Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

Apparent molar volumes, V0 of amino acids i.e. glycine, l-alanine, l-serine, l-threonine and DL-alpha-aminobutyric acid in pure water and in aqueous solutions of imidazolium based ionic liquid, 1-butyl-3-methylimidazolium bromide, [BMIm][Br] were determined from precise density measurements at temperatures T = (288.15-318.15) K and at atmospheric pressure. Partial molar volumes V2o and partial molar volumes of transfer, deltatrV2o of amino acids in aqueous [BMIm][Br] solutions have been obtained from the V0 data. The V2o values follow the order: l-threonine greater than DL-alpha-aminobutyric acid greater than l-serine greater than l-alanine greater than glycine. Positive deltatrV2o values for all the studied amino acids indicate the dominance of hydrophilic-ionic interactions between amino acids and [BMIm][Br]. The partial molar expansibilities (dV2o/dT)P and their second order derivatives (d2V2o/dT2)P, volumetric interaction parameters, VAB and VABB, hydration number, nH have been calculated. The charged end groups, V2o(NH3+,COO-), side chain contributions of the amino acids, V2o(R) and apparent specific volume, v0 have also been obtained from V2o and V0 data. The results have been interpreted in terms of possible molecular interactions.