Effect of colloidal self-assemblies on the basic hydrolysis of 2-(4-bromophenoxy)quinoxaline

In the presence of cationic surfactants (C16H33NR3Cl; R = Me, n-Pr, n-Bu), the shape of rate versus surfactant concentration profiles for the basic hydrolysis of 2-(4-bromophenoxy)quinoxaline depends on substrate concentration. At low substrate concentration there is a single rate maximum and with a 10-fold substrate concentration increase a double rate maximum is observed. The first rate maximum is ascribed to reaction occurring in premicellar aggregates and the second to reaction in micelles. At low substrate concentration the effect of surfactant head group size was examined. Second-order rate constants in the micellar pseudophase increase with increasing head group size. Copyright (C) 2003 John Wiley Sons, Ltd.