Recovery of caprolactam from caprolactam distillation low boilers or high boilers or mixtures thereof

US4882430A · kind A · utility

Assignee

• BASF SE

Inventors

• Gerald Neubauer · Weinheim, DE
• Emile De Decker · Schoten, BE
• Hugo Fuchs · Ludwigshafen, DE
• Bernhard Holzknecht · Ellerstadt, DE
• Josef Ritz · Ludwigshafen, DE

Key dates

• Filing date: Oct 13, 1988
• Grant date: Nov 21, 1989
• Expiry date: Oct 13, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D201/16
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Caprolactam is recovered from caprolactam distillation low boilers or high boilers or mixtures thereof by the following steps: PA1 (a) crystallizing a low or high boiler or a mixture thereof to form purified capro-lactam crystals and a mother liquor, PA1 (b) separating off the purified caprolactam crystals to leave a mother liquor, PA1 (c) recycling from 5 to 90% by weight of the mother liquor of stage (b) into stage (a) and transferring the remainder of the mother liquor into the subsequent stage (d), PA1 (d) crystallizing the remaining mother liquor portion from stage (c) to form caprolactam crystals and a mother liquor, separating off the caprolactam crystals of stage PA1 (e) (d) and recycling the same into stage (a) to leave a mother liquor, PA1 (f) recycling from 20 to 99% by weight of mother liquor of stage (e) into stage (d) and channeling out the remainder of the impurity-containing mother liquor of stage (e).