Catalysis altered surface layers

The kinetics of catalytic reduction of 4-BB in CTAB solutions involves micellar catalysis of the electron transfer (ET) between 9-PA anion radical and 4-BB (Equation 2) in a thick layer of surfactant at the electrode. The effective rate constant for this ET in 0.1 M CTAB increased more than three orders of magnitude compared (Table 1) to the same reaction in surfactant-free DMF. The rate-determining step in CTAB was not Equation 2 as in DMF. In CTAB decomposition of the 4-BB anion radical (Equation 3) became kinetically important. The major cause of the kinetic alterations was compartmentalization of the reactants in high concentrations in surfactant aggregates at the surface of the electrode. The same catalytic reaction was not as successful in non-ionic igepal micelles, which did not provide good stabilization for 9-PA anion radicals. 

---