Oxime - Reactions

Reactions

The hydrolysis of oximes proceeds easily by heating in the presence of various inorganic acids, and the oximes decompose into the corresponding ketones or aldehydes, and hydroxylamines. The reduction of oximes by sodium amalgam, hydrogenation, or reaction with hydride reagents produces amines. The reduction of aldoximes gives both primary amines and secondary amines.

Generally oximes can be changed to the corresponding amide derivatives by treatment with various acids. This reaction is called Beckmann rearrangement. In this reaction, a hydroxyl group is exchanged with the group that is in the anti position of the hydroxyl group. The amide derivatives that are obtained by Beckmann rearrangement can be transformed into a carboxylic acid by means of hydrolysis (base or acid catalyzed).And an amine by hoffman degradation of the amide in the presence of alkali hypoclorites at 80 degrees Celsius, the degradation is itself prone to side reactions namely, the formation of biurets or, cyanate polymers, To avoid this side reaction strict temperature control is necessary, the reaction must be conducted at sufficient temperature to isomerise the cyanate to the isocyante. also, good solvation is also crucial to be successful. Beckmann rearrangement is used for the industrial synthesis of caprolactam (see applications below).

The Ponzio reaction (1906) concerning the conversion of m-nitrobenzaldoxime to m-nitrophenyldinitromethane with dinitrogen tetroxide, was the result of research into TNT-like high explosives:

In the Neber rearrangement certain oximes are converted to the corresponding alpha-amino ketones.

Certain amidoximes react with benzenesulfonyl chloride to substituted ureas in the Tiemann rearrangement