One-Pot Metal Catalyst Free Electrocatalysis for Lignin Valorization: Tandem β-O-4 Linkage Cleavage and In Situ Acetalization

The valorization of lignin into valuable chemicals is a cornerstone of future biorefineries, but it is often hindered by the need for harsh reaction conditions. Electrochemical oxidation offers a promising green alternative, yet many systems lack mechanistic clarity, which impedes rational design. Herein, we report a simple and highly efficient electrochemical system using tetrabutylammonium tetrafluoroborate (TBABF₄) in methanol for the selective cleavage of lignin's β-O-4 ether bond under ambient conditions. On a model compound, this metal-free system achieved over 97% conversion with excellent selectivity toward high-value aldehyde products. Mechanistic studies revealed a dual-pathway mechanism. Crucially, when this mechanistically guided protocol was applied to bagasse lignin, it demonstrated effective depolymerization, leading to the significant cleavage of native β-O-4 bonds, resulting in a total liquid product yield of 15.6%, which included valuable aromatic products such as benzaldehyde dimethyl acetal (7.9% yield). This work not only presents a practical method for lignin upgrading but also provides a clear mechanistic roadmap for the future design of selective electrocatalytic processes.