Thermodynamics of Mixing Primary Alkanolamines with Water.
Thermodynamics of Mixing Primary Alkanolamines with Water.
复制标题
伯烷醇胺与水混合的热力学。
DOI：
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发表时间：
2018
影响因子：
3.3
通讯作者：
P. Jedlovszky
中科院分区：
文献类型：
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作者：
A. Idrissi;P. Jedlovszky
通过广泛的计算机模拟和热力学集成，研究了单乙醇胺、单异丙醇胺、2-氨基-丙-1-醇、2-氨基-2-丁醇、2-氨基-2-甲基-丙-1-醇、1-氨基-2-甲基-丙-2-醇和1-氨基-丁醇这七种最简单的烷烃分子与水混合的体积、能量、熵和亥姆霍兹自由能。为了验证结果与力场的相关性，我们使用了两种常用的水模型（SPC/E和TIP4P）重复所有计算。结果表明，烷醇胺与水混合的热力学在很大程度上与烷醇胺分子的类型无关。根据实验已知的烷醇胺分子与水的完全混溶性，发现在每种组成中所有烷醇胺的混合亥姆霍兹自由能都是负的。混合时发生的这种自由能下降显然是能量来源，因为混合的能量在整个组成范围内总是为负的，而混合的熵也是负的，直到高烷醇胺摩尔分数。所得结果表明，烷醇胺与水形成的氢键平均比两个水分子形成的氢键更强，并且它们通过其侧链的疏水水合作用和强氢键作用诱导水合水分子的某种排序。
The volume, energy, entropy, and Helmholtz free energy of mixing of the seven simplest primary alkanolamine molecules, i.e., monoethanolamine, monoisopropanolamine, 2-amino-propan-1-ol, 2-amino-butan-1-ol, 2-amino-2-methyl-propan-1-ol, 1-amino-2-methyl-propan-2-ol, and 1-amino-butan-2-ol, with water is investigated by extensive computer simulations and thermodynamic integration. To check the force field dependence of the results, all calculations are repeated with two commonly used water models, namely, SPC/E and TIP4P. The obtained results show that the thermodynamics of mixing of alkanolamines and water is largely independent from the type of the alkanolamine molecule. The Helmholtz free energy of mixing is found to be negative for all alkanolamines at every composition, in accordance with the experimentally known full miscibility of these molecules and water. This free energy decrease occurring upon mixing is found to be clearly of energetic origin, as the energy of mixing always turns out to be negative in the entire composition range, while the entropy of mixing is also negative up to high alkanolamine mole fractions. The obtained results suggest that alkanolamines form, on average, stronger hydrogen bonds with water than what is formed by two water molecules, and they induce some ordering of the hydrating water molecules both through the hydrophobic hydration of their side chains and through the strong hydrogen bonding.