Patent ID: 7524405
Filing Date: 2009-04-28
Classification: C07C,Y10S

Abstract:
1. A process for preparing at least one isocyanate, comprising: reacting at least one amine with phosgene in the presence of at least one inert organic solvent in a reactor; and working up the reaction mixture leaving the reactor, wherein the at least one solvent is separated off from the at least one isocyanate in an at least a two-stage distillation process in which the at least one solvent is separated off at a pressure of from 0.1 to 15 bar in a first apparatus in the first stage and at from 1 to 900 mbar in a second apparatus in the second stage, wherein the heat of condensation of a solvent vapor from the first apparatus is utilized for vaporization of solvent in the second apparatus.