On the use of CO as scavenger for OH radicals in the ozonolysis of simple alkenes and isoprene

Gutbrod, Roland; Meyer, Stefan; Rahman, M. M.; Schindler, R. N.

doi:10.1002/(sici)1097-4601(1997)29:9<717::aid-kin9>3.3.co;2-i

Cited by 22 publications

(50 citation statements)

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“…Recycling of HO 2 results in an increased OH yield, especially when ozonolysis yields are low as it is the case for ethene ozonolysis. Moreover, the OH yields determined agree with the values obtained from ab initio calculations [Gutbrod et al, 1997;Olzmann et al, 1997].…”

Section: Yields Of Oh and Hosupporting

confidence: 83%

“…In other studies OH radicals are scavenged by components, whose turnover is observed to deduce the OH yields. The formation yield of cyclohexanol and cyclohexanone from cyclohexane [Atkinson and Aschmann, 1993], butanone from 2-butanol [Chew and Atkinson, 1996;Aschmann et al, 2002], and CO 2 from CO [Gutbrod et al, 1997] was observed to monitor OH production. When fast reacting tracers like trimethylbenzene [Paulson et al, 1999;Rickard et al, 1999] are used, OH yields can be deduced from the diminution in concentration of these species.…”

Section: Introductionmentioning

confidence: 99%

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Simulation chamber investigation of the reactions of ozone with short‐chained alkenes

et al. 2007

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[1] Reaction rate coefficients and product yields in the gas phase reaction of O 3 with the short-chained alkenes ethene, propene, 1-butene, isobutene, (E)-butene, and (Z)-butene were determined by Simulation of Atmospheric Photochemistry in a Large Reaction Chamber (SAPHIR). In a first set of experiments, reaction rate coefficients were acquired in an absolute reaction rate study from the measured concentration time profiles of ozone and the alkenes with side reactions being suppressed by adding a radical scavenger. The rate coefficients obtained agree well with literature data; for all but one alkene, the deviation was less than 10%. In a second set of experiments, OH yields were derived from the additional alkene turnover in the absence of a radical scavenger. In contrast to other studies, the OH yields determined in the dry chamber (propene, 0.10 ± 0.07; 1-butene, 0.00 ± 0.08, isobutene, 0.30 ± 0.14; (Z)-butene, 0.18 ± 0.09; and (E)-butene, 0.70 ± 0.12) differed from the yields obtained under humid conditions (propene, 0.30 ± 0.08; 1-butene, 0.30 ± 0.09; isobutene, 0.80 ± 0.10; (Z)-butene, 0.40 ± 0.05; and (E)-butene, 0.60 ± 0.12). The only exception was ethene ozonolysis, where no OH production was observed. HO 2 yields (propene, 1.50 ± 0.75; 1-butene, 1.60 ± 0.80; and isobutene, 2.00 ± 1.00) estimated from the additional ozone turnover compared to the experiments where radicals were not scavenged are reported here for the first time. Furthermore, the yields of the stable ozonolysis products CO, acetaldehyde, and formaldehyde were acquired by monitoring the concentration time profile of the respective compound.

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Section: Yields Of Oh and Hosupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Simulation chamber investigation of the reactions of ozone with short‐chained alkenes

et al. 2007

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“…Experimental highpressure limit rates are unknown for these reactions. Conditions for known experiments are around the standard conditions of 298 K and 1 atm [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54]. Considerations at higher temperatures and pressures have never been made for these reactions, but will be considered here in the low-temperature combustion of dimethyl ether.…”

Section: Resultsmentioning

confidence: 99%

“…From this work, we know that the barrier to formation of H _ CO and ÁOH (30.8 kcal mol À1 ) [74] is less favourable than the cyclic rearrangement to form dioxirane (19.0 kcal mol À1 ) [15]. However, ÁOH formation in ethylene ozonolysis has been detected experimentally [40][41][42][43][44][45][46][47]. The measured branching ratio for production of ÁOH under atmospheric conditions is about 12-40% [48].…”

Section: Molecular Physics 383mentioning

confidence: 99%

First-principles-derived kinetics of the reactions involved in low-temperature dimethyl ether oxidation

Andersen¹,

Carter²

2008

Molecular Physics

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Spin-polarised density functional theory (DFT-B3LYP) energies, harmonic vibrational frequencies, and moments of inertia are used to construct modified Arrhenius rate expressions for elementary steps in chain-propagation and chain-branching pathways for dimethyl ether combustion. Barrierless reactions were treated with variational RRKM theory, and global kinetics were modeled using master equation and perfectly stirred reactor simulations. Our kinetics analysis suggests that the bottleneck along the chain propagation path is the isomerisation of CH 3 OCH 2 OO, contrary to earlier interpretations. Comparing the rate constants for competing decomposition pathways of the key chain-branching intermediate hydroperoxymethyl formate (HPMF), we find that formation of formic acid and the atmospherically relevant Criegee intermediate (CH 2 OO) via a H-bonded adduct may be more favourable than O-O bond scission. Since the latter forms a source of a second OH radical beyond that supplied in chain propagation, which is necessary for explosive combustion, the more favourable pathway to formic acid may inhibit autoignition of the fuel. We predict that the HPMF O-O scission product, OCH 2 OC(¼O)H, most likely directly dissociates to HCO þ HC(¼O)OH. This implies an overabundance of CO at 550-700 K, since HC(¼O)OH is a fairly stable product in this temperature range and facile H abstraction from HCO leads to CO. We find that CO 2 product yields are sensitive to the creation of CH 2 OO and that creation of CH 2 OO is competitive with the O-O scission reaction.

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“…However, substantial insight into CI behaviour, in particular relative rates of bimolecular reactions, has also accrued through indirect methods, such as simulation chamber and laboratory relative rate kinetics studies. Scaled M06-2X ZPE energies are used throughout Table 6 Total rate coefficients k(T) (cm 3 molecule À1 s À1 ) for the CI + CO reaction forming CO 2 either directly or through the cycloadduct, where the Arrhenius expression is valid for T = 250-350 K Reaction k (298 K) k(T) 71 used very high CO mole fractions (up to 40%, in a 1 bar total pressure He/O 2 mixture) as a scavenger for OH radicals in the ozonolysis of a range of small alkenes in a small (70 litre) darkened glass reactor, detecting the resulting increase in CO 2 upon addition of CO as a marker for OH formation. The impact (or lack thereof) of the presence of CO upon observed product yields in alkene ozonolysis systems therefore provides some constraint upon the possible rate of the CO + CI reaction, as discussed below and summarized in Table 7.…”

Section: D Experimental Evidence For Sci + Comentioning

confidence: 99%

Theoretical study of the reactions of Criegee intermediates with ozone, alkylhydroperoxides, and carbon monoxide

Vereecken

Rickard

Newland

et al. 2015

Phys. Chem. Chem. Phys.

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The reaction of Criegee intermediates (CI) with ozone, O3, has been re-examined with higher levels of theory, following earlier reports that O3 could be a relevant sink of CI. The updated rate coefficients indicate that the reaction is somewhat slower than originally anticipated, and is not expected to play a role in the troposphere. In experimental (laboratory) conditions, the CI + O3 reaction can be important. The reaction of CI with ROOH intermediates is found to proceed through a pre-reactive complex, and the insertion process allows for the formation of oligomers in agreement with recent experimental observations. The CI + ROOH reaction also allows for the formation of ether oxides, which don't react with H2O but can oxidize SO2. Under tropospheric conditions, the ether oxides are expected to re-dissociate to the CI + ROOH complex, and ultimately follow the insertion reaction forming a longer-chain hydroperoxide. The CI + ROOH reaction is not expected to play a significant role in the atmosphere. The reaction of CI with CO molecules was studied at very high levels of theory, but no energetically viable route was found, leading to very low rate coefficients. These results are compared against an extensive literature overview of experimental data.

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On the use of CO as scavenger for OH radicals in the ozonolysis of simple alkenes and isoprene

Cited by 22 publications

References 0 publications

Simulation chamber investigation of the reactions of ozone with short‐chained alkenes

Simulation chamber investigation of the reactions of ozone with short‐chained alkenes

First-principles-derived kinetics of the reactions involved in low-temperature dimethyl ether oxidation

Theoretical study of the reactions of Criegee intermediates with ozone, alkylhydroperoxides, and carbon monoxide

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