Thermochimica Acta, Vol.544, 43-46, 2012
Influence of the composition of aqueous-alcohol solvents on thermodynamic characteristics of DL-alpha-alanyl-DL-norleucine dissolution at 298.15 K
Dissolution enthalpies (Delta H-sol(m)) of DL-alpha-alanyl-DL-norleucine in binary mixtures containing water + (EtOH, 1-PrOH and 2-PrOH at 0-0.4 mole fraction) at 298.15K and atmospheric pressure have been determined as a function of the composition using an isothermic calorimeter. The results obtained have been used to calculate standard enthalpies of a solution (Delta H-sol degrees) and transfer (Delta H-tr) of DL-alpha-alanyl-DL-norleucine from water into the mixtures as well as enthalpy coefficients of pairwise interaction (h(xy)) of the solute with alcohols in aqueous media. The Delta H-tr degrees values are positive for all mixtures over the whole composition range. The influence of the co-solvent structure and of the content of mixtures and of a side-chain of peptide on the change of Delta H-tr degrees (h(xy)) is discussed. (c) 2012 Elsevier B.V. All rights reserved.