146 Report of Schimmel § Co. 1922. 



Ketones. 



As to the preparation of ketones from secondary alcohols, see page 143 of the 

 present Report. 



In order to supplement earlier investigations 1 ), P. Sabatier and B. Kubota 2 ) publish 

 new details on the catalytic reduction of benzaldehyde and of aromatic ketones by means 

 of copper. The metal required for their experiments was prepared by slow reduction, 

 at 200°, of black tetracupfic hydrate. At 350°, benzaldehyde was reduced to benzene, 

 toluene, and carbonic oxide. Contrary to the reduction performed formerly by aid of 

 nickel, the carbonic oxide was not reduced to methane, but remained unchanged. 



Acetophenone and ethylphenylketone were reduced catalytically by copper at 350° 

 to ethylbenzene (b. p. 135°) and propylbenzene (b. p. 158°). Under identical conditions, 

 benzoyl propanone was transformed into acetophenone (fairly good amount), some acetic 

 aldehyde, ethyl alcohol, and ethylbenzene. By reducing benzoquinone over copper, at 300°, 

 nearly exclusively hydroquinone, m. p. 169°, resulted, besides some water and phenol. 



Carvone. — A. Muller 3 ) was successful in preparing crystalline benzalcaryone which 

 hitherto has been obtained by the usual condensation reactions merely as an amorphous 

 product 4 ). The condensation of carvone with benzaldehyde passed off by means of 

 alcoholic potash lye at a temperature not exceeding +2 to +3°. The fraction b.p.170 

 to 180° (10 mm.) of the reaction-product constituted the raw material for the preparation 

 of two isomeric benzalcarvones, the residue forming the amorphous body described 

 already by Wallach 2 ). After several weeks' standing, a crystalline body separated from 

 the viscous benzalcarvone fraction, /?-benzalcarvone, m. p. 114 to 115°, [a] D — 815° 

 (a — 8.15° of a 1 per cent, alcoholic solution in a 100 mm. tube). The residual a-benzal- 

 carvone, b. p. 191 to 193 (10 mm.); d i5 o 1.041; [«] D + 152.30°, contained still a considerable 

 amount of the /^-isomeride. Neither of the isomerides (which showed red-orange and 

 brick-yellow halochromism respectively) yielded an oxime or a semicarbazone. a-Benzal- 

 carvone yielded an addition-product with hydrogen chloride, a dark brown oil which on 

 heating gave off a fair amount of hydrogen chloride. On reduction with sodium both iso- 

 merides yielded benzyldihydrocarveol, the phenylurethane'of which (m. p. 233 to 234°) was 

 identical with the derivative of benzyldihydrocarveol obtained from benzaldihydrocarvone. 



By means of the method founded on the absorption of ultraviolet light the author 

 proved that on the one hand the curves for A-benzal carvone and benzalmenthone, on 

 the other hand those for a-benzalcarvone and benzaldihydrocarvone were, in the main 

 identical. This behaviour shows that both /?-benzal carvone and benzalmenthone have 

 identical structure, the former being, therefore, /5-3-benzalcarvone. 



How the a-isomeride is constituted remains still an open question, since benzal- 

 dihydrocarvone may exist also in a second form. As compared with carvone 

 (Md + 59.5 ), the values for [«] D with «- and /2-benzalcarvone (+152.5° and —815°) 

 are exceedingly high. Both isomerides demonstrate very satisfactorily that on introducing 

 aromatic radicals into the nucleus, i. e. } by accumulating the double linkings, the rotation 

 is markedly increased. 



According to M. Matsui and S. Shimizu 5 ), menthone can be reduced electrolytically 

 in sulphuric or hydrochloric acid solution to menthol. The best results are obtained 



J ) Cf. Sabatier, La catalyse en chimie organique, 2 nd ed., p. 190 to 196. — s ) Compt. rend. 172 (1921), 733. 

 — ») Berl. Berichte 54 (1921), 1471. — *) Liebig's Annalen 305 (1899), 274. — 6 ; Mem. Coll. Sci. Kyoto 4 (1920), 

 245. As per Journ, Soc. chem. Ind. 40 (1921), A. 162. 



