Reactions of methyl radicals with acetaldehyde and acetaldehyde‐d1. II. BEBO calculations of the temperature dependence of the rate constants

T. Bérces, F. MáRta

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Abstract

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 CH3 with CH3CHO and CH3CDO, 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 CH3 + CH3CHO → CH4 + CH3CO (2a), CH3 + CH3CHO → CH4 + CH2CHO (2b), and CH3 + CH3CDO → CH3D + CH3CO (1a) between 298 and 1224°K. It was shown that the curvature apparent in the Arrhenius plot of the rate coefficient k2 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.

Original languageEnglish
Pages (from-to)295-306
Number of pages12
JournalInternational Journal of Chemical Kinetics
Volume8
Issue number2
DOIs
Publication statusPublished - 1976

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Acetaldehyde
acetaldehyde
Isotopes
Rate constants
Arrhenius plots
temperature dependence
Temperature
Methane
isotope effect
plots
curvature
Kinetics
methane
methyl radical
kinetics
curves
coefficients
temperature

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

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title = "Reactions of methyl radicals with acetaldehyde and acetaldehyde‐d1. II. BEBO calculations of the temperature dependence of the rate constants",
abstract = "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 CH3 with CH3CHO and CH3CDO, 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 CH3 + CH3CHO → CH4 + CH3CO (2a), CH3 + CH3CHO → CH4 + CH2CHO (2b), and CH3 + CH3CDO → CH3D + CH3CO (1a) between 298 and 1224°K. It was shown that the curvature apparent in the Arrhenius plot of the rate coefficient k2 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.",
author = "T. B{\'e}rces and F. M{\'a}Rta",
year = "1976",
doi = "10.1002/kin.550080211",
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journal = "International Journal of Chemical Kinetics",
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TY - JOUR

T1 - Reactions of methyl radicals with acetaldehyde and acetaldehyde‐d1. II. BEBO calculations of the temperature dependence of the rate constants

AU - Bérces, T.

AU - MáRta, F.

PY - 1976

Y1 - 1976

N2 - 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 CH3 with CH3CHO and CH3CDO, 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 CH3 + CH3CHO → CH4 + CH3CO (2a), CH3 + CH3CHO → CH4 + CH2CHO (2b), and CH3 + CH3CDO → CH3D + CH3CO (1a) between 298 and 1224°K. It was shown that the curvature apparent in the Arrhenius plot of the rate coefficient k2 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.

AB - 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 CH3 with CH3CHO and CH3CDO, 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 CH3 + CH3CHO → CH4 + CH3CO (2a), CH3 + CH3CHO → CH4 + CH2CHO (2b), and CH3 + CH3CDO → CH3D + CH3CO (1a) between 298 and 1224°K. It was shown that the curvature apparent in the Arrhenius plot of the rate coefficient k2 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.

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