Reactions in Micelles of Cetyltrimethylammonium Hydroxyde. Test of the Pseudophase Model for Kinetics

Article abstract of DOI:10.1021/j150626a033

The rate constants for reactions of OH^- with 2,4-dinitrochlorobenzene (DCNB), 2,4-dinitrochloronaphthalene (DNCN), and p-nitrophenyl diphenyl phosphate (pNPDPP) in micellized cetyltrimethylammonium hydroxyde (CTAOH) do not conform to the pseudophase ion-exchanged model.The rate constants do not become constant when substrates are fully micellar bound and increase on addition of NaOH.However, with the more hydrophobic substrates DNCN and pNPDPP we appear to reach limiting rate constants at high or high .These observations can be explained on the assumption that the charge on a CTAOH micelle decreases on addition of OH^-, i.e., the concentration of OH^- in the micelle increases with increasing -> in the aqueous pseudophase.The rate-surfactant profiles for reactions of DNCN and pNPDPP can be interpreted quantitatively in these terms.For reactions of DNCB the rate data can be interpreted if we assume that added OH^- also increasees binding of DNCB to the micelle.