scholarly journals Interactive comment on “Database for the kinetics of the gas-phase atmospheric reactions of organic compounds”

2020 ◽  
Author(s):  
Anonymous
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Reactions ◽  
Kinetics Of

scholarly journals Database for the kinetics of the gas-phase atmospheric reactions of organic compounds

2020 ◽  
Author(s):  
Max R. McGillen ◽  
William P.L. Carter ◽  
Abdelwahid Mellouki ◽  
John J. Orlando ◽  
Bénédicte Picquet-Varrault ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Degradation Products ◽  
Rate Coefficients ◽  
Training Dataset ◽  
Gas Phase Reactions ◽  
Atmospheric Reactions ◽  
Temperature Dependences ◽  
Potential Applications ◽  
Kinetics Of

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 (McGillen et al., 2019). Although other compilations of much of these data exist, many are out-of-date, most have limited scope, and all are difficult to search and to load completely into a digitized form.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. A large variety of functional groups is 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 were 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).

scholarly journals Database for the kinetics of the gas-phase atmospheric reactions of organic compounds

2020 ◽  
Vol 12 (2) ◽  
pp. 1203-1216 ◽  
Author(s):  
Max R. McGillen ◽  
William P. L. Carter ◽  
Abdelwahid Mellouki ◽  
John J. Orlando ◽  
Bénédicte Picquet-Varrault ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Degradation Products ◽  
Rate Coefficients ◽  
Training Dataset ◽  
Gas Phase Reactions ◽  
Atmospheric Reactions ◽  
Temperature Dependences ◽  
Potential Applications ◽  
Kinetics Of

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).

scholarly journals Supplementary material to "Database for the kinetics of the gas-phase atmospheric reactions of organic compounds"

2020 ◽  
Author(s):  
Max R. McGillen ◽  
William P.L. Carter ◽  
Abdelwahid Mellouki ◽  
John J. Orlando ◽  
Bénédicte Picquet-Varrault ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Atmospheric Reactions ◽  
Supplementary Material ◽  
Kinetics Of

scholarly journals Artifacts in measuring aerosol uptake kinetics: the roles of time, concentration and adsorption

2011 ◽  
Vol 11 (14) ◽  
pp. 6881-6893 ◽  
Author(s):  
L. H. Renbaum ◽  
G. D. Smith
Keyword(s):  
Reaction Time ◽  
Gas Phase ◽  
Separate Flow ◽  
Oh Radicals ◽  
Oxidation Reactions ◽  
Radical Chain ◽  
Atmospheric Reactions ◽  
Radical Concentration ◽  
High Concentrations ◽  
Kinetics Of

Abstract. In laboratory studies of organic aerosol particles reacting with gas-phase oxidants, high concentrations of radicals are often used to study on the timescale of seconds reactions which may be occurring over days or weeks in the troposphere. Implicit in this approach is the assumption that radical concentration and time are interchangeable parameters, though this has not been established. Here, the kinetics of OH- and Cl-initiated oxidation reactions of model single-component liquid (squalane) and supercooled (brassidic acid and 2-octyldodecanoic acid) organic aerosols are studied by varying separately the radical concentration and the reaction time. Two separate flow tubes with residence times of 2 and 66 s are used, and [OH] and [Cl] are varied by adjusting either the laser photolysis fluence or the radical precursor concentration ([O3] or [Cl2], respectively) used to generate the radicals. It is found that the rates measured by varying the radical concentration and the reaction time are equal only if the precursor concentrations are the same in the two approaches. Further, the rates depend on the concentrations of the precursor species with a Langmuir-type functional form suggesting that O3 and Cl2 saturate the surface of the liquid particles. It is believed that the presence of O3 inhibits the rate of OH reaction, perhaps by reacting with OH radicals or by O3 or intermediate species blocking surface sites, while Cl2 enhances the rate of Cl reaction by participating in a radical chain mechanism. These results have important implications for laboratory experiments in which high concentrations of gas-phase oxidants are used to study atmospheric reactions over short timescales and may explain the variability in recent measurements of the reactive uptake of OH on squalane particles in reactor systems used in this and other laboratories.

scholarly journals Artifacts in measuring aerosol uptake kinetics: the roles of time, concentration and adsorption

2011 ◽  
Vol 11 (3) ◽  
pp. 7971-8002 ◽  
Author(s):  
L. H. Renbaum ◽  
G. D. Smith
Keyword(s):  
Reaction Time ◽  
Gas Phase ◽  
Separate Flow ◽  
Oh Radicals ◽  
Oxidation Reactions ◽  
Radical Chain ◽  
Atmospheric Reactions ◽  
Radical Concentration ◽  
High Concentrations ◽  
Kinetics Of

Abstract. In laboratory studies of organic aerosol particles reacting with gas-phase oxidants, high concentrations of radicals are often used to study on the timescale of seconds reactions which may be occurring over days or weeks in the troposphere. Implicit in this approach is the assumption that radical concentration and time are interchangeable parameters, though this has not been established. Here, the kinetics of OH- and Cl-initiated oxidation reactions of model single-component liquid organic aerosols (squalane, brassidic acid and 2-octyldodecanoic acid) are studied by varying separately the radical concentration and the reaction time. Two separate flow tubes with residence times of 2 and 66 s are used, and [OH] and [Cl] are varied by adjusting either the laser photolysis fluence or the radical precursor concentration ([O3] or [Cl2], respectively) used to generate the radicals. It is found that the rates measured by varying the radical concentration and the reaction time are equal only if the precursor concentrations are the same in the two approaches. Further, the rates depend on the concentrations of the precursor species with a Langmuir-type functional form suggesting that O3 and Cl2 saturate the surface of the liquid particles. It is believed that the presence of O3 inhibits the rate of OH reaction, perhaps by reacting with OH radicals or blocking surface sites, while Cl2 enhances the rate of Cl reaction by participating in a radical chain mechanism. These results have important implications for laboratory experiments in which high concentrations of gas-phase oxidants are used to study atmospheric reactions over short timescales and may explain the variability in recent measurements of the reactive uptake of OH on squalane particles in reactor systems used in this and other laboratories.

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