Process for producing isocyanates using diaryl carbonate

摘要

An object of the present invention is to provide a process that enables isocyanate to be produced stably over a long period of time and at high yield without encountering problems of the prior art during production of isocyanate without using phosgene. The present invention provides an isocyanate production process including the steps of: obtaining a reaction mixture containing an aryl carbamate having an aryl group originating in a diaryl carbonate, an aromatic hydroxy compound originating in a diaryl carbonate, and a diaryl carbonate, by reacting a diaryl carbonate and an amine compound in the presence of a reaction solvent in the form of an aromatic hydroxy compound; transferring the reaction mixture to a thermal decomposition reaction vessel; and obtaining isocyanate by applying the aryl carbamate to a thermal decomposition reaction, wherein the reaction vessel in which the reaction between the diaryl carbonate and the amine compound is carried out and the thermal decomposition reaction vessel for the aryl carbamate are different.

主权项

1. A process for producing an isocyanate, comprising the steps of:
obtaining a reaction mixture containing an aryl carbamate having an aryl group originating from a diaryl carbonate, an aromatic hydroxy compound originating from a diaryl carbonate, and a diaryl carbonate, by reacting a diaryl carbonate comprising metal atoms at from 0.001 ppm to 10% and an amine compound in a reaction vessel in which a reaction between the diaryl carbonate and the amine compound is carried out; transferring the reaction mixture to a thermal decomposition reaction vessel connected by a line with the reaction vessel in which the reaction between the diaryl carbonate and the amine compound is carried out; and obtaining the isocyanate by applying the aryl carbamate to a thermal decomposition reaction, wherein a low boiling point component formed in the thermal decomposition reaction is recovered from the thermal decomposition reaction vessel in the form of a gaseous phase component, and a liquid phase component is recovered from a bottom of the reaction vessel, and the recovery of the gaseous phase component and the recovery of the liquid phase component are carried out continuously; wherein the amine compound is a polyamine compound; and an acid cleaning solvent is present in the thermal decomposition reaction.