Aqueous solutions containing amino acids and peptides. Part 30.—The enthalpies of interaction of some alkali-metal halides with some amino acids at 25 °C

Abstract

The enthalpies of mixing of aqueous solutions at 25 °C have been determined for the amino acids: β-alanine, γ-aminobutyric acid, δ-aminovaleric acid and ε-aminocaproic acid with NaCl; for α-alanine, α-aminobutyric acid and α-aminovaleric acid (norvaline) with KCl; for α-aminobutyric acid with KBr and KI, and for serine and threonine with NaCl and with KCl. In addition, the enthalpies of dilution of δ-aminovaleric acid have been determined. The results have been treated using the excess function concept and homotactic interaction coefficients are presented for δ-aminovaleric acid and heterotactic interaction coefficients given for the interaction of the salts with the amino acids. The latter are discussed in terms of intermolecular interactions between the hydrated solute species, and various correlations are given.