Organic Halide Electroreduction on Silver

摘要

Silver, whose extraordinary electrocatalytical properties for organic halide reduction have been recently evidenced, has been used as cathode material for systematic preparative electrolyses in membrane-divided cells. To better elucidate the substrate role on the remarkable positive shift of reduction potentials, and on the "cage effect" i.e. the promotion of intermolecular reaction on absorbed intermediates, three halide substrate patterns are here compared in terms of both voltammetric characterization and prepartive electroreduction products: aliphatic halides (adamantanes), aromatic halides (phenols) and anomeric glycosyl halides. The preparative electroreductions result mainly in dimerization in the case of glycsoyl halides, in H->Br substitution in the case of bromophenosl, in dimerization + substitution in the case of haloadamantanes. The product analysis, both at the end of the reaction and at intermediate times, allos discussing the reaction pathways in terms of intermediate stability and of active surface accessibility. The possibility of complete dehalogenation on a wider substrate variety with remarkably lower energy consumption and almost quantitative current yields makes the process potentially very interesting for environmental purposes.