﻿THE TERPENE OILS OF MANILA ELEMI. 27 



were made and from the rate at which the rotation was found to decrease, 

 the immediate values would be about those found by Wallach. From this 

 there appears no evidence that any racemic form of phellandrene is 

 present in either of the two oils, the first of which had a value, 



on on 



a jj=-f- 73°. 5 and the second, j) = -h 105°. Later, another cause was 



discovered for this varying rotation of the phellandrene oils. 



Stability of phellandrene. — Wallach 24 recognized the fact that phel- 

 landrene is not a stable substance and recommended that it be fractioned 

 in vacuo. Nothing further is to be found in the literature upon the 

 subject. It was ascertained that a sample of phellandrene after distil- 

 lation at ordinary pressure had a rotation which was about 2° lower than 

 it had been before this process. 



( 1 ) The distilled product just mentioned was heated in a tightly stoppered 

 distilling flask, immersed in an oil bath, and maintained at 190° for eight hours, 

 after which time it was distilled from the flask; about one-fifth of the total 

 remained as a viscous residue almost insoluble in alcohol. The oil redistilled 

 from 172° to 174° which is a temperature a little higher than the boiling point 

 of the original. Its rotation had decreased from +105° to -4-70°. 



(2) The last distillate obtained was then sealed in a hard-glass tube and heated 

 in an oven for twenty-four hours at 250°. The product was colored a slight 

 yellow. It was distilled with steam, whereupon about 15 per cent of non- 

 30 

 volatile matter remained behind. The distillate showed a 'r)= — 25°. 5. It boiled 



completely from 171° to 176. °5. Phellandrene was no longer present and after 

 careful trials no other terpenes could be identified. The oil had a very peculiar, 

 benzene-like odor which was quite different from that of any other terpene. 



(3) The experiment was repeated with a fresh amount of the original sample 

 of phellandrene. This time the heating was carried on at 225° for twenty-four 

 hours. The product was colored slightly yellow. It was distilled with steam 

 and a residue of nearly 25 per cent remained behind. The distillate had the 

 same peculiar, benzene-like odor and gave a very slight test for phellandrene; 



30 



a^ = — 23.8. It boiled completely from 171°. 5 to 176°. 5. It appeared to be 



identical with the product obtained in the last experiment. 



(•4) The combined residues obtained in this and the preceding experiments 

 were distilled at 10 or 15 millimeters. A proper thermometer was not used so 

 that the result of the distillation could only be roughly judged. A small amount of 

 terpene oil passed over first, then a quantity of higher boiling, somewhat viscous 

 oil distilled before the temperature had risen much beyond 200°. Later, decom- 

 position set in, the temperature went much higher and the distillate was very 

 viscous. It appeared certain, however, that one of the polymeric products of 

 phellandrene, probably a diterpene, may be . distilled without decomposition. 



In order to obtain evidence as to whether or not phellandrene is con- 

 verted into the racemic form by heating, a quantity of very pure phel- 

 landrene (XVI,A, purified) was heated in a sealed tube at 200° for ten 

 hours. 



"-"Ann.Ghem. (Liebig) ( 1S05), 287, 372. 



