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Temperature‐Dependence of the Rates of Reaction of Trifluoroacetic Acid with Criegee Intermediates
Author(s) -
ChhantyalPun Rabi,
McGillen Max R.,
Beames Joseph M.,
Khan M. Anwar H.,
Percival Carl J.,
Shallcross Dudley E.,
OrrEwing Andrew J.
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201703700
Subject(s) - chemistry , trifluoroacetic acid , formaldehyde , atmospheric temperature range , medicinal chemistry , acetone , reactive intermediate , reaction rate constant , gas phase , computational chemistry , photochemistry , kinetics , organic chemistry , catalysis , thermodynamics , physics , quantum mechanics
Abstract The rate coefficients for gas‐phase reaction of trifluoroacetic acid (TFA) with two Criegee intermediates, formaldehyde oxide and acetone oxide, decrease with increasing temperature in the range 240–340 K. The rate coefficients k(CH 2 OO + CF 3 COOH)=(3.4±0.3)×10 −10 cm 3 s −1 and k((CH 3 ) 2 COO + CF 3 COOH)=(6.1±0.2)×10 −10 cm 3 s −1 at 294 K exceed estimates for collision‐limited values, suggesting rate enhancement by capture mechanisms because of the large permanent dipole moments of the two reactants. The observed temperature dependence is attributed to competitive stabilization of a pre‐reactive complex. Fits to a model incorporating this complex formation give k [cm 3 s −1 ]=(3.8±2.6)×10 −18 T 2 exp((1620±180)/T) + 2.5×10 −10 and k [cm 3 s −1 ]=(4.9±4.1)×10 −18 T 2 exp((1620±230)/T) + 5.2×10 −10 for the CH 2 OO + CF 3 COOH and (CH 3 ) 2 COO + CF 3 COOH reactions, respectively. The consequences are explored for removal of TFA from the atmosphere by reaction with biogenic Criegee intermediates.