— 130 — 



H. Rupe has continued his researches as to the knowledge of 

 carvone, to which we have already referred once before 1 ). Conjointly 

 with K. Liechtenhan he publishes a further communication 2 ). When 

 treating carvone with methylmagnesium iodide there should be pro- 

 duced, analogous to the experiments with dihydrocarveol, methylcarveol : 

 CH Q OH 



C CH 2 



CH 3 .C^ NcH.cf 2 



^ / X CH 8 



CH CH 2 3 



in order to arrive from this, by adding water, etc., to methylpinol. 

 But instead of this, there was formed from carvone, with Grignard's 

 salts, not an alcohol, but a hydrocarbon distilling between 68 and 

 8o°, chiefly at 74 to 75° (10 mm. pressure), or at 195 to 197 

 (745,5 mm. pressure); it represents a water- white liquid with a pleasant 

 odour reminding of cajeput oil and limonene, and has the formula 

 C n H 16 (d 20 o 0,8726; n D20 o 1,5007; M D 20°+ 70,38°). Of the three 

 possible formulae most probably the hydrocarbon possesses the following: — 



C:CH 2 C H 2 



ch - c < > ch ' c C 



CH CH 2 ^ 3 



One fact speaks particularly in favour of this formula. If, namely, the 

 hydrocarbon is reduced with sodium and amyl alcohol, there is formed, 

 according to Rupe, a dihydro derivative (b. p. 72 to 74 at 9,5 mm. 

 pressure). The lowering of the rotatory power thereby observed is 

 explained by the occurrence of a new asymmetric carbon atom. In 

 addition to the above-mentioned crude hydrocarbon, a small quantity 

 of a ketone was formed, methyl dihydrocarvone, of which the oxime 

 was isolated partly in solid and partly in liquid form. The liquid 

 oxime boils at 141 to 145 (11 mm. pressure). The ketone regener- 

 ated from the oxime or the semicarbazone by boiling with sul- 

 phuric acid, passed over chiefly at 102 to 103,5° ( IX mm - pressure). 

 Further examinations must show whether it is here perhaps a question 

 of two isomerides. 



Whilst dihydrocarvone is converted into carvenone, according to 

 Wallach, by boiling with dilute, and according to v. Baeyer by 

 treatment with concentrated sulphuric acid, this conversion, according 

 to Rupe and Liechtenhan, does not take place when dihydro- 



*) Berl. Berichte 38 (1905), 17 19; Report October 1905, 112. 

 2 ) Berl. Berichte 39 (1906), 11 19. 



