A Combined Experimental and Computational Thermodynamic Study of Difluoronitrobenzene Isomers

• Type: Article in International Scientific Journal
• Date: 2010

Authors

Ribeiro Da Silva, MAV (Author) FCUP; Monte, MJS (Author) FCUP; Lobo Ferreira, AIMC (Author) FCUP; Oliveira, JASA (Author) Other; Cimas, A (Author) Other

Journal

Title: Journal of Physical Chemistry B

Vol. 114 No. 1

Pages: 12914-12925

ISSN: 1520-6106

Publisher: American Chemical Society

Indexing

ISI Web of Knowledge - 9 Citations

Scopus - 10 Citations

Scientific classification

CORDIS: Physical sciences > Chemistry > Physical chemistry

Other information

Authenticus ID: P-003-1WM

DOI: 10.1021/jp105885

Abstract (EN): This work reports the experiunental and computational thermochemical study performed on time dilluorinated nitrobenzene isomers: 2,4-dilluoronitrobenzene (2,4-DFNB), 2,5-di fluoronitrobenzene (2.5-DFN13), and 3,4difluoronitrobenzene (3.4-DFNI3). The standard (p(o) = 0.1 WIN) molar enthalpies of formation in the liquid phase of these compounds were derived from the standard molar energies of combustion, in oxygen, at 7' = 298.15 K, measured by rotating bomb combustion ealorimetry. A static method was used to perform the vapor pressure study of the referred compounds allowing the construction of the phase diagrams and determination of the respective triple point coordinates, as well as the standard molar enthalpies of vaporization, sublimation, and fusion for two of the isomers (2,4-DFN13 and 3,4-DFN113). For 2,5-dilluoronitrobenzene, only liquid vapor pressures were measured enabling the determination of the standard molar enthalpies of vaporization. Combining the thermodynamic parameters of the compounds studied, the following standard (p(o) = 0.1 MN) molar enthalpies of formation in the gaseous phase, at T = 298.15 K, were derived: Delta(f)H(m)(o)(2,4-DFNB, g) = (296.3 +/- 1.8) kJ.mol(-1), Delta(f)H(m)(o)(2,5-DFNB, g) = (288.2 +/- 2.1) kJ.mol(-1), and Delta(f)H(m)(o)(3,4-DFNB, g) = -(302.4 +/- 2.1) kJ.mol(-1). Using the empirical scheme developed by Cox, several approaches were evaluated in order to identify the best method for estimating the standard molar gas phase enthalpies of.formation of these compounds. The estimated values were compared to the ones obtained experirrientally, and the approach providing the best comparison with experiment was used to estimate the thermodynamic behavior of the other difluorinated nitrobenzene isomers not included in this study. Additionally, the enthalpies of formation of these compounds along with the enthalpies of formation of the other isomers not studied experimentally, i.e., 2,3-DFNB, 2,6-DFNB, and 3,5-DFNB, were estimated using the composite G3MP2B3 approach together with adequate gas-phase working reactions. Furthermore, we also used this computational approach to calculate the gas-phase hasicities, proton and electron affinities, and, finally, adiabatic ionization enthalpies.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12