urbaf2

242 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

poisoned in the year 1918, 146 of them were poisoned for the first time, 10 for the

second time, 12 for the third time, and 2 women for the fourth time.

EXPLOSIVE PROPERTIES OF DINITROBENZENE

One of the characteristics of m- dinitrobenzene is that it shows an exceptionally

low sensitivity to impact and friction. For this reason attempts have been made

to use it in armour-piercing shells. However they have failed due to its two serious

disadvantages; namely its great toxicity and the difficulty of effective complete

detonation by initiation with an ordinary detonator. Thus, m- dinitrobenzene,

even when compressed to a density of 1.44, requires an additional, secondary de-

tonator.

Sensitivity to impact. According to Wöhler and Wenzelberg [25], energy

of impact per unit area required to initiate 50% explosions is 19.5 kgm/cm^2 Other

authors report that the relative value of the energy necessary for initiation by

impact is 120 as compared with 100 for picric acid.

The explosive decomposition of dinitrobenzene may proceed, as Kast [3a] assumes,

according to the equation:

16C 6 H 4 (NO 2 ) 2 = 10CO 2 + 38CO + 10CH 4 + C 2 H 2 + HCN + 5.5H 2 + 14.5N 2 +

+ 2NH 4 HCO 3 + 33C + Q (6)

where Q is 870 cal/kg

V 0 is 670 l./g

t is 2500°C

f is 7035 m

Lead block expansion is 250 cm^3

The highest rate of detonation is 6100 m/sec.

PREPARATION OF DINITROBENZENE

Deville [26] first prepared dinitrobenzene in 1841 by treating benzene with

concentrated nitric acid and heating it to the boiling point. Soon after that Mus-

Pratt and Hofmann [27] obtained it, using a mixture of nitric and sulphuric acid

for the nitration.

For a long time it was thought that a uniform substance was produced. However,

m 1874 Rinne and Zincke [28], and also Körner [29] found that the o- and p- iso-

mers are also formed along with large quantities of m- dinitrobenzene.

The conditions for preparing dinitrobenzene were described more fully by Beil-

stein and Kurbatov [29a] in 1875. They dissolved 1 part by volume of benzene

in 2 parts by volume of nitric acid (sp. gr. 1.52). After cooling, 3.3 parts by volume.

of sulphuric acid were added.

The possibility that a certain quantity of trinitrobenzene may be formed, as

an impurity in dinitrobenzene, was reported by Hepp [30] in 1882.
Holleman and de Bruyn [31] investigated the influence of the nitration condi-

tions on the quantity of isomers formed. When nitrating nitrobenzene with nitric
acid or a nitrating mixture at temperatures below and above room temperature,
they obtained the following percentages of isomers (Table 38).