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Rate coefficients and mechanisms of the reaction of cl‐atoms with a series of unsaturated hydrocarbons under atmospheric conditions

2003; Wiley; Volume: 35; Issue: 8 Linguagem: Inglês

10.1002/kin.10135

1097-4601

John J. Orlando, Geoffrey S. Tyndall, E. C. Apel, D. D. Riemer, Suzanne E. Paulson,

Indoor Air Quality and Microbial Exposure

Abstract Rate coefficients and/or mechanistic information are provided for the reaction of Cl‐atoms with a number of unsaturated species, including isoprene, methacrolein ( MACR ), methyl vinyl ketone ( MVK ), 1,3‐butadiene, trans ‐2‐butene, and 1‐butene. The following Cl‐atom rate coefficients were obtained at 298 K near 1 atm total pressure: k (isoprene) = (4.3 ± 0.6) × 10 −10 cm 3 molecule −1 s −1 (independent of pressure from 6.2 to 760 Torr); k ( MVK ) = (2.2 ± 0.3) × 10 −10 cm 3 molecule −1 s −1 ; k ( MACR ) = (2.4 ± 0.3) × 10 −10 cm 3 molecule −1 s −1 ; k ( trans ‐2‐butene) = (4.0 ± 0.5) × 10 −10 cm 3 molecule −1 s −1 ; k (1‐butene) = (3.0 ± 0.4) × 10 −10 cm 3 molecule −1 s −1 . Products observed in the Cl‐atom‐initiated oxidation of the unsaturated species at 298 K in 1 atm air are as follows (with % molar yields in parentheses): CH 2 O (9.5 ± 1.0%), HCOCl (5.1 ± 0.7%), and 1‐chloro‐3‐methyl‐3‐buten‐2‐one (CMBO, not quantified) from isoprene; chloroacetaldehyde (75 ± 8%), CO 2 (58 ± 5%), CH 2 O (47 ± 7%), CH 3 OH (8%), HCOCl (7 ± 1%), and peracetic acid (6%) from MVK ; CO (52 ± 4%), chloroacetone (42 ± 5%), CO 2 (23 ± 2%), CH 2 O (18 ± 2%), and HCOCl (5%) from MACR ; CH 2 O (7 ± 1%), HCOCl (3%), acrolein (≈3%), and 4‐chlorocrotonaldehyde (CCA, not quantified) from 1,3‐butadiene; CH 3 CHO (22 ± 3%), CO 2 (13 ± 2%), 3‐chloro‐2‐butanone (13 ± 4%), CH 2 O (7.6 ± 1.1%), and CH 3 OH (1.8 ± 0.6%) from trans ‐2‐butene; and chloroacetaldehyde (20 ± 3%), CH 2 O (7 ± 1%), CO 2 (4 ± 1%), and HCOCl (4 ± 1%) from 1‐butene. Product yields from both trans ‐2‐butene and 1‐butene were found to be O 2 ‐dependent. In the case of trans ‐2‐butene, the observed O 2 ‐dependence is the result of a competition between unimolecular decomposition of the CH 3 CH(Cl)CH(O•)CH 3 radical and its reaction with O 2 , with k decomp / k O2 = (1.6 ± 0.4) × 10 19 molecule cm −3 . The activation energy for decomposition is estimated at 11.5 ± 1.5 kcal mol −1 . The variation of the product yields with O 2 in the case of 1‐butene results from similar competitive reaction pathways for the two β‐chlorobutoxy radicals involved in the oxidation, ClCH 2 CH(O•)CH 2 CH 3 and •OCH 2 CHClCH 2 CH 3 . © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 334–353, 2003