395 



The Phenols of Eucalyptus Oils. 



PRACTICALLY all crude Eucalyptus oils contain phenols, more particularly if the 

 original distillations have been at all extended. 



The actual amount in the oils of most species is, however, very small, and 

 consequently phenols are not usually found in Eucalyptus oils of commerce, for 

 the reason that these have in most cases been rectified by steam distillation before 

 placing on the market, or else the original distillations have not been continued 

 for a sufficiently long period. 



The greatest quantity of crude phenols we have yet obtained frcm the oil 

 of any species of 'Eucalyptus was 2 per cent., from that of E. Risdoni. In most 

 species, however, the amount does not exceed 0-5 per cent., whilst in some of 

 them probably less than ^ of that small quantity is present. 



Two phenols are found in Eucalyptus oils, one of which is now described 

 for the first time. They have been named TASMANOL and AUSTRALOL. The former 

 of these is liquid and occurs in greatest amount in the cineol-phellandrene 

 Eucalyptus oils derived from such species as E. linearis, E. Risdoni, &c. Its 

 presence is indicated by the very red colour of these crude oils when they have 

 been distilled from iron vessels. This group of trees is more extensively developed 

 in Tasmania than in Australia, and for that reason the name tasmanol was 

 chosen for the liquid phenol. 



Australol is a beautifully crystallised phenol and occurs in greatest amount 

 in the oils of the typical " Boxes," as E. hemiphloia, E. Woolkiana, &c. It 

 is also present in the more pronounced cineol oils, derived from species of the 

 " Gum " group. These two Eucalyptus groups (the " Gums " and the " Boxes ") 

 are extensively developed on the mainland of Australia, whilst the "Boxes" 

 do not occur in Tasmania. The name australol has thus been chosen for 

 the crystallised phenol, as it is principally derived from the oils of the main- 

 land species. 



Our experience indicates that both these phenols occur together, one or 

 the other predominating in the oils of species belonging to certain groups. They 

 may thus be somewhat closely related bodies. 



It seems highly probable that the yellow colour of certain rectified cineol- 

 bealing Eucalyptus oils is due to the influence of the crystallised phenol, particularly 

 as it is more pronounced in those species yielding yellow-tinted oils, and when 

 gently oxidised becomes of a bright yellow colour. This is particularly noticeable 

 when the alcoholic solution is treated with ferric chloride. 



Eucalyptus oils in which tasmanol is the pronounced phenol are water- 

 white when rectified, this being traceable, perhaps, to the presence of the 

 methoxy group in tasmanol, as australol has not this grouping. Eucalyptus 

 oils containing over 70 per cent, of cineol thus occur in two forms (a) the 

 water- white oil from E. Australiana, and (6) the yellow-tinted oils from such 

 Eucalypts as E. polybractea, E. globulus, &c. 



The announcement of the occurrence of phenols in Eucalyptus oils was 

 made by Professor R. Robinson and one of us, in a paper published by the 

 Royal Society of New South Wales, in January, 1915. The paper deals with 

 tasmanol, but also mentions the occurrence of a second phenolic body. Professor 

 Robinson now resides in England, so that the further investigation of these 

 phenols has devolved upon us. 



The phenols were removed from the crude oils in the usual manner by shaking 

 with dilute aqueous sodium hydrate, washing the aqueous solution with ether 

 to remove adhering oil, acidifying and extracting with ether. The residue, which 



