Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Volumetric and, 1H and 13C NMR spectroscopic studies have been exploited to study molecular interactions of some polyhyroxy solutes with L-glycine in aqueous solutions. Apparent molar volumes for monosaccharides; (+)-D-mannose, (+)-D-glucose, and (-)-L-sorbose, disaccharides; (+)-maltose monohydrate, and (+)-cellobiose, deoxy-derivatives of hexoses; 6-deoxy-D-mannose, 2- deoxy-D-glucose, methyl glycopyranosides; (+)-methyl .alpha.-D-mannopyranoside, and (+)-methyl .alpha.-Dglucopyranoside, and polyols; D-mannitol, D-sorbitol, and myo-inositol in 0.05, 0.15, 0.25, 0.35 and 0.50 mol kg^-1 aqueous solutions of L-glycine have been determined from density, density data measured at 288.15, 298.15, 308.15 and 318.15 K under atmospheric pressure, p = 0.1 MPa. The data were processed to obtain the standard partial molar volumes at infinite-dilution and the corresponding volumes of transfer of solutes from water to aqueous solution of L-glycine. Other parameters such as partial molar expansion coefficients and their second-order derivatives and pair and higher-order volumetric interaction coefficients (VAB and VABB) have also been obtained. These parameters have been utilized to discuss various types of interactions on the basis of co-sphere overlap model. 1H and 13C NMR spectroscopic studies for polyhydroxy solutes were carried out in 0.10 mol kg-1 L-glycine prepared in 9:1 (w/w) H2O-D2O solvent. NMR results show more downfield shift in ternary system than in pure L-glycine solution, hence suggesting that hydrophilic-ionic interactions predominate over hydrophilic/hydrophobic-hydrophobic interactions occurring between solute and L-glycine molecules.