Organic chemistry

1894 Journal of the Chemical Society Abstracts  
O r g a n i c C l i e m i s t ry. Cryoscopic Behav iour of Substances OP Similar Constitution t o the Solvent. By F. GARELLI (Gazzetta, 23, ii,.- Ferratini and Garelli (Abstr., 1893, 156 ; 512) have already studied numerous cases of abnormal depression of the freezing points of various solvents produced by a number of substances ; the cause of this anomalous behaviour was found in the similarity of constitution nhich exists between the solvent and the substance in such cases, which leads to the
more » ... formation of solid solutions (compare Van Bijlert, Abstr., 1891, 1411. Quinoline and isoquinoline give much too high values for the molecular weight in naphthalene solution, although the former base exercises the normal depression on the freezing point of benzene. Acridine gives too high a molecular weight in phenanthrene solution, the depression is normal, however, in benzene and in naphthalene ; the author supposes that a solid solution of acridine in phenanthrene is formed. Pyrroline and tetrahydroquinoline give very high values in naphthalene solution ; dihydronaphthalene also gives abnormal values, as would be expected from the fact that this substance is isomorphous with naphthalene. Tetrahydrodiphenyl and a-tetrahydronaphthol also behave abnormally if diphenyl and a-naphthol respectively are used as solvents. Tetrahydrocarbazole gives the normal molecular weight in naphthalene, but alters the freezing point of phenanthrene very slightly, this constant being raised if changed at all. These facts indicate that the formation of solid solutions, and the consequent vitiation of the results of the molecular weight determinations, are conditioned not so much by similarity in the chemical behaviour of the substances concerned as by similarity in constitution. This view is supported by the normal depressions of the freezing points of phenol by pyrroline ; these two substances are somewhat similar in respect to chemical behaviour lout totally different in molecular configuration. A possible method is thus indicated for determining the constitution of organic substances. Although the constitution of nicotine is not as yet definitely settled, the old view that this base is hexahydrodipyridyl has been disproved by Pinner and by Blau (Abstr., 1893, i, 489; 736). This is confirmed by the observation that nicotine does n o t form solid solutions with diphenyl whilst rj-dipyridyl does ; the constitution of nicotine should, consequently, not Ice of the same type as that of dipyridyl. The high values obtained for the molecular weight of phenol by the boiling point method in benzene are usually attributed to the formation of solid solutions ; it is much more likely, however, that the abnormal rise in the boiling point is due to the general tendency of hydroxy-compounds to condense. Very high molecular weights are obtained for resorcinol in benzene and naphthalene solutions, operating by the cryoscopic and boiling point methods respectively. Carbazole gives normal values in diphenylamine. F= H,O liquid + CH3*N0, liquid + 36.7 Cal. ; or CEL3.N02 gas + 29.17 Citl. It is thus seen that the heat of formation of nitromethane is a little less than that of nitrobenzene. Heat of dissolution -0.60 Cal. Heat of neutralisation + 7-01 Cal. (potassium hydroxide) ; and + 8.9 Gal. (barium hydroxide). Nitroethane :-Heat of combustion at constant volume + 322.45 Cal., and at constant pressure + 322.30 Cal. Specific heat 0.451 (between 23" and 95'). Heat, of volatilisation + 6.90 Cal. Heat of formation (calculated) from its elements + 38.8 Cal. for the liquid, + 31.8 Cal. for the gaseous compound ; from ethane and nitric acid + 43.0 cal. for the liquid, and + 36.0 Gal. for the gaseous compound. Heat of neutralisation (potassium hydroxide) + 10.
doi:10.1039/ca8946600157 fatcat:ein4ownmy5ffvn3dz2zh34ks5q