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Solution densities and conductivities for solutions of [Cnmim]Br (n= 8, 10, 12) ionic liquids (ILs) in ethylene glycol, N,N-dimethylformamide, and dimethylsulfoxide have been determined at 298.15 K as a function of ionic liquid concentration. The apparent molar volumes, standard partial molar volumes, molar conductivities, and the limiting molar conductivities of the ILs have been derived from the experimental data. On the basis of the values of the standard partial molar volume and the limiting molar conductivity of the Br−anion available in the literature, the standard partial molar volumes and the limiting molar conductivities for the cations have also been reported in the three organic solvents. These data help to examine the effect of alkyl chain length of the cations and properties of the solvents. It was shown that the standard partial molar volumes of the ILs and their cations increased, but the limiting molar conductivities decreased linearly with the increase of the alkyl chain length. The fluidity of the solvents played an important role in the conductivity properties. [ABSTRACT FROM AUTHOR]

The protonation constant pKa2of l-norvaline has been determined in aqueous solution at different ionic strengths and different temperatures, using the pH-metric technique. The thermodynamic quantities (ΔG°, ΔH°, and ΔS°) have been studied and discussed. Evaluation of the effect of organic solvent of the medium on the protonation processes was also reported and discussed. The organic solvents used were methanol, dimethylformamide (DMF), dimethylsulfoxide (DMSO), acetone, and dioxane. The pKa2values for the ionization in a water (1) + dioxane (2) mixture [100 w2= 10 %, 20 %, 30 %, 40 %, and 50 %] have been determined at five different temperatures from T= (288.15 to 308.15) K. The thermodynamic quantities were calculated. [ABSTRACT FROM AUTHOR]