Densities and electrical conductances of amino acids + ionic liquid ([HMIm]Br) + H2O mixtures at 298.15 K

Densities and electrical conductances of amino acids, glycine, l-alanine and l-valine in aqueous ionic liquid, 1-hexyl-3-methylimidazolium bromide ([HMIm]Br) solutions have been measured at 298.15 K. These data have been used to calculate the apparent molar volumes V ϕ , infinite dilution apparent molar volumes V ϕ 0 , and the standard partial molar volumes of transfer Δ t r V ϕ 0 of the amino acids from water to the aqueous ionic liquid solutions. It has been observed that both V ϕ 0 and Δ t r V ϕ 0 in the glycine + [HMIm]Br + H2O system increases with increasing ionic liquid concentrations and decrease in the cases l-alanine and l-valine systems. The contribution of the charged end groups (NH3+, COO−), CH2 group and other alkyl chain of the amino acids was estimated using V ϕ 0 values. Molar conductivities of [HMIm]Br in aqueous amino acids solutions have been applied for determination of association constants Ka, and limiting molar conductivies Λ0, using the low concentration chemical model (lcCM) of conductance equation.