Photoinduced Electron Transfer Double Fragmentation: An Oxygen-Mediated Radical Chain Process in the Cofragmentation of Aminopinacol Donors with Organic Halides

1995 ◽  
Vol 117 (23) ◽  
pp. 6398-6399 ◽  
Author(s):  
Liaohai Chen ◽  
Mohammad S. Farahat ◽  
Hong Gan ◽  
Samir Farid ◽  
David G. Whitten
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Chain Process ◽  
Radical Chain ◽  
Organic Halides ◽  
Radical Chain Process

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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