— 133 — 



of the separate menthones into the menthylamines, and the conversion 

 of the latter by means of nitrous acid, resulted in derivatives of still 

 higher rotating-power; thus, from the laevorotatory total product there 

 was obtained a d-isomenthol, Md -f- 25,6°, and, further, from such 

 a body with [«]p -(-26,3°, m. p. 83 . there was prepared an isomen- 

 thone with the high specific rotation Md -}- 93,2°. 



That inverted d-menthone is made up of several isomers has also 

 been shown recently by the investigation of the oximes. Whereas 

 '-menthone oxime melts at 59 , the oxime of inverted d-menthone ap- 

 pears as a viscous oil, which, however, like the oxime of the former, 

 yields a crystalline hydrochlorate. The solid hydrochloride, which was 

 seperated out from a solution of inverted d-menthone in absolute ether 

 by the introduction of relatively little dry hydrogen chloride, possessed 

 when purified, a melting point of 13 2°, (it turned brown), and a sp. rot. 

 Md -}~35,9 . Hydrochloric acid being again introduced into the filtrate 

 of these crystals, there separated out another hydrochloride, at first of 

 a viscous consistency, but solidifying when dried in vacuo over soda- 

 lime. This hydrochloride had [a] D — 62,6°, and melted at 117 to 11 8° 

 (turning brown in the process). It corresponds to the oxime-hydro- 

 chloride of true 1-menthone, while the hydrochloride which was first 

 separated is identical with the corresponding derivative of d-iso- 

 menthone. 



The oximes which were liberated from the hydrochlorides by means 

 of sodium carbonate possessed the following characteristics: the viscous 

 oxime of inverted d-menthone had [a] D — 6°; the oxime of 1-menthone 

 melted at 59 , and had Md — 42,5°; the oxime of d-isomenthone 

 was again viscous and had [«] D -j- 4 1 ,o°. The pure ketones forming 

 the bases of the oximes could not be recovered unaltered from the 

 latter, on account of the inversion which ensued during the splitting- 

 up process, but after the foregoing there was no doubt that inverted 

 d-menthone consists of a mixture of 1-menthone and d-isomenthone. 



Experiments previously made to separate the ketones over the 

 semicarbazones were repeated and then led to the following results: 

 inverted d-menthone yielded a semicarbazone, m. p. 11 6°, and with 

 a specific rotation, in aqueous solution of chloral hydrate, Md -j- 26,6°, 

 the semicarbazone from d-isomenthone had a melting point of 154 

 and Md -(- 46,5°, and the derivative of 1-menthone, m. p. 184, which 

 had already been prepared before, had a specific rotation of — 64 . 



Pulegomenthone which was previously obtained from pulegone 

 hydrobromide could not be split up by similar treatment of its oxime 

 with hydrochloric acid. 



Beckmann finally announces that he intends to publish elsewhere 

 a detailed report on this and allied investigations. 



