— 182 — 



say, hydrochloric acid is appreciably increased by the presence of one of 

 its neutral salts; and marked differences are also perceptible between 

 the two acids of approximately equal strength: hydrochloric acid and 

 sulphosalicylic acid. 



The author further discusses the dependence of the rate of inversion 

 upon temperature and the absorption of the catalysing agent by the menthone. 

 We are, however, unable to enter further into this matter, for particulars 

 of which we refer to the original article. 



We notice that in a recently published paper by Kotz and Steinhorst 1 ) 

 on monohalogene monoketones from hexacyclic ketones certain deriva- 

 tives of menthone and carvomenthone are described, to which a brief 

 reference may here be made. Bromo-4-p-menthanone-3 (b. p. 120 to 122° 

 at 16 mm.) is obtained from menthone by bromination, and chloro-4-p- 

 menthanone-3 by chlorination : b. p. 115 to 117° (15 mm.). From the last- 

 named body the authors prepared hydroxy-4-p-menthanone-3 (hydroxy-4- 

 methyl-l-isopropyl-4-q/dohexanone-3) which, when boiled with sodium acetate 

 and glacial acetic acid, yields zl 4 -menthenone-3 (methyl- l-^sopropyl-4-q/c?o- 

 hexene-4-one-3) b. p. 213 to 214°. The same ketone is formed from 

 hydroxy-4-p-menthanone-3 by heating it with oxalic acid. The following 

 derivatives of p-menthanone-2 (carvomenthone, tetrahydrocarvone) are 

 described : bromo-1 -p-menthanone-2 (bromo-1 -methyl- 1 -isopvopy\-4-cyclo- 

 hexanone-2) (b. p. 138 to 140° at 14 mm.), chloro-1 -p-menthanone-2 

 (b. p. 130 to 132° at 14 mm.), hydroxy- 1 -p-menthanone-2 (hydroxy- 1-methyl- 

 Hsopropyl-4-q/dohexanone-2) (b. p. 128 to 130° at 14 mm.) and zl 6 -menthe- 

 none-2 (methyl- lnsopropyl-4-q/cZohexene-6-one-2, carvotanacetone) : b. p. 228 

 to 229°. 



o-Menthone-5. A Kotz and E. Anger 2 ) state that they have succeeded 

 in reducing methyl- l-^opropyl-2-q/cfohexene-6-one-5 into methyl-1-isopropyl- 

 2-q/cfohexanone-5 , the first representative of the hitherto unknown 

 o-menthones. This body boils at 95° (25 mm.) and at 204° (normal press.). 

 The oxime melts at 75°, the benzilidene compound at 162°. The authors 

 also succeeded in preparing methyl- l-isopropyl-2-c?/c£ohexene-6-one-5- 

 semicarbazone, which occurred in two isomeric forms melting respectively 

 at 138 and 152°. 



-Camphor. Some time ago Blanc and Thorpe 3 ) attacked the synthesis of 

 camphoric acid originated by Komppa. As was to be expected, Komppa 4 ) 



*) Liebigs Annalen 379 (1911), 1. 



2 ) Berl. Berichte 44 (1911), 466. 



3 ) Journ. chem. Soc. 97 (1910), 836; Report October 1910, 196. 



4 ) Annales Academiae scientarum Fennicae Ser. A. II (1910), No. 9. Bull. Soc. chim. 

 IV. 9 (1911), 49. Journ. chem. Soc. 99(1911), 29. 



