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The reaction methyl 4-nitrobenzenesulfonate + Br- was studied in water-formamide tetradecyltrimethylammonium bromide micellar solutions. A pseudophase kinetic model was used to quantitatively rationalize the kinetic micellar effects observed

The 1-chloro-2,4-dinitrobenzene + OH- reaction was studied in tetradecyltrimethylammonium bromide aqueous micellar solutions. Influence of changes in [surfactant] as well as in [NaOH] on the observed rate constant were rationalized by using pseudophase kinetic models. At high hydroxide ions concentration an additional pathway across the micellar boundary had to be considered.

The elimination reaction between 2-(p-nitrophenyl)ethyl bromide and OH- ions was studied in nonionic aqueous micellar solutions of two esters of long chain fatty acids and sorbitan polyethylene glycol, Tween 20 (monolaurate) and Tween 80 (monooleate). The equilibrium binding constants of the 2-(p-nitrophenyl)ethyl bromide molecules to the nonionic micellar aggregates were obtained by spectroscopic measurements. The experimental kinetic data were quantitatively rationalized by the treatment of first-order reactions based on the pseudophase model. Results from this work and from previous studies show that, whereas the presence of cationic and sulfobetaine micelles accelerates the reaction, the presence of nonionic micelles inhibits the reaction.

The ligand substitution reaction [Fe(CN)5(4-tbupy)]3- + pyrazine (4-tbupy=4-tertbutylpyridine) was studied in aqueous concentrated electrolyte solutions at 298 K. Plots of ln(k/kw) against (γ-γw), where the subscript w refers to pure water and γ is the surface tension of the appropriate salt solution, gave a common straight line for all the electrolytes studied and permits to estimate the activation volume.

The α, β, and π* Kamlet-Taft solvatochromic parameters have been determined for aqueous mixtures of tert-butanol and ethyleneglycol from spectroscopic data.

The acid dissociation constants of nine aliphatic carboxylic acids in several N,N-dimethylformamide-water mixtures were subjected to factor analysis (FA) and two solvent factors emerged. A further target factor analysis (TFA) indicated that the Kamlet and Taft general equation is reduced in these mixtures to two terms: the independent one and that related to the hydrogen bond acceptor (HBA) basicity β solvatochromic parameter. Accordingly, an excellent correlation is found between the logarithmic values of the acidity constants of each acid in the binary mixtures and their corresponding β values.

The kinetics of replacement of 4-cyanopyridine (4-CNpy) by CN− in [Fe(CN)5(4-CNpy)]3− have been studied in different concentrations of electrolyte. Plots of ln (k/kw)versus (γ−γw), where the subscript w refers to pure water and γ is the surface tension of the appropriate salt solution, gave a common straight line for all the electrolytes studied. This result seems to confirm theD character of the process studied and permits an estimate of the activation volume to be made from kinetic data.

A simple working method for the estimation of the aggregation numbers and core radii from weight measurements of sodium bis-2-ethylhexylsulphosuccinate (aerosol-OT orAOT)/decane/water microemulsions of several compositions is proposed. Starting out from the hypotheses that (i) the density of the water inside the droplets is the same as that of free water, (ii) all the surfactant is localized as interface, and (iii) the penetration of the organic phase into the interface is negligible, values for the aggregation number and core radii comparable to those determined using more sophisticated methods were obtained. The results/methodological simplicity ratio may be of great advantage in kinetic work on reaction mechanisms in microemulsions.

The wavelengths of absorption maxima are reported for two ligand field bands of hexathiocyanatochromate(III), $ {⤪ Cr(NCS)_{6}^{3-}} $, over a range of water-cosolvent mixtures and different electrolyte concentrations. Correlations of the shifts of ligand field band energies as a function of dielectric constant and polarizability of the medium have been investigated. The data for binary aqueous mixtures indicate preferential solvation of the complex by the organic solvent.

The oxidation of MnEDTA2−. (EDTA=ethylenediaminetetra-acetate) by hexachloroiridate(IV) has been studied in concentrated electrolyte solutions at 298 K. The estimation of the activity coefficients of the species from the Stokes-Robinson hydration theory indicates that the observed salt effects have their origin in a greater destabilization of the initial state with respect to the transition state when increasing salt concentration.

The kinetics of replacement of 4,4′-bipyridine, (4,4′-bipy), and 4-cyanopyridine, (4-CNpy), by cyanide in [Fe(CN)5-(4,4′-bipy)]3-. at 298 K have been studied in binary aqueous mixtures containing different amounts of t-butanol, methanol, glycerol, ethyleneglycol and sucrose. The plots of logarithms of the limiting rate constantsversus the mole fraction of water are linear over the entire composition range studied, showing the importance of solvation phenomena. A different straight line of log (kL/s−1)versus XH2O is obtained for each mixture, indicating the influence of other solvent parameters on the reaction rate. A multiparameter regression of δΔG exp ≠ with A (acidity vector), B (basicity vector) and GE is used for both reactions; plots of δΔG calc ≠ versus ΔΔG exp ≠ are linear with slopes of near unity.

Charge-transfer transitions of Ru(bipy) 3 2+ , Fe(bipy) 3 2+ , Fe(CN) 6 3- , and free bipy (bipy=2,2′-bipyridine) are solvent dependent. Evidence is presented that dielectric continuum theory provides a reasonable basis for interpreting medium effects on the electronic transition energies in binary solvent mixtures as well as in pure solvents.

Rate constants are reported for the oxidation by peroxodisulphate ions of octacyanomolybdate(IV) in concentrated aqueous salt solutions containing up to 6 mol dm−3 salt including mixed salt solutions. The dependence of the logarthm of rate constant on salt concentration is discussed in terms of ionic hydration enthalpies and B-viscosity coefficients. The analysis confirms that ion-pairs play a key role in determining reactivities in these systems.

The rate of the reaction between permanganate and iodide ions had been measured in several concentrated salt solutions. There is a salt effect, which is dependent on the hydration heat of the salt present in the reaction medium.