Collect. Czech. Chem. Commun. 1994, 59, 1287-1295

Mechanism of the Facilitated Ion Transfer Across a Liquid/Liquid Interface

Alfréd Sabelaa, Vladimír Marečeka, Jiří Korytab and Zdeněk Sameca

a J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic
b Institute of Physiology, Academy of Sciences of the Czech Republic, 142 00 Prague 4, Czech Republic


The facilitated transfer of sodium ion across the water/nitrobenzene interface was examined by faradaic impedance measurements at the thermodynamic equilibrium potential. Kinetic data for the interfacial reaction Na+(w) + L(n) ↔ NaL+(n) (L = dibenzo-18-crown-6, w = water, n = nitrobenzene) were confronted with the theoretical predictions for three possible reaction mechanisms, and a conclusion was reached that the reaction occurs via a single electrochemical step. Its pseudo-first order rate constant depends on the interfacial potential difference and falls between 0.01 and 1 cm s-1, i.e. it is comparable with the first order rate constant for a simple ion transfer.