Thermodynamic stabilization of semiclathrate hydrates by hydrophilic group
Thermodynamic stabilization of semiclathrate hydrates by hydrophilic group
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DOI：
10.1039/c7ra01048f
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发表时间：
2017-01-01
期刊：
影响因子：
3.9
通讯作者：
Takeya, S.
中科院分区：
文献类型：
--
作者：
Muromachi, S.;Kamo, R.;Takeya, S.
在羧酸盐中引入亲水基团是修饰半笼形水合物骨架、改变水合物性质的一种方法。在这项研究中，我们报告的四正丁基铵（TBA）2-羟基丁酸（2 HB）形成的半笼状水合物的表征。此外，TBA乳酸盐和TBA 2 HB盐形成稳定的水合物晶体，其基本上具有矩形柱状形状。我们进行了平衡测量和量热法。TBA 2 HB水合物晶体的熔化温度和熔化热分别为285.3 K和177 kJ kg（-1）。与其他羧酸根阴离子的比较表明，亲水羟基取代碳链2-位氢原子比疏水甲基更能稳定水合物，这是笼形水合物中醇的情况。比较了几种半笼状水合物的相平衡数据。观察到温度依赖于客体阴离子类型的粗略趋势，但尚不清楚是否存在其他相关因素。
Introducing hydrophilic groups into carboxylates is a way to modify semiclathrate hydrate frameworks and change the properties of the hydrates. In this study, we report the characterization of semiclathrate hydrates formed by tetra-n-butylammonium (TBA) 2-hydroxybutyrate (2HB). In addition, TBA lactate and the TBA 2HB salt formed stable hydrate crystals, which basically had rectangular columnar shapes. We performed equilibrium measurements and calorimetry. The melting temperature and fusion heat of the TBA 2HB hydrate crystals were 285.3 K and 177 kJ kg(-1), respectively. A comparison with other carboxylate anions showed that the substitution of hydrogen atom at the 2-position in the carbon chain by a hydrophilic hydroxy group stabilizes the hydrates more than that by hydrophobic methyl group, which is the case for alcohols in clathrate hydrates. The phase equilibrium data for a number of semiclathrate hydrates were compared. A rough trend of temperature depending on type of guest anions was observed, but it is unclear if there are other correlating factors.