ISSN:
0009-2940
Keywords:
C-C Bond cleavage, energetics and kinetics of
;
Radicals, stability of
;
ESR
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The thermal cleavage of the central CC bonds in the title compounds was investigated. The activation parameters were obtained from kinetics and the equilibrium enthalpies and entropies from the temperature dependence of the equilibrium radical concentrations, determined by quantitative ESR. ΔH≠ and ΔHDiss are nearly identical but not ΔS≠ and ΔSDiss, as expected. The radical stabilisation enthalpies RSE obtained from these data (RSE: 7a = 17.9 ± 1.3; 7b = 15.6 ± 1.4 kcal/mol) correspond closely to twice the RSE of α-phenylethyl radicals (8.0 ± 1.5 kcal/mol) determined previously. The smaller RSE of the benzhydryl radical (12.9 ± 0.9 kcal/ mol), therefore, must be due to its nonplanarity.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19941271032