16023-36-2Relevant academic research and scientific papers
Micellar Effects upon Rates of SN2 Reactions of Chloride Ion. 1. Effects of Variations in the Hydrophobic Tails
Bacaloglu, Radu,Blasko, Andrei,Bunton, Clifford,Cerichelli, Giorgio,Ortega, Francisco
, p. 5062 - 5068 (1990)
Interactions of 35Cl- with trimethylammonium surfactants increase with increasing length of the hydrophobic alkyl group on the basis of NMR line widths.The dependence of line width upon and can be fitted by a Langmuir isotherm, and for alkyl = C8H17 - C18H37 the binding parameters, K'Cl, agree reasonably well with those estimated kinetically from rate constants of the reaction of Cl- with methyl naphthalene-2-sulfonate.The second-order rate constants for reaction in the micellar pseudophase decrease modestly with decreasing length of the alkyl group and are similar to those in water.For C8H17NMe3Cl there appear to be interactions of Cl- with both micelles and monomeric surfactant, or small clusters of it.This nonmicellar interaction is also kinetically significant with C6H13NMe3Cl and Me4NCl, but interactions with substrate and Cl- are weak.
Nucleophilicity of bromide ion in mixed cationic/sulfoxide micelles
Foroudian, Houshang,Bunton, Clifford A.,Holland, Paul M.,Nome, Faruk
, p. 557 - 562 (2007/10/03)
Addition of the non-ionic surfactant, n-decyl methylsulfoxide (C10SO) to aqueous cetyltrimethylammonium bromide (CTABr) inhibits the micellar-mediated reaction of Br- with bound methyl naphthalene-2-sulfonate (MeONs).The concentration of Br- at the micellar surface is reduced due to an increase in the fractional micellar ionization, α, and in the volume of the micellar pseudophase, which slows the reaction of Br-.These concentration effects are partially offset by an increase in the second-order rate constant in the micellar pseudophase on addition of C10SO.
SN2 Reactions of a sulfonate ester in mixed cationic/phosphine oxide micelles
Blasko, Andrei,Bunton, Clifford A.,Toledo, Eduardo A.,Hollannd, Paul M.,Nome, Faruk
, p. 2367 - 2373 (2007/10/03)
Addition of the nonionic surfactant, dodecyl(dimethyl)phosphine oxide (C12PO) to aqueous cetyltrimethylammonium bromide (CTABr) inhibits the micellar-mediated reaction of Br- with fully bound methyl naphthalene-2-sulfonate (MeONs).Reaction in the micellar pseudophase depends on the concentration of Br- in the interfacial surface region, which is decreased on addition of C12PO by increases in both the fractional micellar ionization, α, and the volume of the micellar pseudophase.The inhibition of the reaction is partially offset by an increase in the second-order rate constant in the micellar pseudophase on addition of C12PO which appears to be related to a solvent-like effect at the micelle-water interface.Interactions of CTABr and C12PO in the mixed micelles were explored by using 1H and 31P NMR spectroscopy.
Micellar Enhancements of Rates of SN2 Reactions of Halide Ions. The Effect of Headgroup Size
Bacaloglu, Radu,Bunton, Clifford A.,Ortega, Francisco
, p. 1497 - 1502 (2007/10/02)
Observed first-order rate constants for reaction of methyl naphthalene-2-sulfonate with Cl- or Br- in micelles of cetyltrialkylammonium halide (C16H33NR3X, R = Me,Et,n-Pr,n-Bu, X=Cl,Br) increase monotonically with increasing surfactant and halide ion concentrations and tend to limiting values.The variation of rate constants with concentrations of surfactant and halide ions can be fitted to an equation that accounts for the distribution of both reactants between water and micelles.Fractional micellar ionization, α, increases, i.e., the affinity of the micelles for the halide ion decreases, with increasing bulk of the N-alkyl groups, but the second-order rate constants at the micellar surface and the overall rate constants increase.The rate effects of the micelles of the bromide ion surfactants can be understood in terms of NMR evidence on the micellar binding of the reactants and their location at the micellar surface.The reactivity increase with increasing headgroup bulk is related to the disruption of the hydration of Br- and to the electrostatic interaction of the naphthalene ?-system with cationic nitrogen.
Micellar Effects upon Substitutions by Nucleophilic Anions
Bunton, Clifford A.,Moffat, John R.
, p. 2896 - 2902 (2007/10/02)
Micellar effects upon of OH- with p-nitrophenyl diphenyl phosphate or 2,4-dinitro-1-chloronaphthalene have been examined with cetyltrimethylammonium surfactants, (CTAX, X=Cl, Br, (SO4)1/2).Demethylations of methyl benzene- or naphthalene-2-sulfonate by halide ion have been examined. in micelles of CTACl, CTABr, CTA(SO4)1/2, or cetyltrimethylammonium mesylate (CTAOMs) and for demethylation by OH- or SO32- in CTA(SO4)1/2 or CTAOMs.The rate enhancements have been treated in terms of concentrations of the substrates and the nucleophilic anion at the micellar surface.The anion concentrations depended upon nonspecific Coulombic and specific interactions that were calculated by solving the Poisson-Boltzmann equation.The same structural parameters were used in fitting data for reactions with Cl- or Br- as nucleophiles and for systems with Cl- or Br- as inert anions that were competing with OH- or SO32-.The treatment is applicable to mixtures of database to mixtures of dilute mono- and dianions.
Hydrophobic and steric effects on the ion-pair formation of tris(1,10-phenanthroline)iron(II) and arenesulfonate ions. Kinetic determination of the formation constants of the ion pairs and a 1H NMR study of their structures
Tachiyashiki, Satoshi,Yamatera, Hideo
, p. 3209 - 3211 (2008/10/08)
Ion-pair formation constants (K) for Fe(phen)32+ and six kinds of arenesulfonate ions were obtained from kinetic studies of the aquation of the complex ion in aqueous sodium arenesulfonate solutions: K = 5 ± 1, 13 ± 2, 28 ± 5, 19 ± 3, 8 ± 2, and 5 ± 1 mol-1 dm3 for benzene-, 4-methylbenzene-, 4-ethylbenzene-, 2,4-dimethylbenzene-, 1-naphthalene-, and 2-naphthalenesulfonate, respectively. An arenesulfonate of greater hydrophobicity showed a larger formation constant, except that small formation constants were shown by bulky naphthalenesulfonates. The formation constant was smaller for an arenesulfonate than for an alkanesulfonate with the same number of carbon atoms. The 1H NMR signal of arenesulfonate in the ion pair was found to shift upfield. Comparison of the observed shifts with those calculated on the basis of the current loop model supported a model of the ion pair in which the arenesulfonate ion lies in the hydrophobic cavity between two phenanthroline ligands of the complex ion with the sulfonate group directed outside the cavity.
