Thermochimica Acta, Vol.526, No.1-2, 46-49, 2011
Influence of the composition of aqueous-alcohol solvents on the thermodynamic characteristics of L-phenylalanine dissolution at 298.15 K
The enthalpies of L-phenylalanine dissolution in aqueous methanol, ethanol, 1-propanol and 2-propanol have been determined by calorimetry at 298.15 K and alcohol mole fractions up to x(2) similar to 0.4. The standard enthalpies of solution Delta(sol)H degrees and transfer Delta(tr)H degrees from water to the mixed solvent as well as the enthalpy coefficients of L-phenylalanine-alcohol pair-wise interactions were calculated. The interrelation of the enthalpies of dissolution and transfer for L-phenylalanine with structural features of alcohols has been determined. A comparative analysis of the thermodynamic characteristics of dissolution of L-phenylalanine and some other amino acids (glycine, L-alanine, L-threonine and L-valine) in the mixtures studied has been made. (C) 2011 Elsevier B.V. All rights reserved.
Keywords:L-Amino acids;Aqueous alcohols;Enthalpies of solution and transfer;Enthalpic coefficients of pair-wise;interaction