— 168 — 



with the intention of discovering whether the system of conjugated double 

 bonds represented in it involves normal or abnormal refraction values. 

 The hydrocarbon was obtained by boiling c^/cZohexanone pinakone with 

 dilute sulphuric acid in a reflux condenser. J 1,!l '-dic?/cZohexene gave the 

 following constants: b. p. 120 to 125° (15 mm.), d 20o 0,9485, n Daoo 1,5287, 

 mol. refr. calc. as CiaHis/i 52,34, found 52,65. The molecular refraction, 

 therefore, shows a clear rise above the calculated value. The dkyclo- 

 hexene yields a hydrobromide melting at 68 to 69°. 



Cyclo geraniolene. CtycZogeraniolene (1,1 ,3-trimethylq/cZohexene), which 

 was first prepared by Tiemann and Semmler from citral, has recently been 

 obtained by A. W. Crossley and C. Gilling 1 ) by treating 1,1-dimethylct/cZo- 

 hexanone-3, with methyl magnesium iodide. The first derivative of this 

 process was trimethylcz/cZohexane, a body melting at 72,5°, and possessing 

 a pronounced odour of camphor. The alcohol was converted with 

 hydrobromic acid into 3-bromo-l,l,3-trimethylq/cZohexane (b. p. 88°, 

 20 mm.) and the hydrobromic acid eliminated with alcoholic potassium 

 hydroxide, the result being a mixture of «- and /?-c^cZogeraniolene (1,1,3- 

 trimethyl-zl 3 - and -A 2 -c?/cZohexene). Of the «-q/cZogeraniolene the nitro- 

 sate described by Wallach 2 ) was obtained and converted into 1,1,3-tri- 

 methyl-Zl 2 -q/cZ0hexene-4-one oxime by alkalies. 



The authors also prepared l,l-dimethyl-3-ethylci/cZohexanol-3, a colour- 

 less liquid with a marked odour of camphor, b. p. 94° (30 mm.). Hydro- 

 bromic acid converts this alcohol into 3-bromo-l,l-dimethyl-3-ethylc2/cZo- 

 hexane (b. p. 105 to 106° :22 mm.) from which hydrobromic acid is split 

 off by alcoholic potash liquor, giving rise to l,l-dimethyl-3-ethylct/cZohexene 

 (b. p. 156° at 760 mm). 



If the subjoined conception of the molecular structure of camphane, 

 bornylene, and camphene, be correct: 



C-CHs OCH3 CH 



C:CH 2 



C(CH 3 ) 2 



CH CH CH 



Camphane Bornylene Camphene 



it follows that dihydrobornylene should be identical with camphane and 

 that the constitution of dihydrocamphene should be expressed by the 

 following formula: 



x ) Journ. chem. Soc. 97 (1910), 2218. 



2 ) Liebigs Annalen 324 (1910), 97; Report October 1902, 87. 



