Schmidt reaction

In the Schmidt reaction is a reaction in organic chemistry name after its discoverer, the German chemist Karl -Friedrich Schmidt - was named (1887, 1971). By means of the Schmidt reaction carboxylic acids to primary amines and ketones can be reduced to carboxamides.

• 2.1 Overview reaction
• 2.2 mechanism

Schmidt reaction of the carboxylic acids

Overview reaction

Carboxylic acids react with the Schmidt reaction with strong mineral acids (usually sulfuric acid) with hydrazoic acid, and with a subsequent hydrolysis to the primary amines.

Mechanism

Here, the hydroxyl group of the carboxylic acid is first protonated by addition of strong acid ( sulfuric acid), so that after elimination of water a resonance-stabilized acylium ion is formed. This is attacked by the hydrazoic acid nucleophilic. With elimination of nitrogen with 1,2- alkyl shift ( rearrangement of the radical R ) a carbenium ion is obtained. Hydrolysis and elimination of a proton and carbon dioxide, the primary amine is formed finally.

Schmidt reaction of ketones

Overview reaction

Ketones react at this Schmidt reaction with strong mineral acids (usually sulfuric acid) with hydrazoic acid, and with a subsequent hydrolysis to carboxylic acid amides.

Mechanism

In this reaction, first the carboxyl group of the ketone is protonated by addition of strong acid ( sulfuric acid). Then the hydrazoic acid attacks the carbonium ion to nucleophilic, where water is then cleaved. In the next reaction step, nitrogen is released and migrated to the radical R1. This carbenium ion is hydrolyzed and after deprotonation and tautomerization creates the carboxamide.

The reaction is similar to the Curtius reaction or a Beckmann rearrangement. Optionally, the amide can be further hydrolyzed to an amine.