Borohydride Oxidation as Counter Reaction in Reductive Electrosynthesis.

An efficient reaction at the counter electrode is of key importance for the success of net oxidative and net reductive electrochemical transformations. For electrooxidative processes, cathodic proton reduction to H serves as the benchmark counter reaction. In contrast, net reductive electrochemical transformations have less attractive oxidative counter reactions to choose from and commonly rely on dissolution of a sacrificial anode that effectively results in stoichiometric metal consumption for the processes. In this study, we demonstrate that anodic borohydride oxidation has great potential to successfully replace the use of such sacrificial anodes for a variety of electroreductive organic transformations. This anodic transformation effectively serves as the inverse of cathodic proton reduction, producing H using inert carbon-based electrode materials.