Multiple-step process for the preparation of hexamethylene diisocyanate-1,6 and/or isomeric aliphatic diisocyanates with six carbon atoms in the alkylene residue

US4596678A · kind A · utility

Assignee

• BASF SE

Inventors

• Franz Merger · Bischofswerda, DE
• Friedrich Towae · Ludwigshafen, DE
• Hans Hellbach · Bischofswerda, DE
• Gunther Isbarn · Ludwigshafen, DE
• Waldemar Koehler · Bischofswerda, 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: C07C263/04
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

Hexamethylene diisocyanate and/or isomeric alkylene diisocyanates having 6 carbon atoms in the alkylene radical, preferably 2-methylpentamethylene 1,5-diisocyanate and/or 2-ethyltetramethylene 1,4-diisocyanate are prepared without the use of phosgene in a multiple-step process by means of PA1 (a) reacting hexamethylene 1,6-diamine and/or isomeric alkylene diamines having 6 carbon atoms in the alkylene radical with urea and alcohol in the presence of dialkyl carbonate and/or carbamic acid alkyl ester as well as, in some cases, catalysts to form hexamethylene 1,6-dialkylurethane and/or isomeric alkylene dialkylurethanes having 6 carbon atoms in the alkylene radical, PA1 (b) separation and return to reaction step (a) of alcohol, dialkyl carbonate, and/or carbamic acid alkyl ester from the reaction mixture PA1 (c) evaporation of the hexamethylene 1,6-dialkylurethane and/or isomeric alkylene dialkylurethanes having 6 carbon atoms in the alkylene radical, PA1 (d) cleavage of the vaporized diurethanes into hexamethylene diisocyanate and/or isomeric alkylene diisocyanate having 6 carbon atoms in the alkylene radical and alcohol, and PA1 (e) fractional condensation of the cleavage products.