Green chemistry: Electrochemical organic transformations via paired electrolysis

Paired electrolysis is highly valuable from the viewpoint of efficiency as well as atom and energy economies. In order to optimize the latter two for chemical reactions, the development of paired electrochemical processes is necessary. When both of the electrodes in an electrochemical cell (divided and undivided) are applied as working electrodes, and both sides of the processes (oxidation and reduction) yield valuable compounds, this ideal electrolysis phenomena is defined as paired electrosynthesis. This paired electrolysis offers the opportunity to reduce the spent energy and time, when compared with a single electrolysis system that is only used to achieve a product of interest, while ignoring the other side of the electrolysis (anodic or cathodic). In an ideal case, 200% current efficiency could be achieved during paired electrosynthesis using cathodic and anodic processes to provide the same product. Paired electrosynthesis is a highly efficient green process and, therefore, is beneficial for preserving resources and minimizing waste. However, while a paired electrosynthesis is beneficial, both oxidation and reduction processes must be compatible to counter the yield losses and equally ease separation and purification of both sides of the electrode products. Greater efforts are required to perform paired electrosynthesis with a more systematic and rational approach to achieve optimal products under paired conditions. Nevertheless, new computational tools could be applied for assistance in this matter. There is a considerable level of adventure in designing new paired electrosynthetic processes and accompanying opportunities to design innovative and powerful synthetic strategies. Herein, an overview of several examples of paired electrosyntheses and their advantages are summarized that will aid researchers to both develop a greater understanding of this subject and subsequently employ paired electrolysis for green and sustainable synthesis of organic molecules. © 2021 American Chemical Society