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Kinetics of the brominated alkyl radical (CHBr 2 , CH 3 CHBr) reactions with NO 2 in the temperature range 250–480 K
Author(s) -
Rissanen Matti P.,
Eskola Arkke J.,
Timonen Raimo S.
Publication year - 2012
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.20725
Subject(s) - chemistry , radical , analytical chemistry (journal) , kinetics , bromoform , torr , atmospheric temperature range , photodissociation , photochemistry , thermodynamics , organic chemistry , physics , quantum mechanics , chloroform
The gas‐phase kinetics of CHBr 2 + NO 2 and CH 3 CHBr + NO 2 reactions have been studied in direct time resolved measurements using a tubular flow reactor coupled to a photoionization mass spectrometer. The radicals were generated by pulsed laser photolysis of bromoform and 1,1‐dibromoethane at 248 nm. The subsequent decays of the radical concentrations were monitored as a function of [NO 2 ] under pseudo–first‐order conditions. The rate coefficients of both reactions are independent of bath gas (He) pressure and display negative temperature dependence under the conditions of 2–6 Torr pressure (He) and 250–480 K. The obtained bimolecular rate coefficients are k (CHBr 2 + NO 2 ) = (9.8 ± 0.4) × 10 −12 ( T /300 K) −1.65 ± 0.18 cm 3 s −1 (288–483 K) and k (CH 3 CHBr + NO 2 ) = (2.27 ± 0.06) × 10 −11 ( T /300 K) −1.28 ± 0.11 cm 3 s −1 (250–483 K), with the uncertainties given as one standard error. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are ±25%. The reaction products identified were CBr 2 O for the CHBr 2 + NO 2 reaction and CHBrO and CH 3 CHO with minor amounts of CH 3 for the CH 3 CHBr + NO 2 reaction, respectively. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 767–777, 2012