To perform reactive fractionation of a decomposition product by an economical procedure even on an industrial scale by continuously decomposing a carbamic acid ester using an inert solvent while quickly and continuously separating the decomposition product from the starting substance.
A carbamic acid ester (A) is introduced into an injection port of a reactive fractionation column having plural zones at a temperature higher than the melting point of the ester. The component A is thermally decomposed in a reaction/stripping zone of the column at 150-400°C in the presence of a compound having high boiling point and acting as a solvent of the component A (preferably a dibenzyltoluene isomer, etc.). The decomposition reaction product is separated into an alcohol fraction having a concentration of ≥95wt.% and an isocyanate fraction of an amount corresponding to at least 90% of the component A to be used in the concentration zone. The evaporator zone is maintained to 2-1,000mb pressure and 150-400°C. The component A is decomposed in the reaction/stripping zone and an intermediate zone controlled to proper conditions to effect the separation and purification of an isocyanate and a hydroxyl compound.
DEIITAA SHIYUREENSHIYUTAIN
HAINRITSUHI SUCHIYUUDE
OZUWARUDO UIRUMESU
KURISUCHIAN RASUPU
GEORUGU RONGE
KURAUSU NAHATOKAMUPU
BUIRUFURIITO RITSUTSU
SUTEFUAN KABERATSUKU
