Chemical equilibrium of formaldehyde and methanediol in hot water: Free-energy analysis of the solvent effect
Chemical equilibrium of formaldehyde and methanediol in hot water: Free-energy analysis of the solvent effect
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DOI：
10.1016/j.molliq.2006.12.002
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发表时间：
2007-05-15
影响因子：
6
通讯作者：
Takahashi, Hideaki
中科院分区：
文献类型：
--
作者：
Matubayasi, Nobuyuki;Morooka, Saiko;Takahashi, Hideaki
本文计算研究了甲醛（HCHO）及其水合形式甲烷（CH2（OH）（2））在溶剂水中的化学平衡。利用能量表示法，计算了甲烷的溶剂化自由能随溶剂密度和温度的变化，并在较宽的热力学条件下讨论了溶剂效应.它示出，与以前报道的趋势一致，甲烷的溶剂化自由能强烈地依赖于温度，并且在固定的超临界温度下对密度变化不是单调的。在甲醛水合反应中，溶剂水在较低温度下更有利于甲烷化。在不存在溶剂的情况下，甲烷的形成是不利的，并且在高于200摄氏度的热水中的甲醛主要以未水合的形式存在。(c)2006 Elsevier B.V.保留所有权利。
The chemical equilibrium between formaldehyde (HCHO) and its hydrated form, methanediol (CH2(OH)(2)), is computationally investigated in solvent water. Using the method of energy representation, the solvation free energy of methanediol is evaluated as a function of (solvent) density and temperature, and the solvent effect is discussed over a wide range of thermodynamic conditions. It is shown, in agreement with the previously reported tendency, that the solvation free energy of methanediol depends strongly on the temperature and is not monotonic against the density variation at a fixed supercritical temperature. In the hydration reaction of formaldehyde, the solvent water favors methanediol more at a lower temperature. The formation of methanediol is unfavored in the absence of solvent, and formaldehyde in hot water above similar to 200 degrees C is predominantly present in the unhydrated form. (c) 2006 Elsevier B.V. All rights reserved.