Reactions of alkoxyl radicals in the atmosphere

Atkinson, Roger; Kwok, Eric S. C.; Arey, Janet; Aschmann, Sara M.

doi:10.1039/fd9950000023

Cited by 83 publications

(148 citation statements)

References 17 publications

(2 reference statements)

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“…The isomerization pathway leads to the formation of large hydroxycarbonyls, multifunctional products that are likely low in volatility. The relative importance of isomerization increases with the size of alkoxy radicals (Atkinson, 1994(Atkinson, , 1997aAtkinson et al, 1995Atkinson et al, , 1999, and larger compounds could exhibit increasing SOA yields under high-NO x conditions as a consequence of this mechanism. For example, Lim and Ziemann (2005) measured SOA yields up to ∼50% for C 15 alkanes in the presence of ppm levels of NO x .…”

Section: Effect Of Hydrocarbon Size On No X Dependencementioning

confidence: 99%

Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

et al. 2007

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Abstract. Secondary organic aerosol (SOA) formation from the photooxidation of one monoterpene (α-pinene) and two sesquiterpenes (longifolene and aromadendrene) is investigated in the Caltech environmental chambers. The effect of NO x on SOA formation for these biogenic hydrocarbons is evaluated by performing photooxidation experiments under varying NO x conditions. The NO x dependence of α-pinene SOA formation follows the same trend as that observed previously for a number of SOA precursors, including isoprene, in which SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) decreases as NO x level increases. The NO x dependence of SOA yield for the sesquiterpenes, longifolene and aromadendrene, however, differs from that determined for isoprene and α-pinene; the aerosol yield under high-NO x conditions substantially exceeds that under low-NO x conditions. The reversal of the NO x dependence of SOA formation for the sesquiterpenes is consistent with formation of relatively low-volatility organic nitrates, and/or the isomerization of large alkoxy radicals leading to less volatile products. Analysis of the aerosol chemical composition for longifolene confirms the presence of organic nitrates under high-NO x conditions. Consequently the formation of SOA from certain biogenic hydrocarbons such as sesquiterpenes (and possibly large anthropogenic hydrocarbons as well) may be more efficient in polluted air.

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Section: Effect Of Hydrocarbon Size On No X Dependencementioning

confidence: 99%

Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

et al. 2007

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“…Their response was similar but the latter eluted much later than the former. The [1,17] k 55 = (6.6 ± 0.2) × 10 −14 cm 3 molecule −1 s −1 , α 55 = 0.63 ± 0.06 [1,17] 1 k isom = (4.0 ± 1.1) × 10 5 s −1 [9], 2.0 × 10 6 s −1 [12], 2.2 × 10 6 s −1 [14] 2 k isom = 2.5 × 10 5 s −1 [7,11], (1.0 ± 0.2) × 10 5 s −1 [9], 5.0 × 10 5 s −1 [12], 3.3 × 10 5 s −1 [14] 2 k dec = 9.1 × 10 3 s −1 [7,11], (8.4 ± 1.7) × 10 3 s −1 [9], 1.0 × 10 4 s −1 [12], 2.2 × 10 4 s −1 [13] 3 k dec = 2.6 × 10 4 s −1 [8,11], (2.6 ± 0.3) × 10 4 s −1 [9], (3.3 ± 0.65) × 10 4 s −1 [10], 3.3 × 10 4 s −1 [12], 3.4 × 10 4 s −1 [13] present study was not focused on isomerization products, and no attempts were made to identify them.…”

Section: Figurementioning

confidence: 99%

“…Pentoxyl radicals, in turn, react partly with oxygen to form carbonyl compounds, and they undergo isomerization and/or decomposition, thereby generating new alkylperoxyl radicals. Although these processes have received much attention, the rate coefficients associated with reactions of n-pentoxyl isomers have been determined with some reliability only recently, experimentally [7][8][9][10] as well as theoretically [11][12][13][14]. In the absence of NO, the pentylperoxyl radicals react with each other and with other alkylperoxyl radicals generated in the system; one branch of each reaction leads again to pentoxyl radicals, the other to alcohols and carbonyl compounds.…”

Section: Introductionmentioning

confidence: 99%

Product distributions from the OH radical‐induced oxidation of n‐pentane and isopentane (2‐methylbutane) in air

Heimann

Warneck

2006

Int J of Chemical Kinetics

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Hydroxyl radicals, generated by photolysis of H 2 O 2 , were reacted with n-pentane and isopentane in air in the absence of nitrogen oxides. The observed product distributions were compared with similar data derived by computer simulations, based on the known reaction mechanisms, to determine relative probabilities for hydrogen abstraction at different sites of the parent compounds and to estimate branching ratios and relative rate coefficients for cross-combination reactions between different peroxy radicals. For n-pentane, the distribution of the pentanols indicates probabilities for hydrogen abstraction, in percent, of q 1 = 9.1 ± 0.7, q 2 = 56.1 ± 1.8, and q 3 = 34.8 ± 1.3, which agree with predictions based on the algorithm proposed by Atkinson. Branching ratios needed to harmonize calculated and observed product distributions are somewhat larger than, although still within the error ranges of, the values found by us previously. Comparison between experimental and calculated data confirms the isomerization and decomposition constants recently established for the three pentoxyl radical isomers. The product distribution for isopentane, which is dominated by acetone, acetaldehyde, 2-methyl-butan-2-ol, and 2-methyl-butan-2-hydroperoxide, is in harmony with the predicted oxidation mechanism. Probabilities for hydrogen abstraction from isopentane were estimated to occur to 12% at the primary, 28% at the secondary, and 60% at the tertiary sites, again in agreement with predictions based on the algorithm of Atkinson.

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“…20 liter di-Ϫ1 min rectly into the API mass spectrometer source. The operation of the API-MS in the MS (scanning) and MS/ MS [with collision activated dissociation (CAD)] modes has been described elsewhere [17,18,28,29].…”

Section: Teflon Chamber With Analysis By Api-msmentioning

confidence: 99%

“…The MS/MS mode allows the "daughter ion" or "parent ion" spectrum of a given ion peak observed in the MS scanning mode to be obtained [17,18,28,29]. The positive ion mode was used in this work, with protonated water hydrates generated by the…”

Section: Teflon Chamber With Analysis By Api-msmentioning

confidence: 99%

Products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO

Atkinson

Tuazon

Aschmann

1998

Int. J. Chem. Kinet.

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The products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO have been investigated at room temperature and total pressure 740 torr of air by gas chromatography with flame ionization detection, in situ Fourier transform infrared absorption spectroscopy, and direct air sampling atmospheric pressure ionization tandem mass spectrometry. The products identified and quantified by GC-FID and in situ FT-IR absorption spectroscopy were HCHO, 2-methylpropanal, acetone, glycolaldehyde, and methacrolein, with formation yields of and 0.70 Ϯ 0.06, 0.58 Ϯ 0.08, 0.17 Ϯ 0.02, 0.18 Ϯ 0.03, respectively. In addition, IR absorption bands due to organic nitrates were 0.033 Ϯ 0.007, observed, consistent with API-MS observations of product ion peaks attributed to the ␤-hydroxynitrates (CH 3 ) 2 CHCH(ONO 2 )CH 2 OH and/or (CH 3 ) 2 CHCH(OH)CH 2 ONO 2 formed from the reactions of the corresponding ␤-hydroxyalkyl peroxy radicals with NO. A formation yield of ca. 0.15 for these nitrates was estimated using IR absorption band intensities for known organic nitrates. These products account for essentially all of the reacted 3-methyl-1-butene. Analysis of the potential reaction pathways involved shows that H-atom abstraction from the allylic C9 H bond in 3-methyl-1-butene is a minor pathway which accounts for 5-10% of the overall OH radical reaction.

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Reactions of alkoxyl radicals in the atmosphere

Cited by 83 publications

References 17 publications

Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

Product distributions from the OH radical‐induced oxidation of n‐pentane and isopentane (2‐methylbutane) in air

Products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO

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Reactions of alkoxyl radicals in the atmosphere

Cited by 83 publications

References 17 publications

Effect of NO&lt;sub&gt;x&lt;/sub&gt; level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

Effect of NO&lt;sub&gt;x&lt;/sub&gt; level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

Product distributions from the OH radical‐induced oxidation of n‐pentane and isopentane (2‐methylbutane) in air

Products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO

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Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes

Effect of NO<sub>x</sub> level on secondary organic aerosol (SOA) formation from the photooxidation of terpenes