Malviya Bhanwar K, Hansen Eric C, Kong Caleb J, Imbrogno Joseph, Verghese Jenson, Guinness Steven M, Salazar Chase A, Desrosiers Jean-Nicolas, Kappe C Oliver, Cantillo David
Institute of Chemistry, University of Graz, NAWI Graz, Heinrichstrasse 28, A-8010, Graz, Austria.
Research Center Pharmaceutical Engineering GmbH (RCPE), Inffeldgasse 13, 8010, Graz, Austria.
Chemistry. 2023 Nov 24;29(66):e202302664. doi: 10.1002/chem.202302664. Epub 2023 Oct 11.
Electroorganic synthesis is generally considered to be a green alternative to conventional redox reactions. Electrochemical reductions, however, are less advantageous in terms of sustainability, as sacrificial metal anodes are often employed. Divided cell operation avoids contact of the reduction products with the anode and allows for convenient solvent oxidation, enabling metal free greener electrochemical reductions. However, the ion exchange membranes required for divided cell operation on a commercial scale are not amenable to organic solvents, which hinders their applicability. Herein, we demonstrate that electrochemical reduction of oxidatively sensitive compounds can be carried out in an undivided cell without sacrificial metal anodes by controlling the mass transport to a small surface area electrode. The concept is showcased by an electrochemical method for the reductive cleavage of aryl disulfides. Fine tuning of the electrode surface area and current density has enabled the preparation of a wide variety of thiols without formation of any oxidation side products. This strategy is anticipated to encourage further research on greener, metal free electrochemical reductions.
有机电合成通常被认为是传统氧化还原反应的绿色替代方法。然而，就可持续性而言，电化学还原不太具有优势，因为经常使用牺牲金属阳极。分隔式电池操作可避免还原产物与阳极接触，并便于进行溶剂氧化，从而实现无金属的更绿色的电化学还原。然而，商业规模的分隔式电池操作所需的离子交换膜不适用于有机溶剂，这限制了它们的适用性。在此，我们证明了通过控制向小表面积电极的传质，可以在无分隔式电池中且不使用牺牲金属阳极的情况下对氧化敏感化合物进行电化学还原。通过一种用于芳基二硫化物还原裂解的电化学方法展示了这一概念。对电极表面积和电流密度的微调使得能够制备多种硫醇，而不会形成任何氧化副产物。预计这一策略将鼓励对更绿色、无金属的电化学还原进行进一步研究。
