Supported palladium metal as heterogeneous catalyst precursor for the methoxycarbonylation of cyclohexene

The methoxycarbonylation of cyclohexene has been carried out by using Pd metal deposited on a support as heterogeneous precursors instead of the homogeneous Pd(II) complexes usually proposed in literature. The two catalytic systems (homogeneous and heterogeneous) have been compared in methanol in the presence of free triphenylphosphine and p-toluenesulfonic acid as promoter. The precursor Pd on Amberlyst IRC 50 led to the best catalytic activity which is comparable to the activity obtained by using the homogeneous Pd(II)-catalyst. The leaching of the metal was negligible and the system has been efficiently recycled at least for three times. A reaction mechanism has been also proposed and discussed.