Process for the preparation of polyisocyanates

US4388246A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Rudolf Sundermann · New Martinsville, US
• Klaus Konig · Leverkusen, DE
• Theodor Engbert · Recklinghausen, DE
• Gernot Becker · Stuttgart, DE
• Gunther Hammen · Dormagen, DE

Key dates

• Filing date: Mar 4, 1982
• Grant date: Jun 14, 1983
• Expiry date: Mar 4, 2002

Classification

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

Abstract

Polyisocyanates are prepared by thermally splitting a carbamate corresponding to the formula: EQU R.sup.1 (NH--CO--O--R.sup.2).sub.n in which R.sup.1, R.sup.2 and n are as defined herein into the corresponding isocyanate and alcohol. The splitting reaction is carried out at a temperature of from 150.degree. to 350.degree. C., at a pressure of from 0.001 to 20 bar and in the presence of an auxiliary agent. Suitable auxiliary agents are hydrogen chloride, organic acid chlorides, compounds having an alkylating effect and organotin (IV) chlorides. Inert solvents and catalysts may also be employed in the splitting products. The thus-produced isocyanate and alcohol are then separated, if necessary.