(245f) Cobalt(II) Mediated Electro-Oxidation of Toluene and Its Derivatives

The oxidation of toluene and its derivatives is an important process in the chemical industry. Traditional liquid-phase oxidation requires high-temperature and high-pressure conditions, which causes high safety risks and urgently requires alternatives. We developed an electrochemical-mediated oxidation method using cobalt acetate as a mediator and successfully realized mild and green oxidation of toluene. With cobalt acetate as a mediator, the anodic potential was reduced by 1.0 V in contrast to the direct electrolysis of toluene on Pt electrodes. The target products, benzaldehyde and benzoic acid, exhibit high yields at 85°C as the ratio of AcO^- to Co(II) is close to 2 in the homogeneous anhydrous electrolyte. A benzyl radical-centered mechanism is proposed based on the cyclic voltammetry tests and a radical inhibiting experiment. The method has also been successfully applied to some inactive toluene derivatives and ethylbenzene derivatives, showing its promising application value. With the rapid development of clean energy, we believe that this method holds the potential to be a promising alternative to the traditional liquid-phase oxidation of toluene in industry. This work is supported by the National Natural Science Foundation of China (No. 22178194).