Nitration - Aromatic Nitration

Aromatic Nitration

Typical nitration syntheses apply so-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. This active ingredient, which can be isolated in the case of nitronium tetrafluoroborate, also effects nitration without the need for the mixed acid. In mixed-acid syntheses sulfuric acid is not consumed and hence acts as a catalyst as well as an absorbent for water. In the case of nitration of benzene, the reaction is conducted at 50 °C. The process is one example of electrophilic aromatic substitution, which involves the attack by the electron-rich benzene ring:

Alternative mechanisms have also been proposed, including one involving single electron transfer (SET).