Development of Urea Based Heterogeneous Catalysts for Oxidation and CO2 Utilization Reactions

Abstract

The work embodied in the present thesis comprises of five chapters. Chapter 1 newlinegives an account of the brief introduction of catalysis, types of organic transformation, newlineoxidation reaction, CO2 utilization into cyclic carbonate and formate formation newlinereactions, and a few examples with important industrial processes. This chapter also newlinehighlights the scope and objectives of the present work. newlineChapter 2 includes the synthesis of heterogeneous organocatalyst glycoluril newlinethat can be utilized for the direct oxidation of alcohols and benzylic sp3carbons to the newlinecorresponding carbonyls. The organocatalyst gave excellent conversion and newlineselectivity of the products in an aqueous medium using hydrogen peroxide at 60°C. newlineInvestigation of the reaction mechanism using control reactions, electrochemical newlineexperiments, kinetic, and NMR studies indicated that the reaction proceeds via radical newlinepathway assisted by the glycoluril catalyst. Overall, the study demonstrated that our newlinecatalyst, used here for the first time as a heterogeneous organocatalyst, is robust, newlineuniversal, and easily applied to the oxidation of alcohols and benzylic sp3 carbons on newlinethe lab scale. newlineChapter 3 includes efficient heterogeneous catalytic system for the newlineepoxidation of various alkenes using glycoluril an organic promoter, manganese newlinesulphate, sodium bicarbonate, t-butyl alcohol, water as solvent and environment newlinefriendly hydrogen peroxide as an oxidant. Accordingly, Styrene oxide was prepared newlinekilogram scale using heterogeneous catalytic system with 98-99% conversion and newlinegt98% purity. newlineIn chapter 4 developed a catalytic reduction of CO2 to formate in the newlinepresence of metallic cobalt nanoparticles as an elegant heterogeneous catalyst. The newlineaforementioned cobalt nanoparticles was prepared by the pyrolysis of impregnated newlinecobalt precursor on cucurbit[6]uril (CB[6]). During the pyrolysis process, CB[6] newlineframework transform to the nitrogen-rich graphitic carbon support in which cobalt newlinenanoparticles were present in their metallic state. The synthesized catalyst was highly newlineactive