Anodic Oxidation of Unsaturated Aliphatic Ethers in aqueous electrolytes

2,5-dihydrofuran 1 was galvanostatically oxidized in aqueous electrolytes on Pt and PbO₂ anodes at current densities of 10 to 50 mA cm⁻². Under acidic conditions maleic dialdehyde 2 was obtained on both electrodes with a current efficiency (c.e) of up to 50%. In the alkaline region (pH 10) 4-hydroxy crotonic aldehyde 3 (Pt) or 2,5-dihydrofuranone 4 (PbO₂) become the main products with c.e.'s of 29% and 27%, respectively, depending on the anode material. The influence of pH and of the anode material are discussed in detail. 2,3-dihydrofuran 7 , vinyl ethyl ether 8 and for comparison, furan 9 were studied in addition.