.gamma.- vs. .delta.-Hydrogen abstraction in the photochemistry of .beta.-alkoxy ketones. Overlooked reaction of hydroxy biradicals

1971 ◽  
Vol 93 (19) ◽  
pp. 4958-4959 ◽  
Author(s):  
Peter J. Wagner ◽  
Richard G. Zepp
Keyword(s):  
Hydrogen Abstraction ◽  
Hydroxy Biradicals

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

A Reinvestigation of the Deceptively Simple Reaction of Toluene with ●OH, and the Fate of the Benzyl Radical. I. a Combined Thermodynamic and Kinetic Study on the Competition Between ●OH Addition and Hydrogen Abstraction Reactions.

2019 ◽  
Author(s):  
Zoi Salta ◽  
Agnie M. Kosmas ◽  
Marc E. Segovia ◽  
Martina Kieninger ◽  
Oscar Ventura ◽  
...  
Keyword(s):  
Density Functional ◽  
Room Temperature ◽  
Hydrogen Abstraction ◽  
Reaction Rates ◽  
Composite Model ◽  
Alternative Mechanism ◽  
Radical Intermediate ◽  
Experimental Conditions ◽  
Methyl Group ◽  
Benzyl Radical

This work reports density functional and composite model chemistry calculations performed on the reactions of toluene with the hydroxyl radical. Both experimentally observed H-abstraction from the methyl group and possible additions to the phenyl ring were investigated. Reaction enthalpies and heights of the barriers suggest that H-abstraction is more favorable than ●OH addition to the ring. The calculated reaction rates at room temperature and the radical-intermediate product fractions support this view. This is somehow contradictory with the fact that, under most experimental conditions, cresols are observed in a larger concentration than benzaldehyde. Since the accepted mechanism for benzaldehyde formation involves H-abstraction, a contradiction arises that begs for an explanation. In this first part of our work we give the evidences that support the preference of hydrogen abstraction over ●OH addition and suggest an alternative mechanism which shows that cresols can actually arise also from the former reaction and not only from the latter.

Thermochemical and kinetic studies of hydrogen abstraction reaction from C16H10 isomers by H atoms

2021 ◽  
Vol 1201 ◽  
pp. 113257
Author(s):  
Dorra Khiri ◽  
Sonia Taamalli ◽  
Duy Quang Dao ◽  
Thanh-Binh Nguyen ◽  
Laurent Gasnot ◽  
...  
Keyword(s):  
Hydrogen Abstraction ◽  
Kinetic Studies ◽  
Abstraction Reaction ◽  
Hydrogen Abstraction Reaction

Theoretical study of hydrogen abstraction from quadricyclane by small radicals

2021 ◽  
Vol 1200 ◽  
pp. 113232
Author(s):  
Wen-Hui Kong ◽  
Yi-Wei Li ◽  
Jing-Bo Wang ◽  
Xiang-Yuan Li
Keyword(s):  
Theoretical Study ◽  
Hydrogen Abstraction

scholarly journals Thermodynamic and Kinetic Considerations Regarding the Prospects for a Dual-Purpose Hydrogen Extraction and Separation Membrane

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2136
Author(s):  
Karl Sohlberg
Keyword(s):  
Hydrogen Production ◽  
Hydrogen Abstraction ◽  
Hydrogen Gas ◽  
Catalytic Dehydrogenation ◽  
Dual Purpose ◽  
Physical Separation ◽  
Extraction And Separation ◽  
Separation Membrane ◽  
Hydrocarbon Sources ◽  
Critical Materials

Extraction of hydrogen from hydrocarbons is a logical intermediate-term solution for the escalating worldwide demand for hydrogen. This work explores the possibility of using a single membrane to accomplish both the catalytic dehydrogenation and physical separation of hydrogen gas as a possible way to improve the efficiency of hydrogen production from hydrocarbon sources. The present analysis shows that regions of pressure/temperature space exist for which the overall process is thermodynamically spontaneous (ΔG < 0). Each step in the process is based on known physics. The rate of hydrogen production is likely to be controlled by the barrier to hydrogen abstraction, with the density of H-binding sites also playing a role. A critical materials issue will be the strength of the oxide/metal interface.

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