THYMOL, MENTHONE AND MENTHOL FROM EUCALYPTUS OILS. 



45 





CH 



6 



OH 3 



1 



O-H 



1 

 



H.CK > 



PH 2 



HCr/ N 



^OH 



HO 



l\y 



OO 



HO'\ 



,00] 











1 



I 



i 

 o 3 t 



Mperit 



[ 7 



one. 



3 H 7 

 Thymol. 



The thymol as thus prepared crystallised finely in large 

 plates, melted at 49 — 50° O. and at the same temperature 

 when mixed with ordinary thymol. The specific gravity 

 at 20° = 0*975, and refractive index at 20° = 1*5226 ; the 

 phenyl-uretliane melted at 105° O. The phthalein fusion 

 gave the characteristic blue colour for thymol, a reaction 

 identical with that obtained with ordinary thymol when 

 treated in a similar manner. 



Preparation of Menthone. 



Pure piperitone was subjected to the action of purified 

 hydrogen, in the presence of a nickel catalyst, for six hours, 

 the temperature ranging between 175 — 180° C. The double 

 bond in piperitone was readily opened out with the form- 

 ation of menthone, but further action of the hydrogen 

 under these conditions did not reduce the carbonyl group, 

 even after continued treatment for two days. Under cor- 

 rect conditions, however, the reduction to menthol should 

 take place. The ease with which menthone is formed in 

 this way is of special interest, not only in connection with 

 the production of this ketone, but also as a stage in the 

 manufacture of menthol. 



The reduction of piperitone to menthone cannot well be 

 brought about by the action of sodium or of sodium-amalgam 

 in alcoholic solution, because, with the latter particularly, 

 a solid bimolecular ketone is formed at once. This is a 



