Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, Missouri 63121, USA.
J Phys Chem B. 2010 Dec 23;114(50):16959-67. doi: 10.1021/jp1090334. Epub 2010 Nov 24.
The vaporization enthalpies of 1-methyl-, 1-ethyl-, 1-phenyl-, and 1-benzylimidazole, 1-methyl- and 1-phenylpyrazole, and trans-azobenzene are evaluated by correlation-gas chromatography (C-GC) using a variety of azines and diazines as standards. The vaporization enthalpies obtained by C-GC when compared to literature values are approximately 14 kJ·mol(-1) smaller for the imidazoles and 6 kJ·mol(-1) smaller for the pyrazoles. The literature vaporization enthalpies of 1-methylpyrrole and 1-methylindole, two closely related compounds with one less nitrogen, are reproduced by C-GC. These results suggest that the magnitude of the intermolecular interactions present in 1-substituted imidazoles and pyrazoles are significantly larger than the those present in the reference compounds and greater than or equal in magnitude to the enhanced intermolecular interactions observed previously in aromatic 1,2-diazines. The vaporization enthalpy and vapor pressure of a trans-1,2-diazine, trans-azobenzene, measured by C-GC using similar standards reproduced the literature values within experimental error.
使用各种嗪和二嗪作为标准，通过相关气相色谱法（C-GC）评估了 1-甲基-、1-乙基-、1-苯基-和 1-苯甲基咪唑、1-甲基和 1-苯基吡唑以及反式偶氮苯的蒸发焓。与文献值相比，C-GC 获得的蒸发焓对于咪唑，大约小 14 kJ·mol(-1)，对于吡唑，小 6 kJ·mol(-1)。通过 C-GC 重现了具有一个氮原子的两种密切相关化合物 1-甲基吡咯和 1-甲基吲哚的文献蒸发焓。这些结果表明，1-取代咪唑和吡唑中存在的分子间相互作用的大小明显大于参考化合物中存在的相互作用，并且与先前在芳香族 1,2-二嗪中观察到的增强的分子间相互作用相当。通过 C-GC 使用类似的标准测量的反式 1,2-二嗪，反式偶氮苯的蒸发焓和蒸气压在实验误差范围内重现了文献值。
