27974-64-7Relevant articles and documents
Flash Photolysis Study of the Spectra and Self-reactions of Neopentylperoxy and t-Butylperoxy Radicals
Lightfoot, Phillip D.,Roussel, Pascal,Veyret, Bernard,Lesclaux, Robert
, p. 2927 - 2936 (1990)
The self-reaction of neopentylperoxy radicals, neo-C5H11O2 (NPTO2): NPTO2 + NPTO2 --> 2 t-C4H9VH2O + O2 (1a) --> t-C4H9CHO + t-C4H9CH2OH + O2 (1b) --> t-C4H9CH2OOCH2C4H9-t + O2 (1c) has been studied from 248 to 373 K and from 50 to 760 Torr total pressure.The neopentylperoxy radicals formed via channel (1a) react, under most experimental conditions, by unimolecular decomposition: t-C4H9CH2O + M --> t-C4H9 + HCHO + M. (2) The t-butyl radicals so formed are rapidly converted into t-butylperoxy radicals under the conditions employed in this work; these radicals are unreactive on the timescale of the NPTO2 decay and enable the branching ratio for reaction (1) to be determined via their UV absorption.The overall rate constant for reaction (1) diaplays a strong negative temperature dependence, being well described by k1/cm3 molecule-1 s-1 = 3.02 x 10-19(T/298)9.46 exp(4260/T) over the temperature range studied here.The non-terminating channel (1a) becomes increasingly important with increasing temperature, with β = (197+/-67)exp, where β is the ratio of those radicals which react via the non-terminating channel (1a) to those which react via the terminating channels (1b) and (1c).By measuring the reduction in the fraction of NPTO2 radicals converted to t-butylperoxy radicals with increasing oxygen concentration, rate constants for reaction (2) were determined relative to that of CH3O2; both are similar in shape and magnitude to those of other alkylperoxy radicals, displaying maxima around 240 nm, with ?240nm (NPTO2) / cm2 molecule-1 = (6.2 +/- 1.1) x 10-18 and ?240nm (t-C4H9O2) / cm2 molecule-1 = (4.7 +/- 0.8) x 10-18.The self-reaction of t-butylperoxy radicals: 2 t-C4H9O2 --> 2 t-C4H9O + O2 (3) was also briefly studied, resulting in k3/cm3 molecule-1 s-1 ca. 1.0 x 10-11 exp(-3894/T).Errors are 1?.
Kinetics of the Reactions between Alkyl Radicals and Molecular Oxygen in Aqueous Solution
Marchaj, Adam,Kelley, Douglas G.,Bakac, Andreja,Espenson, James H.
, p. 4440 - 4441 (1991)
The rate constant for the reaction R. + O2 -> ROO. in aqueous solution was determined for 18 alkyl radicals by laser flash photolysis.The values are all at the diffusion-controlled limit and lie in the range (1.6 - 4.9) x 109 L mol-1 s-1.The radicals studied are primary, substituted primary, secondary, and benzyl radicals.
The Nucleophilicity of Superoxide towards Different Alkyl Halides Estimated from Kinetic Measurements
Daasbjerg, Kim,Lund, Henning
, p. 597 - 604 (2007/10/02)
Values of the rate constant ksub are measured for the substitution reaction between superoxide O2 anion-radical and the alkyl halides butyl chloride, 2-butyl chloride, benzyl chloride, ethyl bromide, butyl bromide, 2-butyl bromide, neopentyl bromide, benzyl bromide, (1-bromo-2,2-dimethylpropyl)benzene and 1-iodoadamantane.These rate constants are compared with the expected rate constant kET for the electron transfer reaction between the same alkyl halides and an aromatic anion radical A anion-radical with the same standard oxidation potential as O2 anion-radical.The ksub/kET ratios show that the mechanism of the substitution reaction amy shift from SN2-like to ET-like on changes in the steric hindrance and the acceptor ability of the alkyl halide.The influence on ksub/kET of the difference in self-exchange reorganization energy λ(0) between O2 anion-radical/O2 and A anion-radical/A is discussed.
