urbaf2

438 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Since under the conditions of the above reaction partial decarboxylation may

take place, nitrobenzoic acids may also be formed:

C 6 H 4 .NO 2 .COOH

C 6 H 3 (NO 2 ) 2 COOH

In addition nitronaphthols are obtained, which may be formed either by direct

oxidation or through isomerization of nitronaphthalenes to nitrosonaphthol or

its derivatives :

(9)

(10)

It has been found that such reactions can occur under the influence of fuming

sulphuric acid, at 40-50°C. Nitrosonaphthol may then by oxidized to nitronaph-

thol. Moreover, picric acid may be formed during the nitration processes.

Resinous amorphous, brown substances are also formed, and found in dinitro-

and trinitro-naphthalenes. They are partly soluble in alkalis, hence the suggestion

that they are of an acidic or phenolic character and come from products of oxi-

dation of naphthalene.

MANUFACTURE OF NITRO DERIVATIVES OF NAPHTHALENE

NITRATION OF NAPHTHALENE TO MONONITRONAPHTHALENE

Nitration grade naphthalene should be almost chemically pure, purified by

sublimation or crystallization (pressed naphthalene). Sublimated naphthalene

should not melt below 79.6°C, while the melting point of the pressed product (in

lumps, 2-4 cm) should not be lower than 79.0°C.

With concentrated sulphuric acid the naphthalene should not produce a darker

shade than a pale reddish pink.

German method

This method has been applied at I. G. Leverkusen. It consists in charging

naphthalene into a nitrator, containing a part of the spent acid and nitronaphthalene

from the previous batch. To this the nitrating acid is added.

The succession of operations is as follows. A cast iron nitrator of 7 m

3

capacity