Application of 12CaO•7Al2O3 electride as a new electrode for superoxide ion generation and hydroxylation of an arylboronic acid

12CaO
• 7Al2O3 (C12A7) electride, which exhibits metallic conduction and 2.4 eV work function, can be used as an electron emitter and chemical reagent. Herein we reveal a new application for C12A7 electride as electrode in electrochemical reactions. Cathodic reduction of oxygen at C12A7 electrode in acetonitrile generates superoxide ions (O2
• −) using Bu4NClO4 as a supporting electrolyte. Iodometry reveals that this electrode shows a higher yield of O2
• − ions than conventional electrodes such as Pt and glassy carbon. Moreover, O2
• – ion–induced hydroxylation of p-(methylthio)phenylboronic acid using C12A7 electrode gives the corresponding phenol derivative with a yield of 90% at the charge apply of 2.5 F·mol− 1.

► In this study, the electrogeneration of O2
• − ion was firstly observed at C12A7 electride electrode.
► C12A7 electrode gave higher yield on the O2
• − ion formation than GC and Pt electrodes.
► C12A7 electrode showed higher efficiency on the O2
• − ion–induced hydroxylation of p-(methylthio)phenylboronic acid than GC and Pt electrodes, a corresponding phenol with a yield over 90% was achieved at a charge apply of 2.5 F·mol− 1.