Graziano Giuseppe
Dipartimento di Scienze Biologiche ed Ambientali, Università del Sannio, Via Port'Arsa 11-82100 Benevento, Italy.
Biophys Chem. 2005 Jul 1;116(2):137-44. doi: 10.1016/j.bpc.2005.03.007. Epub 2005 Apr 20.
The heat capacity change associated with the hydration of benzene is a large and positive quantity, but it is significantly smaller than that associated with the hydration of an alkane having the same accessible surface area of benzene, the corresponding alkane. This large difference merits attention and should be rationalized. This task is performed by means of the two-state Muller's model for the reorganization of H-bonds. It results that: (a) the hydration shell of both hydrocarbons consists of H-bonds that are enthalpically stronger but slightly more broken than those in bulk water; (b) the hydration shell of benzene consists, on average, of enthalpically slightly weaker H-bonds with respect to the corresponding alkane. The latter feature, due to the presence of the weak benzene-water H-bonds, is the physical cause of the large difference in the hydration heat capacity change, according to the two-state Muller's model.
与苯水合作用相关的热容变化是一个很大的正值，但它明显小于与具有与苯相同可及表面积的烷烃（相应的烷烃）水合作用相关的热容变化。这种巨大差异值得关注，应该加以解释。这项任务通过用于氢键重组的双态穆勒模型来完成。结果表明：(a) 两种烃的水合壳层都由氢键组成，这些氢键在焓上比体相水中的氢键更强，但稍微更易断裂；(b) 相对于相应的烷烃，苯的水合壳层平均由焓上稍弱的氢键组成。根据双态穆勒模型，由于存在弱的苯 - 水氢键，后一个特征是水合热容变化存在巨大差异的物理原因。
