Micellar catalysis by dodecylbenzenesulfonic acid in water: Significance of dynamic micelles

The 4-dodecylbenzenesulfonic acid (DBSA), a Brønsted acid surfactant combined catalyst, forms micelles and vesicles in water. The dynamic DBSA micelles, which are present at lower concentrations (<75 mM), are more efficient in micellar catalysis in water. The dynamic micelles supply high flux of monomers to emulsify the water-insoluble/ non-polar reactant in water creating huge interface. The large intermolecular distance between DBSA at interface of emulsions provides appropriate microenvironment for the reaction (space to accommodate the molecules of reactant(s) and reaction intermediates, and accessible H+ ions). At higher concentrations (>75 mM), micelles become very stable, which have good solubilization capacity for the water-insoluble reactant. However, the stable micelles are less active in micellar catalysis due to the close molecular packing of DBSA strongly solubilizing the reactant(s) and reducing the accessibility of H+ ions due to extensive hydrogen bonding between –SO3H groups.