Efficient photoelectrocatalytic radical dichlorination of alkenes via synergism with Mn

Abstract

Chlorine radicals (Cl·) exhibit a remarkable ability to initiate a variety of highly efficient reactions. However, the sluggish and inefficient generation of Cl· radicals remains a challenge. More critically, the presence of excessive Cl· with a short lifetime leads to the formation of an undesired byproduct. The rational control of Cl· generation is crucial for the efficient dichlorination reaction. Herein, we use a photoelectrochemical (PEC) method to generate a significant amount of Cl· for chlorination reactions. The selectivity for the vicinal dichlorinated product reached 70%. Then, we manipulate the generation of Cl· by introducing a trace amount of Mn²⁺ (10 μmol) and achieve a high yield of 91% and a faradaic efficiency of 90% for the dichlorinated product. The Mn²⁺ participates in the reaction process and forms the [Mn³⁺–Cl] complex, which facilitates the addition reaction of the chlorinated intermediate and then enhances the selectivity of the final products. This study paves a new pathway for solar-driven alkene dichlorination and provides new insights into photoelectrocatalytic synthesis.