13988-39-1Relevant articles and documents
Polar Effects in Halogen Abstraction Reactions of Alkyl Radicals
Giese, Bernd,Hartung, Jens
, p. 1777 - 1782 (2007/10/02)
In a series of structurally similar alkyl radicals 1a-c the tertiary 1,1-dimethyl-5-hexenyl radical 1c reacts 30 times faster with carbon tetrachloride than the primary 5-hexenyl radical 1a.The reactivity of the secondary 1-methyl-5-hexenyl radical 1b aligns itself between the primary and the tertiary radical 1a and 1c.The results indicate that the increasing nucleophilicity of the alkyl radicals is the major factor contributing to the reactivity. Key Words: Polar effects / Radical clock / Cobaloximes, alkyl / Radicals, alkyl / Chlorine abstraction
Rate constant for chlorine abstraction from CCl4 by the 5-hexenyl radical
Jewell, Deborah Rae,Mathew, Lukose,Warkentin, John
, p. 311 - 315 (2007/10/02)
Cyclization of the 5-hexenyl free radical to the cyclopentylmethyl free radical was used to clock chlorine atom abstraction by 5-hexenyl from carbon tetrachloride in solution.The source of 5-hexenyl radicals was 5-hexenyldiazene((CH3)2C(OH)N=N(CH2)4CH=CH2), which decomposes thermally in CCl4 by a radical chain mechanism to afford chloroform, acetone, nitrogen, 6-chloro-1-hexene, cyclopentylchloromethane, 1-hexene, and methylcyclopentane as primary products. 6-Chloro-1-hexene is converted, in part, to a secondary product, 1,1,1,3,7-pentachloroheptane, by radical chain addition of CCl4 to the double bond.The rate constant for chlorine atom abstraction, kCl, was calculated from the product composition and the known rate constant for cyclization of the 5-hexenyl radical.For the temperature range 274-353 K, kCl is given by log(kCl/M-1s-1) = (8.4 +/- 0.3) - (6.2 +/- 0.4)/Τ where Τ = 2.3 RT kcal mol-1, which leads to kCl25 deg C = 7.2E3 M-1s-1.This value is significantly smaller than recently reported estimates for other primary alkyl radicals.
