Kinetics and mechanism of the gas phase reaction of hydroxyl radicals with aromatic hydrocarbons over the temperature range 296-473 K

Perry, R. A.; Atkinson, Roger; Pitts, James N.

doi:10.1021/j100519a004

Cited by 262 publications

(265 citation statements)

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“…However, at higher temperatures (T g 400 K), where the abstraction Reaction 1b dominates, significant differences were observed. 28,33 Tully et al 28 derived Arrhenius expressions for Reaction 1b for toluene and toluene-d 8 . By extrapolation of these expressions, a benzyl radical yield of 2% can be estimated for toluene-d 8 at room temperature, compared with 7% in the case of toluene.…”

Section: Discussionmentioning

confidence: 99%

Formation of Peroxy Radicals from OH−Toluene Adducts and O₂

Bohn

2001

J. Phys. Chem. A

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The gas-phase reaction of OH radicals with toluene and toluene-d 8 and reactions of the resulting OH adducts with O 2 were studied in N 2 /O 2 mixtures at atmospheric pressure and room temperature. OH production was performed by pulsed 248 nm photolysis of H 2 O 2 . Cw UV-laser long-path absorption at 308 nm was used for time-resolved detection of OH and OH-toluene adducts. The reaction OH + toluene was studied in N 2 and O 2 and similar rate constants of (5.70 ( 0.19) × 10 -12 cm 3 s -1 (N 2 ) and (5.60 ( 0.14) × 10 -12 cm 3 s -1 (O 2 ) were obtained at 100 kPa. For toluene-d 8 the corresponding rate constants are (5.34 ( 0.34) × 10 -12 cm 3 s -1 (N 2 ) and (5.47 ( 0.14) × 10 -12 cm 3 s -1 (O 2 ). Absorption cross-sections of (1.1 ( 0.2) × 10 -17 cm 2 were determined for both the OH-toluene and OH-toluene-d 8 adduct at 308 nm. Rate constants of (4.7 ( 1.4) × 10 -11 cm 3 s -1 and (1.8 ( 0.5) × 10 -10 cm 3 s -1 were determined for the OH-toluene adduct self-reaction and the OH-toluene adduct + HO 2 reaction, respectively. Upper limits e8 × 10 -15 cm 3 s -1 were estimated for any reactions of the OH-toluene adduct with H 2 O 2 or toluene. Adduct kinetics in the presence of O 2 is consistent with reversible formation of peroxy radicals with an estimated rate constant of (3 ( 2) × 10 -15 cm 3 s -1 and an equilibrium constant of (3.25 ( 0.33) × 10 -19 cm 3 (toluene-d 8 : (3.1 ( 1.2) × 10 -19 cm 3 ). The effective adduct loss from the equilibrium can be explained by (i) an additional, irreversible reaction of the adduct with O 2 with a rate constant of (6.0 ( 0.5) × 10 -16 cm 3 s -1 (toluene-d 8 : (4.7 ( 1.2) × 10 -16 cm 3 s -1 ), or (ii) a unimolecular reaction of the peroxy radical, with a rate constant of (1.85 ( 0.15) × 10 3 s -1 (toluene-d 8 : (1.5 ( 0.4) × 10 3 s -1 ). Consequences for the atmospheric degradation of toluene will be discussed.

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Section: Discussionmentioning

confidence: 99%

Formation of Peroxy Radicals from OH−Toluene Adducts and O₂

Bohn

2001

J. Phys. Chem. A

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“…Based on that paper, estimated an upper limit of 2×10 −16 cm 3 s −1 , just including our result. Another experiment less than a factor of 2 off the goal to detect a slow O 2 reaction is that of Perry et al (1977), who expressed their result on toluene-OH as being less than 1.0×10 −15 cm 3 s −1 at 353-397K. More recently, several authors studied the transient absorption of HCHD in the presence of O 2 , Johnson et al (2002), Raoult et al (2004), Grebenkin and Krasnoperov (2004)).…”

Section: The Adduct Reaction With Omentioning

confidence: 99%

“…These aspects have been studied by laser photolysis/laser absorption and laser photolysis/UV absorption by Zellner et al (1985), , Bohn (2001), Johnson et al (2002Johnson et al ( , 2005, Raoult et al (2004) and Grebenkin and Krasnoperov (2004); by discharge-flow/laser induced fluorescence (Goumri et al, 1990); in flash photolysis/resonance fluorescence studies by Perry et al (1977), and Knispel et al (1990) for benzene, toluene and phenol; and in product studies by , Atkinson et al (1991), Atkinson and Aschmann (1994), Klotz et al (1998), Smith et al (1998, Bethel et al (2000), Berndt and Böge (2001a, 2001b, 2003 and Volkamer et al (2002a,b), Klotz et al (2002), Olariu et al (2002), Zhao et al (2005) and Coeur-Tourneur et al (2006) for benzene, toluene, o-, m-and p-xylene, 1,2,3-, 1,2,4-and 1,3,5-trimethylbenzene, HMB, phenol and o-, m-and p-cresol. In the following, we present a kinetic study of the consecutive reactions of aromatic-OH adducts in the presence of variable amounts of either NO, NO 2 or O 2 . Most of the results on benzene, toluene, p-xylene, phenol and m-cresol were obtained using the VUV flash photolysis/resonance fluorescence (FP/RF) technique, introduced by Stuhl and Niki (1972).…”

Section: Introductionmentioning

confidence: 99%

Consecutive reactions of aromatic-OH adducts with NO, NO<sub>2</sub> and O<sub>2</sub>: benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline

et al. 2007

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Abstract. Consecutive reactions of adducts, resulting from OH radicals and aromatics, with the tropospheric scavenger molecules O 2 , NO and NO 2 have been studied for benzene, naphthalene, toluene, m-and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline by observing decays of OH at temperatures where the thermal back-decomposition to OH is faster than 3 s −1 , typically between 300 and 340 K. The experimental technique was resonance fluorescence with flash photolysis of water as source of OH. Biexponential decays were observed in the presence of either O 2 or NO, and triexponential decays were obtained in the presence of NO 2 . The kinetic analysis was performed by fitting the relevant rate constants of the reaction mechanism to whole sets of decays obtained at various concentrations of aromatic and scavenger. In the case of hexamethylbenzene, the biexponential decays suggest the existence of the ipso-adduct, and the slightly higher necessary temperatures show that it is even more stable.In addition, smog chamber experiments at O 2 concentrations from atmospheric composition down to well below 100 ppm have been carried out for benzene, toluene and pxylene. The drop of the effective rate constant of removal by OH occurs at reasonable O 2 levels, given the FP/RF results.Comparison of the adduct reactivities shows for all aromatics of this study that the reaction with O 2 predominates over that with NO 2 under all tropospheric conditions, and that a reaction with NO may only occur after the reaction with O 2 .

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“…Accordingly, the reactivity of levoglucosan to OH may be dependent on the reaction relative humidity (RH, which usually varies from 20% to 90% in the atmosphere). Furthermore, the tropospheric temperature varies notably with the changing seasons, and some studies have already found that temperature will affect the reactions between different organic compounds and OH radicals (Lee et al, 2003;Perry et al, 1977). Therefore, it is significant to investigate the effect of relative humidity and temperature on the reaction between levoglucosan and OH radicals to evaluate the atmospheric lifetime of levoglucosan.…”

Section: Introductionmentioning

confidence: 99%

Degradation kinetics of levoglucosan initiated by hydroxyl radical under different environmental conditions

Lai

Liu

et al. 2014

Atmospheric Environment

143

132

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h i g h l i g h t sMixing state significantly slows down the reactivity of levoglucosan toward OH. Low RH and high temperature are favorable to degradation of levoglucosan. Degradation of levoglucosan should be prominent in the atmosphere. To understand the atmospheric stability of levoglucosan, which is a major molecular tracer used for source apportionment of biomass burning aerosols, degradation kinetics of levoglucosan by hydroxyl radical (OH) have been investigated using a flow reactor under different conditions. The second-order rate constant (k 2 ) for the degradation of pure levoglucosan by OH is (9.17 AE 1.16) Â 10 À12 cm 3 molecules À1 s À1 at 25 C and 40% relative humidity (RH), while it depends on environmental conditions such as temperature, RH, and mixing state. At 25 C, k 2 of pure levoglucosan linearly decreases with increasing RH (k 2 ¼ (1.50 AE 0.04) Â 10 À11 À (1.31 AE 0.11) Â 10 À11 RH), while it increases with increasing temperature and follows the Arrhenius equation k 2 ¼ (6.2 AE 5.6) Â 10 À9 exp[(e1922.5 AE 268.2)/T] when the RH is 40%. At 25 C and 40% RH, compared to pure levoglucosan, levoglucosan coated on (NH 4 ) 2 SO 4 or NaCl (levoglucosan@(NH 4 ) 2 SO 4 and levoglucosan@NaCl) shows larger k 2 to OH with (9.53 AE 0.39) Â 10 À12 and (10.3 AE 0.45) Â 10 À12 cm 3 molecules À1 s À1 , respectively, whereas levoglucosan coated on soot (levoglucosan@soot) shows the smaller k 2 of (4.04 AE 0.29) Â 10 À12 cm 3 molecules À1 s À1 . Either (NH 4 ) 2 SO 4 or NaCl internally mixed with levoglucosan ((NH 4 ) 2 SO 4 @levoglucosan and NaCl@levoglucosan) prominently inhibits the degradation of levoglucosan. Based on the rate constants, atmospheric lifetimes of levoglucosan were estimated to be 1.2e3.9 days under different conditions. All the results indicate that the degradation of levoglucosan by OH is prominent during air mass aging, and it should have an important influence on the uncertainty of source apportionment if the contribution of degradation to levoglucosan concentration is not considered in source apportionment models. a r t i c l e i n f o

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Kinetics and mechanism of the gas phase reaction of hydroxyl radicals with aromatic hydrocarbons over the temperature range 296-473 K

Abstract: Impurities were analyzed by gas chromatography to be <25 ppm.

Cited by 262 publications

References 9 publications

Formation of Peroxy Radicals from OH−Toluene Adducts and O₂

Formation of Peroxy Radicals from OH−Toluene Adducts and O₂

Consecutive reactions of aromatic-OH adducts with NO, NO<sub>2</sub> and O<sub>2</sub>: benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline

Degradation kinetics of levoglucosan initiated by hydroxyl radical under different environmental conditions

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Kinetics and mechanism of the gas phase reaction of hydroxyl radicals with aromatic hydrocarbons over the temperature range 296-473 K

Abstract: Impurities were analyzed by gas chromatography to be <25 ppm.

Cited by 262 publications

References 9 publications

Formation of Peroxy Radicals from OH−Toluene Adducts and O2

Formation of Peroxy Radicals from OH−Toluene Adducts and O2

Consecutive reactions of aromatic-OH adducts with NO, NO&lt;sub&gt;2&lt;/sub&gt; and O&lt;sub&gt;2&lt;/sub&gt;: benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline

Degradation kinetics of levoglucosan initiated by hydroxyl radical under different environmental conditions

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Formation of Peroxy Radicals from OH−Toluene Adducts and O₂

Formation of Peroxy Radicals from OH−Toluene Adducts and O₂

Consecutive reactions of aromatic-OH adducts with NO, NO<sub>2</sub> and O<sub>2</sub>: benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline