As a kind of important organic reaction intermediate, isocyanate is the main raw materials to synthesize polyurethane and it has been widely used in industrial, agricultural, pharmaceutical fields. Traditionally, isocyanate is synthesized through the reaction between amine compounds and phosgene. However, phosgene is a kind of highly toxic compound. And during the reaction, a great number of highly corrosive hydrogen chloride can be generated.

With people’s increasing awareness of environmental protection, the synthesis of isocyanate through non-phosgene route has attracted more and more attention. As the important intermediate to synthesize isocyanate, cyclohexylcarbamate has become a hot topic. But the existing methods to synthesize cyclohexylcarbamate all have certain shortcomings.

Researchers at R&D Center for Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics (LICP), Chinese Academy of Sciences (CAS), have developed a new method for synthesizing cyclohexylcarbamate. Using support metal oxides as solid catalysts, they have obtained the final products through the catalytic reaction between dialkyl carbonate and N,N'dicyclohexycarbodiimide. The active component of catalysts is transitional metal oxides and the supports of catalysts are chosen fromsilicon dioxide, aluminium oxide, activated carbon and zirconium dioxide.

With this method, there’s no need to use additional solvent and the products can be separated with high purity. The catalysts can be recycled and easy to be recovered.

The technique has received Chinese Invention Patent on Dec. 24, 2012. The patent number is ZL 200810184474.0.