The enthalpies of solution Delta H-sol(m) have been determined for trans-4-hydroxy-L-proline (4-hydroxyproline) in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF) and N, N-dimethylacetamide (DMA). The measurements have been made at 298.15 K and mole fraction of amide x(2) = (0-0.3) on the precise "isoperobol" calorimeter. The results obtained have been used to calculate the standard enthalpies of solution (Delta solH degrees) and transfer (Delta(tr),H degrees) of 4-hydroxyproline from water into mixtures as well as the enthalpic coefficients of pairwise interaction (h(xy)) of 4-hydroxyproline with amides in aqueous solution. The interrelation between enthalpy characteristics of dissolution (transfer) of 4-hydroxyproline and the composition of (water + amide) binary mixtures has been established. Contributions of the amides properties (molar volume, dipolarity/polarizability, acidity, and basicity) to the variation of the energy of pairwise interactions have been estimated quantitatively by means of a modified Kamlet-Taft equation.
