3 500 g of electrolyte containing 9.4% of furan, 40% of dimethyl maleate, 1% of NaBr and 49.6% of methanol were electrolyzed at 19-24° C. using a current of 5 A until the charge input was 1.1 F with respect to dimethyl maleate (which corresponds to 2.4 F with respect to furan). The effluent contained the products, furan and dimethoxyfurans, in a ratio of 1.0:9.3, which corresponds to a conversion of 90%. The selectivity to dimethoxydihydrofuran/dimethoxytetrahydrofuran was 99%. Dimethyl maleate conversion was more than 99%. Tetramethyl butanetetracarboxylate and dimethyl succinate were formed in a ratio of 1:0.31 and tetramethyl butanetetracarboxylate and methoxysuccinic acid in a ratio of 1:1.15.
