Precise measurements on electrical conductances as well as laser Raman spectra in the wavenumber range 3500-100 cm -1 of five lithium salts in 1,2-dimethoxyethane (DME) have been reported. The conductance data are interpreted by the Fuoss-Kraus theory, yielding values for the ion-pair and triple-ion formation constants. The Raman spectra suggest the presence of "spectroscopically free" ClO 4 -, BF 4 -, and AsF 6 -, ions in solutions, whereas there is no such evidence for either the Clor Brion, thus substantiating the very high ion-pair formation constants for LiCl and LiBr as obtained from conductance measurements. The observed processes have been interpreted by an Eigen multistep mechanism. Changes in the Raman bands at ca. 867, 1147, 1452, and 2805 cm -1 suggest that the solvation of Li + ion in DME occurs through the ethereal oxygen atom of the solvent molecule.

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Conductance measurements are reported for several symmetrical tetraalkylammonium bromides, lithium tetrafluoroborate (LiBF,) and tetrabutylammonium tetrabutylborate (Bu,NBBu,) in propylene carbonate (PC) at 25 "C. The data have been analysed by the 1978 Fuoss conductance equation in terms of the limiting molar conductivity, A', the association constant, K , , and the association distance R. The single-ion conductances have been determined from the A' value of Bu,NBBu, using it as a 'reference electrolyte'. The results indicate that with the exception of LiBF, to some extent, other salts are almost unassociated in this solvent medium. The evaluation of Stokes radii of the ions indicate that Li+ is extensively solvated while the other ions remain almost unsolvated. The results have been discussed in terms of the ion-solvating ability of PC and also compared with the previous values in this system.Propylene carbonate (PC) has drawn much attention in recent years as a solvent medium for electrochemical studies' relating to high-energy batteries2v3 and free-radical species., It is a stable solvent of moderately high relative permittivity5 (64.40 at 25°C) and has good solvent properties6*' for a variety of organic and inorganic salts. Hence, it is of much interest to study the behaviour of electrolytes in such a solvent medium. The conductometric method is well known' to give valuable information regarding ion-solvent interactions of electrolytes in non-aqueous and mixed solvents. Although conductance measurements on alkali-metal iodides9-' and quarternary ammonium perchlorates6*' ' have been reported in PC, no such experimental data for tetraalkylammonium bromides (except tetrabutylammonium bromide) and lithium tetrafluoroborate are available in the literature.Conductance measurements on tetrabutylammonium tetrabutylborate have been reported by Takeda and co-workers,12 but this compound has been further investigated by us in order to maintain an internal consistency amongst the derived values with these electrolytes.We have therefore repeated a few of the earlier measurements and have also measured the electrical conductances of several additional tetraalkylammonium bromides, R,NBr (R = methyl to heptyl), LiBF, and Bu,NBBu, in PC at 25 "C. Single-ion conductances have been derived using Bu,NBBu, as the 'reference electrolyte' in an effort to provide reliable values of the ionic mobilities for these ions in this medium. ExperimentalPC (Merck >99% pure) was dried over freshly ignited quicklime for several hours13 and then distilled three times under reduced pressure under nitrogen, the middle fraction being taken each time. The purified sample had a density of 1.1988 g cm-3, viscosity of 2.471 CP and a specific conductance of ca. 0.73 x S cm-' at 25°C; these values are in good agreement with the literature values.' ', 14 Tetraalkylammonium bromides were of purum or puriss grade (Fluka) and were purified as described in the literature.' 5 * 1 6 The salts were purified by recrystallization and the higher homologues we...

Density and viscosity have been measured over the entire composition range for the binary mixtures of propylene carbonate and 2-methoxyethanol at 298.15, 308.15, and 318.15 K. From the experimental results, the excess molar volume (V^) and deviation of viscosity based on the mole fraction average ( ) have been derived. Kinematic as well as relative viscosity data have also been analyzed by two different methods in terms of interaction parameters. Results have been explained on the basis of molecular interactions and geometric effects of the components in the mixtures.