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234 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

PHYSICAL PROPERTIES

The boiling points of the ortho-, meta-, and para- isomers are 319°C, 303°C,

and 299°C respectively. The corresponding melting points are 118°C, 91°C and

172°C.

They are all crystalline, pale yellow products, highly toxic, the ortho- and para-

isomers even more than m- dinitrobenzene, according to existing data.

Commercial dinitrobenzene is a mixture of the m-dinitro compound, as a prin-

cipal component, with some 8.0% the ortho- and para-isomers. It melts at 80-82°C.

The melting point of dinitrobenzene for military purposes (as a substitute for TNT)

should be 88-89°C.

Dinitrobenzene is of great importance in the organic chemical industry as a raw

material for the manufacture of m- nitroaniline, m- phenylenediamine, sulphur dyes etc.

Dinitrobenzene was used during World War I as a substitute for TNT, since

the raw material benzene, necessary for its production, was more readily available

than that for trinitrotoluene, and the production process itself was more economical.

Dinitrobenzene was used in Russia (1914-1918) for filling naval mines, in

Germany, where it was known as DiFp (Di-Füllpulver), for filling various shells,

and in Switzerland.

Even earlier (1879-1880) liquid explosives known as Hellhoffites (Vol. III) had

been tried as high explosives. They consisted of nitric acid and dinitrobenzene.

When in the molten state, m- dinitrobenzene freezes to form a product having

a density of approximately 1.5 g/cm^3. The specific gravity of m- dinitrobenzene at

different temperatures is given in Table 32 according to Orlova [3]. By com-

pressing powdered m- dinitrobenzene, pellets of various densities can be obtained.

For example Kast [3a] using pressures of 290 kg/cm^2 and 585 kg/cm^2 obtained

products of density 1.29 and 1.44 g/cm

3

respectively.

TABLE 32

SPECIFIC GRAVITY OF m- DINITBOBENZENE

Temperature, °C 20 90 120 140 160

Specific gravity. 1.577 1.3644 1.3349 1.3149 1.2957

The viscosity [3] of molten m-dinitrobenzene is 0.02528 P at 90°C.

m- Dinitrobenzene is readily soluble in acetone, benzene and toluene and less

so in ethyl alcohol. The solubility of the dinitrobenzenes is shown in Table 33,

and the solubility of m- dinitrobenzene in sulphuric acid in Table 34 [3].

m- Dinitrobenzene forms eutectics with higher nitrated aromatics and with
nitric esters. Some of them have been suggested as low melting and low freezing

mixtures respectively (Vol. III).
Here are the most important data (Table 35).