Limitations of the pseudophase model of micellar catalysis. The dehydrochlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane and some of its derivatives

Influence of surface micellar head group neutralized in hexadecyltrimethylammonium bromide (CTAB) and hydroxide (CTAOH) on the dehydrochlorination of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD)

“…(29), and betaine (5) p constant is valid only at low OH-concentrations when r n o~ << rn,, and p = rn,,. Some of the results in the literature at high OH-concentrations had been explained by considering an additional pathway across the micellar boundary, in which the hydroxide ion in the aqueous phase would react with the organic substrate bound to the micelle (12,30). With this new additional reaction step with a pseudo-first-order rate constant:…”

An electrostatic approach to negatively charged substrate reactions with hydroxide ion in cationic CTAB micelles

“…The opposite effect has been found with positively charged substrates for which Br-counterion addition produces a sharp increase in substrate to micelle binding (7)(8)(9). It is also known that the pseudophase ion-exchange model fails at high reactive ion concentrations according to some experimental evidence in literature (10) so that it becomes necessary to consider an increase in the fraction of neutralized micellar head groups (11,12) or to consider an additional reaction pathway in which the reactive ion in the aqueous phase reacts with the micelle bound substrate (13).…”

Deprotonation of Indole Derivatives in Aqueous Cationic Surfactants

“…Classical equilibrium constants and second-order rate constants in solution are generally written with concentrations as molarities, and comparison of data in micelles and water re-quires estimation of local molarities in the micellar pseudophase. [2,3a,3b,3c] Provided that we treat the micellar interfacial reaction region as of uniform composition with molar volume, V M , we can relate concentrations by using Equation (10). (10) where subscript M inside the square brackets denotes local molarity, and outside the brackets it indicates molarity in terms of total solution volume.…”

“…[2,3a,3b,3c] Provided that we treat the micellar interfacial reaction region as of uniform composition with molar volume, V M , we can relate concentrations by using Equation (10). (10) where subscript M inside the square brackets denotes local molarity, and outside the brackets it indicates molarity in terms of total solution volume.…”

“…This treatment fits extensive data, but reaction rates in moderately concentrated OH Ϫ are typically higher than predicted by the PIE model. [10] These rate increases were first explained on the assumption that OH Ϫ in the aqueous pseudophase could react directly with micellar-bound substrate, i.e., that a new reaction path is introduced at high [OH Ϫ ]. [10a,10b] Subsequently the kinetic data were fitted in terms of ''invasion'' of the micellar interfacial region by OH Ϫ and other hydrophilic ions, which means that the postulated constancy of β breaks down at high ionic concentrations.…”