Premium
First rate constants for reactions of OH radicals with amides
Author(s) -
Koch R.,
Palm W.U.,
Zetzsch C.
Publication year - 1997
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/(sici)1097-4601(1997)29:2<81::aid-kin1>3.0.co;2-g
Subject(s) - chemistry , radical , reaction rate constant , dimethylacetamide , flash photolysis , amide , photodissociation , photochemistry , medicinal chemistry , kinetics , organic chemistry , quantum mechanics , solvent , physics
Rate constants have been measured for the reaction of OH radicals with four amides, R 1 N(CH 3 )—C(O)R 2 (R 1 = H or Methyl, R 2 = 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 cm 3 /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. © 1997 John Wiley & Sons, Inc.