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430 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Ward and Hawkins [27] nitrated 1-nitronaphthalene with a mixture of nitric

(sp. gr. 1.42) and sulphuric (sp. gr. 1.84) acids, at a volume ratio 4:1 at 0°C and

obtained a mixture of 1,8- and 1,5-dinitronaphthalenes, their ratio being about

70:30. 2-Nitronaphthalene, nitrated under similar conditions, gave a mixture of

1,6- and 1,7-dinitronaphthalenes along with 1,3,8-trinitronaphthalene, at a ratio

of about 42:52:9.

According to Pictet [28] at very low temperatures ranging from -50°C to

-60°C, nitration with a mixture of nitric and sulphuric acids resulted in the forma-

tion of a large quantity (about 46%) of the 1,3-isomer.

According to German sources (I. G. Ludwigshafen), commercial dinitronaph-

thalene consists of the 1,5-isomer (20%), 1,8-isomer (53%), the rest (27%) being

a resinous substance.

The 1,3-isomer has been obtained from 2,4-dinitro-a-naphthylamine, the amino

group being removed by the conventional method, after diazotization (Liebermann

[29]):

(1)

CHEMICAL PROPERTIES

It was known for long time that the 1,5- and 1,8-dinitronaphthalenes react

under the action of concentrated sulphuric acid to yield naphthazarine - a valuable

compound for dyeing [30]. The mechanism of the formation of this compound

(based on experiments of Dimroth and Ruck [18a]) probably consists in the trans-

formation of the nitro compounds to quinone-oximes and the reduction of one
of the nitro groups by hydroxylamine split off the oxime:

(2)