Interfacial Hydrogen-Bond Network Regulation Tuned Water Dissociation Enables Selective Chlorination of Alkenes.

Abstract

Electrocatalytically selective chlorination of olefins in Cl^--containing solutions is a sustainable method for synthesizing chlorohydrin/vicinal dichloride; however, controlling the selectivity is challenging. Here, aqueous/dimethyl carbonate (DMC) hybrid electrolytes with different H₂O/DMC ratios are designed to modulate the ·OH formation to increase the corresponding selectivities. The combined results of in/ex situ spectroscopies and molecular dynamics simulations reveal the origin of high selectivity. TFSI^- shields the transportation of free H₂O to provide moderate ·OH formation for the synthesis of chlorohydrin. DMC reconstructs hydrogen bonds with free H₂O to minimize the interaction between them and the anode, matching the requirements of vicinal dichloride production. Thus, these hybrid electrolytes not only achieve high selectivities of 80% and 76% for chlorohydrin and vicinal dichloride, respectively, but also enable the selective chlorination of other olefins with high isolated yields of up to 74%. This work provides a facile strategy to regulate the selectivity of anodic chlorination via a rational electrolyte design.