Synthesis of polyphenol microsphere-supported palladium complex and evaluation of its catalytic performance for Heck reaction

摘要

Polyphenol microspheres were prepared by template polymerization of phenol in the presence of horseradish peroxidase as bio-enzyme catalyst and aqueous 1,4-dioxane as solvent. The morphology of polyphenol microspheres thus obtained was observed with a scanning electron microscope. Further, polyphenol microspheres as obtained were loaded with palladium to generate polyphenol microsphere-supported Pd complex. Resultant Pd complex catalyst supported by polyphenol microspheres was characterized by means of Fourier transformation infrared spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy, and its thermal stability was examined. Moreover, the catalytic activity of polyphenol microsphere-supported Pd catalyst as synthesized for the Heck reactions of acrylic acid with aryl iodides was evaluated. Results indicate that the polyphenol microsphere as obtained has a diameter of about 500?nm. Polyphenol microsphere-supported Pd catalyst, as synthesized, at a dosage of 0.37?mol% Pd, possesses good catalytic activity for the Heck reactions of acrylic acid with aryl iodides in air at a low temperature of 50°C, and it also exhibits catalytic activity for bromide and activated chlorobenzene. The polyphenol microsphere-supported Pd complex has good thermal stability, and it can be readily separated and reused; the yield of the reaction of iodobenzene with acrylic acid remains at 82% after five recycle runs, showing promising potential as a catalyst for Heck reactions. Copyright ? 2012 John Wiley & Sons, Ltd.