Preparation and Characterization of Silica-Supported Imine Palladacycle Complex and Its Catalytic Performance

The silica-supported imine palladacycle complex was synthesized by the following procedure as, first, NH2-modified silica was obtained by grafting with organosilane; second, the as-obtained silica compound was treated with o-methoxybenzaldehyde to form SiO2-NH2-Schiff base; at last, the catalyst was attained after being reacted with Li2PdCl4-methanol solution. The as-prepared complex was characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy techniques. The catalytic activity test was carried out in Heck reaction of iodobenzene with acrylamide to the trans-cinnamamide. The effect of reaction parameters on the product yield was investigated, such as solvent, reaction temperature, molar ratio of iodobenzene to acrylamide, kinds and amount of base, amount of catalyst, and reaction time. The optimum reaction conditions were established and the possible reaction mechanism was discussed.