Experimental thermochemical study of 4,5-dichloro-2-nitroaniline

Silva, Manuel A.V. Ribeiro da; Ferreira, Ana I.M.C. Lobo; Santos, Ana Filipa L.O.M.; Galvão, Tiago L. P.

doi:10.1016/j.jct.2009.05.013

Cited by 13 publications

(9 citation statements)

References 32 publications

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“…As it can be seen from the scheme in Figure 5, when the substitution of a fluorine atom occurs in the ortho position of the aromatic ring, the enthalpic effect of stabilization is less significant due to the steric effect caused by the proximity between the fluorine atom and the NO 2 group in the aromatic ring. This enthalpic effect was also noted in the other ortho-halonitrobenzene 31,32 and ortho-halonitroaniline derivatives [28][29][30] studied in this laboratory. 71 The ortho-and meta-isomers of disubstituted benzenes generally possess similar physical-chemical properties, whereas they differ from the para-isomer 72 with the exception of nitrobenzenes, in which the ortho-isomer is quite different from the meta-and para-isomers.…”

Section: R Ln (supporting

confidence: 73%

Experimental and Computational Thermodynamic Study of Three Monofluoronitrobenzene Isomers

et al. 2010

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The present work reports the thermodynamic study performed on three monofluorinated nitrobenzene derivatives by a combination of experimental techniques and computational approaches. The standard (p degrees = 0.1 MPa) molar enthalpies of formation in the liquid phase of the three isomers of fluoronitrobenzene were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by rotating bomb combustion calorimetry. The vapor pressure study of the referred compounds was done by a static method and, from the obtained results, the phase diagrams were elaborated, and the respective triple point coordinates, as well as the standard molar enthalpies of vaporization, sublimation and fusion, at T = 298.15 K, were determined. The combination of some of the referred thermodynamic parameters yielded the standard (p degrees = 0.1 MPa) molar enthalpies of formation in the gaseous phase, at T = 298.15 K, of the studied compounds: Delta(f)H(m)(o) (2-fluoronitrobenzene, g) = -(102.4 +/- 1.5) kJ x mol(-1), Delta(f)H(m)(o) (3-fluoronitrobenzene, g) = -(128.0 +/- 1.7) kJ x mol(-1), and Delta(f)H(m)(o) (4-fluoronitrobenzene, g) = -(133.9 +/- 1.4) kJ x mol(-1). Using the empirical scheme developed by Cox, values of standard molar enthalpies of formation in the gaseous phase were estimated and afterwards compared with the ones obtained experimentally, and both were interpreted in terms of the molecular structure of the compounds. The theoretically estimated gas-phase enthalpies of formation were calculated from high-level ab initio molecular orbital calculations at the G3(MP2)//B3LYP level of theory. The computed values compare very well with the experimental results obtained in this work and show that 4-fluoronitrobenzene is the most stable isomer from the thermodynamic point of view. Furthermore, this composite approach was also used to obtain information about the gas-phase basicities, proton and electron affinities and, finally, adiabatic ionization enthalpies.

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Section: R Ln (supporting

confidence: 73%

Experimental and Computational Thermodynamic Study of Three Monofluoronitrobenzene Isomers

et al. 2010

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“…The correction term of 4 kJ Á mol À1 suggested by Cox [37] due to steric destabilization, whenever two substituents are attached in adjacent carbon atoms of the ring, need to be further evaluated, since a few cases are already known in the literature in which it is necessary to include a higher value of enthalpic correction of destabilization. In particular, Ribeiro da Silva et al [4,[40][41][42][43][44] found that a large additional correction is necessary to account for the interaction between a halogen atom and the nitro group as a ortho pair of substituents in a benzenic ring.…”

Section: Discussionmentioning

confidence: 99%

Standard molar enthalpies of formation of monochloroacetophenone isomers

Silva

Amaral

2010

The Journal of Chemical Thermodynamics

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“…Steric hindrance, hydrogen bonding, inductive, and mesomeric effects are very dependent on the nature of the substituents and a large database is needed to help the understanding of these effects in the aromatic system. A systematic investigation on chloride substituted benzene derivatives has been carried out on our research group with measurements on several chlorinated benzenes derivatives [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%