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 (TOF=282 h^-1) 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.