Life support, 100-cell electrolysis

Figure 4. A 100-cell electrolysis module for submarine life support...

The direct electrochemical methoxylation of furan derivatives represents another technically relevant alkoxylation process. Anodic treatment of furan (14) in an undivided cell provides 2,5-dimethoxy-2,5-dihydrofuran (15). This particular product represents a twofold protected 1,4-dialdehyde and is commonly used as a C4 building block for the synthesis of N-heterocycles in life and material science. The industrial electroorganic processes employ graphite electrodes and sodium bromide which acts both as supporting electrolyte and mediator [60]. The same electrolysis of 14 can be carried out on BDD electrodes, but no mediator is required The conversion is performed with 8% furan in MeOH, 3% Bu4N+BF4, at 15 °C and 10 A/dm2. When 1.5 F/mol were applied, 15 is obtained in 75% yield with more or less quantitative current efficiency. Treatment with 2.3 F/mol is rendered by 84% chemical yield for 15 and a current efficiency of 84% [61, 62]. In contrast to the mediated process, furan is anodically oxidized in the initial step and subsequently methanol enters the scene (Scheme 7). 

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