— 104 — 



during the oxidation of the z^-menthenone, having been isolated in small 

 proportions from the first two soda extracts by means of its sparingly- 

 soluble copper salt. Recrystallised from water, the acid melted at 90 to 93°. 



The acids recovered from the last two soda extracts were liquid and, 

 according to the titration, monobasic. Treatment with semicarbazide gave 

 rise to a semicarbazone melting at 158 to 159°, which proved to be iden- 

 tical with that of «-isopropyl-/-acetylbutyric acid obtained by oxidation 

 from «-hydroxy-«-methyl-r/-isopropyladipic acid. Hence, the oxidation of 

 ^-menthenone with permanganate of potassium yields, in addition to formic 

 acid, three acids possessing a generic relationship, viz.: «-hydroxy-«- 

 methyl-a-^opropyladipic acid, a-isopropyl-y- acetyl butyric acid (methyl- 

 2-heptanone-6-carboxylic-3-acid), and a-isopropyl-glutaric acid; of which the 

 last-named was already known. 



For purposes of comparison the results obtained in the course of the 

 investigation of menthenone are graphically represented in the subjoined 

 formulas. From these it will be seen that the new peppermint-ketone can 

 only possess the structure of a zJMnenthenone^, for it is only on this 

 assumption that its reactions can be explained. 



For the purpose of isolating this ketone, which will probably also be 

 found to occur in other essential oils, the oil itself, or the corresponding 

 fraction, should be treated with bisulphite of sodium solution, after which 

 the free ketone can be identified by the semicarbazone (m. p. 224 to 226°), 

 which is almost insoluble in alcohol. 



Recently Y. Murayama 1 ) found dementholised Japanese peppermint oil 

 to contain 1-limonene. This hydrocarbon, the presence of which in American 

 oil of peppermint had already been discovered by Power and Kleber 2 ), was 

 contained in a fraction boiling at 170 to 178°, (30 g. from 1 kilo oil), and 

 possessed the following constants: d 15 o 0,8632 and [«] D — 58,51°. Its nitro- 

 sochloride melted at 103 to 104°, its tetrabromide at 104 to 105°. The 

 author was unable to find phellandrene in the oil. 



Peppermint Oil, Javanese. Roure-Bertrand Fils 3 ) have found an oil 

 from Mentha arvensis var. javanica, produced in Java, to possess the follo- 

 wing properties: di 5o 0,9979, « D +0°24 f , acid no. 69,8, ester no. 49,7 

 = 13,8°/o esterified menthol, ester no. after acetyl. 153,3= 48,2 °/o total 

 menthol, soluble in 1,5 vol. and more of 70°/o alcohol. With the exception of 

 the density all the above constants were determined in oil which had been 

 previously neutralised. When the deep-yellow oil was cooled, no menthol 

 separated out, not even after inoculation with a few menthol crystals. 



x ) Yakugakuzasshi 37 (1910), 141 ; quoted from Journ. de Pharm. et Chim. VII. 1 (1910), 549. 



2 ) Pharm. Rundschau (New York) 12 (1894), 157; Arch, der Pharm. 232 (1894), 639. 



3 ) Berichte von Roure-Bertrand Fils, April 1910, 65. 



