| 摘要 |
1341311 Production of isocyanates QUIMCO GmbH 25 Oct 1972 [25 Oct 1971] 49458/71 Heading C2C Organic isocyanates are produced from an amine or amine mixture and phosgene by a process wherein the amine, preheated to a temperature below its decomposition temperature at superatmospheric pressure is first reacted with preheated phosgene in the presence of an excess of an organic isocyanate at a temperature and pressure such that the reaction proceeds in a homogeneous liquid phase to give substantially organic carbamoyl chloride(s) dissolved in liquid excess phosgene and excess starting organic isocyanate and then, in a second stage, these organic carbamoyl chloride(s) are thermally decomposed at a lower pressure to give the isocyanate corresponding to the starting amine mixed with the added excess starting isocyanate. Preferably, the isocyanate is a monoisocyanate and the amine contains no functional groups other than amino groups capable of reacting with phosgene. In a preferred embodiment the first stage of the reaction is carried out adiabatically with all the reactants fed in at 120‹ to 180‹ C. and the reactant exit temperature kept at 180‹ to 250‹ C. with the applied pressure being kept constant in the range 100 to 300 atmospheres, the second stage being carried out isothermally with all the reactants fed in at 120‹ to 250‹ C. and the applied pressure being kept constant in the range of 3 to 30 atmospheres. The preferred average residence times of the reactants in the first and second stage zones are 5 to 150 sees. and 3 to 30 minutes respectively. |
