Selective electrodehalogenation of bromophenols on Ag electrocatalyst

Among the innovative technologies for the detoxification and disposal of industrial effluents, our recently described electroreductive dehalogenation of organic halides on silver electrocatalyst provides a promising route, to be easily "plugged-in" into integrated waste treatments. Although electroreductions do not lead to total substrate mineralization, complete and selective dehalogenation may be achieved by the appropriate choice of the cathode material, thus decreasing the biotoxicity of the waste. In particular the use of silver as electrocatalyst greatly reduces the energy demand, and ensures higher yields and no by-products also when treating highly toxic aromatic halides. In the present work the electrocatalytic role of silver in the electroreductive dehalogenation process has been studied on mono- and polyhalogenated bromophenols, taken as model substrates, both in terms of selectivity of the reaction pathway and of reactivity of the position on the aromatic ring of the bromo leaving group. The results point to the possibility of effectively extending the methodology also to the more common and less reactive chlorinated derivatives.