192 — 



j3, s (9)-p-Menthadiene t 



B. p 184 to 188° 



d 0,858 to 0,860 



n 1,4915 to 1,4924 



* (°)-p-Menthadiene (Limonene) 

 175 to 176° 

 0,846 

 1,746 



As will be seen from the above table, the differences in the physical 

 behaviour of the two ketones agree with the rules laid down by Auwers 

 and v. d. Heyden 1 ), inasmuch as in the case of zl 3 -tetrahydro-p-acetyltoluene 

 the increase in the refractive power due to the position of the conjugated 

 double bond towards the carbonyl is especially evident. But, contrary to 

 what occurs in the case of ketones, boiling-point, density, and index of 

 refraction of the alcohols decrease perceptibly, as the ethylene-bond 

 approaches the oxygenated radical while the melting-point rises. In 

 the case of hydrocarbons, the approach of the double-bond of the ring to 

 the double bond of the side-chain causes a considerable increase in the 

 b. p., and the density and the index of refraction increase likewise, as 

 is the case with the ketones. In order to explain the matter more in- 

 structively the formulae of the compounds in question are set forth 

 below: — 



CH 3 



-COCH 3 



CH 3 



-COCH3 



A 3 -Tetrahydro-p-acetyltoluene 

 OH 



cH 3 -^-yi< CH3 



X CH S 

 d 3 -p-Menthenol-8 



CH s -<— >-C< CH2 

 j3, 8 (»)-p-Menthadiene 



A '-Tetrahydro-p-acetyltoluene 

 OH 

 CH 3 



CH 3 



CH S 



J'-p-Menthenol-8 (a-Terpineol) 



CH. 



CH 2 

 CH 3 



ji,8 (9)-p-jvienthadiene (Limonene). 



Wallach' 2 ) also states that in the nitrosochlorides of methyl-1-ethylidene- 

 4-q/dohexane described above, the chlorine-atom may be replaced by an 

 acetyl-group, giving rise to a new type of combination, an acetoxyl ketoxime. 



/ VO.COCH3 



3 \ / N C(NOH).CH 3 



For the preparation of this interesting new body 1 part of nitrosochloride is 

 mixed with 1 part of anhydrous sodium acetate and, after adding 5 parts 

 glacial acetic acid, heated to f^om 60 to 70° under stirring until the original 

 blue colour has disappeared and <*e reaction is completed. The mixture is 

 neutralised with soda, extras* with ether, and the crude product then 



!) Liebigs Annalen 360 (19 ,, ^, 365 (1909), 269; Comp. the present Report, p. 164. 

 2 ) Liebigs Annalen 374 (1910), 217. 



