Combined experimental and computational thermochemistry of isomers of chloronitroanilines

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• 作者：Manuel A.V. Ribeiro da Silva ; Luí ; s M. Spencer S. Lima ; Ana Rita G. Moreno ; Ana I.M.C.L. Ferreira ; José ; R.B. Gomes
• 关键词：Enthalpy of combustion ; Enthalpy of sublimation ; Enthalpy of formation ; Combustion calorimetry ; Calvet microcalorimetry ; Knudsen effusion ; Vapour pressure ; Entropy of sublimation ; Gibbs free energy of sublimation ; Cox scheme ; Computational thermochemistry
• 刊名：Journal of Chemical Thermodynamics
• 出版年：2008
• 出版时间：February 2008
• 年：2008
• 卷：40
• 期：2
• 页码：155-165
• 全文大小：202 K

文摘

The standard (p^{alt=""ring operator"" border=0>} = 0.1 MPa) molar enthalpies of formation, at T = 298.15 K, of 4-chloro-3-nitroaniline and 5-chloro-2-nitroaniline, in the condensed phase, were derived from their standard molar energies of combustion, in oxygen, to yield CO₂(g), N₂(g), and HCl · 600H₂O(l), measured by rotating bomb combustion calorimetry. From the temperature dependence of the vapour pressures of these compounds, measured by the Knudsen effusion technique, their standard molar enthalpies of sublimation, at T = 298.15 K, were derived by means of the Clausius–Clapeyron equation. The Calvet microcalorimetry was also used to measure the standard molar enthalpies of sublimation of these compounds, at T = 298.15 K. The combination of the standard molar enthalpies of formation in the condensed phases and the standard molar enthalpies of sublimation yielded the standard molar enthalpies of formation in the gaseous phase at T = 298.15 K for each isomer. Further, the standard (p^{alt=""ring operator"" border=0>} = 0.1 MPa) molar enthalpies, entropies and Gibbs free energies of sublimation, at T = 298.15 K, were also derived.

The standard molar enthalpies of formation, in the gaseous phase of all the chloronitroaniline isomers were also estimated by the Cox scheme and by the use of computational thermochemistry and compared with the available experimental values.