Apparent molar volumes and viscosity B-coefficients of some α-amino acids in aqueous solutions from 278.15 to 308.15K
1999; Elsevier BV; Volume: 334; Issue: 1-2 Linguagem: Inglês
10.1016/s0040-6031(99)00107-0
ISSN1872-762X
AutoresZhenning Yan, Jianji Wang, Wenbin Liu, Jinsuo Lu,
Tópico(s)Phase Equilibria and Thermodynamics
ResumoViscosities and densities of aqueous solutions of glycine, DL-alanine, DL-α-amino-n-butyric acid, DL-valine, DL-leucine and L-serine have been measured as a function of amino acid concentration at 278.15, 288.15, 298.15 and 308.15 K. These data have been used to calculate the apparent molar volumes V2,φ and viscosity B-coefficients. The calculated standard partial molar volumes V02,φ and B-values were split into the contributions from the (NH3+,COO−) and CH2 groups by linear correlations. Free energies of activation, Δμ0≠2, of aqueous amino acids were obtained by application of the transition-state theory to the B-coefficient data, and the corresponding activation enthalpy ΔH0≠2 and entropy ΔS0≠2 were also given. On the basis of the contributions of (NH3+, COO−) and CH2 groups to V02,φ, B-coefficient and the activation parameters, comments on the effect of amino acids and their groups on the structure of water and the relative orderness of the ground and the transition state of these solutions have been made.
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