Nitration

In organic chemistry, nitration is a general class of chemical processes for the introduction of a nitro group (−NO2) into an organic compound. The term also is applied incorrectly to the different process of forming nitrate esters (−ONO2) between alcohols and nitric acid (as occurs in the synthesis of nitroglycerin). The difference between the resulting molecular structures of nitro compounds and nitrates (NO−3) is that the nitrogen atom in nitro compounds is directly bonded to a non-oxygen atom (typically carbon or another nitrogen atom), whereas in nitrate esters (also called organic nitrates), the nitrogen is bonded to an oxygen atom that in turn usually is bonded to a carbon atom (nitrito group).

There are many major industrial applications of nitration in the strict sense; the most important by volume are for the production of nitroaromatic compounds such as nitrobenzene. The technology is long-standing and mature.

Nitration reactions are notably used for the production of explosives, for example the conversion of guanidine to nitroguanidine and the conversion of toluene to trinitrotoluene (TNT). Nitrations are, however, of wide importance as virtually all aromatic amines (anilines) are produced from nitro precursors. Millions of tons of nitroaromatics are produced annually.

Aromatic nitration

Typical nitrations of aromatic compounds rely on a reagent called "mixed acid", a mixture of concentrated nitric acid and sulfuric acids. This mixture produces the nitronium ion (NO2+), which is the active species in aromatic nitration.