Showing papers by "Hitoshi Ohtaki published in 1973"

Ionic Equilibria in Mixed Solvents. X. Hydrolysis of Nickel(II) Ion in Dioxane-Water Mixtures

Abstract: The hydrolytic reactions of nickel(II) ion were studied at 25 °C in water and dioxane-water mixtures containing 3 M (Li)ClO4 as an ionic medium. Emf measurements were carried out in the range of the total nickel(II) ion concentration of 0.02469–0.7891 M in water, 0.02488–0.7996 M in a 0.1 mole fraction (35.21% w/w) dioxane-water mixture and 0.05170–0.9016 M in a 0.2 mole fraction (55.01% w/w) dioxane-water mixture, respectively. Some supplementary measurements were performed in a 0.5 mole fraction (83.02% w/w) dioxane-water mixture. Only the Ni4(OH)44+ complex was found in all solvent systems and its formation constant in log*β44 was −27.32±0.08 (in water), −27.11±0.08 (in a 0.1 mole fraction dioxane-water mixture), and −27.04±0.05 (in a 0.2 mole fraction dioxane-water mixture). In order to test the relative change of the formation consatnt of the Ni4(OH)44+ complex over the whole solvent composition examined, the variation of the formation constant was measured with the continual change of solvent compos...

Ionic Equilibria in Mixed Solvents. VIII. Solvent Effects on the Dissociation of Diprotic Acids in Aqueous Methanol Mixtures

Abstract: Dissociation constants of protonated 1,6-hexanediamine, 1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, and 1,12-dodecanediamine in aqueous mixtures of 0 to 90% (w/w) methanol were determined potentiometrically at 25°C, 0.1 M sodium chloride being used as an ionic medium. Values of pK2–pK1 of diamines were practically independent of the solvent composition in contrast to those of dicarboxylic acids, which increase monotonously with methanol concentration. Variations of pK1, pK2, and pK2–pK1 of diamines with solvent composition were discussed in comparison with those of dicarboxylic acids.