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  • ion association  (2)
  • methanol  (2)
  • triple ions  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Journal of solution chemistry 23 (1994), S. 579-593 
    ISSN: 1572-8927
    Schlagwort(e): 2-Cyanopyridine ; conductivities ; 1∶1 electrolytes ; dilute solutions ; single ion molar conductivities ; ion association ; mixed solvents ; acetonitrile ; concentrated solutions ; LiAsF6 ; high energy density lithium batteries
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Electrolytic conductivities of eight simple 1∶1 electrolytes have been measured in dilute solutions of 2-cyanopyridine (2CNP) at 30°. Infinite dilution mobilities and association constants were calculated using the Fuoss-Hsia equation. With the exception of LiCF3SO3 all salts show very little association, consistent with the very high dielectric constant of 2CNP. The weak association which does occur is attributed to weak ion-solvent interactions. No evidence was found for triple ion formation. Conductivities of concentrated solutions of LiAsF6 in 2CNP increase slowly with concentration reaching a maximum at a concentration of around 0.65 mol-dm−3. These conductances are slightly lower than those in propylene carbonate which has a lower dielectric constant and a higher viscosity. Conductivities of concentrated LiAsF6 solutions in 2CNP mixtures with acetonitrile vary monotonically, consistent with solution viscosities, and show no sign of the maximum commonly observed in mixed organic solvents.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Journal of solution chemistry 16 (1987), S. 225-235 
    ISSN: 1572-8927
    Schlagwort(e): Conductivities ; 1:1 electrolytes ; methyl formate ; ion pairs ; triple ions ; ion solvation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The electrolytic conductivities of LiClO4, LiAlCl4, LiAsF6, NaClO4, NaBPh4, and Bu4NClO4 have been measured in methyl formate at 25°C. Evidence is presented for strong association between the perchlorate ion and the formyl proton of the solvent. Ion association and triple ion formation constants suggest that LiClO4, LiAlCl4, and NaClO4 form solvent separate ion pairs and triple ions. NaBPh4 forms contact ion pairs and triple ions, and the remaining salts appear to form both types of ion pairs and triple ions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Journal of solution chemistry 18 (1989), S. 977-991 
    ISSN: 1572-8927
    Schlagwort(e): Conductivity ; 1∶1 electrolytes ; methyl acetate ; ion pairs ; triple ions ; ion solvation ; activity coefficients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The electrolytic conductances of NaClO4, NaB(C6H5)4, (n-C4H9)4NClO4 and (n-C4H9)4NPF6 have been measured in methyl acetate at 25°C. A dominating feature of these electrolyte solutions is, as expected, strong ion pairing. In addition it is found that the formation of triple ions makes an important contribution to the overall molar conductivities. The data suggest that there are strong ion-solvent interactions leading to structure-enhanced (after Diamond) ion association and triple ion formation which has an exact analogy in the phenomena of salting-in. The effects of increasing solution permittivity and viscosity are discussed, particularly in regard to comparing two models of treating conductivity data. The first model includes ion pairs and triple ions, and the second model ignores triple ion formation ascribing the anomalous increase in molar conductivities to a decrease in the ion association equilibrium constant caused by increasing solution permittivity.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1572-8927
    Schlagwort(e): Electrolytic conductance ; molar conductance ; ion pair formation ; complex formation ; 18-crown-6 ; calix[4]arene-bis-crown-6 ; lithium perchlorate ; sodium perchlorate ; potassium perchlorate ; rubidium perchlorate ; cesium perchlorate ; acetonitrile ; methanol ; propylene carbonate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Résumé The interactions of Li+, Na+, K+, Rb+, and Cs+ with the “double-crown calix,” calix[4]arene-bis-crown-6, have been studied in methanol, acetonitrile, and propylene carbonate at 25°C using precise conductivity measurements. For Li+ and Na+ in solutions containing this calix[4]arene, only 1:1 cation:ligand complexes are formed which permit the determination of the thermodynamic complexation formation constants,K f. The conductivity data strongly suggest that 2:1 cationcalixarene complexes form with K+, Rb+, and Cs+. The existence of 2:1 complexes was experimentally confirmed for the potassium systems by a mass spectroscopic method.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Journal of solution chemistry 25 (1996), S. 541-553 
    ISSN: 1572-8927
    Schlagwort(e): Potassium ; cesium ; fluoride ; halide ions and perchlorate ; methanol ; water ; molar conductivities ; ion association ; Gibbs energies of transfer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Electrolytic conductivities of KF and CsF in methanol solution have been determined at 25°C. The single ion molar conductivities of the fluoride ion, obtained from the two salts are in excellent agreement and indicate that the F− ion is highly solvated in methanol (MeOH). Combination of the present and literature data for related salts in both water and MeOH indicate that while the primary solvation of ions may be more extensive in H2O there is considerable enhancement of the secondary solvation sheath in MeOH. Recalculation of high precision literature conductivity data using a consistent mathematical approach indicates that ion pair formation constants for simple 1:1 electrolytes in MeOH are 1 or 2 orders of magnitude greater than in H2O. This is shown to be entirely due to the less favorable solvation of ions in MeOH, as the Gibbs energies of transfer of the neutral ion pairs MX from H2O to MeOH are also unfavorable. Calculations also show that ion association in MeOH is strongly influenced by coulombic interactions whereas in H2O short range interactions are generally more important.
    Materialart: Digitale Medien
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