Enthalpies of Dilution of Penicillamines in N,N-Dimethylformamide + Water Mixtures at 298.15 K

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• 作者：Wei-Na Cheng ; Xin-Gen Hu ; Zhao-Peng Jia ; Zheng Guo ; Hong-Yu Liang ; Guoyong Fang
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2013
• 出版时间：January 10, 2013
• 年：2013
• 卷：58
• 期：1
• 页码：55-63
• 全文大小：264K
• 年卷期：v.58,no.1(January 10, 2013)
• ISSN：1520-5134

文摘

Dilution enthalpies of two penicillamine enantiomers, namely, d-penicillamine, l-penicillamine, and their racemate d,l-penicillamine, in N,N-dimethylformamide (DMF) + water mixtures of various compositions have been determined at 298.15 K respectively, using an isothermal titration calorimeter (MicroCal ITC200). According to the McMillan鈥揗ayer theory, homochiral enthalpic pairwise interaction coefficients (h_XX) of the three penicillamines in DMF + water mixtures of different mass fractions (w_DMF = 0 to 0.3) have been calculated regressively. It is found that h_XX coefficients of each enantiomer and their racemate change increasingly with w_DMF to the maxima at w_DMF = 0.20 and then decrease relatively rapidly, which follows the order h_LL > h_DD 鈮?h_RR > 0 (R represents the racemate mixture of penicillamine). The results are discussed from the point of view of competitive equilibrium between hydrophobic and hydrophilic interactions in solutions.