Enthalpies of solution of glycylglycylglycine in aqueous solution of amides at 298.15 K

Calorimetric measurements have been carried out at 298.15 K in aqueous solutions of glycylglycylglycine containing formamide, N-methylformamide, N,N-dimethylformamide and N,N-diethylformamide at concentrations of amides as co-solvents up to 0.4 mole fractions. The results obtained have been used to calculate the standard enthalpies of solution (Delta H-sol degrees) and transfer (Delta H-tr degrees) of the glycylglycylglycine from water into the mixtures as well as enthalpy coefficients of pair-wise interaction (h(xy)) of the solute with amide in aqueous media. The h(xy) values were correlated with the properties of organic solvents using Kamlet-Taft equation. The results of the calorimetric measurements have been discussed with regard to the intermolecular interactions occurring in these systems. (C) 2011 Elsevier B.V. All rights reserved.