Aqueous solutions containing amino acids and peptides. Part 11.—Enthalpy of dilution of single and binary solute solutions of N-acetylglycine amide, N-acetyl-L-alanine amide, N-acetyl-L-valine amide and N-acetyl-L-leucine amide at 298.15 K

Abstract

The enthalpies of dilution of aqueous solutions containing N-acetylglycine amide (G), N-acetyl-L-alanine amide (A), N-acetyl-L-valine amide (V) and N-acetyl-L-leucine amide (L) and equimolal solutions of G + A, G + V, G + L, A + V, A + L and V + L have been measured at 298.15 K. The results obtained have been used to calculate the pairwise enthalpy coefficients for like–like and like–unlike solute interactions. These coefficients have been compared with the predictions of the group additivity approach proposed earlier by Savage and Wood. The group additivity approach works well considering the experimental error and the standard deviation of the original correlations although it seems likely that some refinement of the group interaction parameters is required.