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The Amyl Esters of Eucalyptus Oils. 



ESTERS of the character of amyl-eudesmate and amyl-phenylacetate have, so 

 far, only been found in a very few Eucalyptus oils. They appear to be present 

 in greatest amount in that from E. aggregata, and it was from this species, 

 collected at Pagan's Creek, near Braidwood, New South Wales, that oil was 

 distilled in which amyl-eudesmate was first detected. (See paper by one of us, 

 Proc. Roy Soc., N.S.W., 34, 1900, 72.) The yield of oil from E. aggregata is, 

 unfortunately, almost the least of any, and consequently it was difficult to obtain 

 sufficient oil for complete investigation. 



In 1909 material of E. aggregata was forwarded from Rydal, New South 

 Wales, many miles from the previous locality, but even less oil was distilled from 

 this than from the Pagan's Creek leaves. 



In 1920 we procured fresh material from Rydal, but were still more 

 unfortunate, as oil did not distil in sufficient quantity to enable it to be collected, 

 and attempts to extract the oil from the leaves directly with ether were not more 

 satisfactory. We were desirous of obtaining the oil of this species in some 

 quantity because the investigation of the Rydal material had resulted in the 

 separation of a second solid acid which was different from eudesmic acid, and 

 had the characters of phenylacetic acid. It is thus possible that two esters of 

 amyl alcohol occur in the oil of this species, or else the Rydal trees are not 

 quite identical with those growing at Pagan's Creek. The identity of the amyl- 

 alcohol was, however, proved in the oils from both localities. When further 

 investigation on the oil of this species and its esters is undertaken it would be 

 well to procure material from both the above localities, and collected during the 

 spring or early summer months, as at that period of the year the maximum 

 amount of oil might be expected to occur. 400 Ib. of leaves and terminal 

 branchlets from Pagan's Creek gave only i\ oz. of oil, equal to 0-04 per cent., 

 while that from Rydal gave a yield of 0-038 per cent. 



The saponification number for the Pagan's Creek oil was 112-2, and for the 

 Rydal oil 119-5. 



DETERMINATION OF THE ALCOHOL. 



A portion of the Pagan's Creek oil was boiled for several hours with 

 aqueous potash under a reflex, and the solution then distilled. The aqueous 

 distillate was surmounted by an oil which had the characteristic odour of amyl 

 alcohol, as had also the aqueous portion itself. This gave the iodoform reaction, 

 but as nothing distilled below the boiling-point of water it was apparent that none 

 of the lower boiling alcohols was present. The separated oily layer commenced 

 to distil at 130 C., and the portion which came over between that temperature 

 and 135 was separated. This fraction had the odour of, and gave the reactions 

 for amyl alcohol, and when oxidised with potassium bichromate and sulphuric 

 acid in the usual way, formed valeric acid. The silver salt was prepared and on 

 ignition this gave 51-74 per cent, silver, which is almost the theoretical amount for 

 silver valerate. As almost identical results were obtained with the alcohol of 

 the ester in the Rydal oil, it is evident that amyl alcohol is the alcohol of the 

 esters in the oil of E. aggregata. 



Amyl alcohol was detected in the oil of E. globulus by Bourchardat and 

 Olivier [Bull. Soc. Chem. Ill, 9 (1893), 429], and iso-amyl alcohol is now known 

 to occur in the oils of other species of Eucalyptus. 



