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Kinetic studies of the self‐reaction and reaction with HO 2 of a tertiary β‐brominated peroxy radical between 298 and 393 K
Author(s) -
Villenave E.,
Lesclaux R.
Publication year - 2000
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/1097-4601(20010101)33:1<41::aid-kin5>3.0.co;2-j
Subject(s) - chemistry , reaction rate constant , arrhenius equation , reactivity (psychology) , radical , flash photolysis , substituent , photochemistry , reaction rate , atmospheric temperature range , kinetics , medicinal chemistry , organic chemistry , activation energy , thermodynamics , catalysis , medicine , physics , alternative medicine , pathology , quantum mechanics
The kinetics of reactions of the tertiary β‐brominated peroxy radical BrC(CH 3 ) 2 C(CH 3 ) 2 O 2 (2‐bromo‐1,1,2‐trimethylpropylperoxy) have been studied using the laser flash photolysis technique, photolysing HBr at 248 nm in the presence of O 2 and 2,3‐dimethylbut‐2‐ene. At room temperature, a rate constant of (2.0 ± 0.8) × 10 −14 cm 3 molecule −1 s −1 was determined for the BrC(CH 3 ) 2 C(CH 3 ) 2 O 2 self‐reaction. The reaction of BrC(CH 3 ) 2 C(CH 3 ) 2 O 2 with HO 2 was investigated in the temperature range 306–393 K, yielding the following Arrhenius expression: k (BrC(CH 3 ) 2 C(CH 3 ) 2 O 2 + HO 2 ) = (2.04 ± 0.25) × 10 −12 exp[(501 ± 36) K / T ] cm 3 molecule −1 s −1 , giving by extrapolation (1.10 ± 0.13) × 10 −11 cm 3 molecule −1 s −1 at 298 K. These results confirm the enhancement of the peroxy radical self‐reaction reactivity upon β‐substitution, which is similar for Br and OH substituents. In contrast, no significant effect of substituent has been observed on the rate constant for the reactions of peroxy radicals with HO 2 . The global uncertainty factors on rate constants are equal to nearly 2 for the self‐reaction and to 1.35 for the reaction with HO 2 . © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 33: 41–48, 2001