METHOD FOR PRODUCING CYCLIC LACTAMS

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 plus; m is at least 3, preferably at least 4, R1 and R2 represent C1 C6 alkyl, C5 C7 cycloalkyl or C6 C12 aryl groups, by reacting a compound of the formula (I), wherein R1, R2, 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). Procedimiento para la obtencion de lactamas ciclcas de la formula (II) (ver formula II) en la que n y m pueden tener cada uno los valores 0, 1, 2, 3, 4, 5, 6, 7, 8 y 9 y la suma a partir de n+m asciende por lo menos a 3, preferentemente, por lo menos a 4, R1 y R2 significan grupos C1-C6-alquilo, C5-C7-cicloalquilo o C6-C12-arilo por reaccion de un compuesto (I) de la formula (ver formula I) en la que R1, R2, m y n tienen los signifciados arriba indicados y R significa grupos nitrilo, amida carboxilica y de acido carboxilico con vapor de agua en la fase gaseosa, procedimiento que esta caracterizado porque a) se hace reaccionar el compuesto (I) con vapor de agua en la fase gaseosa, adicionando antes o despues de la reaccion un diluyente organico (III), que presenta una laguna de miscibilidad con agua bajo determinadas condicones de cantidad, presion y temperatura, obteniendose una mezcla (IV) que contiene una lacatama (II) b) se somete la mezcla (IV) antes o despues de l