Multiple-step process for the preparation of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate

US4596679A · kind A · utility

Assignee

• BASF SE

Inventors

• Hans Hellbach · Bischofswerda, DE
• Franz Merger · Bischofswerda, DE
• Friedrich Towae · Ludwigshafen, DE

Key dates

• Filing date: Apr 13, 1984
• Grant date: Jun 24, 1986
• Expiry date: Apr 13, 2004

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C265/10
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

This invention discloses a non-phosgene process for the preparation of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate by the reaction of the precursor diamine with urea and an aliphatic alcohol in the presence of a dialkyl carbonate and an alkyl carbonate. The intermediate diurethane is separated from starting materials and by-products and thermally cleaved to alcohol and diisocyanate which are separated by fractional condensation of the products from the vapor state. This process gives high yields of the desired diisocyanate and lends itself particularly to continuous processing.