The solubility and stability of l-threonine in ionic liquids

The solubility of l-threonine in aqueous ionic liquids, 1-(2-carboxyethyl)-3-methylimidazolium chloride, [HOOCEMIM][Cl] and 1-butyl-3-methylimidazolium bromide, [C4mim][Br] has been measured at various IL concentrations and different pHs at 298.15 K using gravimetric method. The experimental data for the solubility of l-threonine in aqueous IL solutions were accurately correlated with segment-based local composition models such as Wilson, NRTL and modified NRTL. To gain some information concerning the amino acid stability in ionic liquid solutions, transfer Gibbs free energies (∆transferG) of l-threonine from water to aqueous [HOOCEMIM][Cl] and [C4mim][Br] solutions have been calculated.