Process for the isomeric separation of isocyanates

US6271414A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Rudiger Drope · Neunburg vorm Wald, DE
• Dieter Grenner
• Hartmut Hetzel · Cologne, DE
• Hans-Peter Schal · Dormagen, DE
• Gerhard Wegener · Mettmann, DE

Key dates

• Filing date: Apr 29, 1999
• Grant date: Aug 7, 2001
• Expiry date: Apr 29, 2019

Classification

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

Abstract

A process is described for obtaining pure isocyanate isomers from a mixture of isocyanate isomers by suspension crystallization and the isolation of isomerically pure crystals, which is characterized in that, prior to the isolation of the crystals, 5 to 40% by weight of the crystals produced are remelted while simultaneously increasing the temperature of the crystal slurry by 4.5 to 9.degree. C.