Mechanochemically mediated electrosynthesis: unveiling a new pathway for redox reactions under mechanochemical conditions

Abstract

Mechanochemistry has emerged as a powerful technique for conducting chemical transformations under minimal or solvent-free conditions, aligning with the global motivation for green protocols. Simultaneously, electrochemically-driven organic reactions have experienced a resurgence, leveraging electricity as a substitute for hazardous oxidants and reductants. While extensive research has focused on understanding both mechanochemistry and electrochemistry, less attention has been devoted to the use of an external power source in combination with mechanochemistry. Here, we explore the synergy between mechanochemistry and electrochemistry as a sustainable technique for organic transformations. We introduce a uniquely designed two-electrode mechano-electrochemical cell (MEC) connected to an external power source. Mechano-electrochemistry allows for precise control of applied potential during milling under minimal solvent conditions. Our investigation aims to unravel the impact of milling on electrochemically driven reactions and understand the parameters required to control electrochemically driven reactions under milling conditions. We present the design and optimization of the MEC, considering factors like electrode material, size, solvent volume, interelectrode gap, and milling motion. The developed MEC demonstrates its effectiveness in electrochemically reducing aromatic bromides and performing electrochemical oxidative coupling for sulfonamide synthesis with minimal solvent loading under milling conditions. This technique highlights the feasibility of performing mechanochemically mediated electrochemical reactions for substrates with low solubility, potentially leading to reduced solvent use, improved yields, and faster reaction times. The integration of electrochemistry and mechanochemistry paves the way for exploring mechanochemically mediated-electrochemistry as a powerful and sustainable tool for organic reactions, with implications for both academic research and industrial applications.