Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The dilution enthalpies of three isomers of 2,3-butanediol, namely, meso-2,3-butanediol, (2S,3S)-(+)-2,3-butanediol, (2R,3R)-(-)-2,3-butanediol, as well as 1,3-propanediol in dimethylsulfoxide (DMSO) + water mixtures have been determined, respectively, using an isothermal titration calorimeter (ITC) at 298.15 K. On the basis of the McMillan-Mayer theory, the homochiral enthalpic pairwise interaction coefficients (hXX) of the four diols in the DMSO + water mixtures of various mass fractions (w = 0 to 0.3) have been calculated. The results are discussed from the point of view of solute-solute interaction and solute-solvent interaction. It was found that the method of ITC can differentiate the energies of homochiral interactions between different pairs of optical isomers in aqueous solutions. The variations of hXX with w for the four diols depend largely on the competition equilibrium between hydrophobic-hydrophobic, hydrophilic-hydrophilic, and hydrophobic-hydrophilic interactions in DMSO + water mixtures. The five-membered intramolecular hydrogen bonding of vicinal diols plays an important role on homochiral pairwise interactions. The structure of relative rigid ring favors the forming of preferential configuration in molecular pairwise interaction.