Photochemically induced hydrogen abstraction by carbon radicals in an adamantane matrix: generation and photochemical cleavage of 2-adamantyl radicals

1989 ◽  
pp. 1293-1297 ◽  
Author(s):  
Hans-Gert Korth ◽  
Fritz Lange ◽  
Fritz Lübbe ◽  
Wolfgang Müller ◽  
Margret Seidel ◽  
...  
Keyword(s):  
Hydrogen Abstraction ◽  
Carbon Radicals ◽  
Photochemical Cleavage

Cyclobutanes and Cyclobutenes from Photochemical Cleavage of Some Bicyclo[3.2.0]heptan-2-ones

2009 ◽  
Vol 62 (2) ◽  
pp. 101 ◽  
Author(s):  
Leiv K. Sydnes ◽  
Doan Van Ha
Keyword(s):  
Allyl Alcohol ◽  
Hydrogen Abstraction ◽  
Type I ◽  
Mercury Lamp ◽  
Methyl Group ◽  
Primary Products ◽  
Norrish Type ◽  
Photochemical Cleavage ◽  
Isomeric Mixtures ◽  
Better Than

Irradiation of solutions of cyclopent-2-enone or 3-methylcyclopent-2-enone and allyl alcohol with light from a medium-pressure mercury lamp through a Pyrex filter with a cut-off at 295 nm furnishes excellent yields of isomeric mixtures of substituted bicyclo[3.2.0]heptan-2-ones as the primary products. Both enones give predominantly the head-to-head isomer with exo stereochemistry. The primary products turn out to be photolabile and undergo Norrish type I cleavage followed by hydrogen abstraction, but the outcome is influenced by the presence of a methyl group at C5. In the absence of such a methyl group the C1–C2 bond is cleaved, to give rise to two cyclobutenyl aldehydes in better than 90% combined yield; when a methyl group is attached at C5 both C–C bonds to the carbonyl group are broken and a mixture of cyclobutyl aldehydes and ketenes are formed in close to quantitative combined yield.

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.

Side reactions during photochemical cleavage of α-methyl-6-nitroveratryl-based photolabile linker

1999 ◽  
Author(s):  
Markéta Rinnová ◽  
Michaela Nováková ◽  
Václav Kašička ◽  
Jiří Jiráček
Keyword(s):  
Side Reactions ◽  
Photochemical Cleavage

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
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