Isomerization of Alkoxy Radicals under Atmospheric Conditions

Eberhard, Jürg; Müller, C.; Stocker, David; Kerr, J. A.

doi:10.1021/es00001a600

Cited by 77 publications

(93 citation statements)

References 16 publications

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“…The data of Eberhard et al (5) showing dominant isomerization of the 2-hexoxy radical (from photolysis of 2-hexyl nitrite) are consistent with our present observation of significant 5-hydroxy-2-hexanone formation from nhexane (see Table 3). However, we also observe formation of 6-hydroxy-3-hexanone from the n-hexane reaction in comparable yield to 5-hydroxy-2-hexanone, and the 5-hydroxy-2-hexanone yield of Eberhard et al (5) from n-hexane is inconsistent with predictions that H-atom abstraction from the 2-position CH2 group in n-hexane accounts for only 40-45% of the overall reaction (25). It should be noted that Eberhard et al (5) carried out their experiments in dry synthetic air, and cyclization of the hydroxyhexanones with subsequent dehydration to form reactive dihydrofurans could have been important.…”

Section: Table 1 Retention Times and Diagnostic Ions Observed In Thesupporting

confidence: 93%

“…The only previous isomerspecific analyses were made by Eberhard et al (5) using highperformance liquid chromatography MS, and they identified 5-hydroxy-2-hexanone as a major product of the photolysis of 2-hexyl nitrite and from the OH radical initiated reaction of n-hexane, with reported yields of 68 ( 48 and 96 ( 30%, respectively. However, no evidence for the formation of 6-hydroxy-3-hexanone from the photolysis of 3-hexyl nitrite nor from the OH radical initiated reaction of n-hexane was obtained (5). The data of Eberhard et al (5) showing dominant isomerization of the 2-hexoxy radical (from photolysis of 2-hexyl nitrite) are consistent with our present observation of significant 5-hydroxy-2-hexanone formation from nhexane (see Table 3).…”

Section: Table 1 Retention Times and Diagnostic Ions Observed In Thesupporting

confidence: 88%

“…However, no evidence for the formation of 6-hydroxy-3-hexanone from the photolysis of 3-hexyl nitrite nor from the OH radical initiated reaction of n-hexane was obtained (5). The data of Eberhard et al (5) showing dominant isomerization of the 2-hexoxy radical (from photolysis of 2-hexyl nitrite) are consistent with our present observation of significant 5-hydroxy-2-hexanone formation from nhexane (see Table 3). However, we also observe formation of 6-hydroxy-3-hexanone from the n-hexane reaction in comparable yield to 5-hydroxy-2-hexanone, and the 5-hydroxy-2-hexanone yield of Eberhard et al (5) from n-hexane is inconsistent with predictions that H-atom abstraction from the 2-position CH2 group in n-hexane accounts for only 40-45% of the overall reaction (25).…”

Section: Table 1 Retention Times and Diagnostic Ions Observed In Thesupporting

confidence: 88%

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1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C₅−C₈n-Alkanes in the Presence of NO

Reisen

Aschmann

Atkinson

et al. 2005

Environ. Sci. Technol.

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Ambient measurements of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs were carried out during August 2002 and January 2003 in Los Angeles, CA, a source site and in Riverside, CA, a downwind receptor site approximately 90 km to the east of Los Angeles. Atmospheric concentrations of PAHs and nitro-PAHs are of interest because both of these compound classes include potent mutagens and carcinogens. To augment our current understanding of atmospheric formation of nitro-PAHs, four sampling periods were employed to study the diurnal variations of these compounds. The PAH concentrations were highest in Los Angeles during January, as a result of traffic input at this source site undertightwintertime atmospheric inversions. In contrast, nitro-PAH levels were highest in Riverside during August, as a result of enhanced summertime photochemistry. Hydroxyl radical-initiated reactions produced nitro-PAHs in both seasons, while in winter little evidence for nitrate radical chemistry was seen. For the August samples, nitrate radical-initiated formation of nitro-PAHs is suggested by nitro-PAH isomer profiles not only at the downwind location as anticipated, but also atthe source site. In southern California, the contribution of atmospheric formation through gas-phase radical-initiated PAH reactions to the ambient burden of nitro-PAHs is dominant, with the semi-volatile nitro-PAHs being the most abundant and 2-nitrofluoranthene being the major particle-associated nitro-PAH.

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Section: Table 1 Retention Times and Diagnostic Ions Observed In Thesupporting

confidence: 93%

Section: Table 1 Retention Times and Diagnostic Ions Observed In Thesupporting

confidence: 88%

Section: Table 1 Retention Times and Diagnostic Ions Observed In Thesupporting

confidence: 88%

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1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C₅−C₈n-Alkanes in the Presence of NO

Reisen

Aschmann

Atkinson

et al. 2005

Environ. Sci. Technol.

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“…It is disappointing to note that the diols and hydroxycarbonyl compounds predicted to arise from isomerization reactions of the pentan-1-oxyl and pentan-2-oxyl radicals were not observed in the expected amounts. Eberhard et al [20] have used derivatization with 2,4-dinitrophenylhydrazine and liquid chromatography to identify 2-hydroxyhexan-5-one produced in the photolysis of hexan-2-nitrite. Kwok et al [21] have used atmospheric pressure ionization triple quadrupole mass spectrometry to characterize hydroxycarbonyl compounds derived from the reaction of OH with several n-alkanes including n-pentane.…”

Section: Discussionmentioning

confidence: 99%

Photodecomposition of iodopentanes in air: Product distributions from the self‐reactions of n‐pentyl peroxyl radicals

Heimann

Benkelberg

Böge

et al. 2001

Int J of Chemical Kinetics

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Product distributions from the 254-nm photooxidation of the three iodopentane isomers were explored as a technique for studying the self-reactions of individual pentyl peroxyl radicals (in air at ambient temperature and pressure). Pentanols and the associated carbonyl compounds (pentanal or pentanones) were major products as expected. Other major products resulted from the isomerization of pentan-1-oxyl and pentan-2-oxyl radicals, but their nature could not be identified. Minor products were alcohols and carbonyl compounds arising from the decomposition of pentoxyl radicals. Diols and mixed hydroxycarbonyl compounds from cross-combination reactions were essentially absent, in contrast to expectation. The observed product distributions were evaluated to derive branching ratios for the radicalpreserving pathways of the self-reactions, 0.42 ± 0.17, 0.46 ± 0.10, 0.39 ± 0.08, for pentan-1-yl peroxyl, pentan-2-yl peroxyl, and pentan-3-yl peroxyl, respectively. Rate coefficients derived for the decomposition of the corresponding pentoxyl radicals, relative to their reaction with oxygen, are (5.1 ± 0.5) × 10 18 , (1.0 ± 0.2) × 10 18 , and (3.2 ± 0.3) × 10 18 molecule cm −3 , respectively. Rate constants for the isomerization of pentan-1-oxyl and pentan-2-oxyl were estimated from the contributions of isomerization products to the total amounts of products as (4.0 ± 1.1) × 10 5 s −1 and (1.0 ± 2.0) × 10 5 s

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“…ϫ 10 cm molecule s at 300 K [10,11] where R 1 represents the primary alkyl group 1-pentyl and R 22 and R 23 represent the secondary groups 2-pentyl and 3-pentyl. The alkyl radicals are then, in the presence of excess oxygen, converted instantaneously (compared to the time scale of subsequent reaction) into peroxy radicals in the same proportion:…”

Section: Pentylperoxymentioning

confidence: 99%

Structure-reactivity relationships for the self- reactions of linear secondary alkylperoxy radicals: An experimental investigation

Boyd

Villenave

Lesclaux

1999

Int. J. Chem. Kinet.

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The self-reactions of the linear pentylperoxy (C 5 H 11 O 2 ) and decylperoxy (C 10 H 21 O 2 ) radicals have been studied at room temperature. The technique of excimer laser flash photolysis was used to generate pentylperoxy radicals, while conventional flash photolysis was used for decylperoxy radicals. For the former, the recombination rate coefficients were estimated for the primary 1-pentylperoxy isomer (n-C 5 H 11 O 2 ) and for the secondary 2-and 3-pentylperoxy isomers combined (Љsec-C 5 H 11 O 2 Љ) by creating primary and secondary radicals in different ratios of initial concentrations and simulating experimental decay traces using a simplified chemical mechanism. The values obtained at 298 K were:Ϫ14 cm 3 molecule Ϫ1 s Ϫ1 . Quoted errors are 1, whereas the total relative combined uncertainties correspond to an estimated uncertainty factor around 1.65. For decylperoxy radicals, the kinetics of all the types of secondary peroxy isomers reacting with each other were considered equivalent and grouped as sec-C 10 H 21 O 2 (as for sec-C 5 H 11 O 2 ). The UV absorption spectrum of these secondary radicals was measured, and the combined self-reaction rate coefficients then derived as: k(sec-C 10 H 21 O 2 ϩ sec-C 10 H 21 O 2 ) ϭ (9.4 Ϯ 1.3) ϫ 10 Ϫ14 cm 3 molecule Ϫ1 s Ϫ1 at 298 K. Again, quoted errors are 1 and the total uncertainty factor corresponds to a value around 1.75. The sec-dodecylperoxy radical was also investigated using the same procedure, but only an estimate of the rate coefficient could be obtained, due to aerosol formation in the reaction cell: k(sec-C 12 H 25 O 2 ϩ sec-C 12 H 25 O 2 ) Ϸ 1.4 ϫ 10 Ϫ13 cm 3 molecule Ϫ1 s Ϫ1 , with an uncertainty factor of about 2. Despite the fairly high uncertainty factors, a relationship has been identified between the room-temperature rate coefficient for the selfreaction and the number of carbon atoms, n, in the linear secondary radical, suggesting: log(k(sec-RO 2 ϩ sec-RO 2 )/cm 3 molecule Ϫ1 s Ϫ1) ϭ Ϫ13.0-3.2 ϫ exp(Ϫ0.64 ϫ (n-2.3)). Concerning

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Isomerization of Alkoxy Radicals under Atmospheric Conditions

Cited by 77 publications

References 16 publications

1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C₅−C₈n-Alkanes in the Presence of NO

1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C₅−C₈n-Alkanes in the Presence of NO

Photodecomposition of iodopentanes in air: Product distributions from the self‐reactions of n‐pentyl peroxyl radicals

Structure-reactivity relationships for the self- reactions of linear secondary alkylperoxy radicals: An experimental investigation

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Isomerization of Alkoxy Radicals under Atmospheric Conditions

Cited by 77 publications

References 16 publications

1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C5−C8n-Alkanes in the Presence of NO

1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C5−C8n-Alkanes in the Presence of NO

Photodecomposition of iodopentanes in air: Product distributions from the self‐reactions of n‐pentyl peroxyl radicals

Structure-reactivity relationships for the self- reactions of linear secondary alkylperoxy radicals: An experimental investigation

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1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C₅−C₈n-Alkanes in the Presence of NO

1,4-Hydroxycarbonyl Products of the OH Radical Initiated Reactions of C₅−C₈n-Alkanes in the Presence of NO