HETEROGENEOUS PALLADIUM CATALYSTS FOR THE HECK REACTION

The vinylation of iodobenzene with methyl acrylate was studied using p alladium-based heterogeneous catalysts. Methyl cinnamate was formed as vinylation product and benzene as side product. All catalysts were of the type SiO2-X-(NH)(2)-Pd-L(2), where L=P(C6H5)(3) or C6H5CN and X = Sn, Al or Ti. The catalysts were stable and could be reused several t imes in normal atmosphere without suffering appreciable loss in cataly tic activity. The activity of the catalysts was good even at low tempe rature, and selectivities were very high. Strong interaction indicatin g the existence of chemical bonding was found between the modified sil ica support and palladium complex. A model of the active surface compo und is proposed and confirmed.