Direct Electrochemical Oxidation of Benzylic C–H Bond by La2O3@C/CP Composite Electrode with Water as the Green Oxygen Source

Selective oxidation of high-energy C–H bonds to produce carbonyl compounds is a fundamental transformation in fine chemical synthesis. Despite tremendous efforts, the development of green and safe strategies often suffers from harsh reaction conditions and uses homogeneous transition-metal catalysts. Herein, we present an electrochemical oxidation strategy that is green and safe for the direct oxidation of benzylic C–H bonds using La2O3 nanoparticles supported on a carbon paper (La2O3/CP) anode. La2O3/CP can selectively oxidize indane to indanone in 83% yield with 73% Faraday efficiency at room temperature. It also can oxidize different kinds of compounds with benzyl C–H bonds to produce the corresponding ketones with moderate-to-excellent yields. The oxygen source was confirmed to be water by an oxygen isotope (18O) tracer experiment. Additionally, the La2O3@C/CP composite electrode was reconfigured through carbonizing oleic acid to stabilize La2O3 on CP, resulting in an improved stability due to the reinforced catalyst embedding on CP, and retaining 81% initial activity after five cycles.