Piria Reaction

Abstract

This reaction is a two‐step preparation of aromatic amines and amino sulfonic acids by the reduction of aromatic nitro compounds with bisulfite followed by hydrolysis in mineral acid and is generally known as the Piria reaction. All mechanistic features of the reaction have been presented and it has been found that in 4‐nitrophenol, the sulfonic group enters the meta ‐position of the nitro group. In addition, it has been found that sodium sulfite and the partially neutralized NaHSO 3 are very effective in this reaction. This reaction has been applied for the preparation of aromatic amines.