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562 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

PENTANITROANILINE

Flürscheim and Holmes [20] obtained pentanitroaniline (m. p. 238°C, decom-

position) by the nitration of 3,5-dinitroaniline (p. 557). The product has proved

to be a powerful explosive, of the order of penthrite or hexogen. However, its nitro

groups located in the 3- and 5-positions can readily be split off or substituted,

making the compound insufficiently stable for use as an explosive.

HEXANITRODIPHENYLAMINE (HEXYL)

2,2’,4,4’,6,6’-Hexanitrodiphenylamine (m. p. 243-245°C) was first mentioned

in the chemical literature in 1876 and as long ago as 1891 Haussermann [21] drew

attention to its explosive properties. The product is known under the names of

Dipicrylamine, Hexyl, Heksyl, Hexamite, Hexamin, etc.

The application of hexyl as an explosive goes back as far as 1910. It was widely

used in Germany during the two World Wars, mostly in fusible compositions,

with TNT and with or without ammonium nitrate as a third constituent for filling

torpedoes, marine mines, bombs and whenever a particularly high explosive power
was required. During World War II aluminium was also added to hexyl compo-
sitions (Vol. III).
Gnehm [22] prepared hexanitrodiphenylamine by the nitration of diphenyl-
amine with nitric acid, while Mertens [23] used a mixture of anhydrous nitric acid
with concentrated sulphuric acid for the purpose. This method was applied in 1910

for the commercial preparation of hexyl. Since the yields obtained were too low
(some 60% of the theoretical), during World War I a method patented in 1895

by the Griesheim Works was introduced, the starting materials being chlorodi-

nitrobenzene and aniline. The method consists in the preparation of dinitrodi-

phenylamine (m. p. 156-167°C) which is then nitrated in two stages, to obtain
first tetranitrodiphenylamine (m. p. 199°C) and then hexyl: