GB803374A - Process for the production of lactams - Google Patents

Abstract

Lactams are prepared by reacting g -halogenobutyronitrile or d -halogenovaleronitrile, the carbon atoms of which may be substituted by alkyl radicals containing fewer carbon atoms than the alkyl chain of the nitrile, with ammonia or a primary amine in the presence of water and at elevated temperature. It is advantageous to effect the reaction at 150-250 DEG C., preferably at 180-200 DEG C., and under pressure. It is also preferred to use an excess of ammonia or amine, e.g. 20-100 mol. of ammonia or amine per mol. of nitrile, and an excess of water, e.g. 20 to 50 mol. of water per mol. of nitrile. The process is best operated by heating the initial mixture rapidly to reaction temperature, or by preheating the components before they are combined. For example, the nitrile may be gradually introduced into the aqueous ammonia or amine solution heated to reaction temperature. The process may be operated continuously or discontinuously. In examples: (1) valerolactam is obtained by heating together d -chlorovaleronitrile, water and ammonia in a silver-lined autoclave, the product being recovered by evaporating the reaction mixture to dryness and extracting with benzene; (2) valerolactam is prepared as in (2) in a V2A steel-autoclave with magnetic stirring; (3) pyrrolidone is obtained by heating together chlorobutyronitrile, water and ammonia in a V4A steel agitated autoclave and recovered by extraction with ether after evaporating the water and ammonium chloride.