— H5 — 



into the chloride (d2o° 0,9600; « D 19,15°; n D 1,47740), this reduced 

 with sodium and absolute alcohol, and the hydrocarbon formed 

 identified as zls^-menthene, C 10 H 18 ; d20°o,8iO4; n D 1,45662; «d+o°. 

 By oxidation with dilute permanganate solution it was possible 

 to isolate p - menthene - 8, 9-diol, C 10 H 18 (OH) 2 (b. p. 165° [26 mm. 

 pressure]); on further oxidation of this glycol with chromic acid 

 there resulted an as yet unknown methyl ketone, C 9 H 16 (b. p. 70 

 to 73° [13 mm. pressure]; d 2 oo 0,8982; n D 1,44561; «u ±o°), which 

 yielded a semicarbazone (m. p. 164 to 165°) and could be converted 

 with alkaline bromine solution into p-hexahydrotoluic acid, C 8 H 14 2 , 

 m. p. 108°. The progress of the reaction may be explained by the 

 following graphic formulae: — 



H 2 C CH 3 (OH)H 2 C CH 3 



CH Q 





c 





COH 





OC 







COOH 



CH 



H 2 c/\,CH 2 



CH 



H 2 c/\CH 2 



CH 



H 2 c/\CH 2 



CH 



H 2 c/\CH 2 



H 2 C 



x/ iCH 2 

 CH.CH 3 



H 2 C 



CH 



CH 2 

 • CH 3 



H 2 C 



CH 



-> 



CH, 



•CH 3 



H 2 C 



CH 



CH 2 



•CE 



ZJ8(9) 



-menthene 





glycol 





keton( 



i C 9 H 



-10 



p-hexahydro- 

 toluic acid 



When the isopulegol chloride was dissolved in an equal quantity 

 quinoline, and added drop by drop to quinoline heated to 200 to 

 210 , there was obtained a hydrocarbon C 10 H 16 boiling between 

 62 and 65 (14 mm. pressure), or from 174 to 1 77° (norm, pressure); 

 d 2 o° 0,8420; n r> 1,48422; «d -(- 1 5 . From the molecular refraction 

 Semmler and R imp el infer that it is a terpene with two double- 

 linkings, the one in zls(9)- the other in A B - position. It is therefore 

 a question of the terpene As, 8(9)' menthadiene: 



CH 9 CH 



CH„.CH( ^C~CC 



\ / \CH 3 



CH 9 CH, 



Methene hydrocarbons. In connection with the methene-sube- 

 rene 1 ) (methene-cycloheptane) described by him, Wallach 2 ) gives details of 

 the production of methene-cyclopentane, methene-cyclohexane, 



*) Liebig's Annalen 345 (1906), 139. 

 2 ; Liebig's Annalen 347 (1906), 316. 



