Redox-mediated oxidation of cyclohexanone to adipic acid on oxide-nickel anode, with active forms of oxygen involved

Abstract

Redox-mediated oxidation of cyclohexanol to adipic acid on a porous anode with higher nickel oxides was studied, including the process involving active oxygen species (AOS) in situ generated from hydrogen peroxide and molecular oxygen in an alkaline electrolyte. It was found that the current efficiency by adipic acid grows upon addition of AOS. The selectivity of cyclohexanol oxidation to adipic acid depends on the current density, quantity of passed electricity, and method of AOS generation. It is demonstrated that use of AOS enables oxidation of cyclohexanol with a selectivity of adipic acid formation of up to 89% and its single-stage synthesis with a current efficiency of 50.2% at a current density of 22 mA cm−2 and passing the theoretically required quantity of electricity.