Solvation of glycine and its oligomers in a water-acetonitrile binary solvent at 298.15 K

The enthalpies of solution Delta H-sol degrees of glycine, glycylglycine, and diglycylglycine in the water-ace-tonitrile (0-0.4 mole fractions) binary solvent at 298.15 K were deter-mined for the first time by calorimetry. The enthalpy of solvation (Delta H-solv degrees) of glycine, the enthalpy of transfer (Delta H-tr degrees) of the above compounds from water to the binary solvent, and the pair-interaction enthalpy coefficients h(XY) were calculated. The behavior of Delta H-sol degrees = f(x(2)) function is largely determined by the energy of water-organic component interaction. The strength of the intermolecular interaction with acetonitrile increases in the series glycine < glycylglycine < diglycylglycine. An increase in the electron-donor ability of the organic component in the aqueous-organic solvent causes a decrease in the degree of solvation.