A new catalyst for the synthesis of N,N-biphenylurea from aniline and dimethyl carbonate

An environmentally benign method for the synthesis of biphenylurea (BPU) in the presence of ecofriendly catalysts has been reported. Catalytic activity of various metal aluminophosphates, M-AlPO4 (M = V, Fe, Co, Ni and Cu) and cobalt supported on hydrated Al2O3, SiO2 and ZrO2 has been investigated in the synthesis of BPU from aniline and dimethyl carbonate (DMC). All the catalysts used are amorphous. The catalytic activity studies have been carried out in the liquid phase under refluxing conditions. Formation of BPU is found to depend on the type of the catalyst, the molar ratio of aniline to DMC and the duration of the reaction. N-Methylaniline and methyl-N-phenylcarbamate are formed as by-products of the reaction. Of all the catalysts used, Co-AlPO4 has been found to yield the highest percentage of BPU whereas cobalt supported hydrated Al2O3, SiO2 and ZrO2 failed to give any BPU.