Viscosity behavior of some α-amino acids and their groups in water–sodium acetate mixtures

Abstract

Viscosities of glycine, dl-α-alanine, dl-α-amino- n-butyric acid, dl-valine and dl-leucine have been determined in water–sodium acetate mixtures at 298.15 and 308.15 K. The viscosity B-coefficients have been calculated. The corresponding activation free energies (Δμ 2 0≠) for viscous flow have been evaluated with the help of the Feakins equation. The contributions of the charged end group (NH 3 +,COO −) and CH 2 groups of the amino acids to B-coefficient and Δμ 2 0≠ have been also determined using the linear correlation between B-coefficient or Δμ 2 0≠ and the number of carbon atoms in alkyl chains of the amino acids. The results have been interpreted in the light of the solute–solvent interactions in aqueous media.