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

• Published in: Applied organometallic chemistry 2020-04, Vol.34 (4), p.n/a
• Main Authors: Vithalani, Ravi, Patel, Dikin S., Modi, Chetan K., Sharma, Vaishali, Jha, Prafulla K.
• Format: Article
• Language: English
• Subjects: Catalysts; Chemistry; Coordination compounds; density functional theory; Energy gap; Epoxidation; Ethylene glycol; GO supported heterogeneous catalyst; Graphene; Hydrogen peroxide; Imines; Mathematical analysis; Molecular orbitals; Nanocomposites; Oxidation; Oxidizing agents; Parameters; peroxidative epoxidation of styrene; Selectivity; solvent effect; Solvents; Styrenes; Substrates; Transition metal compounds
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.5500

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. Graphene oxide‐based oxovanadium complex via ligand spacer as a heterogeneous catalyst was inspected over the selective peroxidative oxidation of styrene using 30% hydrogen peroxide as an environmentally benign oxidant and ethylene glycol as a potent hygroscopic solvent to avoid the adverse effect of “inborn” water. It shows an excellent 99.2% conversion of styrene with superior 98.7% styrene oxide selectivity.