Electrocatalytic ORR-coupled ammoximation for efficient oxime synthesis.

Abstract

State-of-the-art technology for cyclohexanone oxime production typically demands elevated temperature and pressure, along with the utilization of expensive hydroxylamine sulfate or oxidants. Here, we propose an electrochemistry-assisted cascade strategy for the efficient cyclohexanone ammoximation under ambient conditions by using in situ cathode-generated green oxidants of reactive oxygen species (ROS) such as OOH* and H2O2. This electrochemical reaction can take place at the cathode, achieving over 95% yield, 99% selectivity of cyclohexanone oxime, and an electron-to-oxime (ETO) efficiency of 96%. Mechanistic analysis reveals that, in addition to the direct ammoximation by in situ-generated OOH* by electrocatalytic ORR, Ti-MOR also play a major role in capturing OOH* directly and converting the in situ-generated H2O2 to OOH*, thus accelerating the ORR-coupled cascade production of cyclohexanone oxime. This work paves a mild, economical, and sustainable energy-efficient electrocatalytic route for the oxime production using oxygen, ammonium bicarbonate, and cyclohexanone.