Enthalpic Interaction Coefficients of N,N′-Hexamethylenebisacetamide with Glycine in Aqueous Glucose and Sucrose Solutions at 298.15 K

Abstract

The mixing enthalpies of N,N′-hexamethylenebisacetamide (HMBA) with glycine in aqueous glucose and sucrose solutions have been determined by means of mixing-flow isothermal microcalorimetry at the temperature of 298.15 K. The heterotactic enthalpic interaction coefficients (hxy, hxxy, and hxyy) in the range of the saccharide molality, (0 to 1.5) mol·kg−1, have been calculated according to the McMillan−Mayer theory. It has been found that the heterotactic enthalpic pairwise interaction coefficients hxy between HMBA and glycine in aqueous glucose and sucrose solutions are all positive and pass through a maximum, respectively, at about 0.3 mol·kg−1 of glucose molality and about 0.6 mol·kg−1 of sucrose molality. In the meantime, the value of hxy in aqueous glucose solutions is larger than that in aqueous sucrose solutions of the same molality. The variations of the heterotactic enthalpic pairwise interaction coefficients with the molality of sugar in mixtures are interpreted in terms of solute−solute and solute−solvent interactions.