OH- and O<sub>3</sub>-initiated atmospheric degradation of camphene: temperature dependent rate coefficients, product yields and mechanisms

Gaona-Colmán, Elizabeth; Blanco, Marı́a B.; Barnes, Ian; Wiesen, Peter; Teruel, Mariano A.

doi:10.1039/c6ra26656h

Cited by 20 publications

(19 citation statements)

References 58 publications

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“…Whilst the majority of our data is in good agreement with the internally consistent literature data set, the wider literature contains measurements for many of the compounds not included in the IUPAC evaluations or the review paper, Atkinson and Arey (2003). For example, a recent measurement of the oxidation of -ocimene by OH provided a rate coefficient of 236 (± 54) × 10 -12 cm 3 molecule -1 s -1 , which is in good agreement with our own result for the same reaction, of 222 (± 7) × 10 -12 cm 3 molecule -1 s -1 (Gaona-Colmán et al, 2016). Recent measurements of the OH + myrcene reaction rate, by Hites and Turner (2009) and Kim et al (2011) are 50% greater than that calculated in this work.…”

Section: Results From Relative Rate Experiments At 295 Ksupporting

confidence: 81%

Authors' comments

Shaw¹

2018

Preprint

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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 ( 0.3)  10-11 cm 3 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.

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Section: Results From Relative Rate Experiments At 295 Ksupporting

confidence: 81%

Authors' comments

Shaw¹

2018

Preprint

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“…An average lifetime of MT of (4 ± 2) h (largest at night), resulting from reactions with OH, NO3 and O3 (see Table S2), was calculated from the mean MT composition measured by GC-AED (49 % α-pinene, 13 % β-pinene, 27 % Δ-carene, 3 % Δlimonene and 8 % camphene) and corresponding rate coefficients (Perring et al, 2013;Gaona-Colman et al, 2017;IUPAC, 2020).…”

Section: Autumn Campaign (Ibairn): Pyruvic Acid Emission Rate Relativmentioning

confidence: 99%

Modelling the impact of gas-phase pyruvic acid on acetaldehyde and peroxy radical formation in the boreal forest

Eger

Schuladen

Sobanski

et al. 2020

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Abstract. Based on the first measurements of gas-phase pyruvic acid (CH3C(O)C(O)OH) in the boreal forest, we derive effective emission rates of pyruvic acid and compare them with monoterpene emission rates over the diel cycle. Using a data-constrained box-model, we determine the impact of pyruvic acid photolysis on the formation of acetaldehyde (CH3CHO) and the peroxy radicals CH3C(O)O2, CH3O2 and HO2 during an autumn (IBAIRN) and summer (HUMPPA) campaign at the same site. The results are dependent on the photodissociation mechanism of pyruvic acid and we examine different scenarios in which the main photolysis products are either acetaldehyde or the CH3C(O)O2 radical, with different overall quantum yields. If CH3CHO is taken to be the main product (as presently recommended by evaluation panels) we find that pyruvic acid photolysis can be a dominant source of this aldehyde in the boreal forest with a contribution of 79 % (IBAIRN) and 94 % (HUMPPA) and may help explain the high acetaldehyde levels observed during HUMPPA. On the other hand, if photolysis leads mainly to the formation of radicals, the emission of pyruvic acid has a profound impact on the rates of formation of peroxy radicals (with a contribution of ~20–50 %) and shifts the onset of radical production to earlier in the morning when actinic flux is dominated by wavelengths that are too long to initiate efficient ozone photolysis but which are absorbed by pyruvic acid.

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“…The O 3 reactions with unsaturated compounds are initiated by the 1,3-dipolar addition of O 3 to the C]C bond through a transition state (TS), which leads to the production of a primary ozonide (POZ). 24,37,38 Scheme 1 illustrates the mechanism of cis-3-hexenyl formate with O 3 . Structures of the reactants, the transition states (TS) and the primary ozonide for the reaction of O 3 with cis-3-hexenyl formate are given in Fig.…”

Section: Reaction Mechanism and Theoretical Rate Constantsmentioning

confidence: 99%

Kinetic and mechanistic study on gas phase reactions of ozone with a series ofcis-3-hexenyl esters

et al. 2018

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OH- and O₃-initiated atmospheric degradation of camphene: temperature dependent rate coefficients, product yields and mechanisms

Abstract: Gas-phase rate coefficients for the reactions of OH and O3 with camphene have been measured over the temperature range 288–311 K using the relative rate method.

Cited by 20 publications

References 58 publications

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Authors' comments

Modelling the impact of gas-phase pyruvic acid on acetaldehyde and peroxy radical formation in the boreal forest

Kinetic and mechanistic study on gas phase reactions of ozone with a series ofcis-3-hexenyl esters

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OH- and O3-initiated atmospheric degradation of camphene: temperature dependent rate coefficients, product yields and mechanisms

Abstract: Gas-phase rate coefficients for the reactions of OH and O3 with camphene have been measured over the temperature range 288–311 K using the relative rate method.

Cited by 20 publications

References 58 publications

Authors' comments

Authors' comments

Modelling the impact of gas-phase pyruvic acid on acetaldehyde and peroxy radical formation in the boreal forest

Kinetic and mechanistic study on gas phase reactions of ozone with a series ofcis-3-hexenyl esters

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OH- and O₃-initiated atmospheric degradation of camphene: temperature dependent rate coefficients, product yields and mechanisms