Method for separating out solvent from a reaction mixture resulting from an isocyanate synthesis and for purifying this solvent

US7524405B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Martin Sohn · Mannheim, DE
• Eckhard Stroefer · Mannheim, DE
• Filip Nevejans · Sint-Niklaas, BE
• Ulrich Penzel · Lauscha, DE
• Hans-Juergen Pallasch · Ludwigshafen, DE
• Peter Van Den Abeel · Brasschaat, BE
• Filip Deberdt · Bonheiden, BE
• Jan Jacobs · Hoogerheide, NL
• Wolfgang Mackenroth · Bad Dürkheim, DE

Key dates

• Filing date: Dec 13, 2003
• Grant date: Apr 28, 2009
• Expiry date: Nov 12, 2025

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S203/08
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The invention relates to a process for preparing isocyanates by reaction of amines with phosgene in the presence of inert organic solvents in a reactor and subsequent work-up of the reaction mixture leaving the reactor, wherein the solvent is separated off in a two-stage or multistage, preferably two-stage, distillation process in which the solvent is separated off at a pressure of 0.1-15 bar in a first apparatus and at 1-900 mbar in a second apparatus or further apparatuses, with the heat of condensation of the solvent vapor from the first apparatus being used for partial or complete vaporization of solvent in the second apparatus.