Verfahren zur Herstellung cyclischer Lactame

摘要

The invention relates to a method for producing cyclic lactams of the formula (II), wherein n and m may each represent 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, R<1> and R<2> represent C1-C6 alkyl, C5-C7 cycloalkyl or C6-C12 aryl groups, by reacting a compound of the formula (I), wherein R<1>, R<2>, m and n have the meaning indicated above, and R represents nitrile groups, carboxylic acid amide groups and carboxylic acid groups, with water vapor in the gaseous phase. The inventive method is further characterized in that a) the compound (I) is reacted with water vapor in the gaseous phase, adding an organic diluent (III) before or after the reaction, which diluent has a miscibility gap under certain quantitative, pressure and temperature conditions, said reaction resulting in a mixture (IV) that contains a lactam (II), b) adjusting the mixture (IV) before or after the removal of ammonia to quantitative, pressure and temperature conditions under which the diluent (III) and water are present in a liquid form and have a miscibility gap, and obtaining a two-phase system consisting of a phase (V) that has a higher proportion of diluent (III) than water, and a phase (VI) that has a higher proportion of water than diluent (III), c) separating phase (V) from phase (VI) and, d) removing from phase (V) the diluent (III) and optionally by-products selected from the group of the low-boilers, high-boilers and unreacted compound (I), and obtaining a lactam (II).