57 8 -30 7-90 7 -55 7 '60 7 *30 7 *30 7 -38 6.97 7.00 6 '73 6-59 6 *41 6'54 5 -80 9 -97 9.30 7 *80 5-62 5 -19 6 -05 8.28 8 '82 * These are not experimental values. They have been obtained by interpolation from a density-concentration curve constructed from the other figures. This is rendered necessary by the fact that in so dilute a solution 3s one of p=2*5 a very slight error in density makes a very large error in M.S.V. The experimental values are, forp=2.5, d=0*8118, andp=7*713, d=0*8265. j- This experiment was done much later than the others, and when the alcohol used had probably absorbed some moisture. This research is at present being extended in order that the effect of a considerable number of other solvents, not only upon the rotation of ethyl tartrate, but upon those of other active substances as well, Q 221 6 MELLOR: ON THE UNION OF may be ascertained, and in order t o determine whether the ideas sug- gested here can be further developed so as to explain existing difficultiers and discover new regularities. YORXSHIRE COLLEGE, LEEDS.

ISSN:0368-1645    

DOI:10.1039/CT9017900167

出版商:RSC    

年代:1901

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21 6 MELLOR: ON THE UNION OF X1X.-On the Union of Hydrogen and Oilorine. Parts I to 1.1. By J. W. MELLOB. THIS paper contains the preliminary results of an investigation, sugges- ted by Professor Dixon, on the mode of formation of hydrogen chloride. So far as I can gather, William Cruickshank,l of Woolwich, was the first t o observe the gradual combination of hydrogen and chlorine gases. In reference t o the action of chlorine on hydrogen, hydro- carbons, and carbon monoxide he said on August 10, 1801 : “ If the pure oxigenated muriatic acid, in the form of a gas, be mixed in certain proportiona with any of these inflammable gases and introduced into a bottle filled with and inverted over water, though no immediate action may be at first perceptible, yet, in twenty-four hours a complete decomposition will be found to have taken place, the producte varying according t o the nature of the gases employed., . “I introduced into a phial with a glass stopper, filled with and inverted over water, one measure of pure hydrogen and afterwards two mea- sures of very pure oxigenated muriatic gas, this nearly filled the bottle; the stopper was then introduced very tight under water, and before the stopper was introduced, a whitish cloud appeared in the mixture yet very little or no diminution could be observed . . . ; at the end of twenty-four hours when the stopper was withdrawn the whole of the gas instantly disappeared except about one-tenth of a measure, which was found to be azote, and must have been originally contained in the two measures of oxigenated muriatic acid gas.I n tbis case the products were manifestly common muriatic acid and water, for the water in the phial contained common muriatic acid, but did not in the least smell of the oxigenated.” The words I have italicised appear to be the first record of a, pheno- menon named, Iater, the period of induction. On February 27, 1809, Gay Lussac and Thenard announced that an Compare Desormes and Clement, Ann. Chim., 1801, 89, 26 ; Berthollet’s “Easai de Statique Chimique,” 1803, 1, 423. Cruickshank, Hicholson’s Journ., 1801, [i], 5, 202.HYDROGEN AND CHLORINE, PARTS I TO .III. 217 explosive combination occurs when a mixture of hydrogen and chlorine gases is exposed to direct sunlight.l I n June of the same year, John Dalton showed the influence of light in this reaction, and on repeating Cruickshank’s experiment, also observed that ( I the gases after being put together (over water) seemed to have no effect for one or two minutes, when suddenly the mixture began to diminish with rapidity.” I n a letter to Goethe in 1810, Seebeck intimated that a mixture of hydrogen and chlorine gases contained in a clear glass vessel detonated the sunshine, whilst under a dark blue glass combination occurred without explosion in one minute, and under a dark red glass theaction either took place very slowly or not a t all.3 This observation was more particularly investigated by Berard (1813),4 Draper (1843),5 Favre and Silbermann (1853),6 and finally by Bunsen and Roscoe (1 85 7).7 Draper took up the subject about 1840, and made an instrument, called the tithonometer, to measure the rate of combination of hydro- gen and chlorine under the influence of light.The action of his in- strument is based on the fact, that the hydrogen chloride formed is at once absorbed by the liquid in the same vessel. The resulting con- traction is measured on a suitable index. Draper believed that the first action was to induce a more active, allotropic modification of chlorine, for he found that insolated chlorine combines with hydrogen more readily, and even in the dark. The period of inertness, pre- viously noted by Cruickshank and Dalton, was then also suppressed. This allotropism was not confirmed by Bunsen and Roscoe (1855), or by Askenasy and Meyer (1892),S although Favre and Silbermann (1853), and Amato (1884) have given experimental evidence in favour of Draper’s original statement. Fremy and Becquerel believe it to be due to the presence of oxychlorine compounds formed by tbe action of chlorine on the water vapour present.9 Draper also records that if an intense light, such as that of a spark from a Leyden jar, be momentarily 1 Gay Lussac and Thenard, Mem.phys. Chim. SOC. d’drcueil, 1809, 2, 340, or Gilbert’s Ann., 1810, 35, 8. Alembic Club Reprints, No. 13, p. 43. Dalton’s ‘‘ A New System of Chemieal Philosophy,” 1811, 2, 189. Seebeck, “ Von der Cheniischen Action des Lichts und der farbigen Beleuchtung,” in Goethe’s “ Zur Farbenlehre,” Tubingen, 1810, quoted in Eder’s “Geschichte der Photochemie und Photographie,” 1891, 1, 73. Berard, Ann.Chim., 1813, 85, 309. Draper’s “Collected Memoirs,” 1878 ; Phil. Mag., 1843, [iii], 23, 401 ; 1845, Favre and Silbermann, Ann. Chim. Phys., 1853, [iii], 37, 479. [iii], 27, 327. 7 Bunsen and Roscoe, Pogg. Ann., 1855, 96, 373 ; 1857, 100, 43, 481 ; 1857, 101, 235; 1859, 108, 193 ; 1862, 117, 529 ; Phil. Trans., 1857, 146, 355, 601 ; 1859 148, 879 ; Ostwalcl’s “Klassiker,” Nos. 34 and 38. Askenasy and V. Meyer, AnnaZen, 1892, 269, 72. Becquerel and Fremy, Wurtz’s “Dictionnaire d0 Chimie,” 1879, 2, 255.218 MELLOR: ON THE UNION OF flashed on to the mixture, a sudden expansion, followed instantly by a return to the original volume, takes place (therefore no formation of hydrogen chloride). This phenomenon mill be named, after its first observer, the I‘ Draper effect.” Favre and Silbermannl found that the heat developed in the action of insolated chlorine on potash was greater than that of non- insolated chlorine by some 39 cal.The increase in the activity of the chlorine is not accompanied by a change in volume. The first part of Bunsen and Roscoe’s classical work appeared in 1855. The final result was the establishment of the more important laws of the chemical action of light. These investigators, by means of a perfected form of Draper’s tithonometer, found that an amount of actinic energy disappeared in the act of photochemical combination equivalent to the amount of light absorbed. This phenomenon was styled ‘‘ photochemical extinction.” After the period of inertness, observed by Cruickshank, the rate of combination of hydrogen and chlorine was found to gradually increase until a maximum steady state was attained (period of acceleration 2).The interval between the first impact of light and the periodof constancy was termed the period of “ photochemical induction.” Bunsen and Roscoe also found that the presence of minute traces of oxygen, or of an excess of either of the reacting components, considerably retarded the rate of formation of hydrogen chloride. Gautier and Helier,3 under somewhat different conditions, found an acceleration in the rate when either of the react- ing gases is present in excess. This is what the dynamicnl theory of mass action would lead us to expect. In 1871, Budde discovered that when chlorine is exposed to a source of actinic light it occupies a greater volume.This expansion cannot be attributed to the direct effects of heat. Recklinghausen 5 (1894) found that a photo-expansion also occurs when the chlorine is mixed with hydrogen, carbon monoxide, or ethylene. No change in volume occurs when perfectly pure and dry chlorine is exposed to light under somewhat similar conditions (Baker6 and Shenstone 7). Since Bunsen and Roscoe’s great work, the most important contribu- tion to the subject was published by Pringsheims in 1887. Prings- LOC. cit. Veley, Phil. Mag., 1894, [v], 37, 165. Budde, PhiZ. Mug., 1871, [v], 4 2 , 290; Pqg. Ann. Ergbd., 1873, 6, 477. See Recklinghausen, Zeit. physikal. Chem., 1894,14, 494. Baker, Brit. Assoc. Rep., 1894. 7 Shenstone, Trans., 1897, 71, 471. * Pringsheim, Wied.Ann., 1887, 32, 384 ; Dixon and Harker, Hem. and Proc. 3 Gautier and Helier, Compt. rend., 1897, 124, 1121. also Richardson, Proc. London Phys. Soc., 1891, 11, 186. Manchester Lit. Phil. Soc., 1889, [iv], 3, 118.HYDROaEN AND CHLORINE. PARTS I TO 111. 219 heim rediscovered the Draper effect, and also found that by drying the mixed electrolytic gases the rate of combination was retarded, for in sunlight the reaction was only accompanied by a feeble clicking sound (“ ein sehr schwaches knisterndes Gerausch ”). Pringsheim believes that during the period of induction some such intermediate compound as chlorine monoxide is formed by the action of chlorine on the water vapour present, A most interesting observation has just been recorded by Cordier’ somewhat t o the effect that dry chlorine is transparent, but moist chlorine opaque, to the actinic rays.It has been my purpose to investigate the mode in which light effects the combination of hydrogen with chlorine. With this object in view, I began by studying the electrolysis of hydrochloric acid, and the solution of chlorine in this acid, since an exact knowledge of these processes is necessary to interpret the work of previous investigators. I.-THE ELECTROLYSIS OF HYDROCHLORIC ACID. The general and most convenient mode of preparing a mixture of equal volumes of hydrogen and chlorine gases (Chlorknallgas) is by the electrolysis of hydrochloric acid, under the conditions Bunsen and Roscoe I have examined the gases prepared by this method with a view to finding what impurities, if any, are present, The highly successful experiment of Baker 3 in which a dried mixture of hydrogen and chlorine, prepared by another process, did not completely combine when exposed for two days to the direct rays of the sun, has not been equalled by the use of the electrolytic gases.Bunsen and Roscoe have also shown that the influence of impurities in modifying the rate of combination of electrolytic hydrogen and chlorine is most remarkable. The amount of foreign gas sufficient to materially disturb the normal rate cannot approach the billionth part of the total volume of thegas.” Draper has stated that the electrolysis of hydrochloric acid never yields equal volumes of hydrogen and chlorine. Bunsen and Roscoe, however, very carefully studied the action, and came to the conclusion that small variations from equality in the proportions of the two gases can be brought within the limits of analysis by taking found to be most favourable.Cordier, Monatsh., 1900, 21, 660. Bunsen and Roscoe, Pogg. Ann., 1855, 96, 373. Baker, Trans., 1894, 65, 611. It might also be pointed out that 26 per cent. of the mixture remained uncombined after four days exposure, two of which were of bright sunshine. * Draper, Zoc. cit.220 MELLOR: ON THE UNION OF suitable precautions and keeping the strength of the acid over 23 per cent. of hydrogen chloride.1 If, during the electrolysis of concentrated hydrochloric acid, 4HC1+ 2H,O are decomposed to form 2HOClf 01, + 3R,, the electro- lytic gases would consist of (m + n)H, and (mHOC1 + nCI,), neglecting the hydrogen chloride and steam present.If a cylinder containing these gases be opened under an aqueous solution of potassium iodide, then for every four volumes of HOCl present a quantity of iodine equivalent to two volumes of chlorine will be liberated. In Bunsen and Roscoe’s analyses there is a mean error of - 0.72 per cent., assuming that the mixture contained equal volumes of the gases. Therefore, unless the electrolytic gases contain as impurity an amount of HOCl vapour exceeding 0.18 per cent., it would have escaped detection.2 A slight excess of hydrogen would also occur if a very little water were decomposed in the electrolysis. A large amount of matter has been published on the electrolysis of the hypochlorites and chlorides. The following refers to hydrochloric acid.Riche (1858) observed that dilute hydrochloric acid yields per- chloric acid when a current from 10 Bunsen cells is passed through it. Tommasi4 (1882) found chlorine oxides at the positive pole even with concentrated acid, and pointed out the possibility of their forma- tion by the decomposition of the hydrate, HCI,GH,O, or by the action of oxygen or water on the electrolyte. Haber and Grinberg (1898), in a very complete investigation, con- firm Bunsen and Roscoe’s observation. Working on small quantities, they have shown that concentrated hydrochloric acid, with platinum electrodes, furnishes a 100 per cent. yield of chlorine, which falls to zero with increasing dilution. They also trace the presence of varying quantities of oxygen, perchloric, chloric, and hypochlorous acids t o the combination of C1 ions with the OH ions of water.6 The great solubility of the liberated chlorine and its diffusion over to the cathode is, no doubt, an important factor in the inducing of secondary action^.^ It is this that causes the electrical sign of the 1 It is interesting to observe in this connection that E.Morley (Zeit. phyGkaZ. Chem., 1896, 20, 430) was unable to obtain an electrolytic mixture of hydrogen and oxygen in the proportions H, : 0 by the electrolysis of water. Bunsen, Annulen, 1853, 86, 273. Riche, Compt. rend., 1858, 46, 350. Tommasi, Compt. rend., 1882, 95, 689. 5 Haber and Grinberg, Zeit. anorg. Chem., 1898, 16, 198 ; 18, 37. 6 Matteucci found that the more intense the current, the greater the amount of 7 Townsend, Proc.Camb. Phil. Xoc., 1897, 11, 245, or PhQ. Mag., 1898, [v], a, oxygen evolved (Gmelin’s ‘( Handbook of Chemistry,” Eng. ed., 1848, 1, 455). 25 ; Enright, Phil. Mug., 1890, [v], 49, 56.HYDROGEN AND CHLORINE. PARTS I TO 111. 221 liberated hydrogen to change from its initial positive value to a final negative one. The formation of oxygen compounds of chlorine by the dissociation of chlorine water was first indicated by Millon 1 in an equation subsequently developed by Jakowkin in the following form : + C1,AqS (HOCl + H + 6)Aq. The electrolysis of aqueous solutions of chlorine is said to lead to the production of hydrochloric acid at the negative pole, and of chloric acid at the positive Oette14 has shown that nascent hydrogen at the cathode recombines with the chlorine in the solution.Gautier and Helier say, L’Qlectrolyse de !’acid chlorhydrique ou dos chlorures fournissent, B chaud ou A froid, un gaz m$lh d’oxyde de chlore, comme ou peut s’en assurer en le faisant passer, aprbs dessicca- tion prhalable, dans un tube de porcelain chauffQ au rouge, en receuillant dans une Bprouvette pleine de potasse les gaz dhgaghs, il reste toujours de l’oxyghe ralluman t les corps en ignition.” On carefully repeating this experiment, my equivalent to their “ tube de porcelain chauff B au rouge ” was broken by regurgitation of the potash solution. The ex- periment succeeds equally well without the hot tube, The following experiments prove that variable quantities of oxygen are evolved during the electrolysis of concentrated hydrochloric acid, SERIES 1.-Pure cold hydrochloric acid saturated with dry hydrogen chloride gas was subjected to electrolysis i n a cell from which the spent acid could be removed and new acid introduced without ad- mission of air (see Fig.1, p. 222). The electrode gases were led off separately on account of the subsequent heating of the anode gases, otherwise explosive combination occurs at 430-4409 The pre pared carbon electrodes were cemented in while warm with a pulp of asbestos and sodium silicate (water glass). I n other respects Bunsen and Roscoe’s directions were closely followed. (a), The anode gases were led through a three-way cock and two Mitscherlich absorption bulbs, the one containing water the other con- centrated sulphuric acid of sp.gr. 1 *9 ; then over fragments of glass wet with the same acid in a V-tube 7; thence through a heated glass tube, 1 Millon, Compt. rend., 1849, 28, 42. 2 Jakowkin, Ber., 1897, 30, 518 ; E. Mnller, Zeit. EZektrochem., 1900, 6, 573. 3 Balard, J. pr. Chem., 1835, 4, 167. 4 Oettel, Chem. Centr., 1895, [iv], 7, ii, 3. 5 Gautier and Helier, Compt. rend., 1897, 124, 1129, 1267. 6 Meyer and Freyer, Ber., 1893, 26, 428. 7 Bailey and Fowler (Trans., 1888, 53, 755) have shown that if the gas contains traces of hydrogen chloride, the reaction 2P20, + 3HC1=POC13 + 3HP0, occurs. Chromic and copper compounds are objectionable for removing the hydrogen chloride on acconnt of the possible action of hypochlorous acid. Hence it appeared better not to rise phosphoric oxide (compare Gutmann, Annalen, 1898, 299, 267 ; Baker,222 MELLOR: ON THE UNION OF and finally collected in an eprouvette over an aqueous solution of‘ potassium hydroxide.Air was carefully swept out of the apparatus. by means of a current of chlorine, prepared by Gautier and Helier’s process, until a blank experiment gave no result. The gases evolved during the first two hours electrolysis escaped via the three-way cock. The different parts of the apparatus were sealed together before the blowpipe. In an average experiment, approximately 13-1 4 litres of the anode gases gave 1.2 C.C. of oxygen (at normal temperature and pressure) in successive measurements of 0.4, 0.1, 0.3, and 0.4 C.C. (b). The dried cathode gases, from which chlorine and hydrogen had The experiments were done in a dark cellar.FIG. l.--Electroly2ic vessel. 3 been removed, were passed through a temoirz tube and then over warm palladium asbestos.l The water was absorbed in a weighed phosphoric oxide tube. Air was, as before, swept out of the apparatus by a current of hydrogen previous to an experiment. No perceptible increase in weight was noticed. The large quantity of desiccating agents used in these experiments E. Morley 9 has shown that a slow current of is a serious objection. Trans., 1898, 73, 422). Calcium chloride cannot be used, for any chlorine monoxide present would form hypochlorites (Garzarolli-Thurnlackh and Schachal, Annalen, 1885, 230, 280). 1 Winkler’s “ Anleitung zur chemische Untersuchung der Industrie-Gase,” 258, (1877). Morley, Amer.J. Sci., 1885, [iii], 30, 140.HYDROGEN AND CHLORINE. PARTS I TO 111. 223 air, passed through strong sulphuric acid, failed to remove something like 0.002 milligram of water per litre. This amount of moisture passed along with chlorine through a red hot tube mould probably liberate oxygen, but not sufficient to account for that obtained, The absorption of oxychlorine compounds, as well as of hydrogen chloride, would take place in the first washing bulbs. Whatever the method by which Gautier and Helier performed their (‘ dessiccation prblable, ” their hot tube is unnecessary, for the experiment succeeds equally well without it. Unfortunately, there is no satisfactory means of detecting hypo. chlorous acid (or chlorine monoxide) under the conditions of these experiments, as was shown by Haber and Grinberg in a recent ex- amination of iche delicacy of the various methods proposed for the detection of hypochlorous acid in the presence of hydrochloric acid.They also point out that Wolter’s methodP2 used by Pedler 3 to establish an equation for the action of light on chlorine water, is quite unreliable for ‘ I nachweisbare Mengen unterchloriger Saure konnen selbst in &=& norm. Salzsaure nicht mehr bestehen.” Millon’s * manganous chloride test can, however, be used as a ‘(Vergleichsprobe” with chlorine water, hypochlorous acid giving a brown colour rapidly, chlorine water slowly. Jakowkin confirms this observation and says, I ‘ es est deshalb ganz unerklarlich, auf welche Weise Pedler die An- wesenheit von HClO in einer Chlorlosung, welche (nach der Belichtung) uberschussige Salzsaure enthielt, konstatiert hatte.” SERIES 11.-A double globe (Fig.2) had a t one end three necks- two wider ones for carbon electrodes, and a central one carrying a two- way cock (a)-on the other end was sealed a capillary tube, bent twice a t right angles, and carrying a three-way cock (d). The free end of the capillary had a piece of wider glass tubing sealed on, as shown in the figure, p. 224. Both globes were filled with concentrated hydrochloric acid (completely saturated with hydrogen chloride in the cold) as far as the three-way cock, which was lubricated with glacial phosphoric acid, This filling was easily done by dipping the tip of a in the acid and connectingd with an aspirator, or as shown in the figure.The upper cock d was then closed, and the lower one partially so. An electric current was switched on (2--4volts), and while the globe b was being filled with electrolytic gas, the capillary tube, on the side of the apparatus, was filled with concentrated sulphuric acid by pouring the acid in e and applying suction a t d. A drying tube was then fitted on to e. The lower globe was painted black. 1 LOC. cit. 6 Jakowkin, Zeit. physikak Chem., 1899, 29, 613. Wolters, J. pr. Chem., 1873, [ii], 7, 468. 3 Pedler, Trans., 1890, 57, 613. LOC. eit.224 MELLOR: ON THE UNION OF When the globe b was almost full of the electrolytic gas, the cock at a was closed, and d opened for some two hours. The right and left hand sides of the vessel were then put into communication, and the upper globe exposed to some source of artificial light (coal gas lamp).The current was so regulated by the introduction of a suitable resistance that the ratio of the rate of formation of the gases H2+C12 and the rate of solution of the reformed HCl was approximately cons tan t. After 14 days, the three-way cock d was joined to a Hempel burette containing an aqueous solution of manganous chloride, and the current FIG. 2. stopped. All the air between the capillary of the cock and the burette was driven over into the right hand side of the apparatus. Water was then run into the lower cock, until all the gases in the upper globe were transferred to the burette. Analysis, by Haber and Grinberg’s method, invariably showed that oxygen is formed during the electrolysis.From this and the preceding experiments, it follows that if x be the amount of oxygen in the vessel at the end of the time t , we have: x = +(t). The manganous chloride comparison test generally shows the presenceHYDROGEN AND CHLORINE, PARTS I TO 111. 225 of traces of hypochlorous acid, thus confirming the suspicion of Haber and Grinberg. The gases exposed to the light are, therefore, a mixture of chlorine, hydrogen, steam, hydrogen chloride, and oxygen, There is probably a condensation of water vapour on the glass. A reaction between chlorine and water is, therefore, quite possible. From the thermo- dynamical principle of maximum work, it can be shown that, while gaseous chlorine will not decompose steam at loo’, it will act slowly on water at atmospheric temperatures.Thus, in round numbers : (1). Water Vapour and Chlorine Gas. [H2,0] gas a t looo= + 58 Cal. ; [H,Cl] = + 22 Gal. H20 (gas) + 2Cl (gas) = 2HC1 (gas) + 0 (gas) - 14 Gal. (2). Liquid Water and Chlorine Gas. H,O (liquid) + 2C1 (gas) + Aq = 2HClAq + 0 (gas) -t- 10 Cal. [H2,0] liquid = 68.4 Cal. ; [HCl,Aq] = + 17.2 Cal. Under similar conditions, in a cool cellar and an atmosphere of It is thus evident that : (1). Oxygen is present among the gaseous products of the electro- lysis of hydrochloric acid. (2). Even though traces of the lower chlorine oxides may be formed during the electrolysis, it is unlikely that any escape a preliminary washing of the gases. moist chlorine in the globe 6, a negative result was 0btained.l 11.THE SOLUBILITY OF CHLORINE IN AQUEOUS HYDROCHLORIC ACID. When a mixture of equal volumes of hydrogen and chlorine in the presence of water saturated with the two gases is exposed to the action of light, hydrogen chloride is formed by the water a t a rate pro- portional to the intensity of the light. Thinking that this absorption of the hydrogen chloride might disturb the equilibrium of the gases in the insolation vessel of Bunsen and Roscoe’s actinometer, I have in- vestigated the solubility of chlorine in water containing varying quantities of hydrogen chloride at a constant temperature. See the various reports to the British Association collected by Richardson (23. A. Reports, 1888, 89 ; 1889, 69 ; 1890, 263). Bunsen and Roscoe (this Journ., 1856, 8, 190), investigating Wittwer’s proposal (Pogg. Ann., 1855, 94, 527) to measure the chemical action of light by the decomposition of chlorine water [say, 2C1, (liquid) + 2H20 (liquid) = 4HC1 (liquid) + 0, (gas)], found that the presence of hydrochloric acid greatly retarded the action.226 MELLOR: ON THE UNION OF No systematic work appears to have been done on this subject.Three isolated records were all I could find. I n 1856 Roscoe 1 found that the presence of 1/120th part of hydro- gen chloride lowered the value of the coefficient of absorption of chlorine in water from a=2*3911 to 1.9789 at 14’. (1880) found that a 38 per cent. solution of hydrogen chloride absorbs 17-3 grams of chlorine per litre ; a solution containing 1/3HC1, that is, 33 per cent., 3 absorbs 11.0 grams; whilst a 3 per cent.solution absorbs 6 grams of chlorine per litre (temperature not stated). Berthelot suspects the formation of hydrogen perchloride, HCl,, in strong solutions, and quotes thermochemical data in support of this view. Goodwin 4 (1882) investigated the influence of temperature on the solubility of the following different strengths of acid and found : Berthelot Hydrochloric acid of sp. gr. 1.046, a=2*5403 at 23.6’ (752 mm.). ?, 1, ,, 1.080, a=4*1433 at 15.5’ (763 mm.), 9, 9 , ,, 1.125, a=4-7631 at 20.7’ (762 mm.). In my preliminary work I found that Heidenhain and V. Meyef’s method for saturating the liquid by shaking with the gas did not work so satisfactorily as the one described below. Chlorine, evolved from the liquid, was washed in boiled distilled water, then in chromic acid solution, and again in water, The gas was then passed into a vessel containing the given solution until two titrations, with sodium thiosulphate, showed constant figures, The saturation vessel stood in a water-bath maintained at a temperature of 20-21’ by means of a This work was done in a dark cellar.Ten C.C. of the saturated solution were run 7 into an aqueous N/10 solution of potassium iodide. The free iodine was determined by Roscoe, this Journ., 1856, 8, 14. Berthelot, Ann. Chim. Phys., 1881, [v], 22, 462 ; or Compt. rend., 1880, 91, 194. 3 A. M. Comey, “Dictionary of Solubilities,” 105, 1896, translates this as one- third of the 38 per cent. solution, and, therefore, wrongly reads “ 12.7 per cent. HCl absorbs 11 grains of chlorine per litre.” Goodwin, Trans.Roy. SOC. Edin., 1882, 30, 597 ; or Ber., 1882, 15, 3039. Timofeeff, Zeit. physikal. Chem., 1890, 6, 141. This temperature was chosen t o eliminate, as far as possible, any disturbance due to the formation of hydrates (compare Roozeboom, Rec. trau. Pays-Bas, 1884, 3, 59 ; 1885, 4, 69 ; Isambert, Conzpt. rend., 1878, 86, 481). The slight loss of chlorine involved in the withdrawal of this liquid by a suction pipette is avoided by using a pipette similar to that described by Reid (Chem. News, 1892, 66, 167), or Rnting’s patent pipette (Zeit. physikal. Chem., 1899, 29, 626).HYDROGEN AND CHLORINE. PART8 I TO 111. 227 means of standardised sodium thiosulphate solution in the usual way. The loss due to the decomposing effect of hydrochloric acid on the thiosulphate was negligibly small, since the thiosulphate was added direct to the iodine.2 Let 0 be the temperatuqp the height of the barometer in mm.of mercury, u the coefficient of absorption, X the coefficient of solubility, n, the number of C.C. of the standard thiosulphate required in titrating, w the volume of chlorine in C.C. absorbed by the given solution. Since each C.C. of the thiosulphate solution was equivalent to 0*01386 gram of iodine, or 0*003848 gram or 1.2127 C.C. of chlorine, that is, v = 1.2127, 273 p v a=- 273+8.760 3' For chlorine in pure water a t 2l0, u=2*1167, Schijnfelds gives 2.1148. The variations in the barometer readings were so small that fheir influence on the results is well within the errors of experiment.Temperature variations were, for the same reason, neglected. Hence : 273+0=n. 273 x 1.2127. Absorption coeficients of chlorine. Grams HCI Per 1000 C.C. 313.401 282*060 250'720 2 19 '380 188'040 156.700 125 *3 60 94.020 62.680 31 *340 15'670 12.540 9 *402 6.248 3.134 nil 2%. 31.52 29 *57 27.77 25'82 24-01 22.30 20.18 18.73 16'60 14-87 13-27 12.61 12.38 12.87 1377 18-80 P. 761 761 759 759 761 761 761 760 760 762 759 759 760 760 760 760 ~ t". 21 *o 21.0 21'0 21.0 20'2 20 '2 20 *5 20 *5 20.0 31'0 21'0 21.0 21.0 20 '0 21'0 21 '0 Grams C1, Per 1000 C.C. 12.03 11-87 10.68 9 -93 9 '23 8-58 7 *76 7'19 6'38 5 '81 5-10 4-85 4-76 4'94 5 *30 i 7'23 a. 3'5492 3 '3278 3.1272 2,9243 2.7020 2'5095 2.2711 2'1044 1'8682 1'6736 1 '4933 1 '4200 1'3942 1'4483 1.5496 2.1157 ~ A.3.8224 3.6859 3.3677 3.1312 2.9117 2.7043 2.4473 2,2677 2.0131 1.8033 1.6092 1.5292 1.5013 1.5607 1.6698 2.2799 When the amounts of hydrogen chloride contained in the solution are plotted as abscissz against the amounts of chlorine absorbed, two n, Norton, Arner. J. Xci., 1899, [vii], 7, 237. 3 Schonield, Annalen, 1855, 93, 26. Pickering, this Journ., 1870, 37, 135.228 MELLOR: ON THE UNION OF distinct curves appear. The one is subsequently referred to as the ‘I curve of dissociation,” the other as the ‘‘ curve of association.” The first action of chlorine on dilute hydrochloric acid is apparently represented by some exponential curve which intersects another simpler linear curve represented by the equation : p=ap+b where a and 6 are constants approximately equal to 0.023 and 4.92 respectively, and p and p respectively denote the amounts of hydrogen chloride and of chlorine per 1000 C.C.of solution. Grams of HCl per 100 C.C. = p. Isothemnal curve of the solubility of chlorine in aqueous solutions of hydrochloric acid of varying concentration. Jakowkinl has proved that the action of chlorine on water is a reversible dissociation somewhat in the form of the equation : CI,Aq t (HC1+ HOC1)Aq. He takes advantage of the fact that undissociated chlorine divides in a known ratio between water and carbon tetrachloride, in order to Jakowkin, Zeit. physikal. Chem., 1899, 29, 613.HYDROGEN AND CHLORINE, PARTS I TO 111. 229 determine the amounts of dissociated and undissociated chlorine in aqueous solution, hydrochloric and hypocblorous acids being insoluble in carbon tetrachloride.According to the dissociation theory, HClAq t. (H + Cl)Aq, while the hypochlorous acid suffers little if any dissociation. The latter statement is confirmed by (1) its weak acidity; (2) its easy hydrolysis with strong bases; (3) the rapid increase of its molecular conductivity with dilution ; and (4) its normal molecular weight by cryoscopic methods. + - Even in darkness the action is termolecular, 3 . - C1,Aq (H + C1+ HOCl)Aq, and is therefore denoted by the formula where A represents the total number of gram-molecules of chlorine in the solution, c that of the undissociated chlorine, A - c the number of dissociated chlorine molecules in the solution. The total volume of a substance taken up by unit volume of solvent is often referred to as the apparent solubility, whilst the amount of substance which remains unchanged in unit volume of solution is termed the real solubitity. Applying Nernst’s distribution law,l A = c + ( A - c ) , + + and since for every C1 ion that goes to form HOCl one H ion is set free, we have, according to the mass law, c R = { A - c ) ~ .’ (2) where K has not necessarily its former vahe. If c2 is the concentration of a second electrolyte which has one ion in common with the ions already in solution, we have for H or C1 ions, as before, and But since A’ = d + (A’ - c’), c’R’ = (A‘ - c‘)(A’ - C’ + c2) . (3) ( A - c ) < ( A ‘ - c ’ ) cf > c, that is, the amount of undissociated chlorine will be increased by the addition of a second electrolyte containing either H or C1 ions ; hence Nernst, Zeit.physikal. C%enz., 1889, 4, 372 ; Noyes, i6id., 1890, 6, 241. VOL. LXXIX. R230 MELLOR: ON THE UNION OF it follows from the ‘‘ theorem of constant solubility ” that the soh- bility of chlorine will be diminished. Let X represent the apparent solubility, and x the real solubility of chlorine in hydrochloric acid, x the amount of chlorine or of disso- ciated (Ht-C1) in solution according to Jakowkin’s equation, y the amount of chlorine in solution assumed, for the present, to be in some way combined with HCl. Hence + - X = x + x +ye For dilute solutions we should have x = x + x . The value of x is easily calculated from the dissociation data compiled by Fitzgerald in the Reports to the British Association, 1893.l The results are not altogether in accord with experiment, showing that under these conditions x is either not constant, or y cannot be neglected.Beyond a certain limit, however, y becomes relatively large, while x becomes small. That is assuming x to be constant. This diminution in the solubility of chlorine can be readily shown in a qualitative way, by adding a few C.C. of concentrated hydrochloric acid to a quantity of saturated chlorine water contained in a narrow vessel. Bubbles of chlorine soon form and escape to the surface. It is evident from the termolecular action of chlorine on water : (1) The addition of an electrolyte capable of supplying C1 ions to the solution will cause a diminution in the solubility of chlorine.Thus Kumpf,2 G~odwin,~ and Jakowkin3 have shown this diminu- tion in the solubility of chlorine in saturated solutions of alkali chlorides. The separation of sodium chloride, when chlorine is passed into saturated aqueous solutions, is another consequence of the same law. Conversely, Engel has shown4 that the addition of hydrogen chloride diminishes the solubility of electrolytic chlorides. Non- electrolytic chlorides, however, do not influence tho solution unless molecular association occurs : for example, mercuric chloride. (2) The addition of an electrolyte capable of supplying H ions must also effect a reduction in the solubility of the chlorine. This has been proved, for the electrolytic acids, nitric acid, hydro- 1 Reprinted in Whetham’s ‘‘ Solution and Electrolysis,” 215, (1895).2 Kumpf (Innug. Dissert.) Wied. Biebl., 1882, 6, 276. LOG. cit. Engel, Bull. SOG. Chim., 1889, [iii], 1, 695 ; or ConLpt. rend., 1889, 104, 1710 ; Ditte, Aim. Chirn. Phys., 1897, [vii], 10, 556.HYDROGEN AND CHLORINE. PARTS I TO 111. 231 chloric acid, sulphuric acid, and acetic acid, and its three chloro-deriva- tives. Non-electrolytic acids have no influence on the result: for example, boric acid. (3) The addition of hypochlorous acid reduces the solubility of chlorine in water, since it acts in virtue of the change, C1,Aq = (HC1 + H0Cl)Aq. Hydrogen chloride, supplying as it does both H and C1 ions, has a very marked influence in dilute solution. This is shown in Fig. 3, p. 228, as an isothermal curve of dissociation. The more concentrated the solution of hydrogen chloride the less the dissociation, For very concentrated solutions of hydrogen chloride we should expect a bimole- cular action : C1,Aq (HC1+ HOCl)Aq, and from equation (1) - (4) ( A - c ) ~ K= ~ cK= ( A - c)(A - c + x), C or where x denotes the number of hydrogen chloride molecules added to the solution.When the amount of dissociated chlorine (z) in the solution is exactly equivalent to the amount in combination (y) x, or y = g(X - x). From Berthelot's original paper,l the conclusion may be drawn that there is a concentration of hydrogen chloride having a maximum - NO. - 1 4 5 2 6 3 7 8 7 C.C. Thio- sulphate. 17-7 18'9 21 '7 23'4 31.1 31 *8 34.9 36-2 Gram HCl Per 100 gram If solution. 2'90 3 -22 11 ti3 12.19 31'24 32-00 34.57 35.90 Gram C1 per litre.6-0 6.3 7 -2 7 '76 10'3 10.55 11-6 12.7 t. ~ 15-0 16.3 1 6 3 15'0 16'3 15.0 16.3 16'3 Berthelot. 'e&Et' Gram C1. 1 ---I I- 759 763 763 759 763 759 763 763 3 3 - - 33 33 38 38 6 -0 6-0 - - 11.0 11.0 17'3 17-3 The number 17.3 for the weight of chlorine in a 38 per cent. solution of hydro- chloric acid attributed above to Berthelot is given in his paper as 7-3. He has recently informed me that this is a misprint. The mistake also occurs in Comey's Dictionary. The experiments in the text were made a t the end of 1899 in the attempt to find a point of maximum solubility, before i t was found that 7.3 was not the true number. R 2232 MELLOR: ON THE UNION OF power of absorption for chlorine. Hydrochloric acid saturated with hydrogen chloride in the cold was used for the strongest solution.The chlorine was passed into the solutions as indicated above. Free chlorine was determined by the usual thiosulphate titration, total chlorine by boiling 10 C.C. of the saturated solution with ferrous sul- phate and aqueous potassium hydroxide. The chlorine was then pre- cipitated as chloride from the solution, acidified with nitric acid, and weighed in the usual way. One C.C. of thiosulphate = 0.003319 gram of chlorine. There is thus no indication of a point of a maximum followed by a diminishing solubility with increasing concentration. An objection to the preceding method of finding the solubility of chlorine in the stronger solutions might be pointed out. I f the current of gaseous chlorine occupies any considerable time, the acid will tend to attain that particular concentration which has a constant com- position, and at equilibrium, the chlorine and hydrogen chloride will be distributed according to their partial pressures and the phase rule. On the Zxistence of HCI, in Liquid Solution.The curve of association indicates the possibility of the existence of some combination of hydrogen chloride and chlorine, possibly stable only in the presence of a great excess of hydrogen chloride, just as the great quantity of chlorine retained by strong solutions led Draper 2 to believe in the existence of a, ‘‘ bichloride of hydrogen,” and Ber- thelot of a g‘ perchloride of hydrogen.” I n a quite analogous way, Engel found that the solubility of certain chlorides is increased if hydrochloric acid is present in the solution owing to formation of ‘( chlorhydrates.” Some of these were isolated ; for instance, those of Etannic, ferric, cupric, and mercuric chlorides.The following evidence for the existence of HCI, might be cited : (1). The existence of other well-established tri- and penta-halides.4 (2). The partition-coefficient of iodine, between aqueous solutions of potassium iodide and carbon disulphide, leads t o the formula KI.1, (Jak~wkin).~ 1 Perman, Trans., 1895, 67, 868. Draper, Phi2. Mag., 1843, [iii], 23, 431. 3 Millon (J. Pharm., 1841, 28, 299) regarded the yellow liquid remaining when lend chloride is removed by the cooling of the products of the interaction of lead peroxide and concentrated hydrochloric acid according to the equation PbO, + 6HC1= PbC], + 2H2O+2HC1,.It is now generally believed that the action is Pb02+4HC1= PbCl,+ 2H,O, although the action PbO,+ 5HC1=PbCl2+ 2H,O + HC13 appears to be equally probable. 4 Conipare Wells, Amer. J. Sci., 1892, [iii], 43, 17 ; Wells and Wheeler, ibid., 1892, 44, 42, 475. 5 Jakowkin, Zeit. physikal. Chm., 1894, 13, 539. Compare Wilderman’s BrHBr,, &c., ibid, 1893, 11, 407 ; Noyes and Seidenstraker, ibid., 1898, 27, 357.HYDROGEX AND CHLORINE. PARTS I TO 111. 233 (3). The increasing solubility of chlorine with increasing additions of hydrogen chloride, arid the analogy with Engel’s “ chlorhydrates.” (4). The heat disengaged by solutions of chlorine in concentrated hydrochloric acid approaches that required for HCl,, and resembles that required for KI, and KBr, (Berthelot).On the Existence of HCI, in Guseous Solution. Evidence for the existence of gaseous HCI, was sought by bringing hydrogen chloride and chlorine together in the dark by means of the apparatus devised by Dixon and Harker.l A slightly greater con- traction occurred, differing from that with hydrogen chloride and air, or with chlorine and air. This might be attributed either to a con- densation of the gases on the glass or else to some form of molecular attraction between hydrogen chloride and chlorine. The only evidence of chemical combination between certain gases is a slight difference between the total volume occupied by the separate and by the mixed gases. It is assumed that if no chemical combination takes place, the mixture will obey Dalton’s law of partial pressures, namely, ‘‘ the pressure exerted by a mixture of gases is equal to the sum of the pressures separately exerted by the several components.” The work of Regnault on mixtures of air with carbon dioxide and with sulphur dioxide ; of Andrews on mixtures of carbon dioxide with air and with nitrogen, and of Braun4 on mixtures of sulphur dioxide and carbon dioxide, sulphur dioxide and hydrogen, sulphur dioxide and nitrogen, hydrogen and carbon dioxide, hydrogen and air, hydrogen and nitrogen, and carbon dioxide and air, shows that Dalton’s simple law of addition is not strictly followed.Dalton’s law assumes : (I) That each component exerts the same pressure in, the mixture that it would if it occupied the space alone.To avoid this limitation, Sarrau5 has proposed to recast Dalton’s law somewhat in this form : the specific volume of a mixture of gases is equal t o the sum of the specific volumes of the several components. Leduc and Sacerdote6 find that in this form the law agrees better with the results of their experiments. 1 Dixon and Harker, M e m . and Proc. Maitchester Lit. Phil. Soc., 1890, [iv], 2 Regnault, Mem. de I’Acad., 1862, 26, 256. 8 Andrews, Phil, Mag., 1876, [ v ] , 1, 7 8 ; Phil. Trans., 1888, 178, 57. 4 Braun, Wied. Ann,, 1888, %> 943. G Sarrau’s “ Introduction h la Theorie des Explosifs,” 25, (1895). 3,118. Compt. rend., 1898, 126, 218, 1853 ; Leduc’s “ Recherches sur les gaz,” 106, (1898).234 MELLOR: ON THE UNION OF D. Berthelot 3 has deduced an expression from van der Waals’ equa- tion which gives results in close agreement with experiment for the change of pressure accompanying the mixing of gases, for example : Observed increase.0.0001 1 atm. (Sacerdote). CO, + so, ... ... 0*0019 ,, 1 0*0018 ,, CO, + N,O , . . . . . 0°00013 atm. 9 , Calculated increase. These calculations are based on the assumption that the change of pressure which accompanies the expansion of each component of the mixture obeys van der Waals’ modification of Boyle’s law. Some interesting examples in which the final pressure is obscured by the dissociation of one of the components of the mixture are treated in a recent paper by Professor Dixon and J. D. Peterkin., (2). That the molecules of the diferent gases exert nezther attractive nor repdsive forces on one another.According to the kinetic theory, intermolecular attraction will (1) increase the number of collisions between the molecules, (2) cause certain molecules to swerve from their normal rectilinear path, (3) diminish the outward pressure of the gas. The molecules of such a gas are only attracted from within, its volume will therefore be less than that of a gas containing the same number of non-attracting molecules subject t o the same external pressure. It is proved in works on the kinetic theory of gases that for every molecule that loses its motion by collision, another will acquire the same motion by another simultaneous collision. That is to say, unless the attracting molecules during a collision remain in contact a longer time than non-attracting molecules, their motion will go on just the same as if there were no collision at all.Sutherland 3 by assuming that this attractive force varies in- versely as the fourth power of the distance between the molecules, has deduced very satisfactory formulse to explain certain physical proper- ties of gases. For instance, Lord Kelvin and Joule found that the cooling effect produced when n, mixture of gases undergoes expansion is not exactly the value calculated on the assumption that there are no attractive forces between the molecules. Sutherland, applying his lam of the inverse fourth, obtains results in harmony with experiment. Similarly with the variation of viscosity with temperature, diffusion of gases, &c. The term av-2 in van der Waals’ equation is intended to allow for 1 D.Berthelot, Contpt. rend., 1898, 126, 954, 1030, 1415, 1703, 1857 ; 1899, 2 Dixon and Peterkin, Trans., 1899, 75, 613. 3 Sutherland, Phil. Mag., 1893, [v], 36, 507 ; also 1886, [v], 22, 81 ; 1895, [v], 128, 1159 ; Leduc, ibid., 1898, 126, 1859 ; Van der Waals, ibid., 126, 1856. 40, 433.HYDROGEN AND CHLORINE. PARTS I TO 111. 235 the effects of the attraction OF the molecules when gases undergo certain changes in volume under the influence of a varying pressure. In a private communication last June, M. D. Berthelot pointed out to me that there is no reason to suppose that the increase of pressure calculated for the mixture of hydrogen chloride and chlorine would differ very much from that for the mixture of carbon dioxide and sulphur dioxide, unless the chlorine exercised some action on the walls of the vessel.Of course this action may to some extent be allowed for by a preliminary saturation of the walls of the vessel with chlorine and comparative experiments with other gases. Any slight contraction, therefore, which might occur on mixing two gases (say hydrogen chloride and chlorine) cannot be taken as con- clusive evidence of a chemical combination (say, formation of HCIJ until it has been shown that intermolecular forces are inadequate to account for the discrepancy. 111. THERMODYNAMICS OF SOLUTIONS OF CHLORINE AND HYDROGEN CHLORIDE IN WATER. If hydrogen chloride be added to a saturated solution of chlorine water in equilibrium with its atmosphere, the chlorine will be redis- tributed until the potential energy of the system attains a minimum value.From the properties of the thermodynamical potential, it can be shown t h a t for an increase 6v in the amount of HCl present, there will be an increase or a decrease in the amount of chlorine retained by the solution, according as the van’t Hoff factor i is less or greater than unity. J. Willard Gibbsl (1876) has shown that the differential of the energy of any material system, subject to gain or loss of energy and of mass, is expressed by the equation : dU= ed+ -pdv + pldm, + . . . pndmn . . - (1) where U denotes the energy, 8 the absolute temperature, CP the en- tropy, p the pressure, IJ the volume, ,U the (‘ potential ” (Gibbs) or ‘‘ intensity ” (Helm) factor expressing the rate of increase of energy in a reversible increase of unit mass with constant volume energy, namely : where rn denotes the mass of the body, and as a suffix implies that all other m’s in the above formula are constant.See H. le Chatelier’s ‘‘ Equilibre des S y s t h e s Chimiques, par J. Willard Gibbs,” 54, (1899).236 MELLOR: ON THE UNION OF Putting, with Duhem, aj=U-OQ,+pv . . . . . (2) d@ = - + d O + v d p + S p h . . . . . (3) we get from (1) where CP is clearly a quantity depending only on the parameters describing the particular state of the system, that is, @ is R complete diff erentia1,l and a2Qr - a2Qr aX,aX, ax,ax,’ - - _ _ Consider now the work (W) gained during an isothermal compres- sion from an initial pressure po to a greater pressure pr and, integrating by the aid of the ordinary gas equation, v = RBlog,31 , .. . . ( 5 ) P O By differentiation of (2) d@ = vdp- +do, and since d@ is a perfect differential, as in Massieu’s well known functions, from (4), therefore da? = vdp It now remains to show tbat @ is a function of the amount of chlorine in solution, or that where X is the coefficient of solubility, The extension of the gas laws to dilute solutions by Arrhenius, van’t Hoff, and Nernst, enables the various components of the mixture to be expressed as functions of the parameters describing the thermo- dynamic state of the mixture. Nernst’s distribution law allows us to replace the uapowr phase in the extension of Gibb’s equation to Henry’s law, by a second liquid phase. Let the formula @ = f ( 0 pu = i K 8 .. . . . . . (7) 1 Duhem’s ‘‘ Le Potential Thermodynaniique,” 33, (189s) ; Trevor, J. Phy&Z Ch., 1897, 1, 205, 633.HYDROGEN AND CHLORINE. PARTS I TO 111. 237 be applicable to dilute solutions of electrolytes, p n o w representing the osmotic pressure of the dissolved substance, i the isotonic coeffici- ent greater than unity for dissociated substances, that is to say i = a gram-molecule of the substance in solution. From (2), ( 6 ) , and (7), if a, now represent the potential of a given mass, i, of chlorine in dilute solution of hydrogen chloride, Q2 that of a more dilute solution, we have at constant temperature, where p , and p , represents the osmotic pressures of the chlorine in. the two solutions, hence d@, = iRBdhgeg2. PI If the molecular weight i of chlorine in the two solutions is the Barnel then, by the properties of dilute solutions, where Cl and C, are the cdfiegntrations of the two solutions C =- . ( t) We have, therefore, the relation d@=iI&dlog$2 . . . I . - , (9) c, = df (A> I n words the potential energy of chlorine in dilute solutions of hydrogen chloride is increased by a further addition of the latter gas. By Helmholtz's law, any dynamical system behaves so that the decrease in the potential energy may be a maximum, therefore the solution under these conditions cannot dissolve so much chlorine. If otherwise, the gas is either present in a supersaturated state, that is, in a state of unstable equilibrium (I' faux Bquilibres," Duhem), or else the stipulation that the molecular weight, i, of chlorine is constant in the different solutions, no longer holds. In stronger solutions the same solution has phases in which the. van't Hoff factor may be b l , i"<l, i = l . From the earlier part of this paper it follows that there is a, considerable variation in the relative values of i for chlorine in the different solutions of hydrogen chloride. For the curve of dissociation i'>l, and for the curve of association i"<l. In the more dilute solu- tions of HCl, the relative proportion of i'> 1 is the greater, while in concentrated solutions i"<l is the larger. At the point of inter-238 DAWSON: ON THE NATURE OF POLYIODIDES AND THEIR section of these two curves, we can say no more than that the amount of chlorine (Sx) for which i’>1 may be equal to the amount 89 for which i < 1, or dx: dy dz dy +=@ dp dp or ---=O. where p is the amount of hydrogen chloride in the solution. It is then evident from an equation similar to (9) that if, corre- sponding to HCl,, iff < 1, the solution will dissolve more chlorine in order that the potential energy may be a minimum, an inference which may be deduced from (1) when the system includes another term p2dm,. There is, however, a considerable amount of uncertainty as to what actually takes place in these and all other concentrated solutions. No further progress can be made in a quantitative way until this has been determined. A consistent theory for concentrated solutions is wanting. THE OWENS COLLEGE, M ANCHESTER.

ISSN:0368-1645    

DOI:10.1039/CT9017900216

出版商:RSC    

年代:1901

数据来源: RSC