Hofmann–Martius rearrangement

Under the Hofmann - Martius rearrangement is understood in chemistry, acid-catalyzed rearrangement of N -alkylated aniline derivatives to the corresponding ortho -and para -alkylated aniline derivatives. The reaction is mechanistically related to the Fries rearrangement. Practically, this work in the heat with a mineral acid, usually hydrochloric acid.

The rearrangement reaction is named after its discoverers, the German chemists August Wilhelm von Hofmann (1818-1892) and Carl Alexander von Martius ( 1838-1920 ).

Mechanism

The acid is first added at the amino function of the substrate. Then cleaves the alkyl group of the cationic amino group, and then substitute in a Friedel -Crafts alkylation on the ring.

Variants

As a variant, the Reilly - Hickinbottom rearrangement is known. It runs mechanistically the same, only to be with her instead of inorganic acids metal halides, usually aluminum chloride, used as Lewis acids.