Schmidt reaction

In organic chemistry, the Schmidt reaction is an organic reaction in which an azide reacts with a carbonyl derivative, usually an aldehyde, ketone, or carboxylic acid, under acidic conditions to give an amine or amide, with expulsion of nitrogen.

[1][2][3] It is named after Karl Friedrich Schmidt (1887–1971), who first reported it in 1924 by successfully converting benzophenone and hydrazoic acid to benzanilide.

The carboxylic acid Schmidt reaction starts with acylium ion 1 obtained from protonation and loss of water.

The protonated isocyanate is attacked by water forming carbamate 4, which after deprotonation loses carbon dioxide to the amine.

It has been proposed that the dehydration to 3 to give 5 (and, hence, the Beckmann pathway) is favored by nonaqueous acids like conc.