constants. This we accordingly did, and our results, as will be seen, agree very well with those of Walden. In the following tables, v = number of litres which contain 1 gram-molecule of the acid. molecular conductivity at the dilution v. = = Моо molecular conductivity at infinite dilution. m = degree of dissociation po/MOO. All the determinations were made at a temperature of 23°. Monomethylsuccinic Acid, m. p. 111°. Moo 354. 0.0196. Walden gives K = 0.0191 for acid, m. p. 194°. K. 0.0191 0.0193 0.0201 0.0205 as-Dimethylsuccinic Acid, m. p. 140°. μoo=352. Mean, K=0.00805. Walden gives K=0·0080. Mean, K=0·0321. Walden gives K=0·0307 for acid, m. p. 139.5°. In Table VI, we give the properties of the methyl-substituted succinic acids, their insoluble calcium salts, anhydrides, and anilic acids: One of us, in conjunction with Dr. J. J. Sudborough, is engaged on an investigation of the hitherto little known methylic hydrogen salts of substituted succinic acids, and also in an attempt to resolve one of the s-dimethyl- and trimethyl-succinic acids into their active components. Finally, we are studying the interaction of the sodium derivatives of ethylic cyanosuccinates and the ethylic salts of a-bromofatty acids. The results of these various investigations will in due course be communicated to the Society. OWENS COLLEGE, LXXXI.-Some Derivatives of Dibenzyl Ketone. By FRANCIS E. FRANCIS, B.Sc., Ph.D., Lecturer in Chemistry, University College, Bristol. R. SCHIFF has shown (Ber., 1898, 31, 205, 601, 1304, 1388; 1899, 32, 332), that benzalaniline forms additive products with acetoacetic ester and similar substances, giving, under certain conditions, three isomeric products. These, he considers, correspond with the ketonic, enolic, and keto-enolic forms of the original substance. When acetoacetic ester itself is used, equal molecules generally give rise to an additive product corresponding with different mixtures of the two desmotropic forms of the ester; the melting point lies between 95° and 100°, but in two cases was as high as 103-104°, pointing to the fact that the ester consisted of the pure enolic modification. When two molecules of the ester are mixed with one of benzalaniline, the resulting substance melts at 103°, and corresponds with the enolic form. A trace of piperidine introduced in the second case gives the third isomeride, melting at 78°, and corresponding with the ketonic modification of the ester. A trace of sodium ethylate changes this back to the enolic form, melting at 103°. That acetoacetic ester itself and the additive products melting at higher temperatures contain the enolic group is shown by the fact that they give reddish-blue colorations with ferric chloride. Dibenzyl ketone gives no colour reaction with this reagent; now, if the ferric chloride reaction for the enolic modification holds with such compounds, this might be taken as showing the absence of any such form in the original substance. When an alcoholic solution of the sodium salt is poured into dilute sulphuric acid at a temperature of -10°, the ketone that separates certainly gives a dark coloration with ferric chloride, which rapidly disappears, but the result is not sufficiently definite for any conclusions to be drawn. Dibenzyl Ketone and Benzalaniline. 1. When equal molecules, or two molecules of the ketone to one of benzalaniline, are mixed together, a syrup is obtained which slowly solidifies; when this is dried on a porous plate and recrystallised from boiling benzene, the additive product separates out, on cooling, as a mass of silky needles, giving no reaction with ferric chloride, melting at 164.5°, and yielding the following data on analysis : Found C 86·31; H=6·41; N = 3.82. C28H25ON requires C-85.93; H=6·39; N = 3.58 per cent. VOL. LXXV. 3 M A molecular weight determination by the boiling point method, using benzene as solvent, gave 413, the calculated value being 391. 2. When a trace of piperidine is added to either of the above mixtures, and, after solidification and drying, the mass is recrystallised from benzene, crystals melting at 174.5° are obtained. The same substance can also be produced by recrystallising the additive product melting at 164.5° from benzene containing a trace of piperidine. It gives no reaction with ferric chloride. On analysis, the following figures were obtained : Found C 86.14; H = 6·47. C28H25ON requires C=8593; H = 6.39 per cent. A molecular weight determination by the boiling point method gave 403, the calculated value being 391. 3. When either of the mixtures of dibenzyl ketone and benzalaniline is treated with a trace of sodium ethylate, the additive product, after recrystallisation, melts at 164.5°, but if this form, or that melting at 174.5°, is recrystallised several times from benzene containing a trace of sodium ethylate, the third isomeride, melting at 182.5°, is obtained. This modification is similar to the others in appearance, and, like them, gives no colour reaction with ferric chloride. It gave the following data on analysis: Found C 86.27; H=6·40. C28H25ON requires C=85.93; H=6.39 per cent. Repeated crystallisation, and even fractional crystallisation, did not alter the melting points of the three modifications. The question then arises, supposing these substances are analogous to those of Schiff, of assigning to them a constitution. Schiff states that "Spuren von Piperidin ketisiren die Enolformen, Spuren von Nahrumäthylat Enolisiren die Ketoformen." If such is the case, then presumably the second substance melting at 174.5° is the ketonic form, and that melting at 182° the enolic. That melting at 164.5° would then correspond with the mixed form, but there appears to be no evidence for this view, since the two forms melting at 182.5° and 174.5°, on being mixed and recrystallised, show an intermediate melting point. Moreover, if the original substance consisted of a mixture of the enolic and ketonic modifications, it might be supposed that a trace of sodium ethylate would have been sufficient to alter the equilibrium of the two forms, giving a preponderance of enolic molecules, which, in their turn, with benzalaniline, would have given the enolic compound melting at 182.5°, or at least have raised the melting point of the additive compound; but the presence of sodium ethylate was shown to have no effect on the resulting compound, the substance melting at 182.5° being only formed by the action of the ethylate on either of the other two. On the other hand, if dibenzyl ketone consists of the pure ketonic modification, which appears highly probable from its reactions, the substance melting at 164.5° is the ketonic, and presumably that melting at 174.5° is the mixed, form; but here, again, if equal molecules of the lowest and highest melting points are recrystallised from boiling benzene and light petroleum, in which both are insoluble in the cold, the resulting crystals melt at 173.5-174°, but are easily decomposed into their components by further crystallisation from benzene, whereas the melting point of the substance obtained by the action of piperidine remained constant at 174.5° after repeated recrystallisation. Deoxybenzoin and Benzalaniline. Analogous substances are being investigated, in the hope of elucidating the problem. Deoxybenzoin, for instance, behaves in a very similar way to dibenzyl ketone. It gives no reaction with ferric chloride; an alcoholic solution of the sodium salt, poured into dilute sulphuric acid at -10°, regenerates the ketone, which has the same melting point, and also gives no reaction with ferric chloride. If this test is relied on, then the substance appears to consist only of the ketonic modification. 1. When equal molecules of deoxybenzoin and benzalaniline are mixed together and kept at a temperature slightly above their melting point, the additive compound slowly separates out, the mass becoming solid. On recrystallising from a mixture of benzene and light petroleum or of chloroform and light petroleum, small, colourless needles are formed melting at 154°. The following data were obtained on analysis: Found C 86.18; H=6.05. C27H23 NO requires C-85.94; H=6.10 per cent. 2. If a trace of piperidine is added to the above mixture, besides the second modification melting about 166° which separates, there is a certain quantity of a much less soluble substance crystallising from boiling toluene in needles exactly the same in appearance as the preceding substance melting at 188.5°. The quantity so far obtained was not sufficient for satisfactory purification, but an analysis of the fairly pure substance seemed to indicate that it had the same composi tion as the other modifications. The best method for obtaining the second isomeride is to dissolve the first, melting at 154°, in chloroform containing a trace of piperidine, and after some hours to precipitate the compound from solution by light petroleum; in this way, crystals |
