Study On The Synthetic Method And Process Development Of Aromatic Isocyanate Products

2,6-Diisopropylphenyl isocyanate and 4-(trifluoromethoxy)phenyl isocyanate are two important isocyanate products,the former is a useful starting material which can be used to synthesize polyurethane additive intermediates and drugs,the latter can be applied to synthesize highly efficient and low toxic pesticides,such as cyanourea,cyanogen and a series of new pesticides.Combined with phosgene resources of the company,we attempt to develop safer and more economic synthesis method for the two kinds of isocyanates.Based on the investigation of the literature,the current most widely-used phosgene synthetic route for isocyanate products has a problem of using phosgene solution,which has a great risk potential for safety in actual production.In addition,the quality of raw materials and products has not been studied deeply.In this project,the optimum process for the synthesis of 2,6-diisopropylphenyl isocyanate was optimized by systematic optimization.The phosgene was charged into the solution of 2,6-diisopropylphenyl aniline in xylene at room temperature.The phosgene solution can be avoided in the new process,greatly increasing the safety of industrialization.In the same way,the technological conditions for the synthesis of 4-(trifluoromethoxy)phenyl isocyanate are also proposed,the process of using the hydrogen chloride to form salt and to synthesize the product by phosgene.The process also avoids phosgene solution,greatly increases the process safety and reduce the risk for the human and environment.Meanwhile,the standard analysis methods for the determination of impurities in raw materials and products have been developed.Finally,on the basis of the result of laboratory's experiments,the pilot scale was amplified,and the feasibility of the process was verified.