Multistage continuous preparation of cycloaliphatic disocyanates

US7557242B2 · kind B2 · utility

Assignee

• Degussa AG · DE

Inventors

• Stephan Kohlstruk · Marl, DE
• Manfred Kreczinski · Herne, DE
• Hans-Werner Michalczak · Herne, DE

Key dates

• Filing date: Apr 7, 2005
• Grant date: Jul 7, 2009
• Expiry date: Jul 6, 2026

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C263/04
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Cycloaliphatic diisocyanates can be prepared continuously and phosgene-free by reacting at least one cycloaliphatic diamine with at least one carbonic acid derivative and at least one alcohol to give a cycloaliphatic diurethane; freeing the cycloaliphatic diurethane of a low boiler, a medium boiler and mixtures thereof; thermally cleaving the cycloaliphatic diurethane in a cleavage apparatus to give a cycloaliphatic diisocyanate and a cleavage residue; continuously discharging a portion of the cleavage residue from the cleavage apparatus; removing the high boiler components from the discharge to obtain a purified discharge; reurethanizing the purified discharge with alcohol to obtain a reurethanized discharge; and recycling the reurethanized discharge into the process.