The Enthalpies of Solution and Solvation of L-Serine in Aqueous Alcoholic Solutions at 298.15 K

The integral enthalpies of solution (ΔsolHm) of L-serine in water-alcohol (ethanol, n-propanol, isopropanol) mixtures were measured over the range of alcohol concentrations up to 0.32 mole fractions. The standard enthalpy of solution (ΔsolHo), enthalpy of transfer of L-serine from water into a mixed solvent (ΔtrHo), and enthalpy of solvation (ΔsolvHo) were calculated. The dependences of ΔsolHo, ΔsolvHo, and ΔtrHo on the composition of mixtures had extrema. The calculated enthalpy coefficients of the pair interactions of L-serine with alcohol molecules were positive and increased along the series ethanol, n-propanol, isopropanol. The data obtained were interpreted in terms of different types of interactions in solutions and the influence of the nature of amino acid residues on the thermochemical solution characteristics.