OXIDATIVE COUPLING OF METHYL BENZOATE WITH PALLADIUM HETEROPOLYACID CATALYSTS/

The oxidative coupling of methyl benzoate in the presence of a catalys t system comprising of Pd(OAc)(2) and a vanadium-containing heteropoly acid produced 2,2'-biphenic acid dimethyl ester with a high selectivit y. The mode of coordination of methyl benzoate to palladium and the no n-coordinating nature of the heteropolyacid appeared to be responsible for the unusual selectivity. Addition of Hg(OAc)(2) or triphenyl phos phine increased greatly the conversion of methyl benzoate without impa iring the selectivity to the 2,2'-isomer. The catalyst deactivated wit h reaction time, mainly due to water produced from the reaction.