Electrosynthesis of Chlorohydrins From Alkenes in Seawater Enabled by On-Site Generated Active Surface Chlorine Intermediate.

Chlorohydrins are essential intermediates in organic synthesis, playing a critical role in drug discovery, green catalysis, and bioactive molecule manufacturing. However, conventional chlorohydrin synthesis usually requires harsh conditions, which create safety risks and poor selectivity. Here we develop a direct and efficient electrocatalytic strategy for synthesizing chlorohydrins from commodity alkenes, which are globally produced at over 200 million metric tons annually. Utilizing a RuSnNbOx polymetallic oxide catalyst, cyclohexene is directly converted to 2-chlorocyclohexanol in NaCl solution with a Faradaic efficiency of 96.1 ± 3% and selectivity of 98.2 ± 0.4% at 1.6 V versus reversible hydrogen electrode. This approach is generalizable to other alkenes, such as styrene and cyclopentene, yielding 2-chloro-1-phenylethanol and 2-chlorocyclopentanol with uncompromised Faradaic efficiency. Mechanistic investigations reveal that the adsorbed active chlorine species, electrogenerated via Cl⁻ oxidation on the RuSnNbOx anode, serve as key intermediates for direct alkene chlorination. Notably, this electrosynthesis method is further upscaled to gram-level in acidic seawater, delivering 3.01 g of 2-chlorocyclohexanol and 0.87 g of 2-chloro-1-phenylethanol. This work provides a sustainable and scalable alternative to conventional chlorohydrin production and offers insights into designing efficient electrolysis for related transformations.