78 | : REPORT OF SCHIMMEL & Co. OCTOBER 1915. 
noteworthy results as to the constitution and the identification of this body). He - 
found that azulene easily forms a picrate, by means of which it can be identified and — 
purified. Sherndal added a mixture of 1 g. of azulene and 5 cc. of alcohol to a 
solution of 1 g. of picric acid in 20 cc. of 95p.c. alcohol. In a few minutes the 
solution set to a mass of crystals, which dissolved again on heating and from which 
the picrate deposited on cooling in the form of short shiny black needles. It melts 
at 118°. In order to ascertain the composition of the picrate it was heated with water 
containing a measured amount of barium hydroxide. By titration of the excess of 
barium hydroxide, it was found that the picrate contains 1 molecule of azulene and 
1 molecule of picric acid. 
With the aid of the picrate, the presence of azulene was proved in camphor oil 
and oil of cubebs, the latter containing only 0.03 p.c. The azulene had been prepared 
by shaking the oil of cubebs, dissolved in light petroleum, with sulphuric acid. 
To give an idea of the colour intensity of azulene, Sherndal dissolved 0.064 g. of 
the pure hydrocarbon in 1 litre of benzine and tried to obtain the same intensity of 
colour with an ammoniacal solution of copper sulphate, when 0.24 g. of copper 
sulphate was required per litre. 
Through the action of sulphuric acid and acetic anhydride, blue coloured products 
were obtained from West Indian sandalwood oil, guaiac oil and oil of gurjun balsam. The 
sesquiterpene fraction of eucalyptus oil®) yielded a greenish-blue oil, whereas no green or 
blue fractions could be obtained from cedarwood oil and caryophyllene from clove oil. 
Sherndal mixed 10 cc. of oil of gurjun balsam with the same volume of acetic 
anhydride and allowed 2 cc. of concentrated sulphuric acid to flow in gradually, 
cooling with ice all the while. A violent reaction took place; the mixture turned 
purple, which colour soon changed into dark blue, and sulphur dioxide was evolved. 
Some time afterwards the mixture was distilled with steam, when 4 cc. of a dark blue 
oil were obtained, from which azulene could be isolated by treatment with benzine 
and sulphuric acid. The yield was 0.04 p.c. The picrate melted at 122°. 
On reduction with colloidal palladium and hydrogen, azulene absorbs 8 atoms of — 
hydrogen and forms a colourless hydrocarbon, C,;H».6, which shows the properties of a 
tricyclic sesquiterpene and is probably identical with dihydro-e-gurjunene (deo0 0.8935; 
Npw»0 1.490; “) +0). Hydrogenated azulene affords an intense colour reaction with 
acetic anhydride -++ sulphuric acid and with bromine in acetic acid. 
It is evident from the result of the reduction that azulene is closely allied to the 
sesquiterpenes. It contains four double links and is tricyclic. The easy formation of 
the picrate indicates that it contains an aromatic nucleus. Conjugate hydroaromatic 
double links are absent, for it cannot be reduced with sodium and alcohol. The blue 
colour may be explained by the peculiar arrangement of the double links in the molecule. 
Styrene. Some time ago, H. Stobbe and G. Posnjak*) investigated the polymerization 
of styrene into metastyrene, arriving at the following conclusions on account of the 
results obtained: — 
1. The velocity of the polymerization of freshly distilled styrene increases with 
the time. It is, therefore, abnormal and must be classified among the group 
of autocatalytic processes. 
1) Journ. Americ. chem. Soc. 87 (1915), 1537. — %) As 140 kinds of eucalyptus oil are known so far, 
‘above general indication is insufficient. — %) Liebigs Annalen 371 (1910), 259. — Berl. Berichte 47 (1914), 2701; 
Report April 1915, 88. 
