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 (ΔsolH°) and transfer (ΔtrH°) of the glycylglycylglycine from water into the mixtures as well as enthalpy coefficients of pair-wise interaction (hxy) of the solute with amide in aqueous media. The hxy 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.