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256 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVES

Preparation from m- xylene. Giua [15] suggested sym-trinitrobenzene might

be prepared by the nitration of m- xylene to the trinitro derivative, followed by

oxidation and decarboxylation:

(16)

The method is rarely used, for pure m- xylene is not easily available in industry.

Other preparatory reactions. sym-Trinitrobenzene is also formed as a result

of the prolonged treatment of benzene with nitrogen dioxide in a closed vessel

(Wieland [54]).

The preparation of sym-trinitrobenzene by cyclization of nitromalonic aldehyde

(Hill and Torray [55]):

(17)

is of theoretical importance only.

PREPARATION OF UNSYMMETRICAL ISOMERS OF TRINITROBENZENE

1,2,4-Trinitrobenzene may be obtained only in moderate yield by nitration

of o- or p- dinitrobenzene. A product of high purity may be obtained from 2,4-di-

nitroaniline (Korner and Contardi [56]):

(18)

This isomer dissolves less easily in alcohol or ether than sym-trinitrobenzene.

The nitro group in position 1 can readily be substituted by a hydroxyl or amino

group.