Bamberger Rearrangement

Abstract

Intermolecular rearrangement of N ‐phenylhydroxylamines in acidic aqueous solution to afford the corresponding 4‐aminophenols, e.g., in aqueous sulfuric acid, is generally referred to as the Bamberger rearrangement. It has been reported that in this rearrangement the hydroxyl group is introduced into the aromatic ring via a nucleophilic attack of a hydrosulfate ion on the anilenium ion, which is generated by the heterolytic N‐O bond cleavage of O ‐protonated N ‐phenylhydroxylamine. It has been found that alkoxy, halogen, phenoxy are incorporated into the aromatic ring when the rearrangement of N‐phenylhydroxylamine is carried out in nucleophilic solvents.