Abstract
Abstract. We present a digital, freely available, searchable, and evaluated compilation of rate coefficients for the gas-phase reactions of organic compounds with OH, Cl, and NO3 radicals and with O3. Although other compilations of many of these data exist, many are out of date, most have limited scope, and all are difficult to search and to load completely into a digitized form. This compilation uses results of previous reviews, though many recommendations are updated to incorporate new or omitted data or address errors, and includes recommendations on many reactions that have not been reviewed previously. The database, which incorporates over 50 years of measurements, consists of a total of 2765 recommended bimolecular rate coefficients for the reactions of 1357 organic substances with OH, 709 with Cl, 310 with O3, and 389 with NO3, and is much larger than previous compilations. Many compound types are present in this database, including naturally occurring chemicals formed in or emitted to the atmosphere and anthropogenic compounds such as halocarbons and their degradation products. Recommendations are made for rate coefficients at 298 K and, where possible, the temperature dependences over the entire range of the available data. The primary motivation behind this project has been to provide a large and thoroughly evaluated training dataset for the development of structure–activity relationships (SARs), whose reliability depends fundamentally upon the availability of high-quality experimental data. However, there are other potential applications of this work, such as research related to atmospheric lifetimes and fates of organic compounds, or modelling gas-phase reactions of organics in various environments. This database is freely accessible at https://doi.org/10.25326/36 (McGillen et al., 2019).
Highlights
We find that several laboratories have reported rate coefficients that are considerably larger than would be expected from a simple collision theory calculation
McGillen et al.: Database for the kinetics of the gas-phase atmospheric reactions fined as a compound that possesses no atom type besides carbon and hydrogen and no higher-order bonds – the relatively small number of these compounds relates to the fact that there are fewer possible isomers available within the range of volatility that is convenient for experimentation
Freely available, searchable, and evaluated compilation of chemical kinetic information with a current focus on gas-phase bimolecular reactions
Summary
The composition of realistic atmospheric and combustion chemical mixtures can be forbiddingly complex, as has recently been emphasized by the advent of automated mechanism generation software (Aumont et al, 2005; BattinLeclerc et al, 2011; Carter, 2017; Gao et al, 2016) Such complexity presents a major challenge for chemical modellers, since the physical and chemical properties of the vast majority of oxidation products of volatile organic compounds (VOCs) have not been determined experimentally. Expense, and difficulty of making laboratory measurements, it is clear that with current technologies it will be necessary to estimate or compute the properties of almost all of these compounds To help address this challenge, an expert panel on structure–activity relationship (SAR) evaluation was formed in 2017. The compilation of such data is an essential first step in this process, and is the focus of the current work
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