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NITRO DERIVATIVES OF HIGHER BENZENE HOMOLOGUES 401

Then, by oxidizing one of the methyl groups to a carboxyl group with chromic

acid, he obtained a carboxylic acid which on losing CO 2 was converted to α− trini-

trotoluene.
The isomers of 2,4,6-trinitro-m-xylene formed in the nitration process may

of course be removed from the product by crystallization or by reacting with sodium

sulphite, the substitution of a nitro group by a sulpho group taking place, e.g.:

(2)

The reaction proceeds much more slowly than with the unsymmetrical trinitro

derivatives of toluene.

Explosive properties of 2,4,6-trinitro-m-xylene

2,4,6-Trinitro-m-xylene is more sensitive to impact than TNT. This can be ex-

plained by the presence of a large number of substituents on the benzene ring.

As Wohler and Wenzelberg [14] found, it could explode at only about half the im-

pact energy needed for the explosion of TNT.

Other authors, however, declare that the sensitiveness of trinitro-m-xylene

is only slightly higher than that of TNT. Taking 100 as figure for picric acid, the

sensitiveness of TNT is 127 and that of trinitro-m-xylene is 120.

The explosive properties of trinitro-m-xylene, as measured by Kravchinskii

[3] are: initiation temperature, 330°C; lead block expansion test, 270 ml (for TNT

this author gives 285 ml); rate of detonation, 6600 m/sec (d = 1.51).

Kast [15] found the explosive power of 2,4,6-trinitro-m-xylene to be similar

to that of m- dinitrobenzene.

The heat of formation of 2,4,6-trinitro-m-xylene equals +18.3 kcal/mole.

Applications of TNX

Trinitroxylene is used as an additive for fusible explosive compositions mixed

with TNT, with TNT and picric acid, or with ammonium nitrate (Vol. III). For

the compositions of various eutectics with trinitroxylene see p. 400.