Biphasic carbonylation of vinyl aromatic compounds using novel water-soluble Pd catalyst: activity, selectivity and mechanistic studies

Abstract

The biphasic carbonylation of vinyl aromatic compounds to the isomeric arylpropanoic acids has been studied in detail using a novel water-soluble palladium complex, [Pd(Pyca)(TPPTS)]+TsO−. The effect of various reaction and catalyst parameters such as promoters, solvents, P/Pd ratio, CO partial pressure, temperature and concentration of substrate on the catalytic activity and selectivity has been investigated using styrene as the model substrate. High catalytic activity and selectivity to the branched product (∼91%) was observed with [Pd(Pyca)(TPPTS)]+TsO− catalyst. 31P NMR experiments were carried out to study the mechanistic details and to understand the nature of catalytic species formed under the reaction conditions, based on which a plausible catalytic cycle has been proposed.