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Rupasri Mandal (Karan), Sujit Chandra Lahiri
Gibbs Energies of Transfer of Hydrogen Ion from Water to Tetrahydrofuran + Water Mixtures and Basicity and Structuredness of Aquo-ethers
The thermodynamic dissociation constants for isoelectric reaction of the type LH+ ↔ L + H+ (where L = 2,2´-bipyridine or 1,10-phenanthroline) have been determined pH-metrically at 298°K in aqueous binary mixtures of tetrahydrofuran (0-90 wt% of organic co-solvent). The pK-values have been found to decrease continuously. The data have been utilized to calculate the Gibbs energies of transfer of H+-ion from water to tetrahydrofuran-water mixtures. The results have been explained in terms of ion-solvent interactions, structural variations and basicity of aquo-organic mixtures.
Attempts have been made to understand the basicity and structuredness of different aquo-ethers (D + H2O, THF + H2O and DME + H2O) from a comparative study of ΔG0 t(H+) profiles and excess relative permittivity ΔεE r(X) profiles of the aquo-ethers. The order of basicity has been found to be THF + H2O > DME + H2O > D + H2O.
DME has been found to be structureforming and D has been found to be structure breaking over the whole composition range (0-87 wt% of organic solvent). But THF is slightly structure forming initially but structure breaking above 40 wt%.
Zeitschrift für Physikalische Chemie, Oldenbourg Wissenschaftsverlag
Print ISSN: 0942-9352
Volume: 214, 01/2000
Pages: 001