Alkynes Electrooxidation to α,α-Dichloroketones in Seawater with Natural Chlorine Participation via Competitive Reaction Inhibition and Tip-Enhanced Reagent Concentration.

The traditional synthesis of α,α-dichloroketones usually requires corrosive chlorine, harsh reaction conditions, or excessive electrolytes. Here, we report an electrooxidation strategy of ethynylbenzenes to α,α-dichloroketones by directly utilizing seawater as the chlorine source and electrolyte solution without an additional supporting electrolyte. High-curvature NiCoO nanocones are designed to inhibit competitive O and Cl evolution reactions and concentrate Cl and OH ions, accelerating α,α-dichloroketone electrosynthesis. NiCoO nanocones produce 81% yield, 61% Faradaic efficiency, and 44.2 mmol g h yield rate of α,α-dichloroketones, outperforming NiCoO nanosheets. A Cl radical triggered Cl and OH radical addition mechanism is revealed by a variety of radical-trapping and control experiments. The feasibility of a solar-powered electrosynthesis system, methodological universality, and extended synthesis of α,α-dichloroketone-drug blocks confirm its practical potential. This work may provide a sustainable solution to the electrocatalytic synthesis of α,α-dichloroketones via the utilization of seawater resources.