An Electron Spin Resonance Study of Hydrogen Atom Reactions with Butenes Trapped in Aqueous Sulfuric Acid Glasses

1974 ◽  
Vol 52 (19) ◽  
pp. 3410-3414 ◽  
Author(s):  
Howard Reginald Falle ◽  
Frederick Peter Sargent
Keyword(s):  
Electron Spin Resonance ◽  
Sulfuric Acid ◽  
Hydrogen Atom ◽  
Electron Spin ◽  
Qualitative Agreement ◽  
Electron Spin Resonance Study ◽  
Torsional Motion ◽  
Spin Resonance ◽  
Percentage Ratio ◽  
Spin Resonance Study

Hydrogen atom reactions with butenes trapped in sulfuric acid glasses yield sec-butyl radicals by addition and methallyl radicals by abstraction. The character of the e.s.r. spectra due to the CH3ĊHCH2CH3 radicals depends on whether cis-2-butene or trans-2-butene was the precursor. Computer simulated spectra indicate that the most probable conformation for the CH3ĊHCH2CH3 radicals derived from cis-2-butene and trans-2-butene are 'oblique' and 'trans', respectively. Qualitative agreement between the simulated and experimental spectra is achieved by adding together the spectra computed for CH3ĊHCH2CH3 and [Formula: see text] in the percentage ratio 40:60. In computing the spectra for CH3ĊHCH2CH3, it is assumed that the radicals are distributed over a range of conformations and can undergo torsional motion.

A Kinetic Electron Spin Resonance Study of the Transfer of a Hydrogen Atom from α-Tetralin Hydroperoxide to a Tertiary Alkylperoxy Radical

1975 ◽  
Vol 53 (5) ◽  
pp. 623-627 ◽  
Author(s):  
J. H. B. Chenier ◽  
J. A. Howard
Keyword(s):  
Electron Spin Resonance ◽  
Hydrogen Atom ◽  
Electron Spin ◽  
Hydrogen Atom Transfer ◽  
Electron Spin Resonance Study ◽  
Absolute Rate ◽  
Alkyl Hydroperoxides ◽  
Spin Resonance ◽  
Alkylperoxy Radicals ◽  
Spin Resonance Study

A kinetic electron spin resonance spectroscopic study of the reaction of tertiary alkylperoxy radicals with α-tetralin hydroperoxide is reported. The absolute rate constants for this hydrogen atom transfer process (k1) are given by the equation log (k1/M−1 s−1) = (6.0 ± 0.5 ) − (4.5 ± 0.5 )/θ, where θ = 2.303 RT kcal mol−1.A significant isotope effect is obtained when the hydroperoxidic hydrogen is replaced by deuterium, e.g. k1H/k1D at 21° = 9.Other alkyl hydroperoxides, e.g. triphenylmethyl, s-butyl, and 9,10-dihydro-9-anthracyl have approximately the same reactivity to t-ROO• as α-C10H11OOH.

Electron Spin Resonance Studies of Aliphatic Ammonium Ion Radicals in Aqueous Sulfuric Acid Glasses

1974 ◽  
Vol 52 (19) ◽  
pp. 3401-3409 ◽  
Author(s):  
Howard Reginald Falle ◽  
Frederick Peter Sargent
Keyword(s):  
Electron Spin Resonance ◽  
Sulfuric Acid ◽  
Electron Spin ◽  
Qualitative Agreement ◽  
Hydrogen Abstraction ◽  
Ammonium Ion ◽  
Torsional Motion ◽  
Hydrogen Atoms ◽  
Methylene Carbon ◽  
Spin Resonance

The reaction of hydrogen atoms with n-butylammonium ions in 6 M sulfuric acid glasses yields a characteristic eight-line e.s.r. spectrum, which is attributable to CH3ĊHCH2CH2NH3+. Evidence is drawn from computer simulated spectra and from the spectra of other alkylammonium radicals to account for this spectrum. Qualitative agreement between the simulated and experimental spectra is achieved by assuming that the CH3ĊHCH2— moiety can adopt a range of conformations and can also undergo torsional motion about the sp2 carbon – methylene carbon bond. The site of hydrogen abstraction from alkylammonium ions is evidently influenced by both NH3+ and CH3 groups; abstraction tends to occur away from the former and adjacent to the latter.

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