The Electrocatalytic Cleavage of Carbon-Halide Bonds on Ag, Au and Cu electrodes : from aprotic and protic traditional solvents to ionic liquids

In the last years we have showed in detail how the electrocatalytic cleavage of carbon-halide 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). To both complete and support our interpretative scheme we are now concentrating on the solvent role. Comparing aprotic with protic organic solvents after appropriate intersolvental normalization, interesting peculiarities emerge concerning protic media. Solvent proticity deeply affects both the reaction mechanism (on both non-catalytic and catalytic electrode surfaces) and the extent of the catalytic effects [1]. We will also present a first extension of this study to room temperature ionic liquids (RTILs), which are currently arising considerable interest on account of their advantages over traditional organic solvents. In this context, the electrochemical reduction of a series of aliphatic and aromatic bromides has been investigated in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4). BMIMBF4 behaves like molecular solvents such as acetonitrile and dimethylformamide but, in general, both Ag and Cu are less active in the ionic liquid than in polar aprotic solvents [2]. References [1] S. Arnaboldi, A. Gennaro, A. A. Isse, P. R. Mussini, Electrochimica Acta, 2015, 158, 427–436 [2] A. A. Isse, S. Arnaboldi, C. Durante, A. Gennaro, Journal of Electroanalytical Chemistry, 2017, 804, 240–247