Process for the preparation of (cyclo)aliphatic diisocyanates

US4847408A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Hans-Georg Frosch · Cologne, DE
• Heinrich Grave · Bensberg, DE
• Herbert Stutz · Karlsruhe, DE
• Eckart Waldau · Bocholt, DE
• Peter Fuhrmann · Dormagen, DE

Key dates

• Filing date: Apr 25, 1988
• Grant date: Jul 11, 1989
• Expiry date: Apr 25, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C263/20
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a process for the preparation of diisocyanates corresponding to the formula EQU OCN--R--NCO wherein PA1 R denotes a (cyclo)aliphatic hydrocarbon group with up to 15 carbon atoms by phosgenation of the corresponding diamines represented by the formula EQU H.sub.2 N--R--NH.sub.2 in the gas phase, characterized in that PA1 (a) the diamines in vapor form, optionally diluted with an inert gas or with the vapors of an inert solvent, and phosgene are separately heated to temperatures of about 200.degree. to 600.degree. C. and continuously reacted together in a cylindrical reaction chamber which is free from moving parts and heated to about 200.degree. to 600.degree. C., while a turbulent flow is maintained in the reaction chamber. PA1 (b) the gas mixture continuously leaving the reaction chamber is passed through an inert solvent for the diisocyanate which is maintained at a temperature above the decomposition temperature of the carbamic acid chloride corresponding to the diamine, and PA1 (c) the diisocyanate which is dissolved in the inert solvent is purified by distillation.