Synthesis, characterization and catalytic activity of palladium(ii) aroylhydrazone complexes in mizoroki-heck reaction

Abstract

The palladium catalyzed Mizoroki-Heck reaction represents one of the most important methods for the formation of carbon-carbon bond in organic synthesis. The application of palladium(II) Schiff base complexes as homogenous catalyst have gained interest due to their high stability and flexibility. This dissertation reports on the synthesis, characterization and catalytic activity performance of new palladium(II) aroylhydrazone complexes in the homogenous Mizoroki-Heck cross-coupling reaction under optimum condition. Two new aroylhydrazone ligands have been synthesized by condensation reaction between salicyloylhydrazide with 2-acetylpyridine and 2-benzoylpyridine in a 1:1 molar ratio. The corresponding palladium(II) complexes were synthesized by treating the ligands with one mole equivalent of bis(benzonitrile)palladium(II) chloride at room temperature. All the obtained products were fully characterized by FTIR, 1H-NMR and UV-Vis spectroscopic techniques. The spectroscopic data revealed that the aroylhydrazone ligands acted as monobasic tridentate donor, coordinating through the enolic oxygen, imine nitrogen and pyridyl nitrogen atoms to the palladium2+ ion. The performance of the palladium(II) complexes as homogeneous catalysts were evaluated in the Mizoroki-Heck reaction of arylbromide with methyl acrylate in the presence of triethylamine as base and N,N-dimethylacetamide as solvent at 120 °C. Both catalysts gave the conversion of 4-bromoacetophenone up to 100% after 24 hours with almost 100% selectivity of the expected trans-methyl 3-(4-acetylphenyl)acrylate.