Beckmann rearrangement

A similar migration is found in the Beckmann rearrangement.

This reaction is now known as the Beckmann rearrangement.

He also proposed the mechanism of the Beckmann rearrangement.

Beckmann rearrangement is used for the industrial synthesis of caprolactam (see applications below).

The Beckmann rearrangement is a side reaction.

The reaction is related to the Beckmann rearrangement as both reaction involve a carbon to nitrogen shift.

Treatment of this oxime with acid induces the Beckmann rearrangement to give caprolactam (3):

Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement.

When treated with a Lewis acid, oxime methanesulfonates will undergo a facile Beckmann rearrangement.

The Beckmann rearrangement is another example of a ring expanding reaction in which a heteroatom is inserted into a carbon-carbon bond.

Afterwards he was allowed to use a laboratory at the institute, and he worked again on the Beckmann rearrangement and measurements of physical properties of solutions.

The most famous and important reaction is that cyclohexanone oxime undergoes Beckmann rearrangement when heated with an acid catalyst, yielding ε-caprolactam:

In the presence of sulfuric acid catalyst, the oxime undergoes the Beckmann rearrangement to give the cyclic amide caprolactam:

The amide derivatives that are obtained by Beckmann rearrangement can be transformed into a carboxylic acid by means of hydrolysis (base or acid catalyzed).

The Beckmann rearrangement, named after the German chemist Ernst Otto Beckmann (1853-1923), is an acid-catalyzed rearrangement of an oxime to an amide.

The reaction mechanism of the Beckmann rearrangement is in general believed to consist of an alkyl migration with expulsion of the hydroxyl group to form a nitrilium ion followed by hydrolysis:

A Beckmann rearrangement (methanol, sodium polystyrene sulfonate 2 hrs, 170 C) took place next to lactam 32 (not isolated) which reacted further to the tetracycle 33 called alpha-corrnorsterone in an amine-carbonyl condensation - aldol condensation cascade.

Nitrilium ions are believed to be intermediates in the hydrolysis of nitriles, the Beckmann rearrangement, the Friedel-Crafts cyclization of amines to isoquinolines, the Schmidt reaction with ketones, and the Ugi, Ritter and Passerini reactions.

This example reaction starting with cyclohexanone, forming the reaction intermediate cyclohexanone oxime and resulting in caprolactam is one of the most important applications of the Beckmann rearrangement, as caprolactam is the feedstock in the production of Nylon 6.

A simpler synthesis by Hoechst-Celanese involves direct acylation of phenol with acetic anhydride catalyzed by HF, conversion of the ketone to a ketoxime with hydroxylamine, followed by the acid-catalyzed Beckmann rearrangement to give the amide.