Kinetics and mechanism of the reaction of propylene oxide with chlorine atoms and hydroxy radicals

Abstract

The kinetics and mechanism of gas-phase propylene oxide (PPO) reactions were studied in a 142-L reaction chamber by long-path Fourier transform infrared spectroscopy at atmospheric pressure and 298 K. Rate coefficients for the reaction of PPO with ozone (O 3 ), chlorine atoms (Cl), and hydroxyl radicals (OH) were measured using the relative rate technique. Product yields of acetic acid, acetic formic anhydride, formic acid, and carbon monoxide were determined for the following reactions: PPO with Cl both in the presence and absence of NO, PPO with OH and NO, methyl acetate with Cl both in the presence and absence of NO, and ethyl formate with Cl both in the presence and absence of NO. The measured rate coefficients for PPO with O 3 , Cl, and OH are <3.5 × 10 −21 cm 3 molecule −1 s −1 , (3.0 ± 0.7) × 10 −11 cm 3 molecule −1 s −1 , and (3.0 ± 1.0) × 10 −13 cm 3 molecule −1 s −1 , respectively. The carbon balance for the products measured ranged from 10% (for OH + PPO) to 100% (for Cl + methyl acetate in the absence of NO). The mechanistic and atmospheric implications of these measurements are discussed. C

Rate Coefficients of the Cl + CH3C(O)OCH3 → HCl + CH3C(O)OCH2 Reaction at Different Temperatures Calculated by Transition-State Theory with ab Initio and Density Functional Theory Reaction Paths

“…The title reaction, Cl + CH 3 C(O)OCH 3 → HCl + CH 3 C(O)OCH 2 , has been selected in the present study for the following reasons. First, a large number of experimental studies on the kinetics of the Cl + CH 3 C(O)OCH 3 reaction have been reported, − and it is well established from product yield analyses that the major reaction channel is H abstraction by Cl occurring almost exclusively at the methoxy (CH 3 O) end (>95%). ,,, In this connection, only this reaction channel needs to be considered. Measured k ’s at the temperature ( T ) of 298 K obtained from these kinetic studies have values ranging from 1.93 ± 0.27 to 2.86 ± 0.35 × 10 –12 cm 3 molecule –1 s –1 (these lower and upper limits are from refs and , respectively; note that the value of 7.0 × 10 –13 cm 3 molecule –1 s –1 quoted in ref , which was supposed to be from ref , is most likely a misquote).…”

Experimental and theoretical study of the reactivity of a series of epoxides with chlorine atoms at 298 K

“…31 Table 2 compares the experimental rate coefficients with the values obtained by a SAR estimation method and those found in the literature for other epoxy compounds. The third column in Table 2 shows the rate coefficient, k SAR , predicted from the structure-reactivity relationship (SAR) method 41 that has been tentatively applied for the epoxides studied by using the factor F(O) = 1.18 42,43 and F(O) = 1.45. 31 This factor corresponds to the calculated influence of the ether group on the rate constant.…”

Kinetic Study of the Atmospheric Oxidation of a Series of Epoxy Compounds by OH Radicals

“…Calculated using the SAR estimation of (a) (Kwok and Atkinson, 1995), (b) (Calvert et al, 2011), (c) (Calvert et al, 2015), (d) (Middala et al, 2011), (e) (Jenkin et al, 2018). (Calvert et al, 2015) (Recomended values of the most recent revision of database for the kinetics of the gas-phase atmospheric reactions of organic compounds).…”