焓-熵补偿在芳香化合物位置异构体保留机理研究中的应用

The Use of Enthalpy Entropy Compensation in the Study of Retention Mechanism of Aromatic Positional Isomers

系统地研究了二氯苯等６种芳香化合物在ＰＳＯ－１１－１８Ｃ６等９支冠醚聚硅氧烷和ＯＶ－１７０１，Ｃａｒｂｏｗａｘ－２０Ｍ毛细管色谱柱上分离过程的热力学参数。利用超热力学方法，考察了这些芳香化合物及其异构体在各种色谱柱上分离过程的焓－熵补偿现象。论述了各种冠醚固定液对芳香化合物的保留机理以及取代基在苯环上位置的变化对溶质与冠醚固定液之间的相互作用参数的影响。

In this paper, the thermodynamic parameters of the separation process of six groups of aromatic positional isomers on nine crown ether polysiloxane, OV 1701 and Carbowax 20M capillary chromatographic columns have been investigated systematically. The Gibbs free energies for every compound at harmonic mean temperature, calculated were given. The enthalpy entropy compensation effect of these chromatographic process was examined by using of Krugs ANOVA method. In the light of the axiom of extrathermodynamic relationship, the retention mechanisms of these aromatic compounds on each crown ether stationary phase have been expounded. We come to conclusion that, as a whole, the separation of various aromatic isomers on crown ether stationary phase is governed by multiple retention mechanisms, but the separation of some groups of aromatic isomer on the same crown ether phase can be led to single interaction mechanism since the phenomena of enthalpy entropy compensation is observed. It may be that a kind of interaction parameter, which varies with the configuration of solutes, plays the main role in retention process of these isomers.