GB740891A - Improvements in the production of amides - Google Patents

Abstract

Amides are produced by a process which comprises effecting the Beckmann transformation of the corresponding oxime by means of sulphuric acid partly neutralized with ammonia, i.e. a composition such as can be obtained by reacting sulphuric acid with ammonia in amount less than is required to convert all the sulphuric acid present into ammonium sulphate. Ammonium bisulphate may be employed with or without some sulphuric acid as catalyst. A cyclic process may be carried out by neutralizing the reaction mixture with ammonia, separating the resulting ammonium sulphate, decomposing the ammonium sulphate to ammonium bisulphate and the ammonia with further oxime. When ammonium bisulphate is employed the melting-point thereof may be reduced by the addition of water, monoammonium dihydrogen phosphate or other salt or flux or sulphuric acid. Alternatively the reaction may be carried out in a medium which is liquid at ordinary temperatures, e.g. acetic acid. Small amounts of water may be eliminated by the addition of acetic anhydride. Other solvents may be used, e.g. monochlor-, dichlor- or trichloracetic acid and a mixture of chlorinated acetic acid and acetic acid may be employed such that the boiling point of the mixture is the desired reaction temperature. The reaction product, e.g. caprolactam, may be used instead of or in addition to acetic acid or a mixture of acetic acid and a chlorinated acetic acid, especially in a cyclic process. In examples: cyclohexanone oxime is gradually added to a mixture of ammonium bisulphate, ammonium dihydrogen phosphate and acetic acid under reflux, ammonia is added to the cooled reacted mixture to convert ammonium bisulphate to the sulphate which is filtered off, the crude lactam liquor is extracted and worked up, the ammonium sulphate is heated to form ammonia which is collected in water for further neutralization and ammonium bisulphate which is used in the transformation of further oxime (1); in a similar process cyclohexanone oxime is added to a mixture of ammonium bisulphate, sulphuric acid, monoammonium dihydrogen phosphate and glacial acetic acid (2); and in similar processes cyclohexanone oxime is added to a mixture of ammonium bisulphate, glacial acetic acid and monochloracetic acid (3 and 4). Suberone oxime may be converted to the corresponding lactam and oximes of benzophenone and diethyl ketone may be converted to benzanilide and propionethylamide respectively.