THYMOL, MENTHONE AND MENTHOL FROM EUCALYPTUS OILS. 47 



possible, owing to the ready formation of the bimolecular 

 ketone, but piperitone is so readily reduced to menthone, 

 that no difficulty in the manufacture of menthol from 

 piperitone should be experienced if the production be 

 earried out in two stages. 



The menthone prepared from piperitone was treated with 

 sodium in aqueous ether solution, repeatedly adding the 

 metal in small quantity until the reduction was thought 

 to be complete. The reduced product did not, however, 

 solidify at room temperature, although it readily formed a 

 solid mass when the vessel containing it was stood upon 

 ice. As the melting point of menthol prepared in this way 

 is only 34° 0., it follows that a very small quantity of 

 unreduced menthone would be sufficient to prevent crystal- 

 lisation under atmospheric conditions. The menthol was, 

 therefore, purified by the phthalic acid combination in the 

 ordinary way, when a good return of crystallised menthol 

 was obtained. It should not be difficult, however, to devise 

 methods for the preparation of crystallised menthol, from 

 the partly reduced menthone, by freezing out, and separat- 

 ing by mechanical means, similarly to those employed in 

 the manufacture of cineol. 



Although it might be a difficult matter to economically 

 prepare the optically active components from the inactive 

 menthol thus produced, yet this has been accomplished 

 in the laboratory, and Pickard and Littlebury [Proc. Ohem. 

 Soc. 101, (1912) 111], have shown that when thus separated 

 both the dextro- and lsevo-menthols melted at 43° O. 



