Energetics of pairwise interaction between glycidol enantiomers in (dimethylformamide + water) mixtures rich in water at T = 298.15 K. (August 2015)

• Record Type: Journal Article
• Authors: Wang, Hua-Qin; Cheng, Wei-Na; Chen, Nan; Zhu, Li-Yuan; Hu, Xin-Gen
• Is Part Of: Journal of chemical thermodynamics. Volume 87(2015:Aug.)
• Page Start: 8
• Page End: 12
• Publication Date: 2015-08
• Subjects: Dilution enthalpy -- Enthalpic pairwise interaction -- Isothermal titration calorimetry -- Glycidols -- (DMF + water) mixture; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2015.03.012
• Languages: English
• ISSNs: 0021-9614

Abstract

Graphical abstract: Highlights: Dilution enthalpies of glycidols in (DMF + water) mixtures were determined by ITC. Enthalpic pairwise interaction coefficients ( h XX ) of each compound were evaluated. The h XX values are all positive and decrease gradually with the mass fraction of DMF. The pairwise interaction of S–S pair is slightly stronger than that of R–R pair. The addition of DMF favours endothermic pairwise interactions of these compounds. Abstract: Successive dilution enthalpies ( Δ H ( m N - 1 → m N ) ) of glycidol enantiomers (R-(+)-glycidol, S-(−)-glycidol) and the racemate (R/S-(±)-glycidol) in (dimethylformamide (DMF) + water) mixtures rich in water (mass fractions of DMF, w DMF = 0 to 0.25) have been determined respectively by isothermal titration calorimetry (ITC) at T = 298.15 K. The corresponding homotactic enthalpic pairwise interaction coefficients ( h XX ) of each compound have been evaluated from the framework of McMillan–Mayer theory. Across the studied composition range of (DMF + water) mixtures the h XX values of these compounds are all positive, and decrease gradually with the mass fraction of DMF by the order h RR > h RS ≈ h MM > h SS > 0 (M represents the racemate R/S-(±)-glycidol, and h RS is the estimated value for the heterochiral pair R–S). The positive values of h XX indicate that pairwise interactions of these compounds are endothermic and unfavourable from the point of view of enthalpy. The interaction of S–S pair is considered to be slightly stronger than M–M, R–S and R–R pairs since the former absorbs less heat than the latter in pairwise interactions. The addition of cosolvent (DMF) is in favour of pairwise interactions of these compounds in the mixtures rich in water.