STOICHIOMETRY OF PALLADIUM-CATALYZED N,N'-DIPHENYLUREA SYNTHESIS FROM NITROBENZENE, ANILINE AND CARBON-MONOXIDE

Abstract

By using deuterated nitrobenzene as a reactant, it was found that Pd-catalyzed synthesis of N,N'-diphenylurea from nitrobenzene, aniline and CO proceeded via two parallel routes: (i) PhNO2+PhNH2+3CO-->PhNHCONHPh+2CO2, and (ii) PhNO2+5PhNH2+3CO -->3PhNHCONHPh+2H2O. The relative importance of these two routes depended strongly on the ratio of aniline to nitrobenzene initially fed to the reactor. Mechanisms are proposed that account for these reaction stoichiometries.