REACTION KINETICS IN A MICROEMULSION MEDIUM IV. HEXACYANOFERRATE(III)-IODIDE REACTION IN WATER/AEROSOL-OT/HEPTANE MICROEMULSION AND MIXED SOLVENTS

The kinetics of the reaction between [Fe(CN)6]3− and I− was studied in a W/O microemulsion (Water/AOT/Heptane at different [Water]/[Amphiphile] mole ratios) and in mixed water–organic media (water–formamide, water–ethylene glycol, and water–dioxane). The pseudo-first-order rate constants were observed to radically increase in microemulsion media with a [Water]/[AOT] mole ratio below 6. At a mole ratio of 5.4, the rate constant was found to be about 20-fold greater than that in water. At a constant mole ratio, the rate constant was witnessed to be independent of [AOT]. In all mixed media, the rate decreased with increasing proportion of the nonaqueous solvent. The ionic-strength effect on the reaction did not obey either the modified Bronsted–Bjerrum or Bronsted–Bjerrum–Pitzer relations in the studied nonaqueous media, except for ethylene glycol. This disagreement is very prominent in the studied W/O microemulsion medium at [Water]/[AOT] ω = 9.1. The activation parameters for the pseudo-first-order reactio...