Enthalpic pairwise interactions of isomers of 2,4-pentanediol and 2,5-hexanediol in dimethylsulfoxide + water mixtures at 298.15 K

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• 作者：Zheng Guo^a ; Xingen Hu^a ; ^{hxgwzu@126.com} ; Guoyong Fang^a ; Shuang Shao^b ; Aidi Guo^a ; Hongyu Liang^a
• 关键词：Isothermal titration calorimetry ; Enthalpic pairwise interaction ; Chiral diols ; Dimethylsulfoxide ; Chiral discrimination effect
• 刊名：Thermochimica Acta
• 出版年：2012
• 期刊代码：110_00406031
• 类别：ch
• 出版时间：20 April, 2012
• 卷：534
• 期：Complete
• 页码：51-63
• 文件大小：483 K

摘要

The dilution enthalpies of four chiral diols, namely (2S,4S)-(+)-2,4-pentanediol vs (2R,4R)-(鈭?-2,4-pentanediol and (2S,5S)-(+)-2,5-hexanediol vs (2R,5R)-(鈭?-2,5-hexanediol in dimethylsulfoxide (DMSO) + water mixtures at 298.15 K have been determined respectively, using isothermal titration calorimeter (ITC). On the basis of the McMillan-Mayer theory, homochiral enthalpic pairwise interaction coefficients (h_xx) of the four diols in the mixed solvents of various mass fractions (w = 0-0.3) have been calculated. It is found amazedly that across the whole studied composition range of mixed solvent values of h_xx for S-enantiomer are almost higher than R-enantiomer for each diol. The results are discussed from the point of view of solute-solute interaction and solute-solvent interaction accompanied by chiral discrimination effect. The variations of h_xx with w for the four chiral diols depend largely on the competition equilibrium between hydrophobic-hydrophobic, hydrophilic-hydrophilic and hydrophobic-hydrophilic interactions in the ternary solution systems.