urbaf2

566 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

During the reaction a temperature of 70°C is maintained. After all the tetranitro-

diphenylamine has been added, the reaction mixture is heated to 90°C, kept at

this temperature for one hour, cooled down to room temperature and filtered on

a vacuum filter. A yellow crystalline, easily filterable product is obtained. The

spent acid is approximately of the following composition:

HNO 3 34%

H 2 SO 4 40%

nitrosylsulphuric acid 11%

organic matter 1%

The product is well washed with water, then transferred to a washing tank, where

it is washed 2-3 times by agitating with boiling water. The washings are separated

by decantation. The water remaining in the washed product is separated on a vac-

uum filter (J. Marshall recommends a centrifuge for this purpose but this procedure

should be considered as too hazardous). The wet product, after being dried at 80°C,

is of high purity, as reflected by its melting point which ranges from 238.5°

to 239.5°C.

The yield obtained for the conversion of dinitrodiphenylamine into hexyl is

86% of the theoretical.

Japanese method

Japanese process for preparing hexanitrodiphenylamine from dinitrodiphenyl-

amine was applied at the Maizuru Works. A stainless steel nitrator is charged with

80% nitric acid, followed by dinitrodiphenylamine. A temperature of 45-55°C

is maintained during this procedure, which takes 4 hr. Then the temperature

is raised to 90-95°C during one hour and a half and kept there for another hour

and a half. Then the whole is cooled to 45°C, the precipitated hexanitrodiphenyl-

amine is filtered off on a vacuum filter and transferred to a tank, where it is washed

with cold water, then three times with hot water, and finally again with cold water.

The remaining water is separated from hexyl by centrifugation, followed by dry-

ing.

The spent nitric acid may be fortsed by mixing with 98% nitric acid.

NITRO DERIVATIVES OF CARBAZOLE

The nitration of carbazole has been studied by Graebe [29], Ciamician and

Silber [30], VotoEek [31], Escales [32] and Raudmtz [33].

Mono-, di- and tetra-nitro derivatives of carbazole have been obtained. Among

them only tetranitrocarbazole is of practical importance. It was used in Germany

under the name of “Nitrosan” as an insecticide. During World War II it was used

under the name of “Gelbmehl” in combustible compositions for delayed action
time fuses.