Effect of Halide Ions on Single-Electron Oxidation Reactions in Microdroplets

The single-electron oxidation reaction is a critical initial step in organic synthesis. Currently, the influence of halide ions on single-electron oxidation in water microdroplets remains unclear. In this study, different halide ions were observed to have the opposite influence on single-electron oxidation reactions. Specifically, F^- and Cl^- inhibited single-electron oxidation, while Br^- and I^- promoted this reaction. These influences had a distinct dependence on the concentration. The microdroplet size distribution, quantity of microdroplets, and generation of radicals were systematically investigated to probe the mechanism. The inhibitory effects of F^- and Cl^- were mainly attributed to charge neutralization, while the promotional effects of Br^- and I^- were mainly due to the generation of radicals. Overall, this study reveals the dual nature of halide ions in the unique environment of microdroplets, enhancing our understanding of ion-specific effects in microdroplet chemistry.