Synthesis of Poly(p-aminophenol) Microsphere-Supported Palladium Complex and Evaluation of Its Catalytic Performance for Heck Reaction

Abstract

Poly(p-aminophenol) microspheres were prepared by template polymerization of p-aminophenol in the presence of horseradish peroxidase as bio-enzyme catalyst. The average size of poly(p-aminophenol) microsphere is about 2 µm. Further, poly(p-aminophenol) microspheres as obtained were loaded with palladium to generate poly(p-aminophenol) microsphere-supported Pd complex. Resultant Pd complex catalyst supported by poly(p-aminophenol) microsphere was characterized by means of IR, XRD, XPS, SEM, TG etc. XPS confirms the presence of zerovalent palladium. Poly(p-aminophenol) microsphere maintains their configuration after coordination with palladium chloride, while a large number of fine Pd particulates are uniformly adsorbed on poly(p-aminophenol) microspheres. The complex is an efficient catalyst for Heck arylation of acrylic acid, styrene with aryl iodide under solvent-free condition and it also exhibits catalytic activity for activated bromobenzene. Yield of cinnamic acid was 92% for Heck reaction of acrylic acid with iodobenzene even though the complex was used 5 times.