Reactions of p-nitrophenyl dodecanoate in normal and modified cholic acid micelles

Abstract

The mild catalysis by cholic acid micelles of p-nitrophenyl dodecanoate hydrolysis, and of p-nitrophenoxide release in the presence of imidazole groups, provide useful probes of micellar growth and structure. We have made a molecule consisting of two cholic acid residues joined by a flexible hydrophilic oligomer. This molecule shows a small catalysis on its won at low concentrations in the presence of 40% dioxan, and it can halve the critical micelle concentration of cholic acid when present in a proportion of one part in 50.