Experimental Mechanistic Studies on Alternating Polarity Electrolysis for Carbon-Centered Radical Generation
Year: 2025
Type: article
Abstract: Electrosynthesis offers a sustainable and tunable approach to organic transformations, enabling precise control over reaction thermodynamics and kinetics via the applied potential and current. A key recent advancement is alternating polarity (AP) electrolysis, where periodic electrode polarity reversal enhances selectivity and yield by mitigating electrode fouling, balancing redox processes, and stabilizing reactive intermediates. However, experimental mechanistic studies to understand the key factors controlling AP electrolysis, such as current magnitude, waveform frequency, and electrode material together with the type of radical intermediates generated, remain underexplored. In this study, we investigate the mechanistic basis of AP electrolysis using anodic oxidation for the generation of carbon-centered radicals as the model reactivity profile. Specifically, we utilize the well-documented anodic oxidation of organoboron or carboxylic acids in the generation of aryl, alkyl, and benzyl radicals under AP electrolysis. Experimental mechanistic studies using electroanalytical techniques reveal that the electrode potential depends on both current and frequency, serving as a reliable predictor of synthetic efficiency. Maps of electrode potential as a function of current and frequency were constructed for each radical type to enable identification of optimal AP electrolysis conditions aligned with key reaction potentials and substrate reactivity. Applying these insights to benzyl radical generation, a challenging case due to facile radical overoxidation, led to a 63% yield of the dimer product under the predicted optimal conditions. This work provides a predictive framework for AP electrolysis, empowering chemists to optimize conditions for efficient and selective radical-mediated electrosynthesis.
DOI: 10.1021/jacs.5c11621
Institution: Northwestern University
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, Northwestern University, Materials Research Science and Engineering Center, Harvard University, International Institute for Nanotechnology, Northwestern University, National Institute of General Medical Sciences, Division of Materials Research, Division of Electrical, Communications and Cyber Systems, National Science Foundation Graduate Research Fellowship Program
Awards: NNCI: Soft Hybrid Nanotechnology Experimental (SHyNE) Resource, G1820835029, G2233802770, G2343375527, G2788453484, G3010471893, G3203750490, G3892126996, Electrocatalysis for the synthesis of chiral and PET imaging pharmaceuticals, Northwestern University Materials Research Science and Engineering Center, G4958141111, G6540817556, G7397830644
OpenAlex ID: W4416724429