Electrocatalytic potentialities of silver as a cathode for organic halide reductions

The peculiar halide affinity for silver results in an extraordinary electro catalytic activity for the reduction of halides (either glycosyl halides or , more generally, aryl and alkyl halides). The most striking features are: (a) a reduction potential shift in the positive direction of about 1000 mV with respect to glassy carbon and 500 mV with respect to mercury; (b) a cag e effect, evidenced in previous synthetic work concerning bromosugars, prom oted by the halide acting as a bridge between the electrode surface and the reacting substrate, which mainly results in dimerization and/or addition p roducts. The above electrocatalytic effect is here investigated by means of a systematic reactivity study on Ag, Hg and glassy carbon cathodes, with a variety of substrates. The effect of the supporting electrolyte is also an alysed in detail, providing a first inspection on specific halide/silver in teractions in acetonitrile media. (C) 2000 Elsevier Science S.A. All rights reserved.