Tutin and Kipping consider it very probable that dilute sul- 
phuric acid already yields these two menthones on oxidation, and the 
oximes of two ketones, to which therefore belong the configurations 
and \-, on the reduction by which a third asymmetric 
carbon atom is formed, must yield 4 optically active amines: from 
the ketone , the bases and j , and from the 
ketone — -[-, the bases — — -\- and • — -] [-. The authors 
assume that the same conditions will prevail in the formation of 
menthylamine from menthone and ammonium formate, on the sup- 
position that the high temperature of the reaction does not affect 
the direction of the rotatory power of the asymmetric carbon atom 
carrying the methyl-group. In this case, four more amines of the 
configurations -j , -] 1 , -| \-, and -| 1 \- would 
be formed in addition to the above-mentioned four bases; the result 
would then be an optically inactive mixture of eight bases, whose 
rotations would neutralise each other. With regard to the nomen- 
clature of the individual amines, it should be noted that Tutin 
and Kipping give to true laeve - menthone the configuration — — , 
and to true dextro -menthone the symbol -| [-. The ketone which 
can be produced from the first-named ketone by means of alkalis 
or acids w^ould then have the configuration [-, and the name 
1-isomenthone. The two bases to be obtained from 1-menthone are 
named 1-menthylamine and 1-neomenthylamine, — those obtained from 
1-isomenthone, 1-iso- and 1-isoneomenthylamine. The four bases from 
d-menthone are distinguished in the same manner. 
Of the four bases from Isevo -menthone mentioned by Tutin and 
Kipping, 1-menthylamine is formed in the largest quantity. 
Of the three others, two are very indifferent, the fourth undergoes 
partially a racemisation of the CHg • NHg -group; as in this case the 
base yields no menthylamine — , the configuration which be- 
longs to it and to its products of racemisation, is that of a base 
belonging to the iso -series — it -|-. 
The very troublesome separation of the individual bases, which 
is described in detail in the original work, was accomplished by 
fractional crystallisation of various acid derivatives, such as the hydro- 
chlorides, and also of the d-camphor and d-bromcamphor sulphonates, 
or the formyl and benzoyl compounds. Every one of the bases was 
identified by pure, uniform salts in respect of rotatory power, melting 
point etc. 
Semmler^) reports on more recent derivatives of menthone, 
camphor-phorone and pinophorone. 
^) Berliner Berichte 37 (1904), 234. 
