A model case of DET in ionic liquids : the reductive cleavage of carbon-halogen bonds on non catalytic and catalytic electrode surfaces

In the last years we have shown how the electrocatalytic cleavage of carbon-halogen bonds is modulated by (a) the stepwise or concerted nature of the DET mechanism (as a function of the electrode surface, of the nature of the halogen atom, and of the molecular structure of RX) and (b) the double layer structure (as a function of the nature and bulkiness of the supporting electrolyte ions). Recently, in order to both complete and support our interpretative scheme, we have been concentrating on the solvent role, comparing aprotic solvents with protic organic solvents, and evidencing the attractive peculiarities of the latter, which dramatically enhance the electrocatalytic properties of silver surfaces. With this background we are now looking forward to extending our study to room temperature ionic liquids (RTILs), which are currently arising considerable interest on account of their advantages over traditional organic solvents, including negligible vapour pressure, high intrinsic conductivity and easy recyclability. RTILs appear to be attractive in the frame of the above mechanistic studies, particularly on account of (a) their two-fold role as both solvent and supporting electrolyte and (b) their high viscosity. In this frame, we will present a first investigation on the reduction of model organic halides on glassy carbon GC, Au and Ag electrodes (representing non-catalytic, moderately catalytic, and highly catalytic electrodes, respectively, in traditional solvents), by a combination of cyclic voltammetry and electrochemical impedance spectroscopy, evaluating (i) whether the catalytic effects also persist in ionic liquids and to what extent, and if there is any relationship with the nature of the electrode material; (ii) whether in ionic liquids the same relations previously observed in traditional media hold between catalytic effects and molecular structure of the halide.