scholarly journals Free-Radical Chlorination of Alkylsilanes. VI. The Hydrogen Abstraction from α-Substituted Hydrosilanes by Chlorinated Methyl Radicals

1971 ◽  
Vol 44 (11) ◽  
pp. 3113-3116 ◽  
Author(s):  
Yoichiro Nagai ◽  
Hideyuki Matsumoto ◽  
Masaki Hayashi ◽  
Eiji Tajima ◽  
Hamao Watanabe
Keyword(s):  
Free Radical ◽  
Hydrogen Abstraction ◽  
Methyl Radicals ◽  
Radical Chlorination

Hydrogen abstraction by methyl radicals in glasses

1984 ◽  
Vol 78 ◽  
pp. 175 ◽  
Author(s):  
Takahisa Doba ◽  
Keith U. Ingold ◽  
Willem Siebrand ◽  
Timothy A. Wildman
Keyword(s):  
Hydrogen Abstraction ◽  
Methyl Radicals

Aromatic substitution. XV. The homolytic methylation of pyridine and 3- and 4-picoline

1967 ◽  
Vol 45 (5) ◽  
pp. 509-513 ◽  
Author(s):  
R. A. Abramovitch ◽  
K. Kenaschuk
Keyword(s):  
Free Radical ◽  
Methyl Radicals ◽  
Aromatic Substitution ◽  
Phenyl Radicals

The ratios of isomers formed in the free-radical methylation of pyridine and 3- and 4-picoline have been determined and the results compared with the corresponding phenylations. The results support the concept that methyl radicals are more nucleophilic than phenyl radicals.

Oxidations with lead tetraacetate. III. Oxidations of 2-substituted-1,3-benzodioxoles

1980 ◽  
Vol 33 (7) ◽  
pp. 1553 ◽  
Author(s):  
ER Cole ◽  
G Crank ◽  
HTH Minh
Keyword(s):  
Free Radical ◽  
Hydrogen Abstraction ◽  
Lead Tetraacetate ◽  
Ring Formation ◽  
Radical Reactions ◽  
Initial Attack ◽  
Free Radical Reactions

Oxidation of 2-alkyl- and 2-aryl-1,3-benzodioxoles with lead tetraacetate gives products mainly derived from cleavage of the dioxole ring. Formation of products is suggested to follow initial attack and hydrogen abstraction at the 2-position of the benzodioxole. Subsequent reactions then occur to give the observed products. The processes are seen as free radical reactions.

The homogeneous conversion of methane to higher hydrocarbons in the presence of ethylene in the temperature range 925–1023 K

1991 ◽  
Vol 69 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Alain R. Bossard ◽  
Margaret H. Back
Keyword(s):  
Hydrogen Abstraction ◽  
Homogeneous System ◽  
Catalytic Reactions ◽  
The Other ◽  
Methyl Radicals ◽  
Temperature Range ◽  
Vinyl Radicals ◽  
Conversion Of Methane ◽  
Radical Distribution ◽  
Higher Hydrocarbons

Mixtures of ethylene and methane have been pyrolyzed in the temperature range 925–1023 K for the purpose of converting methane to higher hydrocarbons. Addition of methane to thermally-reacting ethylene increases the rate of formation of propylene but decreases the rates of formation of the other major products, ethane, acetylene, and butadiene. Hydrogen abstraction from methane is a major propagation reaction and causes a shift in the radical distribution from ethyl and vinyl radicals, the main radicals in the pyrolysis reactions of ethylene alone, to methyl radicals, which lead to the formation of propylene. At 1023 K with a pressure of ethylene of 6.5 Torr and of methane of 356 Torr, 1.5 mol of methane is converted to higher molecular weight products for every mole of ethylene reacted. The rate of conversion of methane in the homogeneous system is lower than in catalytic reactions but the product is entirely hydrocarbon and no methane is lost to carbon monoxide or carbon dioxide. Key words: methane, ethylene, kinetics, pyrolysis, fuels.

Evidence Against a Hydrogen Abstraction Mechanism in the Photorearrangement of Azoxybenzene to 2-Hydroxyazobenzene

1973 ◽  
Vol 51 (23) ◽  
pp. 3827-3841 ◽  
Author(s):  
David J. W. Goon ◽  
N. G. Murray ◽  
Jean-Pierre Schoch ◽  
N. J. Bunce
Keyword(s):  
Free Radical ◽  
Quantum Yield ◽  
Isotope Effect ◽  
Polar Solvent ◽  
Hydrogen Abstraction ◽  
Fold Increase ◽  
Transfer Mechanism ◽  
Deuterium Isotope Effect ◽  
Ring Carbon

In an attempt to distinguish between ionic and free radical mechanisms for the photorearrangement of azoxybenzene to 2-hydroxyazobenzene, aromatic azoxycompounds carrying C—H functions ortho to the azoxy linkage have been prepared and irradiated. The failure of these weaker C—H bonds to divert the reaction from its normal course argues against a hydrogen abstraction–hydroxyl transfer mechanism. This conclusion is supported by the observation of a 30-fold increase in quantum yield for 2-hydroxyazobenzene formation on changing from a non-polar to a polar solvent and by the kinetic deuterium isotope effect, which is too small for the primary isotope effect required by the abstraction mechanism. It is concluded that the experimental observations to date may most easily be accommodated in the route originally proposed by Badger and Buttery, where the rearrangement is seen as a substitution by oxygen at the ortho ring carbon.

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