Graphene Oxide Supported Oxovanadium (IV) Complex for Catalytic Peroxidative Epoxidation of Styrene: An Eye‐Catching Impact of Solvent

Abstract

Graphene oxide (GO) supported transition metal complexes are apprised as sturdy and everlasting heterogeneous catalysts. GO surface was functionalized with 3‐triethoxysilylpropylamine (TSPA) and this amino functionalized GO (A‐f‐GO) nanocomposite with vanadyl Schiff base complex (VO‐f‐GO) was prepared and to give credence of its potentiality, it was chosen for the selective epoxidation of styrene using environmentally benign 30% H2O2 to styrene oxide (SO). To evade the detrimental exposure of “inborn” water, a selective high boiling and potent hygroscopic solvent, ethylene glycol was chosen to make this transformation productively successful. With the assistance of theoretical studies, we have probed the effect of H2O2 on to structural properties, binding mechanism and electronic properties of the catalyst and substrate. Adsorption energy (Ead), energy band gap (Eg) and HOMO‐LUMO were also calculated. Based on DFT calculations, resonance Raman and UV/Vis studies, we confirmed the formation of metal‐peroxo species and propose the plausible catalytic pathway. The influence of the diverse experimental parameters, like substrate to oxidant mole ratio, catalyst concentration, type of solvents, solvent amount, time, temperature and oxidant were tested. A clear relationship was found between different reaction parameters like solvent amount, oxidant, catalyst concentration and temperature etc. and product distribution. This heterogeneous catalyst yielded styrene oxide as nearly the sole product (selectivity = 98.7%) with a conversion value of 99.2% in the oxidation of styrene with hydrogen peroxide in ethylene glycol.

ZnO Nanoparticles Embedded on a Reduced Graphene Oxide Nanosheet (ZnO−NPs@r‐GO) as a Proficient Heterogeneous Catalyst for a One‐Pot A3‐Coupling Reaction

“…[31] Though for organic transformations, [43][44] ZnO nanoparticles (NPs) have been established as solitary heterogeneous catalysts however, to the best of our knowledge, only few reports on rGO/ZnO nanocomposites as catalysts have been reported in the literature. [45][46][47] In continuation of our earlier work [48][49][50] , here in we report highly efficient ZnOÀ NPs@r-GO as a proficient heterogeneous catalyst and substantiated through various characterization tools. The accountability of rGO in ZnOÀ NPs@r-GO nanocatalyst is mainly providing tangible support which enhances the mechanical strength of the catalyst and also uniform dispersibility of ZnOÀ NPs.…”

Heterogeneous vanadium Schiff base complexes in catalytic oxidation reactions

“…There is an improvement in the catalytic activity and an easy separation because of the magnetic core and oxo-vanadium presence. 110 Epoxidation reactions were reported to give a low selectivity and a high conversion, but with vanadyl Schiff base complex supported on graphene oxide (VO-f-GO), epoxidation of styrene gave 99.2% conversion and 98.7% selectivity, and a sole product was obtained 111 Finally, the epoxidation of 2-naphthol and styrene was catalysed with an effective heterogeneous and homogeneous dinuclear and mononuclear oxido vanadium Schiff base complexes, the catalyst demonstrates excellent activity in yield and enantioselectivity towards epoxidation of styrene. Also, a change in the structural variation of a metal complex brings about differences in the catalytic activity of the metal Schiff base complexes.…”

Recent Investigation on Epoxidation of Styrene with Hydrogen Peroxide by Heterogeneous Catalysis

“…Ravi Vithalani et al [64] studied impact of solvent on epoxidation of styrene catalyzed with graphene oxide supported oxovanadium (IV) complex. The synthesis procedure was drawn in Scheme 29.…”