García-Castro Miguel A, Amador Patricia, Hernández-Pérez Julio M, Medina-Favela Adrián E, Flores Henoc
Facultad de Ciencias Químicas de la Benemérita Universidad Autónoma de Puebla , 14 Sur y Avenida San Claudio, C.P. 72570, Puebla Pue, México.
J Phys Chem A. 2014 May 29;118(21):3820-3826. doi: 10.1021/jp5003929. Epub 2014 May 16.
In order to understand the influence that the position of the nitro group on the aromatic ring has on the relative stability of two isomers, the standard enthalpies of formation of 3- and 4-nitrophthalic anhydride in the gaseous phase, at T = 298.15 K, were obtained by experimental thermochemistry and theoretical studies. The standard enthalpies of formation in the crystalline phase, at T = 298.15 K, were obtained by combustion calorimetry and the enthalpies of sublimation by the Knudsen method. For the theoretical calculations, a standard ab initio molecular orbital method at the G3 level was used. The enthalpies of formation in the gaseous phase were obtained from atomization and isodesmic reactions. A theoretical study of the molecular and electronic structures of these compounds was also performed. Differences of -9.7 kJ·mol, for 3-nitrophthalic anhydride, and -2.6 kJ·mol for 4-nitrophthalic anhydride, were found from a comparison between our theoretical and experimental results.
为了理解芳香环上硝基的位置对两种异构体相对稳定性的影响，通过实验热化学和理论研究获得了3 - 和4 - 硝基邻苯二甲酸酐在气相中（T = 298.15 K）的标准生成焓。通过燃烧量热法获得了在T = 298.15 K时结晶相的标准生成焓，并通过克努森法获得了升华焓。对于理论计算，使用了G3水平的标准从头算分子轨道方法。通过原子化和等键反应获得了气相中的生成焓。还对这些化合物的分子和电子结构进行了理论研究。通过比较我们的理论和实验结果发现，3 - 硝基邻苯二甲酸酐的差异为 - 9.7 kJ·mol，4 - 硝基邻苯二甲酸酐的差异为 - 2.6 kJ·mol。
