— 183 — 



resembling that of citral), f-phenylcapronic aldehyde (b. p. 141 to 144° 

 *at 9 mm.; faint odour), S-phenylcenanthol (b. p. 155 to 159° at 9 mm.; 

 m. p. of the nitrophenylhydrazone 68 to 70°). 



Ketones. 



W. L. Ipatiew, in collaboration with G. Balatschinsky 1 ) has continued 

 his experiments on catalytic reactions at high temperature 2 ) and high 

 pressure, and has investigated the course of hydrogenation of unsaturated 

 terpene ketones. The authors reduced Z-carvone, d-pulegone and d-men- 

 thone with nickel oxide as a catalyser and hydrogen under high pressure 

 at 220 to 280°, and found that hydrogenation is accomplished between 

 220 and 240°, no matter whether the double bond is in the ring or in the 

 side-chain. The carbonyl-group is attacked between 260 and 280°, but in 

 the case of the menthol series a temperature of 260° must not be ex- 

 ceeded, as otherwise menthane would be formed. The lower the tem- 

 perature of the reaction, the less is the change in optical rotation. At 

 280° the reduction of carvone gives rise to carvomenthol, at 240° the 

 double bond is attacked, while the keto-group remains unchanged. At 280° 

 the hydrogenation of pulegone yields menthane, between 220 and 240°, 

 menthone is formed. Menthone at 250° yielded a menthol, m. p. —8° 

 (d 2 oo 0,8948), which showed some similarity to the menthol obtained by 

 Kondakow and Bachtschiew 3 ) in the reduction of diosphenol. It also re- 

 sembles the menthol (m. p. — 9°) which was obtained in the hydrogenation 

 of thymol at 260°. 



Pinolone. The ketone pinolone 4 ), a conversion-product of pinol, has 

 been found by Wallach 5 ) to be an acetyHsopropylci/cZopentane. Wallach 

 reduced the pinolone recovered from the semicarbazone by Paal's method, 

 whereby he obtained a ketone Ci Hi 8 O (dihydropinolone, l-acetyl-3-isopropyl- 

 cycZopentane), possessing the following properties: b. p. 211°, d 2 io 0,8880 to 

 0,8885, n D21 o 1,4466 to 1,4476. In contradistinction to pinolone, which has a 

 yellow colour, dihydropinolone is colourless; a point of difference which is 

 often found in saturated and in unsaturated ketones 6 ). Dihydropinolone 

 semicarbazone melts at 164 to 165°. When dihydropinolone is oxidised 

 with hypobromite liquor there results an acid (1,3-isopropylq/cfopentane 

 carboxylic acid), of which the amide, m. p. 164 to 165°, was identical with 

 f jae body which was obtained by Semmler from camphenilone, and to 



*) Berl. Bericht 44(1911), 3461. 



2 ) Comp. Report April 1911, 166. 



*) Journ. f. prakt. Chem. II. 63 (1901), 61; Report April 1901, 71. 



*) Comp. Schimmers Bericht, October 1899, 64. 



5 ) Liebigs Annalerf 384 (1911), 193. 



6 ) Wallach, Terpene und Campher. Leipzig 1909, p. 169. 



