Gas-Phase Reaction of trans-2-Methyl-2-butenal with Cl: Kinetics, Gaseous Products, and SOA Formation

Abstract

<jats:p>The gas-phase reaction between trans-2-methyl-2-butenal and chlorine (Cl) atoms has been studied in a simulation chamber at 298 ± 2 K and 760 ± 5 Torr of air under free-NOx conditions. The rate coefficient of this reaction was determined as k = (2.45 ± 0.32) × 10−10 cm3 molecule−1 s−1 by using a relative method and Fourier transform infrared spectroscopy. In addition to this technique, gas chromatography coupled to mass spectrometry and proton transfer time-of-flight mass spectrometry were used to detect and monitor the time evolution of the gas-phase reaction products. The major primary reaction product from the addition of Cl to the C-3 of trans-2-methyl-2-butenal was 3-chloro-2-butanone, with a molar yield (YProd) of (52.5 ± 7.3)%. Acetaldehyde (Y = (40.8 ± 0.6)%) and HCl were also identified, indicating that the H-abstraction by Cl from the aldehyde group is a reaction pathway as well. Secondary organic aerosol (SOA) formation was investigated by using a fast mobility particle sizer spectrometer. The SOA yield in the Cl + trans-2-methyl-2-butenal reaction is reported to be lower than 2.4%, thus its impact can be considered negligible. The atmospheric importance of the titled reaction is similar to the corresponding OH reaction in areas with high Cl concentration.</jats:p>

An experimental study of the gas-phase reaction between Cl atoms and trans-2-pentenal: Kinetics, products and SOA formation

“…The SOA formation yields for the reaction of other unsaturated compounds with Cl have been previously determined. For trans-2-methyl-2-butenal, Y SOA were recently determined to be between 0.26 and 1.65% (Antiñolo et al, 2020). These SOA yields are a little lower than the values determined in the present work for the reaction of Cl with T2P.…”

Kinetic and Products Study of the Atmospheric Degradation of trans-2-Hexenal with Cl Atoms

“…These values are found to be higher than the results obtained for the Cl reaction of trans -2-pentenal, which were in the 1–7% range, 25 and trans -2-methyl-2-butenal, which were between 0.3 and 1.7%. 41 SOA yields in the range of 7 to 36% 53 were obtained for the reaction of Cl with isoprene being these SOA yields more similar to the values determined in the present work for the reaction of Cl with T2H.…”

“…This setup and the methodology used are succinctly described in "Product Study", since it has been detailed in Ballesteros et al 40 In separate experiments, the 16-L White cell was connected, in a closed circuit, to the CR-ASC and an FMPS spectrometer (TSI 3091) for carrying out the SOA formation study. This apparatus, procedure, and methodology were previously described in detail elsewhere 25,41 but are concisely explained below in "Monitoring Ultrafine Particles and Determination of the SOA Yield".…”

Atmospheric chemistry of CF3CHFCF2OCH3 (HFE-356mec3) and CHF2CHFOCF3 (HFE-236ea1) initiated by OH and Cl and their contribution to global warming

“…elsewhere (Antiñolo et al, 2020;Asensio et al, 2023Asensio et al, , 2022Ballesteros et al, 2017;Ceacero-Vega et al, 2012). In the kinetic study of reaction R3, methane (CH4) and 1,2,2trichloroethane (CH2ClCHCl2) were used as reference compounds, while for R4 due to the difficulty of finding a suitable reference compound, only 1,1,1-trichloroethane (CH3CCl3) was used.…”

“…for HFE-356mec3, 150min for HFE-236ea1 and 90min for CH2ClCHCl2. kloss and kRef,loss (Table S4) were measured prior to each experiment and include heterogeneous losses, photolysis and/or reaction with Cl2, as described in previous works (Antiñolo et al, 2020;Asensio et al, 2022).…”