Method for producing cyclic lactams

Abstract

A process is provided for the preparation of cyclic lactams of formula (II): 1 in which n and m can each have the values 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9 and the sum of n+m is at least 3, preferably at least 4, and R1 and R2 are C1-C6-alkyl, C5-C7-cycloalkyl or C6-C12-aryl groups, by reacting a compound (I) of the formula 2 in which R1, R2, m and n are as defined above and R are [sic] nitrile, carboxamide and carboxylic acid groups, with steam in the gas phase, wherein a) the compound (I) is reacted with steam in the gas phase with the addition, before or after the reaction, of an organic diluent (III) which exhibits a miscibility gap with water under specific quantity, pressure and temperature conditions, to give a mixture (IV) containing a lactam (II), b) the mixture (IV) is converted, before or after the separation of ammonia, under quantity, pressure and temperature conditions such that the diluent (III) and water are liquid and exhibit a miscibility gap, to give a two-phase system consisting of a phase (V) containing a higher proportion of diluent (III) than water, and a phase (VI) containing a higher proportion of water than diluent (III), c) the phase (V) is separated from the phase (VI), and d) the diluent (III) and optionally by-products selected from the group consisting of low-boiling component [sic], high-boiling component [sic] and unreacted compound (I) are separated from the phase (V) to give a lactam (II).

Dependencies are inferred from the claim text.