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NITRO DERIVATIVES OF BENZENE^257

1,2,3-Trinitrobenzene cannot be obtained by the nitration of o- dinitrobenzene.

Kamer and Contardi have prepared this isomer from 2,6-dinitroaniline:

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The nitro group in position 2 can readily be substituted by a hydroxyl or amine

group.

TETRANITROBENZENES

Two isomers of tetranitrobenzene are known : 1,2,4,6-tetranitrobenzene and

1,2,4,5-tetranitrobenzene:

Their melting points arc 129-130°C and 188°C respectively.

1,2,4,6-Tetranitrohenzene. It was Borsche [57] who first prepared 1,2,4,6-tetra-

nitrobenzene in 1923, by treating picrylhydroxylamine with anhydrous nitric acid.

According to Borsche, the reaction steps are as follows:

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m. p. 125-126°C

Picrylhydroxylamine is oxidized in a yield of about 60% of theory.

Holleman [58] obtained tetranitrobenzene in another way, starting from picr-

amide:

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