Influence of the composition of aqueous-amide solvents on enthalpic characteristics of l-proline dissolution at T = 298.15 K

Abstract

The dissolution enthalpies of l-proline in aqueous solution of formamide, N-methylformamide and N,N-dimethylacetamide with a mole-fraction of amides from x2=(0 to 0.35) have been measured at T=298.15K. The results obtained have been used to calculate the standard enthalpies (ΔsolH°) and transfer (ΔtrH°) of l-proline from water into mixtures as well as the enthalpy coefficients of pairwise interaction (hxy) of the solute with amide in aqueous solutions. The interdependence between enthalpy characteristics of l-proline dissolution (transfer) and the composition of (water+amide) mixtures has been established. Comparison of the resulting data with those obtained earlier for l-phenylalanine and l-tryptophan in the same mixed solvents at 298.15K has been made.