Halogenation with N-haloamines in strong acids. I. The nature of the chain propagating radical

1970 ◽  
Vol 48 (4) ◽  
pp. 546-553 ◽  
Author(s):  
J. Spanswick ◽  
K. U. Ingold
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Hydrogen Atom ◽  
Chloride Ion ◽  
Chain Process ◽  
Molecular Chlorine ◽  
Radical Chain ◽  
Atom Chain ◽  
Strong Acids ◽  
Radical Chain Process

The N-haloamine halogenation of 1-chlorobutane in 4 M sulfuric acid in acetic acid as solvent is a radical chain process in which aminium radicals are the principal hydrogen atom abstracting species. With N-chloroamines, a concurrent chlorine atom chain is promoted by impurities such as molecular chlorine, hydrogen chloride, and chloride ion.

Metal ion initiated halogenation reactions of N-haloamines

1969 ◽  
Vol 47 (5) ◽  
pp. 715-721 ◽  
Author(s):  
Dennis D. Tanner ◽  
Melvyn W. Mosher
Keyword(s):  
Metal Ion ◽  
Cuprous Chloride ◽  
Chain Process ◽  
Chain Mechanism ◽  
Molecular Chlorine ◽  
Ferrous Chloride ◽  
Radical Chain ◽  
Acid Media ◽  
Hydrocarbon Substrates ◽  
Radical Chain Process

The metal ion catalyzed chlorination of hydrocarbon substrates by N-chloroamines and imides in acid media proceeds by a free radical chain mechanism. Reactions of four different N-chloro halogenating reagents with cuprous chloride, ferrous sulfate, and ferrous chloride initiators have been investigated. Contrary to the previously reported observations no experimental differences were observed in the halogenation reactions of individual N-halo compounds or with the different initiators. The chain carrying species in all cases was shown to be the chlorine atom and the radical chain process showed identical reactivity to that of photo-chlorination by molecular chlorine.

The Hg 6(3P)-Photosensitized Oxidation of C2Cl4

1974 ◽  
Vol 52 (23) ◽  
pp. 3863-3869 ◽  
Author(s):  
Eugenio Sanhueza ◽  
Julian Heicklen
Keyword(s):  
Quantum Yield ◽  
Chlorine Atom ◽  
Quantum Yields ◽  
Chain Process ◽  
Reaction Conditions ◽  
Radical Chain ◽  
Detailed Mechanism ◽  
Chain Oxidation ◽  
Atom Chain ◽  
Radical Chain Process

The Hg 6(3P) sensitized photolysis of C2Cl4 was studied at 25 °C both in the absence and presence of N2O and O2. For C2Cl4 alone, the only products are polymer and Hg2Cl2. The quantum yield of C2Cl4 disappearance, −Φ{C2Cl4} ∼ 1. Thus, the photolysis produces C2Cl3 radicals and Hg2Cl2, the C2Cl3 radicals dimerize, and the resultant 1,3-C4Cl6 polymerizes. The relative quenching of Hg 6(6P) by C2Cl4 compared to N2O is 3.0.In the presence of O2 the products are CCl3CCl(O) and CCl2O which are formed in a radical chain process in a ratio of 2.6 independent of reaction conditions. CO is also produced with a quantum yield of unity. The quantum yields of the chlorine-containing products are independent of the O2 pressure and the absorbed intensity, but are proportional to the C2Cl4 pressure, the proportionality constants being 1.4 and 3.7 Torr−1, respectively, for CCl2O and CCl3CCl(O). A detailed mechanism, based on the chlorine atom chain oxidation, is presented, and appropriate rate constant ratios are evaluated.

On the electron transfer and hydrogen atom abstraction mechanism for 1-benzyl-1,4-dihydronicotinamide reduction of benzoquinones

1990 ◽  
Vol 68 (10) ◽  
pp. 1662-1667 ◽  
Author(s):  
Dennis D. Tanner ◽  
Abdelmajid Kharrat ◽  
H. Oumar-Mahamat
Keyword(s):  
Electron Transfer ◽  
Free Radical ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Chain Process ◽  
Single Electron Transfer ◽  
Second Order Reaction ◽  
Radical Chain ◽  
Radical Reduction ◽  
Radical Chain Process

The reduction of p-benzoquinone (BQ) by 1-benzyl-1,4-dihydronicotinamide (BNAH) proceeds by a free-radical chain mechanism initiated by single electron transfer (SET). In dry deoxygenated acetonitrile, the chain, whose propagation steps contain a SET–hydrogen atom transfer sequence, could be inhibited by dinitrobenzene and initiated by di-tert-butylperoxyoxalate. The reduction does not follow second-order reaction kinetics. The fractional order of each reactant was found to be 0.80 and 1.36 for BNAH and BQ, respectively. The AG0 values for both the initiation and the propagation steps were evaluated electro-chemically (CV) and were found to be of a reasonable magnitude to sustain a free-radical chain process. Keywords: 1-benzyl-1,4-dihydronicotinamide, p-benzoquinone, free radical, reduction.

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