Abstract

DELGADO, Daniel R.; VARGAS, Edgar F.  and  MARTINEZ, Fleming. Preferential solvation of xylitol in ethanol + water co-solvent mixtures according to the IKBI and QLQC methods. Rev.Colomb.Quim. [online]. 2013, vol.42, n.1, pp.125-133. ISSN 0120-2804.

The preferential solvation parameters, i.e., the differences between the local around the solute and bulk mole fractions of the solvents in solutions of xylitol in ethanol + water binary mixtures are derived from their thermodynamic properties by means of the inverse Kirkwood-Buff integrals (IKBI) and quasi-lattice quasi-chemical (QLQC) methods. According to IKBI method it is found that xylitol is sensitive to solvation effects, so the preferential solvation parameter δx_E,S, is slightly positive in water-rich and negative in mixtures beyond 0.25 in mole fraction of ethanol. In different way, according to QLQC method, negative values of δx_E,S are found in all the compositions evaluated. The more solvation by ethanol observed in water-rich mixtures could be due mainly to polarity effects. Otherwise, the preference of this compound for water in ethanol-rich mixtures could be explained in terms of the bigger acidic behavior of water interacting with hydrogen-acceptor hydroxyl groups in xylitol.

Keywords : xylitol; ethanol; solubility; IKBI; QLQC; preferential solvation.

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