A kinetics and mechanistic study of the OH and NO2 initiated oxidation of cyclohexa-1,3-diene in the gas phase

M. E. Jenkin; Mads Peter Sulbæk Andersen; M. D. Hurley; T. J. Wallington; F. Taketani; Y. Matsumi

doi:10.1039/b417525e

A kinetics and mechanistic study of the OH and NO₂ initiated oxidation of cyclohexa-1,3-diene in the gas phase

M. E. Jenkin, Mads Peter Sulbæk Andersen, M. D. Hurley, T. J. Wallington, F. Taketani, Y. Matsumi

Department of Chemistry

13 Citations (Scopus)

Abstract

The kinetics and products of the OH and NO2-initiated oxidation of cyclohexa-1,3-diene have been investigated at 296 K and 700 Torr using long path FTIR spectroscopy. Relative rate methods were employed using the photolysis of cyclohexa-1,3-diene/CH3ONO/NO/air mixtures to measure k(OH + cyclohexa-1,3-diene) = (1.68 +/- 0.43) x 10(-10) cm(3) molecule(-1) s(-1). From the pseudo-first order decay of cyclohexa-1,3-diene in the presence of excess NO2, a value of k(NO2 + cyclohexa- 1,3- diene) = (1.75 +/- 0.15) x 10(-18) cm(3) molecule(-1) s(-1) was derived. An upper limit of k less than or equal to 7 x 10(-21) cm(3) molecule(-1) s(-1) was established for the reaction of NO with cyclohexa- 1,3- diene. Benzene was observed as a product of both the OH and NO2 initiated oxidation, providing evidence of H atom abstraction in both reactions. Assuming the reaction of cyclohexadienyl radicals (C6H7) with O-2 produces benzene as the sole organic product, the results are consistent with abstraction channel branching ratios of (8.1 +/- 0.2)% and ( 1.5 +/- 0.4) respectively. The results also indicate that C6H7 reacts with NO2, with a relative rate coefficient k(C6H7 + NO2)/ k(C6H7 + O-2) = ( 1.8 +/- 0.5) x 10(5), and that this partially forms benzene, with a branching ratio of ( 27 +/- 7) The stoichiometry and products of the NO2 reaction were investigated in the absence of O-2, in the presence of O-2, and in the presence of O-2 and NO. Reaction mechanisms consistent with the observations are presented. In the presence of NO and O-2, the NO2-initiated chemistry leads to NO- to-NO2 conversion, and the formation of HOx radicals in significant yield, (0.79 +/- 0.05), such that cyclohexa- 1,3-diene removal occurs by reaction with both NO2 and OH. HCOOH was detected as a product in this system, providing evidence for significant formation of stabilised C-6 alpha-hydroxyperoxy radicals from the OH-initiated chemistry, and their subsequent reaction with NO. An estimate of ca. 500 - 1000 s(-1) is made for their decomposition rate, based on the [ NO]- dependence of the HCOOH yields. The implications of the results are discussed within the context of the atmospheric chemistry of conjugated dienes.

Original language	Undefined/Unknown
Journal	Physical Chemistry Chemical Physics
Volume	7
Issue number	6
Pages (from-to)	1194-1204
Number of pages	11
ISSN	1463-9076
DOIs	https://doi.org/10.1039/b417525e
Publication status	Published - 2005

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10.1039/b417525e

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@article{eb757d19bc0e4146a55d61a7f9297025,

title = "A kinetics and mechanistic study of the OH and NO2 initiated oxidation of cyclohexa-1,3-diene in the gas phase",

abstract = "The kinetics and products of the OH and NO2-initiated oxidation of cyclohexa-1,3-diene have been investigated at 296 K and 700 Torr using long path FTIR spectroscopy. Relative rate methods were employed using the photolysis of cyclohexa-1,3-diene/CH3ONO/NO/air mixtures to measure k(OH + cyclohexa-1,3-diene) = (1.68 +/- 0.43) x 10(-10) cm(3) molecule(-1) s(-1). From the pseudo-first order decay of cyclohexa-1,3-diene in the presence of excess NO2, a value of k(NO2 + cyclohexa- 1,3- diene) = (1.75 +/- 0.15) x 10(-18) cm(3) molecule(-1) s(-1) was derived. An upper limit of k less than or equal to 7 x 10(-21) cm(3) molecule(-1) s(-1) was established for the reaction of NO with cyclohexa- 1,3- diene. Benzene was observed as a product of both the OH and NO2 initiated oxidation, providing evidence of H atom abstraction in both reactions. Assuming the reaction of cyclohexadienyl radicals (C6H7) with O-2 produces benzene as the sole organic product, the results are consistent with abstraction channel branching ratios of (8.1 +/- 0.2)% and ( 1.5 +/- 0.4) respectively. The results also indicate that C6H7 reacts with NO2, with a relative rate coefficient k(C6H7 + NO2)/ k(C6H7 + O-2) = ( 1.8 +/- 0.5) x 10(5), and that this partially forms benzene, with a branching ratio of ( 27 +/- 7) The stoichiometry and products of the NO2 reaction were investigated in the absence of O-2, in the presence of O-2, and in the presence of O-2 and NO. Reaction mechanisms consistent with the observations are presented. In the presence of NO and O-2, the NO2-initiated chemistry leads to NO- to-NO2 conversion, and the formation of HOx radicals in significant yield, (0.79 +/- 0.05), such that cyclohexa- 1,3-diene removal occurs by reaction with both NO2 and OH. HCOOH was detected as a product in this system, providing evidence for significant formation of stabilised C-6 alpha-hydroxyperoxy radicals from the OH-initiated chemistry, and their subsequent reaction with NO. An estimate of ca. 500 - 1000 s(-1) is made for their decomposition rate, based on the [ NO]- dependence of the HCOOH yields. The implications of the results are discussed within the context of the atmospheric chemistry of conjugated dienes.",

author = "Jenkin, {M. E.} and Andersen, {Mads Peter Sulb{\ae}k} and Hurley, {M. D.} and Wallington, {T. J.} and F. Taketani and Y. Matsumi",

year = "2005",

doi = "10.1039/b417525e",

language = "Udefineret/Ukendt",

volume = "7",

pages = "1194--1204",

journal = "Physical Chemistry Chemical Physics",

issn = "1463-9076",

publisher = "Royal Society of Chemistry",

number = "6",

}

TY - JOUR

T1 - A kinetics and mechanistic study of the OH and NO2 initiated oxidation of cyclohexa-1,3-diene in the gas phase

AU - Jenkin, M. E.

AU - Andersen, Mads Peter Sulbæk

AU - Hurley, M. D.

AU - Wallington, T. J.

AU - Taketani, F.

AU - Matsumi, Y.

PY - 2005

Y1 - 2005

N2 - The kinetics and products of the OH and NO2-initiated oxidation of cyclohexa-1,3-diene have been investigated at 296 K and 700 Torr using long path FTIR spectroscopy. Relative rate methods were employed using the photolysis of cyclohexa-1,3-diene/CH3ONO/NO/air mixtures to measure k(OH + cyclohexa-1,3-diene) = (1.68 +/- 0.43) x 10(-10) cm(3) molecule(-1) s(-1). From the pseudo-first order decay of cyclohexa-1,3-diene in the presence of excess NO2, a value of k(NO2 + cyclohexa- 1,3- diene) = (1.75 +/- 0.15) x 10(-18) cm(3) molecule(-1) s(-1) was derived. An upper limit of k less than or equal to 7 x 10(-21) cm(3) molecule(-1) s(-1) was established for the reaction of NO with cyclohexa- 1,3- diene. Benzene was observed as a product of both the OH and NO2 initiated oxidation, providing evidence of H atom abstraction in both reactions. Assuming the reaction of cyclohexadienyl radicals (C6H7) with O-2 produces benzene as the sole organic product, the results are consistent with abstraction channel branching ratios of (8.1 +/- 0.2)% and ( 1.5 +/- 0.4) respectively. The results also indicate that C6H7 reacts with NO2, with a relative rate coefficient k(C6H7 + NO2)/ k(C6H7 + O-2) = ( 1.8 +/- 0.5) x 10(5), and that this partially forms benzene, with a branching ratio of ( 27 +/- 7) The stoichiometry and products of the NO2 reaction were investigated in the absence of O-2, in the presence of O-2, and in the presence of O-2 and NO. Reaction mechanisms consistent with the observations are presented. In the presence of NO and O-2, the NO2-initiated chemistry leads to NO- to-NO2 conversion, and the formation of HOx radicals in significant yield, (0.79 +/- 0.05), such that cyclohexa- 1,3-diene removal occurs by reaction with both NO2 and OH. HCOOH was detected as a product in this system, providing evidence for significant formation of stabilised C-6 alpha-hydroxyperoxy radicals from the OH-initiated chemistry, and their subsequent reaction with NO. An estimate of ca. 500 - 1000 s(-1) is made for their decomposition rate, based on the [ NO]- dependence of the HCOOH yields. The implications of the results are discussed within the context of the atmospheric chemistry of conjugated dienes.

AB - The kinetics and products of the OH and NO2-initiated oxidation of cyclohexa-1,3-diene have been investigated at 296 K and 700 Torr using long path FTIR spectroscopy. Relative rate methods were employed using the photolysis of cyclohexa-1,3-diene/CH3ONO/NO/air mixtures to measure k(OH + cyclohexa-1,3-diene) = (1.68 +/- 0.43) x 10(-10) cm(3) molecule(-1) s(-1). From the pseudo-first order decay of cyclohexa-1,3-diene in the presence of excess NO2, a value of k(NO2 + cyclohexa- 1,3- diene) = (1.75 +/- 0.15) x 10(-18) cm(3) molecule(-1) s(-1) was derived. An upper limit of k less than or equal to 7 x 10(-21) cm(3) molecule(-1) s(-1) was established for the reaction of NO with cyclohexa- 1,3- diene. Benzene was observed as a product of both the OH and NO2 initiated oxidation, providing evidence of H atom abstraction in both reactions. Assuming the reaction of cyclohexadienyl radicals (C6H7) with O-2 produces benzene as the sole organic product, the results are consistent with abstraction channel branching ratios of (8.1 +/- 0.2)% and ( 1.5 +/- 0.4) respectively. The results also indicate that C6H7 reacts with NO2, with a relative rate coefficient k(C6H7 + NO2)/ k(C6H7 + O-2) = ( 1.8 +/- 0.5) x 10(5), and that this partially forms benzene, with a branching ratio of ( 27 +/- 7) The stoichiometry and products of the NO2 reaction were investigated in the absence of O-2, in the presence of O-2, and in the presence of O-2 and NO. Reaction mechanisms consistent with the observations are presented. In the presence of NO and O-2, the NO2-initiated chemistry leads to NO- to-NO2 conversion, and the formation of HOx radicals in significant yield, (0.79 +/- 0.05), such that cyclohexa- 1,3-diene removal occurs by reaction with both NO2 and OH. HCOOH was detected as a product in this system, providing evidence for significant formation of stabilised C-6 alpha-hydroxyperoxy radicals from the OH-initiated chemistry, and their subsequent reaction with NO. An estimate of ca. 500 - 1000 s(-1) is made for their decomposition rate, based on the [ NO]- dependence of the HCOOH yields. The implications of the results are discussed within the context of the atmospheric chemistry of conjugated dienes.

U2 - 10.1039/b417525e

DO - 10.1039/b417525e

M3 - Tidsskriftartikel

SN - 1463-9076

VL - 7

SP - 1194

EP - 1204

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

IS - 6

ER -