Side-reactions and by-products from nitration

5-Trinitrobenzene is present in crude TNT manufactured by mixed acid nitration and results from methyl group oxidation followed by decarboxylation. In fact, a convenient method for the synthesis of 1,3,5-trinitrobenzene involves oxidation of 2,4,6-trinitrotoluene with a solution of sodium dichromate in sulfuric acid, followed by decarboxylation of the resulting 2,4,6-trinitrobenzoic acid in boiling water. 1,3,5-Trinitrobenzene is prepared from 2,4,6-trinitro-m-xylene by a similar route. 2,4,6-Trinitroanisole can be prepared from the 

As a general rule, the lower the temperature of a nitration, the fewer the oxidation byproducts that are formed. 

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