Synthesis of chitosan derivatives supported palladium complexes and their catalytic behavior in the Heck reaction

Two kinds of chitosan derivatives, crosslinked chitosan and crosslinked chitosan condense with salilylaldehyde, supported palladium complexes (CL-CTS-Pd and CL-S-CTS-Pd) were synthesized and characterized by X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential thermal analysis (DTA), etc. These complexes are efficient catalysts for the Heck reaction under atmospheric conditions and can be easily recovered and reused. The detailed studies show that the catalyst CL-S-CTS-Pd is much more efficient than CL-CTS-Pd under the same conditions. CL-S-CTS-Pd keeps its catalytic activity in the Heck reaction of acrylic acid with iodobenzene even at a low temperature (60 degrees C) or with tiny amounts of the catalyst (0.05 mol%Pd). Yields of making cinnamic acid were even as high as 75.3% in the Heck reaction of acrylic acid with iodobenzene using CL-S-CTS-Pd that was recovered 10 times. Copyright (c) 2005 John Wiley & Sons, Ltd.