| 摘要 |
In a process for the preparation of organic isocyanates having the general formula: <CHEM> where Ar is a single or multiple substituted phenylgroup; R is a methylene or an ethylene group; and n is a whole number of from 0 and 2, by thermal decomposition of corresponding carbamates in the presence of an inert solvent, the improvement of which comprises in multiple and separate steps thermally treating the carbamate dissolved in the solvent and, thereby, decomposing the carbamate to isocyanate and an alcohol; in intermediate steps between the steps of thermal treatment removing the alcohol formed during the thermal treatment by stripping the solvent with an inert stripping agent; and finally recovering a solution being rich in the isocyanate. |
