The electrocatalytic reductive dehalogenation of aromatic halides on silver

The remarkable electrocatalytic properties of Ag, recently evidenced by the research group for org. halide redn., were advantageously applied to obtain quant. direct dehalogenation of mono- and polyhalophenols. The process, environmentally friendly as based on a nontoxic electrocatalytic material, also appears highly competitive on account of its mildness of operating conditions, selectivity and current efficiency. Peculiar care was devoted to the anal. of the reaction mixts., never finding any product but those of hydrogenation of the halogen position(s). Another interesting feature is the absence of filming effect allowing the reaction to proceed with fairly high c.d. Structure effects on the reaction pathways are discussed with the support of systematic cyclic voltammetric expts. on Ag, Hg, and glassy C. The role of the solvent is also discussed from expts. carried out in MeCN, in MeCN/H2O 1:1 mixed solvent, and in H2O esp. focusing on current yield and energy consumption parameters. Finally, a preliminary reactivity study points to the possibility of generalizing the same advantageous process to all arom. halides.