Hydrogen abstraction of carbon/phosphorus-containing radicals in photoassisted polymerization

RSC Advances ◽  
2016 ◽  
Vol 6 (73) ◽  
pp. 68952-68959 ◽  
Author(s):  
Hua Zhou ◽  
Yugang Huang ◽  
Yun Zhang ◽  
Dandan Song ◽  
Hong Huang ◽  
...  
Keyword(s):  
Free Radical ◽  
Hydrogen Abstraction ◽  
Phosphorus Containing ◽  
Cationic Photopolymerization

Free-radical-promoted photopolymerization has successfully improved the curing performance in cationic photopolymerization and is now employed in promoted autoxidation.

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.

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.

ChemInform Abstract: Stereochemical Effects in Free Radical Hydrogen Abstraction from 2,3-Dichlorobutane.

ChemInform ◽  
1987 ◽  
Vol 18 (30) ◽  
Author(s):  
N. J. BUNCE ◽  
H. K. Y. CHEUNG ◽  
J.-A. LANGSHAW
Keyword(s):  
Free Radical ◽  
Hydrogen Abstraction

HYDROGEN ABSTRACTION REACTIONS OF DIPHENYLPICRYLHYDRAZYL

1958 ◽  
Vol 36 (1) ◽  
pp. 159-166 ◽  
Author(s):  
A. G. Brook ◽  
R. J. Anderson ◽  
J. Tissot Van Patot
Keyword(s):  
Nitrous Oxide ◽  
Free Radical ◽  
Hydrogen Abstraction ◽  
Reaction Conditions ◽  
Stable Free Radical ◽  
Variable Stoichiometry ◽  
Formation Of Complexes

The stable free radical diphenylpicrylhydrazyl (DPP•) has been found to react quantitatively with ammonia and hydrazine forming nitrogen and diphenylpicrylhydrazine, and less cleanly with hydroxylamine forming diphenylpicrylhydrazine and nitrous oxide. The reactions of DPP• with a variety of amines are not clean, in part owing to the formation of complexes of the amines with the reaction product diphenylpicrylhydrazine. Preliminary investigations of the reactions of DPP• with mercaptans have shown that these otherwise clean reactions have a variable stoichiometry, dependent on the concentration and other reaction conditions.

Photoinduced free radical promoted cationic polymerization 40 years after its discovery

2020 ◽  
Vol 11 (6) ◽  
pp. 1111-1121 ◽  
Author(s):  
Mehmet Atilla Tasdelen ◽  
Jacques Lalevée ◽  
Yusuf Yagci
Keyword(s):  
Free Radical ◽  
Cationic Polymerization ◽  
Polymer Synthesis ◽  
Historical Background ◽  
Cationic Photopolymerization

Free radical promoted cationic photopolymerization has been described with its historical background, main principles and usage in polymer synthesis.

Oxidations of aromatic amines by superoxide ion

1984 ◽  
Vol 37 (4) ◽  
pp. 845 ◽  
Author(s):  
G Crank ◽  
MIH Makin
Keyword(s):  
Free Radical ◽  
Aromatic Amines ◽  
Hydrogen Abstraction ◽  
Biological Significance ◽  
Oxidizing Agent ◽  
Superoxide Ion ◽  
Free Radical Processes ◽  
Radical Processes

Superoxide ion acts as a mild and highly selective oxidizing agent for aromatic amines. Aniline and α-naphthylamine were not oxidized, but β-naphthylamine formed dibenzo[a,h]phenazine, dibenzo- [a,i]phenazine and 2,2'-azonaphthalen-1-ol. o-and p-Diamines are oxidized to diaminoazobenzenes but m-diamines are unreactive. Similarly o- and p-aminophenols are oxidized to dihydroxyazo- benzenes but m-aminophenols are unaffected, and o-mercaptoaniline forms the disulfide. The oxidations are considered to be free-radical processes, initiated by hydrogen abstraction by superoxide from the substrates. The biological significance of the results is discussed.

The Free Radical Photooximation of Alkanes by Nitrosyl Chloride

1971 ◽  
Vol 49 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Melvyn W. Mosher ◽  
N. J. Bunce
Keyword(s):  
Free Radical ◽  
Hydrogen Abstraction ◽  
Chain Process ◽  
Nitrosyl Chloride ◽  
Deuterium Isotope Effect ◽  
Radical Chain ◽  
Elemental Chlorine ◽  
Probable Reaction ◽  
Radical Initiators ◽  
Atomic Chlorine

The mechanism of the photooximation of alkanes with nitrosyl chloride has been reinvestigated. The lack of initiation of the reaction with free radical initiators suggests that a free radical chain pathway is not involved. Nevertheless, the relative reactivities of hydrocarbons of different structure and the deuterium isotope effect are very similar to those obtained in chlorinations with elemental chlorine, and in particular, primary and tertiary hydrogens are not inert to photooximation as has been previously supposed. A probable reaction mechanism involves hydrogen abstraction from the substrate by atomic chlorine in a free radical non-chain process. This hydrogen abstraction step is shown not to be significantly reversible.

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