SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITIES OF DIOXIDOMOLYBDENUM(VI) COMPLEXES

Abstract

The pyrazolone based bidentate (O,O) donor type ligands were synthesized from the reaction of pyrazolone with acetyl chloride, butyryl chloride and isobutyryl chloride respectively. All these complexes were characterized by various spectroscopic (FT-IR, UV/Vis, 1H and13C NMR) techniques, thermal analysis and single crystal X-ray analysis of MoO2(isobutp)2. These complexes adopt a distorted six-coordinated octahedral geometry where ligands act as bidentate, coordinating through the two O atoms. The catalytic activity of these complexes was studied for the epoxidation of styrene and oxidative bromination of thymol. The catalytic epoxidation of styrene resulted in the formation of one product namely styrene oxide. Styrene was used as a reference to obtain the optimized conditions. The optimized reaction conditions have been obtained considering the concentration of styrene, catalyst, NaHCO3 and oxidant (H2O2) for the maximum yield of oxidized products. Under the optimized reaction conditions, the product selectivity for all the prepared complexes was investigated. They are found to be competent homogeneous catalysts to afford the products in good yield. The catalytic oxidative bromination of thymol resulted in the formation of three product namely 2-bromothymol, 4-bromothymol and 2,4-bromothymol. The optimized reaction conditions have been obtained considering the concentration of thymol, HClO4, KBr and oxidant (H2O2) for the maximum yield of brominated products. Under the optimized reaction conditions, the product selectivity for all the prepared complexes was investigated. They are found to be competent homogeneous catalysts to afford the products in good yield.