Electrolyte effects on the cationic micelle catalyzed decarboxylation of 6-nitrobenzisoxazole-3-carboxylate anion

The unimolecular decarboxylation of 6-nitrobenzisoxazole-3-carboxylate ion is strongly catalyzed by micelles of cationic and nonionic surfactants. The catalysis by cationic micelles can be enhanced by adding some electrolytes or nonionic surfactants or by using dicationic surfactants, indicating that the catalysis is sensitive to changes in micellar structure and charge density. The mode of incorporation of aromatic sulfonate and carboxylate anions into cationic micelles has been investigated by nmr spectroscopy and by electrochemical and viscosity measurements, and the effects of such incorporated anions on micellar catalysis and structure are discussed. It appears that the anions insert into the micelle with the aryl groups fitting between the ammonium head groups of the surfactant.