scholarly journals Rate coefficients for reactions of OH with aromatic and aliphatic volatile organic compounds determined by the multivariate relative rate technique

2020 ◽  
Vol 20 (16) ◽  
pp. 9725-9736
Author(s):  
Jacob T. Shaw ◽  
Andrew R. Rickard ◽  
Mike J. Newland ◽  
Terry J. Dillon
Keyword(s):  
Relative Rate ◽  
Ozone Production ◽  
Rate Coefficients ◽  
Phase Reaction ◽  
Air Masses ◽  
Volatile Organic ◽  
Aromatic Species ◽  
Simultaneous Study ◽  
Oxidation Chemistry ◽  
Alkyl Benzenes

Abstract. The multivariate relative rate method was applied to a range of volatile organic compound (VOC) reactions with OH. This previously published method (Shaw et al., 2018) was improved to increase the sensitivity towards more slowly reacting VOCs, broadening the range of compounds which can be examined. A total of 35 room temperature relative rate coefficients were determined, eight of which have not previously been reported. Five of the new reaction rate coefficients were for large alkyl substituted mono-aromatic species recently identified in urban air masses, likely with large ozone production potentials. The new results (with kOH (296 K) values in units of 10−12 cm3 molec.−1 s−1) were n-butylbenzene, 11 (±4); n-pentylbenzene, 7 (±2); 1,2-diethylbenzene, 14 (±4); 1,3-diethylbenzene, 22 (±4); and 1,4-diethylbenzene, 16 (±4). Interestingly, whilst results for smaller VOCs agreed well with available structure–activity relationship (SAR) calculations, the larger alkyl benzenes were found to be less reactive than the SAR prediction, indicating that our understanding of the oxidation chemistry of these compounds is still limited. kOH (296 K) rate coefficients (in units of 10−12 cm3 molec.−1 s−1) for reactions of three large alkanes with OH were also determined for the first time: 2-methylheptane, 9.1 (±0.3); 2-methylnonane, 11.0 (±0.3); and ethylcyclohexane, 14.4 (±0.3), all in reasonable agreement with SAR predictions. Rate coefficients for the 27 previously studied OH + VOC reactions agreed well with available literature values, lending confidence to the application of this method for the rapid and efficient simultaneous study of gas-phase reaction kinetics.

scholarly journals Rate coefficients for reactions of OH with aromatic and aliphatic volatile organic compounds determined by the Multivariate Relative Rate Technique

2020 ◽  
Author(s):  
Jacob T. Shaw ◽  
Andrew R. Rickard ◽  
Mike J. Newland ◽  
Terry J. Dillon
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Relative Rate ◽  
Ozone Production ◽  
Rate Coefficients ◽  
Phase Reaction ◽  
Volatile Organic ◽  
Simultaneous Study ◽  
Oxidation Chemistry ◽  
Alkyl Benzenes

Abstract. The multivariate relative rate method was applied to a range of volatile organic compounds (VOC) reactions with OH. This previously published method (Shaw et al., 2018b) was improved to increase the sensitivity towards slower reacting VOC, broadening the range of compounds which can be examined. A total of thirty-five room temperature relative rate coefficients were determined; eight of which have not previously been reported. Five of the new reaction rate coefficients were for large alkyl substituted monoaromatic species recently identified in urban air masses, likely with large ozone production potentials. The new results (with kOH (296 K) values in units of 10–12 cm3 molecule−1 s−1) were: n-butylbenzene, 11 (± 4); n-pentylbenzene, 7 (± 2); 1,2-diethylbenzene, 14 (± 4); 1,3-diethylbenzene, 22 (± 4) and 1,4-diethylbenzene, 16 (± 4). Interestingly, whilst results for smaller VOC agreed well with available structure activity relationship (SAR) calculations, the larger alkyl benzenes were found to be less reactive than the SAR prediction, indicating that our understanding of the oxidation chemistry of these compounds is still limited. kOH (296 K) rate coefficients (in units of 10–12 cm3 molecule−1 s−1) for reactions of three large alkanes with OH were also determined for the first time: 2-methylheptane, 9.1 (± 0.3); 2-methylnonane, 11.0 (± 0.3) and ethylcyclohexane, 14.4 (± 0.3), all in reasonable agreement with SAR predictions. Rate coefficients for the twenty-seven previously studied OH + VOC reactions agreed well with available literature values, lending confidence to the application of this method for the rapid and efficient simultaneous study of gas-phase reaction kinetics.

scholarly journals Direct and relative rate coefficients for the gas-phase reaction of OH radicals with 2-methyltetrahydrofuran at room temperature

2016 ◽  
Vol 119 (1) ◽  
pp. 5-18
Author(s):  
Ádám Illés ◽  
Mária Farkas ◽  
Gábor László Zügner ◽  
Gyula Novodárszki ◽  
Magdolna Mihályi ◽  
...  
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Relative Rate ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
Gas Phase Reaction ◽  
Relative Rate Coefficients

scholarly journals Rate coefficients for the reaction of methylglyoxal (CH<sub>3</sub>COCHO) with OH and NO<sub>3</sub> and glyoxal (HCO)<sub>2</sub> with NO<sub>3</sub>

2011 ◽  
Vol 11 (21) ◽  
pp. 10837-10851 ◽  
Author(s):  
R. K. Talukdar ◽  
L. Zhu ◽  
K. J. Feierabend ◽  
J. B. Burkholder
Keyword(s):  
Relative Rate ◽  
Order Conditions ◽  
Rate Coefficients ◽  
Oh Radicals ◽  
Phase Reaction ◽  
First Order ◽  
No3 Radical ◽  
Pseudo First Order ◽  
Arrhenius Expression ◽  
Coefficient Method

Abstract. Rate coefficients, k, for the gas-phase reaction of CH3COCHO (methylglyoxal) with the OH and NO3 radicals and (CHO)2 (glyoxal) with the NO3 radical are reported. Rate coefficients for the OH + CH3COCHO (k1) reaction were measured under pseudo-first-order conditions in OH as a function of temperature (211–373 K) and pressure (100–220 Torr, He and N2 bath gases) using pulsed laser photolysis to produce OH radicals and laser induced fluorescence to measure its temporal profile. k1 was found to be independent of the bath gas pressure with k1(295 K) = (1.29 ± 0.13) × 10−11 cm3 molecule−1 s−1 and a temperature dependence that is well represented by the Arrhenius expression k1(T) = (1.74 ± 0.20) × 10−12 exp[(590 ± 40)/T] cm3 molecule−1 s−1 where the uncertainties are 2σ and include estimated systematic errors. Rate coefficients for the NO3 + (CHO)2 (k3) and NO3 + CH3COCHO (k4) reactions were measured using a relative rate technique to be k3(296 K) = (4.0 ± 1.0) × 10−16 cm3 molecule−1 s−1 and k4(296 K) = (5.1 ± 2.1) × 10−16 cm3 molecule−1 s−1. k3(T) was also measured using an absolute rate coefficient method under pseudo-first-order conditions at 296 and 353 K to be (4.2 ± 0.8) × 10−16 and (7.9 ± 3.6) × 10−16 cm3 molecule−1 s−1, respectively, in agreement with the relative rate result obtained at room temperature. The atmospheric implications of the OH and NO3 reaction rate coefficients measured in this work are discussed.

scholarly journals Kinetic study of the gas-phase reaction of atomic chlorine with a series of aldehydes

2005 ◽  
Vol 5 (12) ◽  
pp. 3433-3440 ◽  
Author(s):  
D. Rodríguez ◽  
A. Rodríguez ◽  
A. Notario ◽  
A. Aranda ◽  
Y. Díaz-de-Mera ◽  
...  
Keyword(s):  
Relative Rate ◽  
Weighted Average ◽  
Rate Coefficients ◽  
Phase Reaction ◽  
Additional Information ◽  
Relative Rate Constants ◽  
Relative Measurements ◽  
First Time ◽  
Structure Versus ◽  
Atomic Chlorine

Abstract. The reactions of Cl atoms with a series of unsaturated aldehydes have been investigated for the first time using a relative method. In order to obtain additional information for a qualitative structure versus reactivity discussion, we have also determined the rate coefficients for the reactions of atomic chlorine with their respective saturated aldehydes. These relative measurements were performed at room temperature and atmospheric pressure of air and N2, by using ethane, propene and 1-butene as reference compounds. The weighted average relative rate constants obtained, kCl±2σ (in units of cm3 molecule−1 s−1) were: trans-2-pentenal (1.31±0.19)×10−10; trans-2-hexenal (1.92±0.22)×10−10; trans-2-heptenal (2.40±0.29)×10−10; n-pentanal (2.56±0.27)×10−10; n-hexanal (2.88±0.37)×10−10; n-heptanal (3.00±0.34)×10−10. Finally, results and atmospheric implications are discussed and compared with the reactivity with OH and NO3 radicals.

scholarly journals Sources and photochemistry of volatile organic compounds in the remote atmosphere of western China: results from the Mt. Waliguan Observatory

2013 ◽  
Vol 13 (5) ◽  
pp. 11745-11788 ◽  
Author(s):  
L. K. Xue ◽  
T. Wang ◽  
H. Guo ◽  
D. R. Blake ◽  
J. Tang ◽  
...  
Keyword(s):  
Air Pollution ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Late Spring ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Western China ◽  
Air Masses ◽  
Eurasian Continent ◽  
Volatile Organic

Abstract. The chemistry of the natural atmosphere and the influence by long-range transport of air pollution are key issues in the atmospheric sciences. Here we present two intensive field measurements of volatile organic compounds (VOCs) in late spring and summer of 2003 at Mt. Waliguan (WLG, 36.28° N, 100.90° E, 3816 m a.s.l.), a baseline station in the northeast part of Qinghai-Tibetan Plateau. Most VOC species exhibited higher concentrations in late spring than in summer. A typical diurnal variation was observed with higher nighttime levels, in contrast to results from other mountainous sites. Five different air masses were identified from backward trajectory analysis showing distinct VOC speciation. Air masses originating from the central Eurasian continent contained the lowest VOC levels compared to the others that were impacted by anthropogenic emissions from China and the Indian sub-continent. The data were compared with the TRACE-P (Transport and Chemical Evolution over the Pacific) data to examine the inflow and outflow of air pollution over the China sub-continent. The results show that the free troposphere over China may be affected by the inflow from the Eurasian continent in spring, and the emissions in China may not have a significant influence on the free tropospheric outflow. A photochemical box model based on the Master Chemical Mechanism (version 3.2) and constrained by a full suite of measurements was developed to probe the photochemistry of atmosphere at WLG. Our results show net ozone production from in-situ photochemistry during both late spring and summer. Oxidation of nitric oxide (NO) by the hydroperoxyl radical (HO2) dominates the ozone production relative to the oxidation by the organic peroxy radicals (RO2), and the ozone is primarily destroyed by photolysis and reactions with the HOx(HOx = OH + HO2) radicals. Ozone photolysis is the predominant primary source of radicals (ROx = OH + HO2 + RO2), followed by the photolysis of oxygenated VOCs and hydrogen peroxides. The radical losses are governed by the self and cross reactions among the radicals. The findings can provide insights into the background chemistry and the impacts of pollution transport on the pristine atmosphere over the Eurasian continent.

scholarly journals A self-consistent, multivariate method for the determination of gas-phase rate coefficients, applied to reactions of atmospheric VOCs and the hydroxyl radical

2018 ◽  
Vol 18 (6) ◽  
pp. 4039-4054 ◽  
Author(s):  
Jacob T. Shaw ◽  
Richard T. Lidster ◽  
Danny R. Cryer ◽  
Noelia Ramirez ◽  
Fiona C. Whiting ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Rate Coefficient ◽  
Relative Rate ◽  
Ambient Air ◽  
Rate Coefficients ◽  
Oxidation Reactions ◽  
Simultaneous Study ◽  
The University ◽  
Good Agreement

Abstract. Gas-phase rate coefficients are fundamental to understanding atmospheric chemistry, yet experimental data are not available for the oxidation reactions of many of the thousands of volatile organic compounds (VOCs) observed in the troposphere. Here, a new experimental method is reported for the simultaneous study of reactions between multiple different VOCs and OH, the most important daytime atmospheric radical oxidant. This technique is based upon established relative rate concepts but has the advantage of a much higher throughput of target VOCs. By evaluating multiple VOCs in each experiment, and through measurement of the depletion in each VOC after reaction with OH, the OH + VOC reaction rate coefficients can be derived. Results from experiments conducted under controlled laboratory conditions were in good agreement with the available literature for the reaction of 19 VOCs, prepared in synthetic gas mixtures, with OH. This approach was used to determine a rate coefficient for the reaction of OH with 2,3-dimethylpent-1-ene for the first time; k =  5.7 (±0.3)  ×  10−11 cm3 molecule−1 s−1. In addition, a further seven VOCs had only two, or fewer, individual OH rate coefficient measurements available in the literature. The results from this work were in good agreement with those measurements. A similar dataset, at an elevated temperature of 323 (±10) K, was used to determine new OH rate coefficients for 12 aromatic, 5 alkane, 5 alkene and 3 monoterpene VOC + OH reactions. In OH relative reactivity experiments that used ambient air at the University of York, a large number of different VOCs were observed, of which 23 were positively identified. Due to difficulties with detection limits and fully resolving peaks, only 19 OH rate coefficients were derived from these ambient air samples, including 10 reactions for which data were previously unavailable at the elevated reaction temperature of T =  323 (±10) K.

scholarly journals A self-consistent, multi-variate method for the determination of gas phase rate coefficients, applied to reactions of atmospheric VOCs and the hydroxyl radical

2017 ◽  
Author(s):  
Jacob T. Shaw ◽  
Richard T. Lidster ◽  
Danny R. Cryer ◽  
Noelia Ramirez ◽  
Graham A. Boustead ◽  
...  
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Rate Coefficient ◽  
Relative Rate ◽  
Ambient Air ◽  
Rate Coefficients ◽  
Oxidation Reactions ◽  
Oh Reactions ◽  
Simultaneous Study ◽  
Good Agreement

Abstract. Gas-phase rate coefficients are fundamental to understanding atmospheric chemistry, yet experimental data are not available for the oxidation reactions of many of the thousands of volatile organic compounds (VOCs) observed in the troposphere. Here a new experimental method is reported for the simultaneous study of reactions between multiple different VOCs and OH, the most important daytime atmospheric radical oxidant. This technique is based upon established relative rate concepts but has the advantage of a much higher throughput of target VOCs. By evaluating multiple VOCs in each experiment, and through measurement of the depletion in each VOC after reaction with OH, the OH + VOC reaction rate coefficients can be derived. Results from experiments conducted under controlled laboratory conditions were in good agreement with the available literature for the reaction of nineteen VOCs, prepared in synthetic gas mixtures, with OH. This approach was used to determine a rate coefficient for the reaction of OH with 2,3-dimethylpent-1-ene for the first time; k = 5.7 (&amp;pm;0.3) × 10–11–cm3 molecule−1 s−1. In addition, a further seven VOCs had only two, or fewer, individual OH rate coefficient measurements available in the literature. The results from this work were in good agreement with those measurements. A similar dataset, at an elevated temperature of 323 (±10) K, was used to determine new OH rate coefficients for twelve aromatic, five alkane, five alkene and three monoterpene VOC + OH reactions. In OH relative reactivity experiments that used ambient air at the University of York, a large number of different VOCs were observed, of which 23 were positively identified. 19 OH rate coefficients were derived from these ambient air samples, including ten reactions for which data was previously unavailable at the elevated reaction temperature of T = 323 (±10) K.

scholarly journals Sources and photochemistry of volatile organic compounds in the remote atmosphere of western China: results from the Mt. Waliguan Observatory

2013 ◽  
Vol 13 (17) ◽  
pp. 8551-8567 ◽  
Author(s):  
L. K. Xue ◽  
T. Wang ◽  
H. Guo ◽  
D. R. Blake ◽  
J. Tang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Late Spring ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Western China ◽  
Pollution Transport ◽  
Air Masses ◽  
Eurasian Continent ◽  
Volatile Organic

Abstract. The chemistry of the natural atmosphere and the influence by long-range transport of air pollution are key issues in the atmospheric sciences. Here we present two intensive field measurements of volatile organic compounds (VOCs) in late spring and summer of 2003 at Mt. Waliguan (WLG, 36.28° N, 100.90° E, 3816 m a.s.l.), a baseline station in the northeast part of the Qinghai-Tibetan Plateau. Most VOC species exhibited higher concentrations in late spring than in summer. A typical diurnal variation was observed with higher nighttime levels, in contrast to results from other mountainous sites. Five different air masses were identified from backward trajectory analysis showing distinct VOC speciation. Air masses originating from the central Eurasian continent contained the lowest VOC levels compared to the others that were impacted by anthropogenic emissions from China and the Indian subcontinent. A photochemical box model based on the Master Chemical Mechanism (version 3.2) and constrained by a full suite of measurements was developed to probe the photochemistry of atmosphere at WLG. Our results show net ozone production from in situ photochemistry during both late spring and summer. Oxidation of nitric oxide (NO) by the hydroperoxyl radical (HO2) dominates the ozone production relative to the oxidation by the organic peroxy radicals (RO2), and the ozone is primarily destroyed by photolysis and reactions with the HOx (HOx = OH + HO2) radicals. Ozone photolysis is the predominant primary source of radicals (ROx = OH + HO2 + RO2), followed by the photolysis of secondary oxygenated VOCs and hydrogen peroxides. The radical losses are governed by the self and cross reactions among the radicals. Overall, the findings of the present study provide insights into the background chemistry and the impacts of pollution transport on the pristine atmosphere over the Eurasian continent.

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