Partial molar volumes of molecules of arbitrary shape and the effect of hydrogen bonding with water
Partial molar volumes of molecules of arbitrary shape and the effect of hydrogen bonding with water
复制标题
任意形状分子的偏摩尔体积以及与水氢键的影响
DOI：
10.1007/bf00649565
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发表时间：
1992
影响因子：
1.2
通讯作者：
D. P. Kharakoz
中科院分区：
文献类型：
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作者：
D. P. Kharakoz
本文对描述水溶液偏摩尔体积的方法进行了评述，并提出了一种新的计算偏摩尔体积的方法，使人们能够分析任意形状的有机分子。定量分析了不同极性基团与水形成氢键的体积效应。该模型基于这样的假设，即热(或空)体积可以几何地考虑为邻近分子表面的一层空空间，该层的厚度与表面曲率的局部差异无关。这个假设使得在么正方法的框架内描述任意形状的分子的部分体积成为可能。通过比较实验测得的极性分子的偏摩尔体积和计算出的相同形状的参考非极性分子的偏摩尔体积，估算了极性基团与水相互作用产生的体积效应。溶液中形成一个氢键的体积效应为2.2cm2·−。利用此值分析了极性基团水合的化学计量比。结果发现，−O−，−CO−(在酮中)和≥N基团与水形成一个氢键(在醚中，这种键很弱)。−OH(在大多数情况下)、−CHO(在醛中)和>；NH基团与水形成两个氢键。氨基−NH_2与水形成三个氢键。
The paper presents a critical review of approaches for the description of partial molar volumes of aqueous solutions and offers a new procedure for calculation of these volumes which allows one to analyze organic molecules of arbitrary shape. Quantitative analysis of the volume effect of hydrogen bonding of different polar groups with water is given. The model is based on the assumption that thermal (or empty) volume may be cosidered geometrically as a layer of empty space adjacent to the molecule surface with the thickness of the layer being independent of local differences in surface curvature. The assumption makes it possible to describe partial volumes of molecules of arbitrary shape within the framework of a unitary approach. The estimation of the volume effects resulting from the interaction of polar groups with water was made by comparing the experimental partial molar volume of a polar molecule with the calculated partial molar volume of a hypothetical reference nonpolar molecule of the same shape. The volume effect of formation of one hydrogen bond in solution was found to be −2.2 cm2-mol. Using this value the stoichiometry of hydration of polar groups was analyzed. As a result, the −O−, −CO− (in ketones) and ≥N groups were found to form one hydrogen bond with water (in ethers, this bond is weak). The −OH (in most cases), −CHO (in aldehydes), and >NH groups form two hydrogen bonds with water. The amino group −NH2 forms three hydrogen bonds with water.