First rate constants reactions of OH radicals with amides

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Rate constants have been measured for the reaction of OH radicals with four amides, R1N(CH3)-C(O)R2 (R1 = H or Methyl, R2 = Methyl or Ethyl), at 300 and 384 K using flash photolysis/resonance fluorescence. Reactants are introduced under slow flow conditions and are controlled by two independent methods, gas saturation and continuous injection. It turns out that the reactivities of the amides are considerably lower than those of the corresponding amines. The pattern of rate constants obtained at 300 K: 14, 21, 5.2, and 7.6 · 10-12 cm3/s for N,N-Dimethylacetamide (dmaa), N,N-Dimethylpropionamide (dmpa), N-Methylacetamide (maa), and N-Methylpropionamide (mpa), respectively, indicates a single, dominating reaction center and strong electronic effects of the substituents at both sides of the amide function. Correspondingly, the observed negative temperature dependence (E/R= - 400 to - 600 K) excludes a direct abstraction mechanism.

Original languageEnglish
JournalInternational Journal of Chemical Kinetics
Volume29
Issue number2
Pages (from-to)81-87
Number of pages7
ISSN0538-8066
DOIs
Publication statusPublished - 1997
Externally publishedYes