Thermochemistry of Glycyl-DL-alpha-Alanine Dissolution in Water-Alcohol Solutions at 298.15 K

摘要

Integral enthalpies of glycyl-DL-alpha-alanine dissolution in aqueous solutions of ethanol,1-propanol,and 2-propanol at concentrations of alcohols up to 0.4 mol fraction were measured by the calorimetry method.Standard values of the enthalpies of the peptide dissolution DELTA_(sol)H~0 and transfer DELTA_(sol)H~0 from water in mixed solvents were calculated.Dependences of the thermochemical characteristics of glycyl-DL-alpha-alanine dissolution on the concentration of cosolvents are of an extreme character.Within the limits of McMillan-Mayer's theory enthalpy coefficients of pairwise interactions(h_(xy))of the studied compound with molecules of alcohols were calculated.They have positive values increasing in the series ethanol,1-propanol,2-propanol.The effect of the structure of dipeptides and composition of water-alcohol solvents on the dissolution enthalpy characteristics was considered on the basis of the obtained experimental and calculated data.