Micellar Catalysis in Aqueous Solution

A - Reactant of same sign impeded approach - slow reaction B - Reactant of opposite sign - accelerated reaction C - Solubilization in palisades improves solvent character 

The ability of a micellar system to solubilize a reactant may affect its action as a catalyst or inhibitor in a reaction. When a surfactant system serves as a reservoir for increasing the availability of one reactant, any change that increases the solubilizing capacity of the micelle should also increase its effectiveness as a catalysis. If, on the other hand, the reaction must occur in the bulk phase, increased solubilizing power may remove reactant from the reaction medium and therefore decrease catalytic or increase inhibitor efficiency. 

As might be expected, the stracture of the reactive substrate can have as much influence on miceUe-assisted rate enhancement as that of the surfactant. Since the catalytic effectiveness of the micelle can be related to the location and orientation of the substrate in the micellar structure, the more hydrophobic the substrate (and the surfactant), the more significant may be the catalytic effect. 

As new experimental techniques produce more detailed information on the location of the various components in micellar systems, and the thermodynamics of substrate-micelle interactions become better imderstood, our ability to expand the applicability of such systems on the basis of good science and good judgment will be greatly enhanced. 

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Foidler, J. H. Fendl, E. J. Principles of Micellar Catalysis in Aqueous Solutions. Catalysis in Micellar and Macromokcular Systems-, Academic Press New York, 1975 pp 86-103. 

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