From the gaseous crude phosgenation, the method of separating the isocyanate prepared by phosgenation of primary amines in the gas phase

摘要

The present invention relates to a method for separating the primary amine, the isocyanate which is prepared by the reaction of excess phosgene in the gas phase from the gaseous crude product obtained in the reaction, partial in the method, the (i) the gaseous crude product is partially liquefied by contact with quench liquid, (ii) step gas phase obtained in (i) the to condense, condensate obtained in (iii) step (ii), and used as quench liquid in step (i), not condensed by (iv) step (ii) a portion of the gas phase were, at least partially liquefied, (v) step (iv) Similarly to the liquid phase obtained in, is used as the quench liquid in step (i), the obtained liquid phase in (vi) step (i), the previously worked up without the use as quench liquid to pure isocyanate.