— ii6 — 
In order to prove by further experiments the formula accepted 
for menthenone: 
O. Wallach^) reduced menthenone with sodium and alcohol into 
menthol, and showed that dibromomenthenone , when heated, yields 
thymol, with loss of hydrobromic acid. Both results agree with the 
above formula. 
Menthone. At the 75^^ Meeting of the Society of German 
Scientists and Physicians, at Cassel, E. Beckmann^) reported on his 
studies relating to the menthol-series. Natural 1-menthol, on careful 
oxidation with Beckmann's mixture, yields 1-menthone, which can be 
converted with concentrated sulphuric acid into d-menthone. Dilute 
acids and bases produce a mixture of d- and 1-menthone. Similar 
mixtures are also obtained from d-menthone. 
From the possible 4 isomeric menthones, 8 menthols can be derived 
theoretically, of which, however, in practice, on reduction, the natural 
1-menthol is always produced in the largest quantity. In addition to 
the menthols, there is formed on reduction with sodium in indifferent 
media, menthopinacone (melting point 95°) which can be oxidised 
with Beckmann's chromic acid mixture into d-menthone. When 
the reduction is made in alcohoHc solution this body is not formed. 
A separation of the isomeric menthols did not succeed. On the 
other hand, the attempt to arrive at isomeric amines and isomeric 
menthols by reduction of the menthone oximes, had the desired re- 
sult. The bases could be separated by fractional crystallisation from 
benzene of the picrates and hydrochlorides of the amines. In this 
manner a pure d-menthylamine hydrochloride could be separated from 
d-menthone oxime, which could be converted into a new d-menthol 
by means of nitrous acid. The separation of the amines succeeded 
also by fractional crystallisation of their benzoates from alcohol. The 
more readily soluble benzoates yielded on saponification d-menthyl- 
amine. Finally the author also succeeded in separating d-menthol 
as a more readily soluble benzoyl - compound from the menthol- 
mixtures which are formed by reduction of the menthones. The 
^) Nachr. k. Ges. Wiss. Getting. 1903, part 4 (abstr. according to Chem. Centralbl. 
1903, 11. 1324). 
2) Pharm. Ztg. 48 (1903), 780. 
HC . CH 
