— 141 — 



Fenchene. The formation of isomeric fenchenes from fenchyl 

 alcohol, which had been previously observed, induced Wallach 1 ) to 

 extend his examinations also to the higher homologues 2 ) which can 

 be produced with the help of Grignard's reaction from fenchone. 



Homofenchyl alcohol (a-methyl fenchol), C n H 19 OH had already 

 been produced by Zelinski 3 ) from d-fenchone and methyl magnesium 

 iodide. But the product obtained by him, boiling at 208 to 209 , 

 melting at 51 to 52 (Wd-[-ii in alcoholic solution), could not 

 be pure, for on continuing the fractionating, Wallach and Wi en ha us 

 obtained an alcohol whose melting point lay distinctly higher, whilst 

 the optical activity was considerably lower. The purest portions of 

 the homofenchyl alcohol produced by the last-named authors had the 

 following properties: b. p. 215 to 216 ; m. p. 6i°; M D -j- 1,725°, 

 -j-i, 12°, -(-2,2° (in ethereal solution). The solubility of the alcohol 

 in all organic solvents is so high, that it cannot be recrystallised from 

 any of them. 



If homofenchyl alcohol is heated with 2 1 \ % times its quantity of 

 fused and powdered potassium bisulphate for 1 to 2 hours in an 

 oil bath to 160°, it is possible to distil over in a current of hydrogen 

 a hydrocarbon solid at ordinary temperature, which after repeated 

 distillation over sodium boils at 170 to 172°, but is not yet completely 

 uniform, as it still contains small quantities of liquid portions (probably 

 homocamphene). The body, homofenchene, C U H 18 , freed as 

 much as possible from all impurities, melts at 32 to 37°, and has 

 the following physical constants: d^to 47° 0,8520; M© -\- 23,06° (in 

 ethereal solution); n D 46 to 47° I >4557- This hydrocarbon contains one 

 ethylene linking. The oxidation of homofenchene with 4 per cent, 

 permanganate solution takes place only very slowly; after repeating 

 this operation several times, unattacked portions are obtained which 

 can scarcely be considered as unsaturated, and consequently show the 

 character of cyclene. The oxidation did not give unobjectionable 

 results, as a fenchone had been used as crude material, whose camphor- 

 content was not known at that time. The experiments shall be repeated 

 with pure fenchone. 



The progress of the reaction is shown by the following graphic 

 formulae (see page 142). 



In accordance with the foregoing, the derivation of several hydro- 

 carbons from homofenchyl alcohol can be imagined, which also would 

 yield quite different products on oxidation. 



x ) Liebig's Annalen 315 (1901), 279; Report October 1901, 60. 



2 ) Ibidem 353 (1907), 218. 



3 ) Ibidem 340 (1905), 17. 



