Catalytic synthesis of toluene-2,4-diisocyanate from dimethyl carbonate

The process for catalytic synthesis of toluene-2,4-diisocyanate (TDI) from dimethyl carbonate (DMC) consists of two steps. Starting from the catalytic reaction between toluene-2,4-diamine (TDA) and DMC, dimethyl toluene-2,4-d icarbamate (TDC) is formed, and then decomposed to TDI. For the first step, the yield of TDC is 53.5% at a temperature of 250 degreesC, over Zn(OAC)(2 )/alpha -Al2O3 catalyst. For the second step, the yield of TDI is 92.6% at temperatures of 250-270 degreesC and under pressure of 2.7kPa, over uranyl zinc acetate catalyst, when di-n-octyl sebacate(DOS) is used as heat-carrie r, and a mixture of tetrahydrofuran (THF) and nitrobenzene is used as solve nt. (C) 2001 Society of Chemical Industry.