The 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF4, is an ionic liquid when pure. The acid base properties of aqueous solutions of [bmim]BF4 were examined by potentiometric titration. Then, protonation constants of glycine in binary mixtures of water and [bmim]BF 4 were determined, from potentiometric titration data obtained at T = 298.2 K and various ionic strengths of sodium chloride (0.25 ≤ I ≤ 1.00 mol · dm-3). The ionic strength dependence of the equilibrium constants of glycine was fitted to an extended Debye-Hückel equation to derive ionic strength dependence parameters. Comparison with literature data showed that, even at high concentrations, [bmim]BF4 is similar to the electrolyte [(C2H5)4NI], in that it does not interact significantly with other solutes. Solvatochromic parameters in the binary mixtures of water and [bmim]BF4 have been calculated by using Redlich-Kister equation. Kamlet-Abboud-Taft (KAT) solvatochromic equation allows us to determine the values of calculated protonation constants in different media.
Thermodynamic study on the protonation of glycine in different (water+1-butyl-3-methylimidazolium tetrafluoroborate) mixed solvents and ionic strengths
DE STEFANO, Concetta;LANDO, GABRIELE;SAMMARTANO, Silvio
2013-01-01
Abstract
The 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF4, is an ionic liquid when pure. The acid base properties of aqueous solutions of [bmim]BF4 were examined by potentiometric titration. Then, protonation constants of glycine in binary mixtures of water and [bmim]BF 4 were determined, from potentiometric titration data obtained at T = 298.2 K and various ionic strengths of sodium chloride (0.25 ≤ I ≤ 1.00 mol · dm-3). The ionic strength dependence of the equilibrium constants of glycine was fitted to an extended Debye-Hückel equation to derive ionic strength dependence parameters. Comparison with literature data showed that, even at high concentrations, [bmim]BF4 is similar to the electrolyte [(C2H5)4NI], in that it does not interact significantly with other solutes. Solvatochromic parameters in the binary mixtures of water and [bmim]BF4 have been calculated by using Redlich-Kister equation. Kamlet-Abboud-Taft (KAT) solvatochromic equation allows us to determine the values of calculated protonation constants in different media.Pubblicazioni consigliate
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