Formation and stability of gas-phase o-benzoquinone from oxidation of ortho-hydroxyphenyl: a combined neutral and distonic radical study

Prendergast, Matthew B.; Kirk, Benjamin B.; Savee, John David; Osborn, David L.; Taatjes, Craig A.; Masters, Kye; Blanksby, Stephen J.; Silva, Gabriel da; Trevitt, Adam J.

doi:10.1039/c5cp02953h

Cited by 24 publications

(35 citation statements)

References 64 publications

(121 reference statements)

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“…Evidence of the presence of benzoquinone in the product spectra was not found. Formation of ortho-benzoquinone was recently studied by the oxidation of orthohydroxyphenyl radicals in a slow-flow tube reactor [31]. Prompt CO elimination via ring opening and cyclisation yields cyclopentadienone (C 5 H 4 O) [31] which is also considered in the reaction mechanism.…”

Section: Resultsmentioning

confidence: 99%

Flame structure of laminar premixed anisole flames investigated by photoionization mass spectrometry and photoelectron spectroscopy

Bierkandt

Hemberger

Oßwald

et al. 2019

Proceedings of the Combustion Institute

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Section: Resultsmentioning

confidence: 99%

Flame structure of laminar premixed anisole flames investigated by photoionization mass spectrometry and photoelectron spectroscopy

Bierkandt

Hemberger

Oßwald

et al. 2019

Proceedings of the Combustion Institute

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“…11,12 Following this line of enquiry, Schyman et al reported in a computational study that the peroxyl radical would actually be a less efficient at H atom abstraction from deoxyribose than the uracil-5-yl parent. 13 However, following our recent work on orthohydroxylphenyl radicals, which showed characteristic reaction pathways, 14 we posit that the enol form of the uracil-5-yl radical, with an OH group adjacent to the radical at the 5 position, will significantly change the outcome the radical reaction with O 2 . Thus we set out to investigate the gas-phase reaction of protonated uracil-5-yl radical cation, which should be in the enolic form.…”

Section: Introductionmentioning

confidence: 93%

Gas-Phase Oxidation of the Protonated Uracil-5-yl Radical Cation

et al. 2018

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This study targets the kinetics and product detection of the gas-phase oxidation reaction of the protonated 5-dehydrouracil (uracil-5-yl) distonic radical cation using ion-trap mass spectrometry. Protonated 5-dehydrouracil radical ions (5-dehydrouracilH radical ion, m/z 112) are produced within an ion trap by laser photolysis of protonated 5-iodouracil. Storage of the 5-dehydrouracilH radical ion in the presence of controlled concentration of O reveals two main products. The major reaction product pathway is assigned as the formation of protonated 2-hydroxypyrimidine-4,5-dione (m/z 127) + OH. A second product ion (m/z 99), putatively assigned as a five-member-ring ketone structure, is tentatively explained as arising from the decarbonylation (-CO) of protonated 2-hydroxypyrimidine-4,5-dione. Because protonation of the 5-dehydrouracil radical likely forms a dienol structure, the O reaction at the 5 position is ortho to an -OH group. Following this addition of O, the peroxyl-radical intermediate isomerizes by H atom transfer from the -OH group. The ensuing hydroperoxide then decomposes to eliminate OH radical. It is shown that this elimination ofOH radical (-17 Da) is evidence for the presence of an -OH group ortho to the initial phenyl radical site, in good accord with calculations. The subsequent CO loss mechanism, to form the aforementioned five-member-ring structure, is unclear, but some pathways are discussed. By following the kinetics of the reaction, the room temperature second-order rate coefficient of the 5-dehydrouracilH distonic radical cation with molecular oxygen is measured at 7.2 × 10 cm molecule s, Φ = 12% (with ±50% total accuracy). For aryl radical reactions with O, the presence of the OH elimination product pathway, following the peroxyl-radical formation, is an indicator of an -OH group ortho to the radical site.

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“…More fundamental quantum calculations have been performed mainly for the C2–C4 hydrocarbon oxidation systems. 16 − 27 All these Waddington mechanism-related studies are summarized in Table S1 of the Supporting Information 1 ; however, there is still a lack of advanced theoretical treatment of the rate coefficient of this reaction class, and few studies have been concerned specifically with the effect of the reactivity of the isomeric molecule structures.…”

Section: Introductionmentioning

confidence: 99%

A Systematic Theoretical Kinetics Analysis for the Waddington Mechanism in the Low-Temperature Oxidation of Butene and Butanol Isomers

Zhao

Zhang

et al. 2020

J. Phys. Chem. A

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The Waddington mechanism, or the Waddington-type reaction pathway, is crucial for low-temperature oxidation of both alkenes and alcohols. In this study, the Waddington mechanism in the oxidation chemistry of butene and butanol isomers was systematically investigated. Fundamental quantum chemical calculations were conducted for the rate constants and thermodynamic properties of the reactions and species in this mechanism. Calculations were performed using two different ab initio solvers: Gaussian 09 and Orca 4.0.0, and two different kinetic solvers: PAPR and MultiWell, comprehensively. Temperature- and pressure-dependent rate constants were performed based on the transition state theory, associated with the Rice Ramsperger Kassel Marcus and master equation theories. Temperature-dependent thermochemistry (enthalpies of formation, entropy, and heat capacity) of all major species was also conducted, based on the statistical thermodynamics. Of the two types of reaction, dissociation reactions were significantly faster than isomerization reactions, while the rate constants of both reactions converged toward higher temperatures. In comparison, between two ab initio solvers, the barrier height difference among all isomerization and dissociation reactions was about 2 and 0.5 kcal/mol, respectively, resulting in less than 50%, and a factor of 2–10 differences for the predicted rate coefficients of the two reaction types, respectively. Comparing the two kinetic solvers, the rate constants of the isomerization reactions showed less than a 32% difference, while the rate of one dissociation reaction (P1 ↔ WDT12) exhibited 1–2 orders of magnitude discrepancy. Compared with results from the literature, both reaction rate coefficients (R4 and R5 reaction systems) and species’ thermochemistry (all closed shell molecules and open shell radicals R4 and R5) showed good agreement with the corresponding values obtained from the literature. All calculated results can be directly used for the chemical kinetic model development of butene and butanol isomer oxidation.

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Formation and stability of gas-phase o-benzoquinone from oxidation of ortho-hydroxyphenyl: a combined neutral and distonic radical study

Cited by 24 publications

References 64 publications

Flame structure of laminar premixed anisole flames investigated by photoionization mass spectrometry and photoelectron spectroscopy

Flame structure of laminar premixed anisole flames investigated by photoionization mass spectrometry and photoelectron spectroscopy

Gas-Phase Oxidation of the Protonated Uracil-5-yl Radical Cation

A Systematic Theoretical Kinetics Analysis for the Waddington Mechanism in the Low-Temperature Oxidation of Butene and Butanol Isomers

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