The kinetics of facilitated proton transfer by polyether 18-crown-6 across the water-1,2-dichloroethane interface has been investigated by cyclic voltammetry and ac impedance. It was found that rate apparent constant is quite similar for the several concentrations of 18-crown-6 used in the experiments, the rate constant values (ks) were in the range: 0.028, 0.031, 0.027, and 0. 03 cm/s for 0.1, 0.15, 0.2, and 0.25 mM of 18-crown-6.
A formal transfer potential of Δ0wϕi0′= 0.01 V was found for the facilitated proton transfer by 18-crown-6 at the water-1,2-dichloroethane interface; this value remained constant in the range of concentration considered in this work. According to the kinetic results, an interfacial reaction between the proton and the polyether 18-crown-6 is discussed in which the polyether does not transfer into the aqueous phase, in the time scale of the experiments. As a consequence, it can be concluded that the solvation and desolvation of ligand and proton play an important role in the rate-determining step.