Fischer–Hepp rearrangement

The Fischer- Hepp rearrangement is a rearrangement in the chemical reaction in which an aromatic nitrosamine rearranges to an isomeric nitroso compound:

The reaction is named after its discoverers, the German chemists Otto Philipp Fischer (1852-1932) and Eduard Hepp ( 1851-1917 ). It allows the preparation of N- monoalkylated aniline substituted in the para -position by a nitroso.

The rearrangement is carried out by the action of hydrochloric acid on the nitrosamine. The chemical yield of the reaction is generally well under these conditions, but often reduced when using a different acid. The exact reaction mechanism is unknown, but obviously there is an intramolecular reaction, since the rearrangement takes place in the presence of urea, which would have intercepted nitrous acid or nitrosyl chloride.