4-Nitrotoluene

4-Nitrotoluene or para-nitrotoluene is an organic compound with the formula CH₃C₆H₄NO₂. It is a pale yellow solid. It is one of three isomers of nitrotoluene.

Synthesis and reactions

Together with other isomers, 4-nitrotoluene is prepared by nitration of toluene, commonly using titanium(IV) nitrate. It undergoes the reactions typical for nitrobenzene derivatives, e.g. hydrogenation gives p-toluidine.
Oxidation of the methyl substituent of 4-nitrotoluene has been extensively investigated. Depending on the conditions, oxidation yields 4-nitrobenzaldehyde diacetate, 4-nitrobenzenoic acid, and 4,4'-dinitrobibenzyl. Treatment of 4-nitrotoluene with bromine gives the 4-nitrobenzyl bromide.

Applications

The principal application involves its sulfonation to give the 4-nitrotoluene-2-sulfonic acid. This species can be oxidatively coupled to produce stilbene derivatives, which are used as dyes. Representative derivatives include the molecular and salt forms of 4,4'-dinitroso- and the 4,4'-dinitro-2,2'-stilbenedisulfonic acids, e.g. disodium 4,4'-dinitrostilbene-2,2'-disulfonate.

Safety

Evidence exists for toxicity and carcinogenicity in mice.