Process for the preparation of toluene-diisocyanate

US8063241B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Wolfgang Lorenz · Dormagen, DE
• Lars Padeken · Itzehoe, DE
• Bernd Pennemann · Moitzfeld, DE
• Friedhelm Steffens · Leverkusen, DE
• Lothar Weismantel · Neunburg vorm Wald, DE

Key dates

• Filing date: Sep 30, 2010
• Grant date: Nov 22, 2011
• Expiry date: Sep 30, 2030

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C209/62
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a process for the preparation of toluene-diisocyanate. In this process, toluenediamine is reacted with phosgene to give crude toluene-diisocyanate, the crude toluene-diisocyanate is purified by distillation, the distillation residue formed during the distillation is hydrolysed at temperatures of less than 230° C. under absolute pressures of less than 30 bar, and the toluenediamine formed by this process is subsequently recycled into the reaction of toluenediamine and phosgene.