Enthalpic characteristics of interactions occurring between an ascorbic acid and some saccharides in aqueous solutions

The enthalpies of solution of mono- and disaccharides were measured in water and aqueous ascorbic acid solutions at 298.15 K using a calorimeter of solution. Enthalpies of transfer of saccharides from water to aqueous ascorbic acid solutions were derived, and enthalpic coefficients of pair interaction hxy were calculated according to MacMillan–Mayer theory. Interactions of ascorbic acid with d-fructose and sucrose are energetically favorable and characterized by negative hxy coefficients while hxy for the interactions occurring between ascorbic acid and α-d glucose, d-galactose and maltose are positive. The obtained results are interpreted in terms of the influence of structure and solvation of solutes on the thermodynamic parameters of their interaction in solutions.