Abstract:
Three new palladium catalysts, PdCat-I, PdCat-II and PdCat-III, immobilized over heterogeneous silica
support have been synthesized using different ligands attached to the palladium precursor. The ligands that
have been used in this study are acetate, triphenylphosphine and chloride in PdCat-I, PdCat-II and PdCat III, respectively. The ligands have different effect on stability of the compounds and impart different oxidation
states to the metal center. The materials have been characterized by powder X-ray diffraction, nitrogen
adsorption-desorption studies, transmission electron microscopy, thermal analysis, and different spectroscopic
techniques. The Pd-content of the samples have been determined by ICP-AES analysis. The materials have been
used as catalysts for Suzuki coupling reaction of aryl halides with phenylboronic acid under mild conditions. A
comparative study has been carried out to ascertain the effect of the nature of different ligands on the outcome
of the catalytic reactions. Products have been identified and estimated by 1
H NMR and gas chromatography.
The results show that the best yields are obtained with the catalyst containing triphenylphosphine as the ligand
in methanol. Such type of work to study the effect of ligand on Suzuki coupling reaction over functionalized
mesoporous silica heterogeneous catalysts have not been carried out so far
