Peroxide activation by selenium-doped graphite

Abstract

Selenium (Se), an essential trace element present in several antioxidant enzymes, is responsible for protecting cells from oxidative damage. In the recent past, a large number of naturally inspired Se-containing biomimetic molecular oxidation catalysts have been developed. In this report, a selenium-doped graphitic material (Se-DG) was synthesized using glucose and benzeneseleninic acid (BSA) via a simple hydrothermal method. Se-DG has shown glutathione peroxidase (GPx)-like activity and carried out epoxidation of various aromatic and aliphatic alkenes using H₂O₂, a green oxidant. In most cases, ∼90% conversion with ∼75% yield of epoxide was achieved in acetonitrile medium. The adduct of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) with hydroperoxyl radical (˙OOH) was observed in HRMS which confirmed that the Se-DG produced ˙OOH from H₂O₂via hydrogen atom abstraction (HAA). A mechanistic insight of the olefin epoxidation was described in the presence of hydrocarbons and it was observed that the hydroxyl radical (˙OH) generated during the epoxidation facilitated C–H activation successfully. The plausible reaction mechanism of epoxidation was established with density functional theory (DFT) using Gaussian code.