scholarly journals Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aliphatic organic compounds for use in automated mechanism construction

2018 ◽  
Vol 18 (13) ◽  
pp. 9297-9328 ◽  
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Andrew R. Rickard ◽  
Timothy J. Wallington
Keyword(s):  
Organic Compounds ◽  
Companion Paper ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Transport Models ◽  
Chemical Mechanisms ◽  
Oxidation Rates ◽  
Oh Reactions ◽  
The Given ◽  
Detailed Chemical

Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models, and are required more generally for impact assessments involving the estimation of atmospheric lifetimes or oxidation rates for VOCs. Updated and extended structure–activity relationship (SAR) methods are presented for the reactions of OH with aliphatic organic compounds, with the reactions of aromatic organic compounds considered in a companion paper. The methods are optimized using a preferred set of data including reactions of OH with 489 aliphatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The information can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the subsequent reactions of the product radicals under tropospheric conditions are also summarized, specifically their reactions with O2 and competing processes.

scholarly journals Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aliphatic organic compounds for use in automated mechanism construction

2018 ◽  
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Andrew R. Rickard ◽  
Timothy J. Wallington
Keyword(s):  
Organic Compounds ◽  
Companion Paper ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Transport Models ◽  
Chemical Mechanisms ◽  
Oxidation Rates ◽  
Oh Reactions ◽  
The Given ◽  
Detailed Chemical

Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry-transport models, and are required more generally for impact assessments involving estimation of atmospheric lifetimes or oxidation rates for VOCs. Updated and extended structure-activity relationship (SAR) methods are presented for the reactions of OH with aliphatic organic compounds, with the reactions of aromatic organic compounds considered in a companion paper. The methods are optimized using a preferred set of data including reactions of OH with 489 aliphatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The information can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the subsequent reactions of the product radicals under tropospheric conditions are also summarized, specifically their reactions with O2 and competing processes.

scholarly journals Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aromatic organic compounds for use in automated mechanism construction

2018 ◽  
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Andrew R. Rickard ◽  
Timothy J. Wallington
Keyword(s):  
Organic Compounds ◽  
Companion Paper ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Transport Models ◽  
Chemical Mechanisms ◽  
Oxidation Rates ◽  
Oh Reactions ◽  
The Given ◽  
Detailed Chemical

Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for the reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry-transport models, and are required more generally for impact assessments involving estimation of atmospheric lifetimes or oxidation rates for VOCs. A structure-activity relationship (SAR) method is presented for the reactions of OH with aromatic organic compounds, with the reactions of aliphatic organic compounds considered in the preceding companion paper. The SAR is optimized using a preferred set of data including reactions of OH with 67 monocyclic aromatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The SAR can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the reactions of the product radicals under tropospheric conditions are also summarized, specifically the rapid reaction sequences initiated by their reactions with O2.

scholarly journals Estimation of rate coefficients and branching ratios for gas-phase reactions of OH with aromatic organic compounds for use in automated mechanism construction

2018 ◽  
Vol 18 (13) ◽  
pp. 9329-9349 ◽  
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Andrew R. Rickard ◽  
Timothy J. Wallington
Keyword(s):  
Organic Compounds ◽  
Companion Paper ◽  
Rate Coefficients ◽  
Gas Phase Reactions ◽  
Transport Models ◽  
Chemical Mechanisms ◽  
Oxidation Rates ◽  
Oh Reactions ◽  
The Given ◽  
Detailed Chemical

Abstract. Reaction with the hydroxyl (OH) radical is the dominant removal process for volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for the reactions of OH with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models, and are required more generally for impact assessments involving estimation of atmospheric lifetimes or oxidation rates for VOCs. A structure–activity relationship (SAR) method is presented for the reactions of OH with aromatic organic compounds, with the reactions of aliphatic organic compounds considered in the preceding companion paper. The SAR is optimized using a preferred set of data including reactions of OH with 67 monocyclic aromatic hydrocarbons and oxygenated organic compounds. In each case, the rate coefficient is defined in terms of a summation of partial rate coefficients for H abstraction or OH addition at each relevant site in the given organic compound, so that the attack distribution is defined. The SAR can therefore guide the representation of the OH reactions in the next generation of explicit detailed chemical mechanisms. Rules governing the representation of the reactions of the product radicals under tropospheric conditions are also summarized, specifically the rapid reaction sequences initiated by their reactions with O2.

scholarly journals Estimation of rate coefficients for the reactions of O<sub>3</sub> with unsaturated organic compounds for use in automated mechanism construction

2020 ◽  
Vol 20 (21) ◽  
pp. 12921-12937
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Mike J. Newland ◽  
Andrew R. Rickard
Keyword(s):  
Double Bond ◽  
Organic Compounds ◽  
Branching Ratios ◽  
Rate Coefficients ◽  
Transport Models ◽  
Site Specific ◽  
Chemical Mechanisms ◽  
Structure Activity ◽  
Volatile Organic ◽  
Detailed Chemical

Abstract. Reaction with ozone (O3) is an important removal process for unsaturated volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for reactions of O3 with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models. Updated and extended structure–activity relationship (SAR) methods are presented for the reactions of O3 with mono- and poly-unsaturated organic compounds. The methods are optimized using a preferred set of data including reactions of O3 with 221 unsaturated compounds. For conjugated dialkene structures, site-specific rates are defined, and for isolated poly-alkenes rates are defined for each double bond to determine the branching ratios for primary ozonide formation. The information can therefore guide the representation of the O3 reactions in the next generation of explicit detailed chemical mechanisms.

scholarly journals Estimation of rate coefficients for the reactions of O<sub>3</sub> with unsaturated organic compounds for use in automated mechanism construction

2020 ◽  
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Mike J. Newland ◽  
Andrew R. Rickard
Keyword(s):  
Double Bond ◽  
Organic Compounds ◽  
Branching Ratios ◽  
Rate Coefficients ◽  
Transport Models ◽  
Site Specific ◽  
Chemical Mechanisms ◽  
Structure Activity ◽  
Volatile Organic ◽  
Detailed Chemical

Abstract. Reaction with ozone (O3) is an important removal process for unsaturated volatile organic compounds (VOCs) in the atmosphere. Rate coefficients for reactions of O3 with VOCs are therefore essential parameters for chemical mechanisms used in chemistry transport models. Updated and extended structure–activity relationship (SAR) methods are presented for the reactions of O3 with mono- and poly-unsaturated organic compounds. The methods are optimized using a preferred set of data including reactions of O3 with 222 unsaturated compounds. For conjugated dialkene structures, site specific rates are defined, and for isolated poly-alkenes rates are defined for each double bond to determine the branching ratios for primary ozonide formation. The information can therefore guide the representation of the O3 reactions in the next generation of explicit detailed chemical mechanisms.

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 Estimation of rate coefficients and branching ratios for reactions of organic peroxy radicals for use in automated mechanism construction

2019 ◽  
Vol 19 (11) ◽  
pp. 7691-7717 ◽  
Author(s):  
Michael E. Jenkin ◽  
Richard Valorso ◽  
Bernard Aumont ◽  
Andrew R. Rickard
Keyword(s):  
Branching Ratio ◽  
Ring Closure ◽  
Rate Coefficients ◽  
Peroxy Radicals ◽  
Ambient Conditions ◽  
Bimolecular Reactions ◽  
Chemical Mechanisms ◽  
Ratio Data ◽  
Oxidation Mechanisms ◽  
Detailed Chemical

Abstract. Organic peroxy radicals (RO2), formed from the degradation of hydrocarbons and other volatile organic compounds (VOCs), play a key role in tropospheric oxidation mechanisms. Several competing reactions may be available for a given RO2 radical, the relative rates of which depend on both the structure of RO2 and the ambient conditions. Published kinetics and branching ratio data are reviewed for the bimolecular reactions of RO2 with NO, NO2, NO3, OH and HO2; and for their self-reactions and cross-reactions with other RO2 radicals. This information is used to define generic rate coefficients and structure–activity relationship (SAR) methods that can be applied to the bimolecular reactions of a series of important classes of hydrocarbon and oxygenated RO2 radicals. Information for selected unimolecular isomerization reactions (i.e. H-atom shift and ring-closure reactions) is also summarized and discussed. The methods presented here are intended to guide the representation of RO2 radical chemistry in the next generation of explicit detailed chemical mechanisms.

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