Comment on acp-2021-962

doi:10.5194/acp-2021-962-rc2

Abstract

The kinetics of the gas-phase reactions of hydroxyl radicals with cyclohexene oxide (CHO), 1,2-epoxyhexane (EHX), 1,2-epoxybutane (12EB), trans-2,3-epoxybutane (tEB) and cis-2,3-epoxybutane (cEB) have been investigated using the relative rate technique. The experiments have been performed at (298 ± 3) K and (760 ± 10) Torr total pressure of synthetic air using different reference compounds in a 1080 l Quartz Reactor (QUAREC) and a 480 l Duran glass chamber. The following room temperature rate coefficients (cm3 molecule−1 s−1) were obtained: k1 (OH+CHO) = (5.93 ± 1.78) × 10−12, k2 (OH+EHX) = (5.77 ± 1.29) × 10−12, k3 (OH+12EB) = (1.98 ± 0.39) × 10−12, k4 (OH+cEB) = (1.50 ± 0.26) × 10−12, k5 (OH+tEB) = (1.81 ± 0.42) × 10−12. With the exception of previous studies for 1,2-epoxybutane and cyclohexene oxide, this is to the best of our knowledge the first kinetic study of the reaction of these compounds with OH radicals. Atmospheric lifetimes, reactivity trends and atmospheric implications are discussed considering the epoxy compound rate coefficients obtained in the present study. In addition to a direct comparison with the literature data where possible, the results from the present study are compared with values estimated from the Structure Activity Relationship method.

Highlights

Oxygenated volatile organic compounds (OVOCs) play an important role in atmospheric chemistry and have an impact on 25 climate and human health (Calvert et al, 2011)
The rate coefficients are averages from the experiments with each reference compound from the experiments performed in 180 both reactors: k1(OH+cyclohexene oxide (CHO)) = (5.93±1.78) × 10-12, k2(OH+EHX) = (5.77±1.29) × 10-12, k3(OH+12EB) = (1.98±0.39) × 10-12, k4(OH+cEB) = (1.50±0.26) × 10-12, k5(OH+tEB) = (1.81±0.42) × 10-12
Since all rate coefficients obtained in this study, except those for 12EB and CHO, were measured for the first time; the errors quoted for the rate coefficients include the 2σ statistical error from the linear regression analyses for kEpoxide/kReference ratios and up to 35% contribution in the recommended values of the rate coefficients for reference compounds with OH radicals

Summary

Introduction

Oxygenated volatile organic compounds (OVOCs) play an important role in atmospheric chemistry and have an impact on 25 climate and human health (Calvert et al, 2011). From those OVOCs emitted from either biogenic or anthropogenic sources, cyclic ethers, with the exception of furans (Villanueva et al, 2009; Li et al, 2018) have received very little attention. As simplest cyclic ethers, are an important and valuable class of raw materials and intermediates for chemical industry. Epoxides are considered a key element in “click-chemistry” (Kolb et al, 2001; Fokin and Wu, 2006).

Methods

Results

Conclusion