3-diphenyl urea(DPU) by reaction of aniline with carbon dioxide was studied,and the emphasis was put on the investigation of the catalytic performance of Lewis acidic ionic liquids. Firstly
the effects of a series of alkaline or Lewis acid catalysts and solvents on the synthesis of DPU were investigated
and it was found that AlCl3/acetonitrile system showed excellent catalytic performance. Then the influence of the kind of cation and anion in ionic liquids
initial pressure of CO2
reaction time
reaction temperature
and catalyst dosage was discussed in the presence of chloroaluminate ionic liquids as both Lewis acid catalyst and solvent. Under the reaction conditions of [Bmim]Cl-AlCl3 as both the catalyst and solvent
initial pressure of CO2 of 1 MPa
reaction time of 7 h
reaction temperature of 160℃
and mass ratio of AlCl3 to aniline of 1∶1
the conversion of aniline was 18.1%
and the yield and selectivity to DPU were 17.9% and 98.9%
respectively. Additionally
a plausible catalytic reaction mechanism was also proposed.