Nitroaromatic compound

A member of the class of organic compounds in which the nitro group (NO₂) is attached directly to the cyclic, aromatic nucleus. The prototypal compound is nitrobenzene. It is prepared by the reaction of benzene with nitric acid in the presence of sulfuric acid, as shown in the reaction below.

The most significant use of nitrobenzene is in the manufacture of aniline (1). About 97% of
1
the nitrobenzene produced in the United States is converted to aniline, which is used in the manufacture of plastics, rubber additives, dyes, drugs, and other products. See also Benzene.

Second to nitrobenzene in commercial importance are the mononitrotoluenes, particularly the ortho and para isomers, (2) and (3), respectively. Reaction of toluene with a mixture of nitric and sulfuric acid at about 40°C (104°F) gives a high yield of a mixture of the isomers, which are separated by a combination of fractional distillation
2

3
and crystallization. The nitrotoluenes are important intermediates in the preparation of dyes, rubber chemicals, and agricultural chemicals.

2,4,6-Trinitrotoluene (TNT; 4) is a military explosive that is stable, nonhygroscopic,
4

and relatively insensitive to impact, friction, shock, and electric spark. It is produced by nitration of toluene in successive stages at progressively higher temperatures and concentrations of acid.

Although literally thousands of other aromatic ring compounds, including the heterocyclics, have been converted to their nitro derivatives, few such compounds have achieved any significant industrial importance. See also Aromatic hydrocarbon; Nitration.

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