Abstraction of the Hydrogen Atom of Methane by Iron−Oxo Species:  The Concerted Reaction Path Is Energetically More Favorable

1998 ◽  
Vol 17 (13) ◽  
pp. 2825-2831 ◽  
Author(s):  
Kazunari Yoshizawa ◽  
Yoshihito Shiota ◽  
Tokio Yamabe
Keyword(s):  
Hydrogen Atom ◽  
Reaction Path ◽  
Concerted Reaction

scholarly journals Reaction of the hydrogen atom with nitrous oxide in aqueous solution – pulse radiolysis and theoretical study

RSC Advances ◽  
2017 ◽  
Vol 7 (15) ◽  
pp. 8800-8807 ◽  
Author(s):  
Lukasz Kazmierczak ◽  
Dorota Swiatla-Wojcik ◽  
Marian Wolszczak
Keyword(s):  
Aqueous Solution ◽  
Nitrous Oxide ◽  
Hydrogen Atom ◽  
Pulse Radiolysis ◽  
Theoretical Study ◽  
Reaction Path ◽  
Direct Reaction ◽  
Solvent Models

The UB3LYP/cc-pVTZ computations using three solvent models and pulse radiolysis measurements show predominance of the direct reaction path via [H–ONN]‡ in aqueous solution.

DECOMPOSITION OF SiH4 ON THE SA TYPE STEPPED Si(100) SURFACE

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1401-1407 ◽  
Author(s):  
ŞENAY KATIRCIOĞlu ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Reaction Path ◽  
Density Functional Theory Method ◽  
Dissociative Adsorption ◽  
Theory Method ◽  
Functional Theory ◽  
Initial Stage ◽  
The Density Functional Theory

The density functional theory method is used to explore the mechanism of dissociative adsorption of silane (SiH4) on the SA type stepped Si(100) surface. Two reaction paths are described that produce silyl (SiH3) and hydrogen atom fragments adsorbed on the dimer bonds present on each terrace. It has been found that the initial stage of the dissociation of SiH4 on the SA type stepped Si(100) surface shows similarity to the dissociation of SiH4 on the flat Si(100) surface; SiH3 and hydrogen fragments bond to the Si dimer atoms by following the first reaction path.

Novel [2 + 1] Concerted Reaction Path for Disilacyclobutenes with Acetylene

2014 ◽  
Vol 33 (3) ◽  
pp. 763-770 ◽  
Author(s):  
Yoshihiro Hayashi ◽  
Takafumi Natsumeda ◽  
Shun Otsu ◽  
Ryo Yamada ◽  
Akinobu Naka ◽  
...  
Keyword(s):  
Reaction Path ◽  
Concerted Reaction

DECOMPOSITION OF CH4 ON SA TYPE STEPPED Si(100) SURFACE

2002 ◽  
Vol 16 (16) ◽  
pp. 2191-2200
Author(s):  
ŞENAY KATIRCIOĞLU
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Reaction Path ◽  
Density Functional Theory Method ◽  
Dissociative Adsorption ◽  
Theory Method ◽  
Functional Theory ◽  
Initial Stage ◽  
Adsorption Of Methane

Density functional theory method is used to explore the mechanism of dissociative adsorption of methane ( CH 4) on S A type stepped Si(100) surface. Two reaction paths are described that produce CH 3 and hydrogen atom fragments adsorbed on the dimer bonds present on each terraces. It has been found that, in the initial stage of the carbonization of stepped Si(100) surface, the CH 3 and H fragments bound to the Si dimer atoms by following the first reaction path.

Topological aspects of chemical reactivity. Reorganisation of electron density in allowed and forbidden reactions

1985 ◽  
Vol 50 (5) ◽  
pp. 1121-1132 ◽  
Author(s):  
Robert Ponec
Keyword(s):  
Critical Point ◽  
Electron Density ◽  
Electron Pair ◽  
Reaction Path ◽  
Chemical Reactivity ◽  
Point Of View ◽  
The Other ◽  
Selection Rules ◽  
Electron Pairing ◽  
Concerted Reaction

The selection rules in chemical reactivity are discussed from the point of view of the differences in the character of the electron density reorganisation in allowed and forbidden reactions. It was shown that the allowed reactions are characterized by the maximum conservation of electron pairing along the whole reaction path. On the other hand for the forbidden reactions a critical point lies on the corresponding concerted reaction coordinate in which one electron pair is completely splitted.

scholarly journals Hydrogen atom transfer in the photochemical isomerization of hydrazones of 1,2,4-oxadiazole derivatives

2021 ◽  
Author(s):  
Maurizio D’Auria
Keyword(s):  
Hydrogen Atom ◽  
Nitrogen Atom ◽  
Ring Opening ◽  
Singlet State ◽  
Hydrogen Atom Transfer ◽  
Atom Transfer ◽  
Excited Singlet ◽  
Photochemical Isomerization ◽  
Oxadiazole Derivatives ◽  
Concerted Reaction

AbstractDFT calculations on the photoisomerization of hydrazones of 1,2,4-oxadiazole derivatives to 1,2,5-triazoles have been performed showing that the reaction occurred through the first excited singlet state. The Z isomer gave the reaction through a hydrogen atom transfer of the hydrazonic nitrogen atom to the nitrogen atom in four position on the oxadiazole ring. In this case, the isomerization was a concerted reaction. The E isomer could undergo the same reaction. However, it could not be a concerted reaction but required the presence of a ring opening intermediate.

scholarly journals Diverting Radical-Anionic C-H Amidation to a C-N/C-O Cascade for the Construction of Hydroxyisoindolines from Unprotected Amides

2019 ◽  
Author(s):  
Quintin Elliott ◽  
Gabriel dos Passos Gomes ◽  
Christopher Evoniuk ◽  
Igor Alabugin
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Molecular Oxygen ◽  
Radical Anion ◽  
Reaction Path ◽  
Hydrogen Atom Transfer ◽  
Second Stage ◽  
Ch Activation ◽  
Computational Data ◽  
Extra Electron

<p>An intramolecular C(sp<sup>3</sup>)-H amidation proceeds in the presence of <i>t</i>-BuOK, molecular oxygen, and DMF. The success of this reaction hinges on the deprotonation of a mildly acidic N-H bond and selective radical activation of a benzylic C(sp<sup>3</sup>)-H bond towards hydrogen atom transfer (HAT)<i>. </i>DFT calculations suggest a thermodynamically favorable sequence of steps mediated by the generation of a radical-anion intermediate. As this intermediate starts to form a two-centered/three-electron (<i>2c,3e)</i>C-N bond, the extra electron is “ejected” into the π*-orbital of the aromatic core. The resulting cyclic radical-anion is readily oxidized by molecular oxygen to forge the C-N bond of the product. The transformation of a relatively weak reductant into a stronger reductant (i.e., “reductant upconversion”) allows one to use mild oxidants such as molecular oxygen. In contrast, the second stage of NH/CH activation forms a highly stabilized radical-anion intermediate incapable of electron transfer to molecular oxygen. Hence, the oxidation is impossible and an alternative reaction path opens via coupling between the radical anion intermediate and either superoxide or hydroperoxide radical. The hydroperoxide intermediate transforms into the final hydroxyisoindoline products under basic conditions. The use of TEMPO as an additive was found to activate less reactive amides. The combination of experimental and computational data outlines a conceptually new mechanism for the conversion of unprotected amides into hydroxyisoindolines proceeding as a sequence of C-H amidation and C-H oxidation.</p>

scholarly journals Diverting Radical-Anionic C-H Amidation to a C-N/C-O Cascade for the Construction of Hydroxyisoindolines from Unprotected Amides

2019 ◽  
Author(s):  
Quintin Elliott ◽  
Gabriel dos Passos Gomes ◽  
Christopher Evoniuk ◽  
Igor Alabugin
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Molecular Oxygen ◽  
Radical Anion ◽  
Reaction Path ◽  
Hydrogen Atom Transfer ◽  
Second Stage ◽  
Ch Activation ◽  
Computational Data ◽  
Extra Electron

<p>An intramolecular C(sp<sup>3</sup>)-H amidation proceeds in the presence of <i>t</i>-BuOK, molecular oxygen, and DMF. The success of this reaction hinges on the deprotonation of a mildly acidic N-H bond and selective radical activation of a benzylic C(sp<sup>3</sup>)-H bond towards hydrogen atom transfer (HAT)<i>. </i>DFT calculations suggest a thermodynamically favorable sequence of steps mediated by the generation of a radical-anion intermediate. As this intermediate starts to form a two-centered/three-electron (<i>2c,3e)</i>C-N bond, the extra electron is “ejected” into the π*-orbital of the aromatic core. The resulting cyclic radical-anion is readily oxidized by molecular oxygen to forge the C-N bond of the product. The transformation of a relatively weak reductant into a stronger reductant (i.e., “reductant upconversion”) allows one to use mild oxidants such as molecular oxygen. In contrast, the second stage of NH/CH activation forms a highly stabilized radical-anion intermediate incapable of electron transfer to molecular oxygen. Hence, the oxidation is impossible and an alternative reaction path opens via coupling between the radical anion intermediate and either superoxide or hydroperoxide radical. The hydroperoxide intermediate transforms into the final hydroxyisoindoline products under basic conditions. The use of TEMPO as an additive was found to activate less reactive amides. The combination of experimental and computational data outlines a conceptually new mechanism for the conversion of unprotected amides into hydroxyisoindolines proceeding as a sequence of C-H amidation and C-H oxidation.</p>

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