Preparation of caprolactam

Abstract

Caprolactam is prepared by reacting a solution of 6-aminocapronitrile with water in the liquid phase at elevated temperatures by a process in which (a) an aqueous solution of 6-aminocapronitrile in the liquid phase is heated without the addition of a catalyst in a reactor A to give a mixture I consisting essentially of water, caprolactam and a high-boiling fraction (high boiler), then (b) the water is removed from the resulting mixture I to give a mixture II consisting essentially of caprolactam and the high boilers, then (c) the caprolactam and the high boilers from mixture II are separated from one another by distillation, and then either (d1) the high boilers from stage (c) are fed into the reactor A of stage (a) or (d2) the high boilers are heated similarly to stage (a) in a further reactor B and then worked up similarly to stages (b) and (c) to give further caprolactam, or (d3) the high boilers are heated under reduced pressure in the presence of a base in a reactor C and the reacted mixture is worked up by distillation to give caprolactam.

Dependencies are inferred from the claim text.