Transfer free energies of fluoride ion in aqueous mixtures of some organic solvents.

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概要

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• Standard free energies of transfer, <I>ΔG<SUB>t</SUB></I><SUP>°</SUP>, of potassium fluoride (KF) from water to aqueous mixtures of dimethyl sulfoxide (DMSO), <I>N</I>,<I>N</I>-dimethylformamide (DMF), acetonitrile (ACN), 1,2-dimethoxyethane (DME), and 2-methoxyethanol (ME) have been determined at 25 °C from emf measurements performed on the double cell: Pb(Hg)–PbF<SUB>2</SUB>/KF(m), solvent/K(Hg)/KF(m), water/PbF<SUB>2</SUB>–Pb(Hg). <I>ΔG<SUB>t</SUB></I><SUP>°</SUP> values of F<SUP>−</SUP> were obtained from these values using the corresponding values of K<SUP>+</SUP>, as obtained earlier by use of tetraphenylarsonium tetraphenylborate reference electrolyte assumption. In each solvent system <I>ΔG<SUB>t</SUB></I><SUP>°</SUP>(F<SUP>−</SUP>) values are found to be increasingly positive with cosolvent composition reflecting the pronounced destabilization of F<SUP>−</SUP> and their relative order : DME>DMSO<I>≥</I>DMF>>ACN≈ME conforms to what is expected from the relative 'aproticity' of the dipolar aprotic cosolvents and that induced in the protic ME by the possible intramolecular H-bonding. The observed larger destabilization of F<SUP>−</SUP> compared to OH<SUP>−</SUP> in ME–water system has been attributed to the H-bonding effect of the protic cosolvent ME and the reverse behaviour in DME–water and DMSO–water systems to the absence of such effect of these cosolvents. Moreover, tests of Feakins-type extrapolation for assigning individual ion contribution using <I>ΔG<SUB>t</SUB></I><SUP>°</SUP>(KF) values along with those of other potassium halides, provided some important reflections on the inadequacy of such plots made without the data points of F<SUP>−</SUP>.

• 公益社団法人 日本化学会の論文

著者

• Das Asim

  Physical Chemistry Laboratories, Jadavpur University

• Kundu Kiron

  Physical Chemistry Laboratories, Jadavpur University

• Das Kaushik

  Physical Chemistry Laboratories, Jadavpur University

• Bhattacharya Abhijit

  Physical Chemistry Laboratories, Jadavpur University

関連論文

• Transfer free energies of fluoride ion in aqueous mixtures of some organic solvents.
• Kinetic solvent effects on K+/K(Hg)electrodes in some dipolar aprotic solvent systems by cyclic voltammetry.
• Relative standard electrode potentials of I3-/I-, I2/I3-, and I2/I- redox couples and the related formation constants of I3- in some pure and mixed dipolar aprotic solvents.

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