Micellar Catalysis of Organic Reactions. 25. Orientational Effects in Hydroxy-Functionalized Micelles

Article abstract of DOI:10.1021/jo00269a031

The basic hydrolysis of a number of aspirin derivatives in the presence of the hydroxy-functionalized micelles cetyl(2-hydroxyethyl)dimethylammonium bromide (CHEDAB), cetyl(2-hydroxypropyl)dimethylammonium bromide (CHPDAB), and (2-hydroxycetyl)trimethylammonium bromide (2-OH CTAB) and in the presence of cetyltrimethylammonium bromide (CTAB) has been compared.It has been found that of the hydroxy-functionalized micelles CHEDAB best discriminates between substrates with reaction centers at the micelle-water interface and those with reaction centers that are more deeplyburied in the micellar interior.This discrimination is shown in differences in the ratios of the optimum rates of hydrolysis in the hydroxy-functionalized micelles and in CTAB.It is also shown in the ratios of the calculated rates of reaction in the micellar pseudophase for the hydroxy-functionalized micelles and for CTAB.Thus the orientation of substrates within micellar aggregates is important in determining the magnitude of micellar catalysis.