The enthalpies of solution of L-α-alanyl-L-α-alanine in water-organic solvent mixtures at 298.15 K

Abstract

The integral enthalpies of solution (T = 298.15 K) of L-α-alanyl-L-α-alanine in aqueous-organic solvents (acetonitrile, 1,4-dioxane, acetone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, and N,N-dimethylsulfoxide) were measured at organic component concentrations x2 = 0–0.3 mole fractions. The standard enthalpies of solution (ΔsolHo) and transfer (ΔtrHo) of the peptide from water into mixed solvents were calculated. The influence of the structure and properties of solutes and mixture composition on solute thermochemical characteristics is considered. The enthalpy pair interaction coefficients hxy between L-α-alanyl-L-α-alanine and organic solvent molecules were calculated. The linear Kamlet-Taft four-parameter equation was used to reveal correlation between the hxy values and the properties of organic solvents.