Showing papers on "Ionic liquid published in 1971"
TL;DR: In this paper, the authors describe a procedure for maintaining good chemical stability in molten alkali-metal carboxylates, up to about 350 degrees C. Valid physical measurements can be made and the fluids can be used up to this temperature, above which spontaneous decomposition of the anions is difficult to repress.
Abstract: Procedures are described for maintaining good chemical stability in molten alkali-metal carboxylates, up to about 350 degrees C. Valid physical measurements can be made and the fluids can be used up to about this temperature, above which spontaneous decomposition of the anions is difficult to repress. Molten sodium propionate has a useful liquid range of about 60 degrees C and sodium isobutyrate of about 90 degrees C. Sodium n-butyrate transforms into a 'liquid crystal' at about 250 degrees C and into the isotropic liquid at 324 degrees C. For sodium isovalerate corresponding transition points are respectively 188 and 280 degrees C. Thermodynamic measurements are reported of volume and enthalpy changes at transition and melting points. Transport parameters measured include the viscosity and the electrical conductivity. The viscosity of these ionic melts undergoes a steep decrease at the transition from mesomorphic to isotropic liquids. Jumps in ionic conductivity are found both at the melting and clearing points. Even for the isotropic liquids, the ratio of viscosity to electrical conductivity is exceptionally high, compared with the other ionic melts. Mechanisms of melting for these ionic solids are discussed.
32 citations
16 citations
TL;DR: In this article, a homolytic mechanism was proposed for the decomposition of phenyliodoso acetate in acetic acid and perchloric acid was used to accelerate the process.
Abstract: Phenyliodoso acetate appears capable of sustaining both free-radical and ionic reactions. Conductivity studies on solutions of phenyliodoso acetate in acetic acid indicate a small degree of ionic dissociation at temperatures above room temperature. Photolysis of the iodoso compound is a zero-order reaction and a homolytic mechanism is proposed for the decomposition. Evidence from conductivity and spectroscopic studies indicates that there is interaction between the iodoso compound and hydrogen ions. The decomposition of phenyliodoso acetate in acetic acid is markedly accelerated by the addition of perchloric acid. In the absence of acid no conclusion about mechanism is possible; when acid is present decomposition occurs by an ionic mechanism.
7 citations
01 Jan 1971
TL;DR: In this article, the properties of molten salts, their being ionic liquids with predominantly Coulombic forces between the ions, and the circumstances of their use, that is, relatively high temperatures, limited number of materials is suitable as the second liquid phase.
Abstract: Several technologies use molten salts as reaction media or as solvents for valuable solutes, and it is necessary to remove the solute into another phase at a certain stage. This can be done by volatilization, by electrodeposition, by precipitation, or finally by extraction into another liquid phase. Because of the properties of molten salts, their being ionic liquids with predominantly Coulombic forces between the ions, and the circumstances of their use, that is, relatively high temperatures, only a limited number of materials is suitable as the second liquid phase. These are certain metals with appropriate melting points (such as bismuth), certain molten salts with predominantly covalent forces between their ions, making them immiscible with ionic melts (such as silver bromide or boron oxide), and certain organic materials that are thermally stable and have high boiling points (such as terphenyls). Only the first category has as yet found practical use in technology.(1)
4 citations
TL;DR: In this article, the effect of salt on the free energy of acetic anhydride was investigated in concentrated salt solutions at 20°, where Sine salts were used in concentrations of up to 5 mol 1-1; all inhibited the reaction and the salt effect was resolved into its component effects on the reactants and the transition state by use of the Bronsted-Bjerrum equation to calculate transition state activity coefficients from rate constants and measured activity coefficients.
Abstract: The kinetics of the hydrolysis of acetic anhydride have been investigated in concentrated salt solutions at 20°. Sine salts were used in concentrations of up to 5 mol 1-1; all inhibited the reaction. The salt effect was resolved into its component effects on the reactants and the transition state by use of the Bronsted-Bjerrum equation to calculate transition state activity coefficients from rate constants and measured activity coefficients of acetic anhydride. The effect of a salt on the free energy of the reactants was always significant and in some cases it was the major component of the effect of the salt on the free energy of activation. The enthalpy and entropy of transfer from water to 1 mol l-1 sodium chloride, for both acetic anhydride and the transition state, show the enthalpy-entropy compensation effect which is typical of aqueous solutions. These salt effects are considered to be part of the general phenomenon of the effect of salts on the activity coefficients of non-electrolytes. The inhibition is not caused by formation of a complex between salt and acetic anhydride. Rate constants could not be correlated with dielectric constant and ionic strength, using Gold's equation, and changes in water structure which occur in these salt solutions were shown to have no direct effect on the reaction rate.
3 citations