Absolute rate constants for hydrocarbon autoxidation. 29. Rate constants for abstraction of primary aliphatic hydrogens from 2,2-dimethylbutane by the tert-butylperoxy radical

1980 ◽  
Vol 58 (24) ◽  
pp. 2808-2812 ◽  
Author(s):  
J. A. Howard ◽  
J. H. B. Chenier

Rate constants for abstraction of primary and secondary hydrogens from 2,2-dimethylbutane by the tert-butylperoxy radical at temperatures from 323 to 353 K have been determined from autoxidations and co-autoxidations in the presence of tert-butyl hydroperoxide. At 333 K the rate constant for abstraction of a secondary hydrogen is ~1.5 × 10−3 M−1 s−1 and the rate constants for abstraction of a primary hydrogen from the tert-butyl and methyl groups of 2,2-dimethylbutane are ~4 × 10−5 and ~6 × 10−5 M−5 s−1 respectively.

1978 ◽  
Vol 56 (2) ◽  
pp. 170-175 ◽  
Author(s):  
J. A. Howard ◽  
J. H. B. Chenier ◽  
D. A. Holden

Autoxidation of 3-methylpentane in the presence of tert-butyl hydroperoxide gives, after reduction with triphenylphosphine, 3-methyl-3-pentanol and 3-methyl-2-pentanol as the major reaction products. The overall rate constant for reaction of (CH3)3COO· with this substrate at 30 °C is 0.008 ± 0.001 M−1 s−1 which consists of k/tertiary C—H = 0.007 ± 0.001 M−1 s−1 and k/secondary C—H = 0.0002 ± 0.0001 M−1 s−1. The products from cooxidation of cumene and 3-methylpentane in the presence of tert-butyl hydroperoxide are formed in yields which are consistent with these rate constants relative to a value of 0.16 M−1 s−1 for cumene. The Arrhenius equations for reaction of (CH3)3COO• with the t-C—H and s-C—H of 3-methylpentane relative to the Arrhenius equation for reaction of (CH3)3COO• with cumene (log (k10/M−1 s−1) = (8.7 ± 0.3) − (13.2 ± 0.4)/θ) are[Formula: see text]respectively, where θ = 2.303 RT kcal mol−1.


Author(s):  
G. Vijayalakshmmi ◽  
M. Adinarayanna ◽  
P. Jayaprrakash Rao

The rates of oxidation of adenosine and α-tocopherol by tert-butoxyl radicals (t-BuO•) were studied spectrophotometrically. Radicals (t-BuO•) were generated by the photolysis of tert-butyl hydroperoxide (t-BuOOH) in presence of tert-butyl alcohol to scavenge •OH radicals. The rates and the quantum yields () of oxidation of α-tocopherol by t-BuO• radicals were determined in the absence and presence of varying concentrations of adenosine. An increase in the concentration of adenosine was found to decrease the rate of oxidation of α-tocopherol, suggesting that adenosine and α-tocopherol competed for t-BuO• radicals. From competition kinetics, the rate constant of α-tocopherol reaction with t-BuO• was calculated to be 7.29 x 108 dm3 mol-1 s-1. The quantum yields expt and cal values suggested that α-tocopherol not only protected adenosine from t-BuO• radicals, but also repaired adenosine radicals, formed by the reaction of adenosine with t-BuO• radicals.


2012 ◽  
Vol 14 (13) ◽  
pp. 3384-3387 ◽  
Author(s):  
Erbo Shi ◽  
Ying Shao ◽  
Shulin Chen ◽  
Huayou Hu ◽  
Zhaojun Liu ◽  
...  

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