Apparent Molar Volumes and Viscosity <i>B</i>-Coefficients of Some Amino Acids in Aqueous Tetramethylammonium Iodide Solutions at 298.15 K

Abstract

Apparent molar volumes and viscosity B -coefficients of glycine, l -alanine, and l -valine in 0.05, 0.10, and 0.15 mol·dm -3 aqueous tetramethylammonium iodide (TMAI) solutions have been determined at 298.15 K from density and viscosity measurements. The standard partial molar volumes, standard volumes of transfer, and hydration number of the amino acids have been calculated for rationalizing various interactions in the ternary solutions. It has been found that the partial molar volume and viscosity B -coefficient varies linearly with the number of carbon atoms in the alkyl chain of the amino acids, and they were split into contributions from charged end groups (NH 3 +, COO - ) and the CH 2 − group of amino acids. Furthermore, the side chain contribution to the partial molar volume and viscosity B -coefficient of the amino acids has been determined using a group additivity approach. The results have been discussed in terms of ion−dipolar, hydrophobic−hydrophobic, and hydrophilic−hydrophobic group interactions.