Voltammetry of Ion Transfer at a Water–Toluene Micro‐ Interface

Voltammograms of ion transfer at the water (W)|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 W|toluene interface is about 1.09 V, which is 0.30 V larger than that at the W|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 W|toluene interface were found to be reversible. Formal potentials for ion transfer from W to toluene were evaluated, and linear correlations were observed between these formal potentials and the standard potentials reported at the W|nitrobenzene, W|1,2‐dichloroethane, and W|2‐nitrophenyl octyl ether interfaces.