PALLADIUM-CATALYZED N,N'-DIPHENYLUREA SYNTHESIS FROM NITROBENZENE, ANILINE, AND CARBON-MONOXIDE .4. LIGAND EFFECTS

Abstract

The effects of various ligands on the catalytic properties of palladium complex in the synthesis of N,N'-diphenylurea from nitrobenzene, aniline and carbon monoxide have been studied. Both the electronic and the steric properties of the ligands were found to have a profound effect. Compared to monodentate phosphines, bidentate ligands showed higher activity and promoted preferentially a path of the reaction network that involved steps in which the cis coordination of ligands to palladium was favored. The higher reaction rates were observed for those complexes with a greater electron density on palladium metal.