Voltammetry of Ion Transfer at a Water-Toluene Micro-Interface

Voltammograms of ion transfer at the water (W)vertical bar toluene interface were recorded for the first time by using a micro-interface electrolytic cell and bis(triphenylphosphoranylidene) ammonium tetrakis[3,5-bis(trifluoromethyl) phenyl] borate (BTPPA(+) TFPB-). The high solubility of BTPPA(+)TFPB(-) in toluene at room temperature enabled the electrochemical measurements. The potential window at the Wjtoluene interface is about 1.09 V, which is 0.30 V larger than that at the W vertical bar 1,2-dichloroethane interface when using 10 mmol dm(-3) NaCl as the supporting electrolyte in W. The transfer reactions of quaternary ammonium ions across the Wjtoluene interface were found to be reversible. Formal potentials for ion transfer from W vertical bar to toluene were evaluated, and linear correlations were observed between these formal potentials and the standard potentials reported at the Wjnitrobenzene, W vertical bar 1,2-dichloroethane, and W vertical bar 2-nitrophenyl octyl ether interfaces.