The title reaction has been studied under restricted geometry conditions, comprising aqueous solutions of a polymer (DNA), cyclodextrins, and dendrimers as well as (CTA)Cl micellar solutions and sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/water/oil microemulsions. The results are interpreted by taking as a general basis the pseudophase model, modified in some cases in order to take into account the specificity of the reaction medium. These modifications describe the anti-cooperative character of the binding of the substrates to the surfaces and the changes of the electric potential at the surfaces. The conclusion is that the pseudophase model is a powerful tool for the interpretation of kinetic data in the reaction media considered in this work, provided that the specificity of these media were incorporated into the model.

The kinetics of the electron-transfer reaction between pentaaminepyrazine ruthenium(II), [Ru(NH3)5-pz] 2+ , and trisoxalatecobaltate(III), [Co(C2O4)3] 3-, was studied in sodium bis(2-ethylhexyl)sulfosuccinateoil-water microemulsions and in micellar solutions of hexadecyltrimethylammonium chloride. The results can be interpreted by taking as a starting point the pseudophase model. However, the model must be modified according to the characteristics of the reaction media. In this way, two different equations result for this model in the two reaction media studied. The influence of the surface potential on the parameters (equilibrium and rate constants) of the model is shown.

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Micellar effects on the oxidation reaction of [Ru(NH3)5pz]2+ with [Co(C2O4)3]3- in the presence of different NaCl concentrations were studied. Experimental results are discussed by using an approach based on the transition-state theory. It is shown that this approach used here is better than others based on the pseudophase model, which can also be used, because the former is able to give a clear meaning to the parameters of the model. Changes in the observed reactivity are explained by a change in the degree of association of the reactant to the micelles, which depends on the surface potential of the micelles. This potential determines the strength of binding of one of the reactants ([Ru(NH3)5pz]2+) to the micellar surface.