The Limonene Group of Ter penes. 
325 
OCCURRENCE'. 
Dextrogyrate Limonene: 
In the oil of Citrus Limonum. 16 
aurantium. 17 
medica. 18 
r 15 
l 
“ bigaradia sienensis. 19 | 
“ “ myrtifolia. 19 J 
“ Bergamia. 20 
Carum Carvi. 21 
Anethnm gravelens (Dill oil). 22 
Erigeron Canadense. 23 
Lcevogyrate Limonene: 
In the oil of Lauras camphora (camphor oil). 24 
| (“ Fichtennadel oel”). 25 
Pinus picea. 
Dipentene: 
In Camphor oil. 29 
“ Cubeb oil. 30 
“ Elemi oil. 31 
“ Olebanum oil. 32 
“ Swedish turpentine oil (modified natural product). 33 
“ Russian turpentine oil 34 (modified natural product). 
“ Oil from leaves of Citrus Limetta. 35 
“ Oil of black pepper. 36 
The statements that 01. Cinae, 01. cajeputi and 01. Eucalypti contain 
dipentene as natural product, are without proof. 37 
The presence of limonene can readily be ascertained in the fractions 
of volatile oils boiling about 175° by Tilden’s nitrosylchloride reaction 
as modified by Wallach. 26 If the yield is not too small the n-nitroso- 
chloride can be recrystallized from ether and recognized by its crystal¬ 
line form. 47 The conversion of the crude nitrosochloride into carvoxime 
is characteristic but not easily performed. The double decomposition 
of the crude nitrosochloride with benzylamine is much simpler. 28 The 
u-nitrol-benzylamine base crystallizes in dull needles which melt at 93°. 
The tetrabromide reaction is also very characteristic but not as easily 
and readily performed as the one mentioned last. 
Dipentene is found in fractions boiling from 175-180° It is character¬ 
ized by means of its tetrabromide 38 melting at 124°, by means of its 
nitrosochloride and the benzylamine base obtained therefrom. 39 The 
u-base crystallizes well from dilute alcohol in colorless transparent crys¬ 
tals, melting at 109-110°. 
