Decoupled Photoelectrochemical Cerium-Catalyzed Oxydichlorination of Alkynes: Slow Releasing of Chloride Ions and Chlorine Radicals

Synthetic photoelectrochemistry shows significant advantages in handling of reactive intermediates via a sustainable way and has developed to be the frontier of single electron transfer chemistry. The exploration of new photoelectrocatalysts, especially uncommon metal-based ones, will contribute to the exploitation of new synthetic strategies. Benefiting from reversible redox ability and photoactivity, the cerium salt is expected to become a new photo-electro-response medium to generate active species. In this work, with a green and sustainable reaction system (neutral conditions and renewable light and electricity as energy sources), we developed a novel type of generation of Cl· via electrooxidation and photoinduced ligand-to-metal charge transfer by using CeCl3 as the photoelectrocatalyst in the oxydichlorination of aryl acetylene. Importantly, we found that the slow releasing of chloride ions and chlorine radicals played an important role in radical chlorination. In addition, several analytical methods including cyclic voltammetry, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and control experiments were conducted to investigate the reasonable mechanism.