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Reactions of methyl radicals with acetaldehyde and acetaldehyde‐ d 1 . II. BEBO calculations of the temperature dependence of the rate constants
Author(s) -
BéRces T.,
MáRta F.
Publication year - 1976
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/kin.550080211
Subject(s) - chemistry , arrhenius equation , reaction rate constant , kinetic isotope effect , radical , acetaldehyde , arrhenius plot , atmospheric temperature range , hydrogen atom abstraction , isobutane , computational chemistry , activation energy , thermodynamics , deuterium , kinetics , organic chemistry , atomic physics , physics , quantum mechanics , ethanol , catalysis
The BEBO method was used to calculate the kinetic isotope effect for formyl‐hydrogen abstraction from acetaldehyde by methyl radicals. The calculated isotope effect and experimental ratios of the rate constants obtained at 785°K for the reactions of CH 3 with CH 3 CHO and CH 3 CDO, together with the theoretical temperature dependence of the specific rates (as formulated by the BEBO theory), were used to obtain rate constants for the steps CH 3 + CH 3 CHO → CH 4 + CH 3 CO (2a), CH 3 + CH 3 CHO → CH 4 + CH 2 CHO (2b), and CH 3 + CH 3 CDO → CH 3 D + CH 3 CO (1a) between 298 and 1224°K. It was shown that the curvature apparent in the Arrhenius plot of the rate coefficient k 2 reported for the reaction of methyl radicals with acetaldehyde in the temperature range of 298–1224°K is caused both by the simultaneous contribution of steps (2a) and (2b) to methane formation, and by the curvature in the Arrhenius plots of the two elementary rate constants themselves. The predicted curve agrees well with the experimental data, especially if the tunneling correction is applied.