Selective Cleavage of C–O Bond in Diaryl Ether Contaminants via Anodic Oxidation

Abstract

The cleavage of C–O–C linkage is a critical step in the degradation of diaryl ether contaminants and lignin, which holds great significance of environmental protection and lignocellulosic biomass utilization. Traditional chemical cleavage methods require harsh operation conditions such as using strong acids/bases and/or at high temperatures. Herein, we report an anodic oxidation process on the carbon electrode, which displays high efficiency for the selective electrochemical cleavage of the C–O bond in diaryl ethers under room conditions. Application of such an electrochemically oxidative cleavage approach on triclosan, 4-hydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ether, and rhodamine B demonstrates high reaction selectivity to the aryl C–O bond. Notably, the production of quinone compounds as the main products is highlighted to open the opportunity for acquiring quinone derivatives from diaryl ethers. The anodic oxidation process is found to apply a direct electrochemical oxidation pattern under the catalysis of surface oxygenated groups of the carbon electrode. Enlightened by this finding, a surface modification strategy of the carbon electrode is proposed to accelerate the oxidative cleavage of diaryl ethers. The anodic oxidation process not only provides a novel way to design economic routes for the removal of diaryl ether contaminants but also has potential application in degrading lignocellulosic biomass for the production of value-added chemicals.

High-Value Chemicals from Electrocatalytic Depolymerization of Lignin: Challenges and Opportunities

“…C–O bond cleavage in lignin model compounds is reported to proceed via anodic oxidation on the carbon electrodes at +1.1 V under room temperature conditions [ 113 ]. After 20 h, diaryl ethers completely degrade to C–O bond cleavage products.…”