MICELLAR CATALYSIS OF ORGANIC-REACTIONS .35. KINETIC DETERMINATION OFTHE CRITICAL MICELLE CONCENTRATION OF CATIONIC MICELLES IN THE PRESENCE OF ADDITIVES

The critical micelle concentration of solutions of cetyltrimethylammon ium bromide and of tetradecyltrimethyl-ammonium bromides were determin ed by a kinetic method. This involved the determination of the rates o f the hydroxydehalogenation of some activated aromatic substrates over a wide range of detergent concentrations. Measurements were made in s olutions containing significant quantities of added hydroxyl ion and s ubstrates which were themselves amphiphilic. Conventional methods cann ot be applied with confidence to such systems. The effects of changing hydroxyl ion concentrations, added sodium bromide, changing the natur e of the aromatic substrate (whether neutral or charged), the identity of the micellar counterion and the temperature were investigated. It was wound that added bromide or hydroxyl ions resulted in a lower CMC whereas increased temperature led to an increase in the CMC. The natur e of the micellar counterion (Br, F, OH, SO4) had little effect on the CMC. The presence of a charged aromatic substrate led to a considerab le lowering of the CMC, whereas the neutral aromatic substrate used sh owed very little effect.