Study on the Optimization of 1,3-Bis (Isocyanatomethyl) Benzene Synthesis with Bis (Trichloromethyl) Carbonate

摘要

1,3-Bis(isocyanatomethyl) benzene is an isocyanate with high quality performance, excellent yellowing resistance and weather resistance. It has wide application in optical polymer composite materials, construction, automotive and other industries. The current production process is mainly prepared by the liquid phase reaction of m-xylylenediamine with highly toxic phosgene. Due to the particularity of phosgene, the synthesis and application of 1,3-bis(isocyanatomethyl) benzene is greatly restricted, the production threshold and the price remains high, which seriously affects the promotion of products. Exploring the non-phosgene green synthesis process for the preparation of 1,3-bis(isocyanatomethyl) benzene is one of hotspots in the isocyanate research and development. The research target of this paper is to explore a safe, convenient and environmentally friendly synthesis route for 1,3-bis(isocyanatomethyl) benzene. The synthesis optimization of 1,3-Bis(isocyanatomethyl) benzene from m-xylylenediamine and bis(trichloromethyl) Carbonate was comprehensively studied. Factors such as molar ratio of raw materials, reaction temperature, reaction time and nitrogen rate were also studied. The optimal conditions were as follows: the molar ratio of m-xylylenediamine to bis(triehloromethyl) carbonate was 1.2:1.0, the nitrogen gas velocity was 8 mL·min~(-1), the reaction temperature was 125℃ and the reaction time was 8.0 hours. Under the optimum condition, the 1,3-Bis (isocyanatomethyl) benzene yield was 83.35%. The reaction mechanism and the key steps involved in the reaction process were also deeply analyzed.