| 摘要 |
1,271,991. Production of isocyanates. E. I. DU PONT DE NEMOURS & CO. 10 April, 1969 [11 April, 1968; 19 April, 1968], No. 18545/69. Heading C2C. A continuous process for the preparation of organic isocyanates comprises (1) continuously introducing an organic amine, at least 5 parts of an inert organic solvent per part by weight of organic amine, and at least 1À25 moles of phosgene per equivalent of organic amine into a constant composition primary reaction zone providing an average liquid residence time of from 20 to 120 minutes at a temperature of at least 105‹ C., (2) continuously removing from said primary reaction zone a gaseous mixture of phosgene and by-product HCl and a liquid reaction mass, (3) continuously contacting, in a secondary reaction zone, said removed liquid reaction mass with at least 0À75 moles of phosgene per equivalent of organic amine fed to said primary reaction zone, said secondary reaction zone providing an average liquid residence time of 5-45 minutes at a temperature of at least 130‹ C. and (4) continuously removing a gaseous mixture of phosgene and by-product hydrogen chloride and a solution of organic isocyanate from said secondary reaction zone. |
