416 



Aromadcndrcnc — the Sesquiterpene of 

 Eucalyptus Oils. 



A sesquitertene occurs in most crude Eucalyptus oils, perhaps in all of them, 

 although it is present in but small amount in many of those belonging to the 

 " Peppermint " group. It does not appear to be associated with one terpene 

 more than another, because it has been found in quantity in some of the pinene 

 oils (those occupying the earlier portion of the series), in which phellandrene is 

 absent ; and also in oils in which pinene is only present in small quantity, 

 with phellandrene the principal terpene. It is also found in the oils belonging 

 to the cineol-pinene group. 



The sesquiterpene was first detected in quantity in the oil of E. 

 Dawsoni, where it occurs with phellandrene; it was also present in quantity in 

 those of the following species : — E. eximia (with pinene) ; E. nova-anglica (with 

 pinene) ; E. trachyphloia (with pinene) ; E. affinis (with pinene and cineol) ; 

 E. macidata (with pinene and cineol) ; E. acmenioides (with pinene and phellan- 

 drene) ; E. crebra (with pinene, phellandrene, and cineol); E. viminalis (with 

 pinene, phellandrene, and cineol); E. hcemastoma (with phellandrene), and as 

 a well-defined constituent in the oils of many other species. The oil of E. 

 nova-anglica contains the sesquiterpene in great quantity, and over 50 per cent, 

 of the crude oil distilled above 255 ° C. It appears to be a constant constituent 

 in those oils in which it is found, and in that of E. hcemastoma distilled from 

 material sent from Gosford, N.S.W., and from Barber's Creek, N.S.W., localities 

 about 140 miles apart, practically the same amount of the sesquiterpene was 

 present. The oil from the Gosford sample gave 50 per cent, boiling between 

 255° and 280 C, and that from Barber's Creek, 55 per cent, distilling between 

 245 and 283 C. The oil of E. hcemastoma was the one employed originally for 

 the separation of the sesquiterpene. In all the above oils the sesquiteipene was 

 accompanied by a sesquiterpene alcohol in larger or smaller amount. 



There appears to be only the one sesquiterpene in Eucalyptus oils, because 

 the high-boiling portions of those of several species were added together, and 

 the product obtained from this, by fractional distillation, finally over sodium, 

 was practically identical with that obtained from the oil of E. hcemastoma in a 

 similar manner. 



Although the sesquiterpene has been prepared as free as possible from 

 associated constituents by fractional distillation, finally over sodium, yet it cannot, 

 as thus obtained, be considered pure. All efforts, so far, to form crystallised 

 chemical compounds with it have not been successful ; the constants cannot, 

 therefore, be given with any very great degree of accuracy. Attempts were 

 made to form the crystalline dihydrochloride, the nitrosochloride, and the 

 nitrosite, but these were not satisfactory ; nor did it appear possible to obtain a 

 solid sesquiterpene alcohol from it by treatment with glacial acetic acid and 

 sulphuric acid, so that its derivatives have yet to be prepared. 



When treated with bromine, very energetic action takes place with the 

 evolution of hydrobromic acid ; the bromide is of a very dark colour, and 

 not obtained in a crystallised condition. 



