Thermochemistry of 2- and 3-Acetylthiophenes: Calorimetric and Computational Study

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• 作者：Marí ; a Victoria Roux ; Manuel Temprado ; Pilar Jim&eacute ; nez ; Rafael Notario ; James S. Chickos ; Ana Filipa L. O. M. Santos ; Manuel A. V. Ribeiro da Silva
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：November 1, 2007
• 年：2007
• 卷：111
• 期：43
• 页码：11084 - 11092
• 全文大小：139K
• 年卷期：v.111,no.43(November 1, 2007)
• ISSN：1520-5215

文摘

The relative stabilities of 2- and 3-acetylthiophenes have been evaluated by experimental thermochemistryand the results compared to high-level ab initio calculations. The enthalpies of combustion, vaporization, andsublimation were measured by rotating-bomb combustion calorimetry, Calvet microcalorimetry, correlationgas chromatography, and Knudsen effusion techniques and the gas-phase enthalpies of formation, at T =298.15 K, were determined. Standard ab initio molecular orbital calculations at the G2 and G3 levels wereperformed, and a theoretical study on the molecular and electronic structures of the compounds studied hasbeen conducted. Calculated enthalpies of formation using atomization and isodesmic reactions are comparedwith the experimental data. Experimental and theoretical results show that 2-acetylthiophene is thermodynamically more stable than the 3-isomer. A comparison of the substituent effect of the acetyl group in benzeneand thiophene rings has been carried out.