The proton affinity of ammonia. A theoretical determination

Eades, Robert A.; Scanlon, Kerin; Ellenberger, Mark R.; Dixon, David A.; Marynick, Dennis S.

doi:10.1021/j100459a002

Cited by 42 publications

(7 citation statements)

References 4 publications

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“…Taking the former experimental energy as a benchmark produces the correction of roughly 5 kcal/mol to be applied to the theoretical BDEs. This correction works well for the C−Cl BDE of chlorobenzene, for which it yields the value of 93.2 kcal/mol, in good agreement with the experimental estimates (obtained from the respective Δ H 298 data by subtracting (5/2) RT ≈ 1.5 kcal/mol to account for thermal effects) of 93.6, 93.0, and 94.2 ± 2 kcal/mol 3 Dependence of the Calculated C−H and C−Cl Bond Dissociation Energies on the Parent Molecule and the Abstraction Site C−X BDE (kcal/mol) for the siteparent molecule123456 C 6 H 6 106.94106.94106.94106.94106.94106.94 C 6 H 5 Cl88.18108.45107.10107.98107.10108.45 1,2-C 6 H 4 Cl 2 86.0686.06107.96107.96107.96107.96 1,3-C 6 H 4 Cl 2 87.30109.9587.30109.37107.21109.37 1,4-C 6 H 4 Cl 2 88.24108.60108.6088.24108.60108.60 1,2,3-C 6 H 3 Cl 3 84.7584.1684.75108.57107.96108.57 1,2,4-C 6 H 3 Cl 3 86.3385.50109.4387.51109.37108.08 1,3,5-C 6 H 3 Cl 3 86.50110.7486.50110.7486.50110.74 1,2,3,4-C 6 H 2 Cl 4 84.8882.9882.9884.88108.65108.65 1,2,3,5-C 6 H 2 Cl 4 84.1784.5084.17109.9386.81109.93 1,2,4,5-C 6 H 2 Cl 4 85.8385.83108.9585.8385.83108.95 C 6 HCl 5 84.3683.1081.7683.1084.36109.26 C 6 Cl 6 81.5881.5881.5881.5881.5881.58 …”

Section: Resultssupporting

confidence: 80%

Energetics of the Homolytic C−H and C−Cl Bond Cleavages in Polychlorobenzenes: The Role of Electronic and Steric Effects

1997

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Geometries of (poly)chlorosubstituted benzenes and phenyl radicals are optimized at the BLYP/6-311G** level of theory. The radicals, which are all planar and of the σ-type, possess geometries that are influenced by both electronic and indirect steric effects. The total energies of the species under study are quantitatively analyzed with simple additive schemes involving the chlorine−chlorine and chlorine−trivalent carbon interactions. Comparisons with the few available experimental data reveal that the computed C−H and C−Cl bond dissociation energies (BDEs) of benzene and its chloro- derivatives are systematically too low by ca. 5 kcal/mol and that the experimental C−Cl BDE of 1,3-dichlorobenzene is most probably in error. The substituents are predicted to facilitate the homolytic C−Cl bond cleavage by up to 6.6 kcal/mol while making the C−H cleavage less favorable by as much as 3.8 kcal/mol. The trends in BDEs are readily accounted for by a superposition of electronic end steric effects. In all cases, the C−Cl bond cleavages are found to require significantly less energy than the C−H ones, implying kinetic control of the aryl radical formation in the course of pyrolysis of (poly)chlorobenzenes.

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Section: Resultssupporting

confidence: 80%

Energetics of the Homolytic C−H and C−Cl Bond Cleavages in Polychlorobenzenes: The Role of Electronic and Steric Effects

1997

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“…Therefore, proton affinity rather than the p K a value has been adopted as an indicator of relative basicity. 96 Proton affinity of 2-CPh and ammonia corresponds to 1410 97 and 857 kJ mol –1 , 98 respectively, at 25 °C. According to the Brønsted–Lowry theory, a base is a proton acceptor, and the higher the proton affinity, the stronger the base is.…”

Section: Resultsmentioning

confidence: 99%

On the Chemistry of Iron Oxide Supported on γ-Alumina and Silica Catalysts

et al. 2018

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Catalysts of iron oxide on γ-alumina and silica which were prepared by an incipient wetness impregnation technique have been investigated in an effort to understand how the surface chemical properties are influenced by the nature of the supports. Surprisingly, this is the first study to compare in depth the influence of the supports on physicochemical parameters such as acidity, site nuclearity, and reducibility. In this study, surface characterisation techniques including N 2 physisorption at −196 °C, ammonia temperature-programmed desorption, inductively coupled plasma optical emission spectrometry, temperature-programmed reduction with hydrogen, CO-chemisorption, scanning electron microscopy, transmission electron microscopy, and NO adsorption by in situ Fourier transform infrared spectroscopy have been performed to understand the different surface reactions occurring over the two different supports. The aim of this study is to ascertain the primary differences between these two catalysts using several catalyst characterization techniques and correlate their chemical and structural differences to their catalytic activity in the conversion of 2-chlorophenol. The results disclose a higher density of acid sites, a smaller particle size of iron oxide, stabilization of Fe(II) aluminate after reduction on the alumina surface, and finally, the formation of isolated iron cations on the surface of alumina which are notably absent on the silica-supported catalyst.

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“…OH2 by Kebarle,64 and a value of -19.9 kcal/mol, which was adjusted to -20. 6 kcal/mol by M e~t -N e r .~~ The computed enthalpy is -18.9 kcal/mol. Table I.…”

Section: Neutral Complexesmentioning

confidence: 95%

An ab initio molecular orbital study of the structures and energies of neutral and charged bimolecular complexes of NH₃ with the hydrides AH_n (A = N, O, F, P, S, and Cl)

Bene

1989

J Comput Chem

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Hartree-Fock 6-31G(d) structures for the neutral, positive ion, and negative ion bimolecular complexes of NH3 with the first-and second-row hydrides AH, (AH, = NH3,0Hz, FH, PH3, SH2, and ClH) have been determined. All of the stable neutral complexes except (NH3)2, the positive ion complexes with NH3 as the proton acceptor, and the negative ion complexes containing first-row anions exhibit conventional hydrogen bonded structures with essentially linear hydrogen bonds and directed lone pairs of electrons. The positive ion complex NH,' . . . OH2 has the dipole moment vector of H 2 0 instead of a lone pair directed along the intermolecular line, while the complexes of NH,' with SH2, FH, and C1H have structures intermediate between the lone-pair directed and dipole directed forms. The negative ion complexes containing second-row anions have nonlinear hydrogen bonds. The addition of diffuse functions on nonhydrogen atoms to the valence double-split plus polarization 6-31G(d,p) basis set usually decreases the computed stabilization energies of these complexes. Splitting d polarization functions usually destabilizes these complexes, whereas splitting p polarization functions either has no effect or leads to stabilization. The overall effect of augmenting the 6-31G(d,p) basis set with diffuse functions on nonhydrogen atoms and two sets of polarization functions is to lower computed stabilization energies. Electron correlation stabilizes all of these complexes. The second-order MZller-Plesset correlation term is the largest term and always has a stabilizing effect, whereas the third and fourth-order terms are smaller and often of opposite sign. The recommended level of theory for computing the stabilization energies of these complexes is MP2/6-31+G(2d, 2p), although MP2/6-31+G(d,p) is appropriate for the negative ion complexes.

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The proton affinity of ammonia. A theoretical determination

Cited by 42 publications

References 4 publications

Energetics of the Homolytic C−H and C−Cl Bond Cleavages in Polychlorobenzenes: The Role of Electronic and Steric Effects

Energetics of the Homolytic C−H and C−Cl Bond Cleavages in Polychlorobenzenes: The Role of Electronic and Steric Effects

On the Chemistry of Iron Oxide Supported on γ-Alumina and Silica Catalysts

An ab initio molecular orbital study of the structures and energies of neutral and charged bimolecular complexes of NH₃ with the hydrides AH_n (A = N, O, F, P, S, and Cl)

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The proton affinity of ammonia. A theoretical determination

Cited by 42 publications

References 4 publications

Energetics of the Homolytic C−H and C−Cl Bond Cleavages in Polychlorobenzenes: The Role of Electronic and Steric Effects

Energetics of the Homolytic C−H and C−Cl Bond Cleavages in Polychlorobenzenes: The Role of Electronic and Steric Effects

On the Chemistry of Iron Oxide Supported on γ-Alumina and Silica Catalysts

An ab initio molecular orbital study of the structures and energies of neutral and charged bimolecular complexes of NH3 with the hydrides AHn (A = N, O, F, P, S, and Cl)

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Product

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An ab initio molecular orbital study of the structures and energies of neutral and charged bimolecular complexes of NH₃ with the hydrides AH_n (A = N, O, F, P, S, and Cl)