Electrosynthesis of Agrochemicals via Alternating-Current-Driven Selective, Continuous Dehalogenation

Dehalogenation is a critical transformation in chemical synthesis but remains limited by catalyst deactivation and low selectivity in industrial processes. Here, we report an alternating current (AC) electrolysis strategy for the selective, continuous dechlorination of picloram to aminopyralid, a widely used herbicide. Conventional electrolysis, currently used in industrial aminopyralid electrosynthesis, suffers from structural degradation of the Ag catalyst and the in situ formation of reactive species (ClO^-, NH₃, and NO₂^-), leading to reduced product yields (<30%) and increased side-product formation. By contrast, AC electrolysis sustains catalytically active, defect-rich Ag surfaces through periodic redox cycling and minimizes the accumulation of ClO^- and NO₂^-, thereby suppressing side reactions. The optimized AC protocol achieves a yield of >85% aminopyralid with >90% conversion, enabling uninterrupted operation in a flow system for over 50 days. This work not only advances the industrial electrosynthesis of aminopyralid but also highlights AC electrolysis as a broadly applicable platform for enhancing selectivity and catalyst durability in electrocatalytic transformations.