- Arrhenius Parameters of Elementary Reactions Involved in the Oxidation of Neopentane
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The reactions of neopentyl radicals in an oxidising environment have been studied by adding neopentane to slowly reacting mixtures of H2 + O2 over the temperature range 380 - 520 deg C.Over a wide range of mixture composition, the only detectable initial products at these temperatures are 3,3-dimethyloxetan (DMO), acetone, i-butene, methane, and formaldehyde.A relative simple mechanism involving the formation of neopentylhydroperoxide (QOOH) radicals gives a quantitative interpretation of the product yields.Although the major source of i-butene is the C-C homolysis of neopentyl radicals, a significant proportion is formed in reaction (6) (CH3)2C(CH2OOH)CH2 (CH3)2C=CH2 + HCHO + OH.From measurements of the product ratios ( + )/ and / at each temperature used, Arrhenius parameters have been determined for a number of the elementary steps.The recommended value of k3 =1.20 x 1013 exp (-120 kJ mol-1/RT) s-1 for the 1,5p H-atom transfer in neopentylperoxy radicals is compared with previously determined parameters for the 1,4p H-atom transfer in ethylperoxy radicals.With the Arrhenius expressions for these two transfers as a basis, thermochemical calculations are used to obtain a self-consistent set of Arrhenius parameters from values of rate constants at 480 deg C for primary, secondary and tertiary H-atom transfers in alkylperoxy radicals involving ring sizes in the transition state varying from 4 to 8 (CH3)3CCH2O2 (CH3)2C(CH2OOH)CH2.
- Baldwin, Robert R.,Hisham, Mohamed W. M.,Walker, Raymond W.
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p. 1615 - 1628
(2007/10/02)
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