Measurement of the organic nitrate yield from OH reaction with isoprene

Chen, Xiaohui; Hulbert, D.G.; Shepson, P. B.

doi:10.1029/98jd01483

Cited by 150 publications

(200 citation statements)

References 24 publications

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“…Since the ratio of nitrate formation increases with the number of carbon atoms of the parent molecule, it was expected that the branching ratio of formation of the secondary nitrate from a-pinene would be larger than the corresponding ratio for 2-hexyl nitrate (19%) or cyclohexane (7-16%) [Lightfoot et al, 1991, and references therein]. However, as discussed in a recent work [Chen et al, 1998], the presence of the/3-hydroxy group next to the nitrate group should lower this branching ratio compared to the similar nitrate compound without the/3-hydroxy group.…”

Section: Reaction Of T•-pinene Withmentioning

confidence: 94%

Product study and mechanisms of the reactions of α‐pinene and of pinonaldehyde with OH radicals

Nozière¹,

Barnes²,

Becker³

1999

J. Geophys. Res.

177

192

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Abstract. The reactions of a-pinene and of its main oxidation product, pinonaldehyde (3-acetyl-2,2-dimethyl-cyclobutyl-ethanal), with OH radicals have been studied in the laboratory using Fourier transform infrared spectroscopy for real-time monitoring of the gas-phase chemical species and a Scanning Mobility Particle Sizer system (3071 A, TSI) for the study of the secondary aerosol formation. All gas-phase molar yields were quantified using calibrated reference of the pure compound, except for the nitrates products. The results were: for the a-pinene experiments in the presence of NOx, pinonaldehyde, (87 _ 20)%; total nitrates (18 _+ 9)%; formaldehyde, (23 +_ 9)%; acetone (9 _ 6)%; for the a-pinene experiments in the absence of NOx: pinonaldehyde, (37 _+ 7)%; formaldehyde, (8 _ 1)%; acetone, (7 _+ 2)%; for the pinonaldehyde experiments in the presence of NO, formaldehyde (152 _ 56)% and acetone (15 _+ 7)%. The aerosol measurements showed that the condensed products accounted for the missing carbon in the gas-phase balance. The partitioning of the products into the condensed phase was found to be potentially .significant under experimental conditions but less than 10% for initial a-pinene concentrations lower than 1013 molecule cm -3 and hence negligible under atmospheric conditions in the absence of aerosol seeds. On the basis of these results a comprehensive mechanism for the gas-phase reaction of a-pinene with OH in the presence of NOx has been proposed, including quantitative values for all the involved branching ratios. al., 1998], have been studied in laboratory. These studies have generally focused on the first oxidation step and only a few products have been quantified. Pinonaldehyde (3-acetyl-2,2-dimethyl-cyclobutyl-ethanal) was found to be the main product but has never been quantified on an absolute basis by means of a calibrated sample of the pure compound. The only other reaction product identified and quantified is acetone. Moreover, most of the studies have not taken into account the condensed products formed by these reactions, which may represent a significant fraction of the carbon balance under laboratory conditions as it will be shown in the present work. As a result, the understanding of the mechanism for the reaction of a-pinene with OH radicals remained difficult. Furthermore, secondary oxidation steps such as the further reactions of pinonaldehyde, which are important to assess the overall effect of a-pinene on tropospheric chemistry, have never been studied.In the present work, the mechanism of the reaction of a-pinene with OH radicals has been studied. Several gas-phase products such as pinonaldehyde, alkyl nitrates, acetone, and formaldehyde, have been identified and, except for the alkyInitrates, quantified using calibrated reference samples. This work also gives a first insight into the oxidation mechanism beyond the initial oxidation step by studying the reaction of pinonaldehyde with OH radicals. A quantification of the condensed products formed in these reactions has been performe...

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Section: Reaction Of T•-pinene Withmentioning

confidence: 94%

Product study and mechanisms of the reactions of α‐pinene and of pinonaldehyde with OH radicals

Nozière¹,

Barnes²,

Becker³

1999

J. Geophys. Res.

177

192

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“…The chamber is described in detail elsewhere (Chen et al, 1998). NO 3 and N 2 O 5 were produced in the chamber, via reactions 1 and 2, by injecting 400 ppbv of NO 2 and 145 ppbv of O 3 into dry zero air and allowing the mixture to react for ∼4 h.…”

Section: Methodsmentioning

confidence: 99%

A product study of the isoprene+NO<sub>3</sub> reaction

et al. 2009

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Abstract. Oxidation of isoprene through reaction with NO 3 radicals is a significant sink for isoprene that persists after dark. The main products of the reaction are multifunctional nitrates. These nitrates constitute a significant NO x sink in the nocturnal boundary layer and they likely play an important role in formation of secondary organic aerosol. Products of the isoprene+NO 3 reaction will, in many locations, be abundant enough to affect nighttime radical chemistry and to persist into daytime where they may represent a source of NO x . Product formation in the isoprene + NO 3 reaction was studied in a smog chamber at Purdue University. Isoprene nitrates and other hydrocarbon products were observed using Proton Transfer Reaction-Mass Spectrometry (PTR-MS) and reactive nitrogen products were observed using Thermal Dissociation-Laser Induced Fluorescence (TD-LIF). The organic nitrate yield is found to be 65±12% of which the majority was nitrooxy carbonyls and the combined yield of methacrolein and methyl vinyl ketone (MACR+MVK) is found to be ∼10%. PTR-MS measurements of nitrooxy carbonyls and TD-LIF measurements of total organic nitrates agreed well. The PTR-MS also observed a series of minor oxidation products which were tentatively identified and their yields quantified These other oxidation products are used as additional constraints on the reaction mechanism.

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“…Previous estimates for the isoprene nitrate yield, α, span a very large range. Chen et al (1998) reported an overall yield of 4.4%, Chuong and Stevens (2002), 15% using an indirect method, Sprengnether et al (2002), 12%, Patchen et al (2007), 7% at 130 hPa. Using experimental yields collected for compounds similar to isoprene, Giacopelli et al (2005) estimated the nitrate yield of the β and δ-hydroxy isoprene nitrates to be respectively 5.5% for the former and 15% for the latter, for an overall yield of 8.6%.…”

Section: Atmospheric Relevance 441 Fate Of Organic Nitrogenmentioning

confidence: 99%

Isoprene photooxidation: new insights into the production of acids and organic nitrates

et al. 2009

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Abstract. We describe a nearly explicit chemical mechanism for isoprene photooxidation guided by chamber studies that include time-resolved observation of an extensive suite of volatile compounds. We provide new constraints on the chemistry of the poorly-understood isoprene δ-hydroxy channels, which account for more than one third of the total isoprene carbon flux and a larger fraction of the nitrate yields. We show that the cis branch dominates the chemistry of the δ-hydroxy channel with less than 5% of the carbon following the trans branch. The modelled yield of isoprene nitrates is 12±3% with a large difference between the δ and β branches. The oxidation of these nitrates releases about 50% of the NO x . Methacrolein nitrates (modelled yield 15±3% from methacrolein) and methylvinylketone nitrates (modelled yield 11±3% yield from methylvinylketone) are also observed. Propanone nitrate, produced with a yield of 1% from isoprene, appears to be the longest-lived nitrate formed in the total oxidation of isoprene. We find a large molar yield of formic acid and suggest a novel mechanism leading to its formation from the organic nitrates. Finally, the most important features of this mechanism are summarized in a condensed scheme appropriate for use in global chemical transport models.

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Measurement of the organic nitrate yield from OH reaction with isoprene

Cited by 150 publications

References 24 publications

Product study and mechanisms of the reactions of α‐pinene and of pinonaldehyde with OH radicals

Product study and mechanisms of the reactions of α‐pinene and of pinonaldehyde with OH radicals

A product study of the isoprene+NO<sub>3</sub> reaction

Isoprene photooxidation: new insights into the production of acids and organic nitrates

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Measurement of the organic nitrate yield from OH reaction with isoprene

Cited by 150 publications

References 24 publications

Product study and mechanisms of the reactions of α‐pinene and of pinonaldehyde with OH radicals

Product study and mechanisms of the reactions of α‐pinene and of pinonaldehyde with OH radicals

A product study of the isoprene+NO&lt;sub&gt;3&lt;/sub&gt; reaction

Isoprene photooxidation: new insights into the production of acids and organic nitrates

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Product

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A product study of the isoprene+NO<sub>3</sub> reaction