| 摘要 |
PURPOSE:To obtain continuously the titled compound of high quality without forming polymeric by-products, by introducing a mixture of a carbamic acid ester with a thermal decomposition solvent from the top of a vertical tubular reactor, feeding the thermal decomposition solvent vapor from the bottom thereof, and thermally decomposing the mixture. CONSTITUTION:A mixture of a carbamic acid ester with a thermal decomposition solvent inert under reaction conditions (preferably in 5-30wt% concentration of the former) is continuously introduced from the top of a vertical tubular reactor packed with a solid packing material and/or solid catalyst, and a thermal decomposition solvent vapor is continuously introduced from the bottom of the reactor thereinto to carry out thermal decomposition at 140-380 deg.C, preferably 180-330 deg.C under a pressure to give the reaction temperature of the boiling point of the thremal decomposition solvent or below to take out a low-boiling product in the gaseous form and a high-boiling product as a thermal decomposition solvent solution continuously from the bottom thereof. The process is particularly effective for preparing high-boiling isocyanates, and the aimed product having no residual compound having the undecomposed carbamate group is obtained.
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