Gas-Phase Thermodynamic Properties of Dichlorophenols Determined from Density Functional Theory Calculations

Gomes, José R. B.; Silva, Manuel A. V. Ribeiro Da

doi:10.1021/jp026707k

Cited by 43 publications

(47 citation statements)

References 30 publications

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“…The B3LYP method comprises an exchange-correlation functional that mixes the non-local Fock exchange with the gradient-corrected form of Becke 23 and adds the correlation functional proposed by Lee et al 26 The use of the B3LYP method is known to be an excellent computational choice both to obtain geometric and thermodynamic data. [27][28][29] In fact, the three a, b and c parameters in this hybrid approach were determined by fitting to experimental thermochemical data which include atomization energies, ionization energies, proton affinities and atomic energies of a large set of molecules. 23 Very recently, several different thermochemical properties have been computed at the B3LYP level of theory and the results obtained compare excellently with available experimental data.…”

Section: Computationals Detailsmentioning

confidence: 99%

“…23 Very recently, several different thermochemical properties have been computed at the B3LYP level of theory and the results obtained compare excellently with available experimental data. 29,[30][31][32][33][34][35][36] In the DFT calculations, the geometry optimization runs were performed without symmetry constraints for all compounds considered and the atomic electronic density of all atoms was described by the standard 6-31CG(d) basis set. The calculation of frequencies was performed to ensure that a minimum is located and also to correct total energies by including the Zero-Point Energies, ZPE, as well as translational (H T ), rotational (H R ) and vibrational (H V ) contributions to the enthalpy at TZ298.15 K. Then, a single-point energy calculation (E 0 ) was performed at the B3LYP/6-311CG(2d,2p) level of theory on the 6-31CG(d) optimized geometries.…”

Section: Computationals Detailsmentioning

confidence: 99%

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Gas-phase acidity of sulfonamides: implications for reactivity and prodrug design

Gomes

2005

Tetrahedron

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Abstract-A computational study at the density functional theory level was performed on bioactive and model sulfonamides with the aim of determining the factors affecting the acidity of the sulfonamido group. The effects of introducing different substituents at either the para-aryl or the N 1 -sulfonamide positions were independently analyzed. A linear correlation was found between sulfonamide acidity and the Hammett constants or charge of the SO 2 group of substituents at the para-aryl position. Most N 1 -substituents were taken from bacteriostatic sulfonamide structures and presented a more complex behavior, possibly due to a conjugation of steric and electronic factors. In the latter situation, sulfonamide acidity and the charge of the SO 2 group were not linearly correlated. Interestingly, the acidity of the sulfonamido group was found to be correlated with the reactivity of sulfa drugs towards acylating agents. The implications for the design of suitable sulfonamide prodrugs are discussed. q

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Section: Computationals Detailsmentioning

confidence: 99%

Section: Computationals Detailsmentioning

confidence: 99%

Gas-phase acidity of sulfonamides: implications for reactivity and prodrug design

Gomes

2005

Tetrahedron

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“…32 Vibrational frequencies have also been calculated at the same level of theory used in the optimization procedure. This is used to correct the computed electronic energy values for Zero-Point Energies, ZPE, as well as translational, rotational, and vibrational contributions to the enthalpy at T ¼ 298:15 K. The above mentioned exchange-correlation functional was chosen since, in previous works devoted to the thermochemistry of halogenated anilines, 10,[33][34][35] it was found that the use of this functional permitted estimation of accurate gas-phase enthalpies of formation for this class of compounds. Atoms in Molecules calculations have been performed by means of the TOPMOD code.…”

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confidence: 99%

“…45,46 The presence of halogen-hydrogen bonds in 2-chloro and 2-bromoanilines was determined by the use of a topological analysis using wave functions resulting from B3LYP/6-31G(d) calculations, I enable direct comparison with previous results for com- pounds containing weak hydrogen bonds 47,48 available in the literature, that were computed using the same theoretical approach. A critical point appears in the region between the halogen and the amino group's hydrogen atom with the following parameters: in 2-chloroaniline, electron density () = 0.013, laplacian of the electron density (r The energies of all bromoanilines, and those of aniline, benzene, and bromobenzene, which were all corrected for T ¼ 298:15 K, were used to compute the energy of the reaction described by the following equation: 33 the DFT results for the dibromoanilines given in Table 8 must be used with caution. An uncertainty of AE6 kJ mol À1 is proposed.…”

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confidence: 99%

Experimental and Computational Study on the Thermochemistry of Bromoanilines

Silva¹,

Ferreira²,

Gomes³

2006

Bulletin of the Chemical Society of Japan

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The standard (p ¼ 0:1 MPa) molar enthalpies of formation of 2-, 3-, and 4-bromoaniline, 2,4-, 2,5-, and 2,6-dibromoaniline, and 2,4,6-tribromoaniline were derived from the standard molar enthalpies of combustion, in oxygen, which yields CO 2 (g), N 2 (g), and HBr Á 600H 2 O(l), at T ¼ 298:15 K, measured by using rotating-bomb calorimetry.The standard molar enthalpies of sublimation, or vaporization, of these compounds at T ¼ 298:15 K were measured by using Calvet microcalorimetry, and so their standard molar enthalpies of formation in the gaseous state were derived. The enthalpies of fusion of the solid compounds were determined by DSC. The gas-phase enthalpies of formation were also estimated by density functional theory calculations performed at the BP86/6-31+G Ã level. As a result it is confirmed that thermodynamic data is consistent with intramolecular N-HÁÁÁBr hydrogen bonding.Aromatic amines are of great importance in biological and material sciences as well as in pharmaceutical and chemical industries. Halogenated anilines have gained the most focus of all of the aromatic amines, due to their high toxicity and wide uses. For example, they may be used as reagents or precursors for synthesizing organic dyes, in pigments, in agricultural agents, in pharmaceuticals and in the rubber industries.1,2 Haloanilines are frequently found in both effluents of waste water treatment plants and surface water, due to chemical degradation or biotransformation of pesticides and herbicides, or due to accidental spills and illegal release of industrial and municipal wastewater. 3 These compounds have been determined to induce several kinds of toxicity, like methemoglobinemia, splenotoxicity, hepatotoxicity, and nephrotoxicity. 2,4Because of their stability in the presence of air and humidity, and potentially attractive economics, 5,6 aniline and haloanilines have been also used in the synthesis of conducting polymers with applications in rechargeable batteries, electromagnetic interference shielding, electrochromic display devices, sensors, and electrocatalysis.The current work presents the results of calorimetric and computational thermochemistry studies on bromoanilines. The experimental investigation includes the determination of the standard massic energies of combustion in oxygen at T ¼ 298:15 K of the different bromoanilines using a rotatingbomb combustion calorimeter, from which the values of the standard molar enthalpies of formation in the condensed phase were derived. The determination of the standard molar enthalpies of sublimation or vaporization at T ¼ 298:15 K was done by using Calvet microcalorimetry with the high-temperature vacuum sublimation technique; these values allowed the derivation of the standard molar enthalpies of formation, in the gaseous state, of 2-, 3-, and 4-bromoaniline, 2,4-, 2,5-, and 2,6-dibromoaniline, and 2,4,6-tribromoaniline, which were compared with values estimated by the Cox scheme 7 and those obtained by density functional theory calculations. Experimental Materials.The three mono...

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“…39 The present approach is known to generate very good optimized structures and also accurate thermochemical data. 40 These calculations have been performed using the GAMESS-US package.…”

Section: Computational Detailsmentioning

confidence: 99%

Amino acids as selective sulfonamide acylating agents

Gomes

Rodrigues

et al. 2003

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Abstract-Acylation of antimalarial and bacteriostatic sulfonamides with N-protected amino acids and peptides was carried out using standard peptide coupling methods. These acylation reactions are regioselective for the N 4 nitrogen atom of diazine-containing sulfonamides. In contrast, only N 1 coupling was found for sulfisoxazole, an isoxazole-based sulfonamide. Computational studies suggest that a combination of geometrical, thermodynamic and electronic factors are responsible for the different reactivities reported. q

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Gas-Phase Thermodynamic Properties of Dichlorophenols Determined from Density Functional Theory Calculations

Cited by 43 publications

References 30 publications

Gas-phase acidity of sulfonamides: implications for reactivity and prodrug design

Gas-phase acidity of sulfonamides: implications for reactivity and prodrug design

Experimental and Computational Study on the Thermochemistry of Bromoanilines

Amino acids as selective sulfonamide acylating agents

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