Emulsion droplet-enabled selective electrochemical oxidation of alcohols at industrially relevant current densities

Abstract

Selective oxidation plays a pivotal role in the interconversion of organic compounds and the synthesis of high-value products. However, industrial-scale electrochemical oxidation is often hindered by low reaction efficiency, limited current density, and excessive electrolyte waste. Herein, we reported a highly efficient one-pot emulsion-based electrochemical approach for aldehyde synthesis using catalytic amounts of TEMPO with sodium chloride and sodium bromide as electrolytes in a biphasic solvent system. This method achieves benzaldehyde in excellent yields (80–99%) with high Faraday efficiencies (76.4–90.9%) at 100–900 mA cm⁻² current densities and tolerates substrate concentrations up to 4 mol L⁻¹. Gram-scale electrolysis of benzaldehyde at 2 A for 21.3 min produced 1.16 g of benzaldehyde with a 90.9% isolated yield and a production rate of 816.9 g m⁻² h⁻¹. Furthermore, the method features recyclable electrolytes, reusable immobilized TEMPO, a representative substrate scope, and gram-scale synthesis, demonstrating both robustness and generality of the emulsion strategy, emphasizing its promise for industrial implementation.