1
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Chen S, Li J, Zhu Q, Li Z. Theoretical kinetic studies on intramolecular H-migration reactions of peroxy radicals of diethoxymethane. Phys Chem Chem Phys 2024; 26:24676-24688. [PMID: 39282693 DOI: 10.1039/d4cp02302a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2024]
Abstract
Diethoxymethane (DEM), a promising carbon-neutral fuel, has high reactivity at low temperatures. The intramolecular hydrogen migration reaction of the DEM peroxy radicals can be viewed as a critical step in the low temperature oxidation mechanism of DEM. In this work, multistructural transition state theory (MS-TST) was utilized to calculate the high-pressure limit rate constants of 1,5, 1,6 and 1,7 H-migration reactions for DEM peroxy radicals. In addition to the tunneling effects and anharmonic effects, the intramolecular effects, including steric hindrance, intramolecular hydrogen bonding and conformational changes in reactants and transition states, are also considered in the rate constant calculations. The calculated energy barriers and rate constants demonstrated the substantial impact of intramolecular effects on the kinetics of H-migration reactions in DEM peroxy radicals. Specifically, the distinct configurations of transition states could potentially influence the reaction kinetics. The pressure-dependent rate constants are computed using system-specific quantum RRK theory. The calculated results show that the falloff effect of 1,5 and 1,6 H-migration reactions is more pronounced than that of the 1,7 H-migration reaction. The thermodynamics and kinetics presented in this study could be instrumental in understanding the low-temperature oxidation mechanism of DEM and might prove crucial for future research on comprehensively analyzing the autoignition behavior.
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Affiliation(s)
- Siyu Chen
- College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Juanqin Li
- College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China.
| | - Quan Zhu
- College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China.
- Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, Sichuan 610065, P. R. China
| | - Zerong Li
- College of Chemistry, Sichuan University, Chengdu 610064, P. R. China
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2
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Li J, Wang L, Wang L. Computational Study on the Reaction of β-Hydroxyethylperoxy Radical with HO 2 and Effects of Water Vapor. J Phys Chem A 2022; 126:2234-2243. [PMID: 35362984 DOI: 10.1021/acs.jpca.1c09009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of β-hydroxyethylperoxy radical (β-HEP) and HO2 with and without water was studied using quantum chemistry and kinetic calculations. The main products are HOCH2CH2OOH and 3O2 for the reaction with and without water, while all other reaction channels can be neglected. The rate coefficients of the reaction follow negative temperature dependence. The pseudo-second-order rate coefficients are 2-4 orders of magnitude smaller for the reaction with saturated water vapor, indicating the negligible contribution of water in this reaction. This is probably also true for other peroxy radicals (except for HO2), indicating that a large part of previous results on the water enhancement of reaction rate coefficients might have overestimated the influence of water.
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Affiliation(s)
- Junjie Li
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Lingyu Wang
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China
| | - Liming Wang
- School of Chemistry & Chemical Engineering, South China University of Technology, Guangzhou 510640, China.,Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou 510006, China
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3
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Xi S, Xue J, Wang F, Li X. Theoretical Study on Reactions of α-Site Hydroxyethyl and Hydroxypropyl Radicals with O 2. J Phys Chem A 2021; 125:5423-5437. [PMID: 34132092 DOI: 10.1021/acs.jpca.1c00784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
α-Site alcohol radicals are the most important products of H-abstract reactions from alcohols since the hydroxyl moiety weakens the α-site C-H bond. Reactions between α-site alcohol radicals and O2 play an important role in combustion of alcohols, especially at relatively low temperatures. However, reliable reaction pathways and rate constants for these reactions are still lacking. Theoretical studies on reactions in α-hydroxyethyl radical (CH3C•HOH) + O2 and α-hydroxypropyl radical (C2H5C•HOH and CH3C•OHCH3) + O2 reaction systems are performed in this work. Pressure-dependent rate constants for the involved reactions in a wide range of temperatures are determined using the Rice-Ramsperger-Kassel-Marcus/master equation (RRKM/ME) method. Our results show that rate constants for reactions in the α-hydroxypropyl radical + O2 system are quite different from those in the CH3C•HOH + O2 system. Detailed reaction pathways for these reaction systems are clarified, although combustion characteristics of ethanol and propanol do not change much with the obtained rate constants for these reactions. Important reaction channels in producing enols, especially in the combustion of propanol, are also provided. The obtained rate constants for these reactions over a wide range of temperatures and pressures are helpful in developing combustion mechanisms for ethanol and propanol.
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Affiliation(s)
- Shuanghui Xi
- College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
| | - Jie Xue
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, P. R. China
| | - Fan Wang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, P. R. China
| | - Xiangyuan Li
- College of Chemical Engineering, Sichuan University, Chengdu 610065, P. R. China
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4
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Wagner JP. Criegee Intermediates in Autoxidation Reactions: Mechanistic Considerations. J Phys Chem A 2021; 125:406-410. [PMID: 33393293 DOI: 10.1021/acs.jpca.0c09971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Products of Criegee intermediate (CI) chemistry were recently detected in radical chain autoxidation reactions involving β-hydroxyperoxy radicals. Here, we demonstrate by means of accurate G4 computations that direct scission of the latter to CIs and radical byproducts is thermodynamically highly unfavorable. Instead, the reaction becomes possible through a hydrogen abstraction reaction that could proceed by reversible formation of a dimeric tetroxide and a subsequent [1,6] hydrogen shift of the hydroxy hydrogen.
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Affiliation(s)
- J Philipp Wagner
- Institut für Organische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
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5
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Li Y, Zhao Q, Zhang Y, Huang Z, Sarathy SM. A Systematic Theoretical Kinetics Analysis for the Waddington Mechanism in the Low-Temperature Oxidation of Butene and Butanol Isomers. J Phys Chem A 2020; 124:5646-5656. [PMID: 32574048 PMCID: PMC7467721 DOI: 10.1021/acs.jpca.0c03515] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
![]()
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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Affiliation(s)
- Yang Li
- King Abdullah University of Science and Technology, Clean Combustion Research Centre, Thuwal 23955, Saudi Arabia
| | - Qian Zhao
- State Key Laboratory of Multiphase Flows in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Yingjia Zhang
- State Key Laboratory of Multiphase Flows in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Zuohua Huang
- State Key Laboratory of Multiphase Flows in Power Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - S Mani Sarathy
- King Abdullah University of Science and Technology, Clean Combustion Research Centre, Thuwal 23955, Saudi Arabia
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6
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Lei X, Wang W, Cai J, Wang C, Liu F, Wang W. Atmospheric Chemistry of Enols: Vinyl Alcohol + OH + O2 Reaction Revisited. J Phys Chem A 2019; 123:3205-3213. [DOI: 10.1021/acs.jpca.8b12240] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Xiaoyang Lei
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
| | - Weina Wang
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
| | - Jie Cai
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
| | - Changwei Wang
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
| | - Fengyi Liu
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
| | - Wenliang Wang
- Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
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7
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Lizardo-Huerta JC, Sirjean B, Bounaceur R, Fournet R. Intramolecular effects on the kinetics of unimolecular reactions of β-HOROO˙ and HOQ˙OOH radicals. Phys Chem Chem Phys 2017; 18:12231-51. [PMID: 27080359 DOI: 10.1039/c6cp00111d] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A theoretical study describing the influence of intramolecular effects on the energy barriers and rate constants of unimolecular reactions involving β-HOROO˙ and HOQ˙OOH radicals is proposed. The reactions considered are HO2˙ elimination, the Waddington mechanism, H-shift, cyclic ether formation and β-scission. All the calculations are performed at the CBS-QB3 level of theory along with canonical transition state theory and statistical thermodynamics, including a specific treatment of hindered rotors. Several structural parameters are investigated, such as the location of the hydroxyl function in the cyclic transition states or the substitution of H atoms by alkyl groups on carbon atoms involved in the reaction coordinate. It is shown that these molecular systems involve numerous transition states, especially for reactions such as 1,5 or 1,6 H-shift, and that, a priori simplification is not possible. It is also shown that the position of the -OH group in the transition state can largely modify both the barrier heights and the rate constants. However, opposite trends can be observed depending on the competition between energetic and entropic effects. Similar observations are made when H atoms are replaced by methyl or alkyl groups. These results can largely be explained by intramolecular effects such as hydrogen bonds, stabilization effects (from -OH or -CH3 groups), steric influences and by the coupling between them. The last point renders the classic establishment of the structure-reactivity relationship challenging.
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Affiliation(s)
- J C Lizardo-Huerta
- Laboratoire Réactions et Génie des Procédés, CNRS, Université de Lorraine, 1 rue Grandville BP 20451, 54001 Nancy Cedex, France.
| | - B Sirjean
- Laboratoire Réactions et Génie des Procédés, CNRS, Université de Lorraine, 1 rue Grandville BP 20451, 54001 Nancy Cedex, France.
| | - R Bounaceur
- Laboratoire Réactions et Génie des Procédés, CNRS, Université de Lorraine, 1 rue Grandville BP 20451, 54001 Nancy Cedex, France.
| | - R Fournet
- Laboratoire Réactions et Génie des Procédés, CNRS, Université de Lorraine, 1 rue Grandville BP 20451, 54001 Nancy Cedex, France.
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8
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Bao JL, Truhlar DG. Variational transition state theory: theoretical framework and recent developments. Chem Soc Rev 2017; 46:7548-7596. [DOI: 10.1039/c7cs00602k] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This article reviews the fundamentals of variational transition state theory (VTST), its recent theoretical development, and some modern applications.
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Affiliation(s)
- Junwei Lucas Bao
- Department of Chemistry
- Chemical Theory Center, and Minnesota Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
| | - Donald G. Truhlar
- Department of Chemistry
- Chemical Theory Center, and Minnesota Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
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9
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Vereecken L, Glowacki DR, Pilling MJ. Theoretical Chemical Kinetics in Tropospheric Chemistry: Methodologies and Applications. Chem Rev 2015; 115:4063-114. [DOI: 10.1021/cr500488p] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Luc Vereecken
- Max Planck Institute for Chemistry, 55128 Mainz, Germany
| | - David R. Glowacki
- PULSE
Institute and Department of Chemistry, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- School
of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
- Department
of Computer Science, University of Bristol, Bristol BS8 1UB, United Kingdom
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10
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Knap HC, Jørgensen S, Kjaergaard HG. Theoretical investigation of the hydrogen shift reactions in peroxy radicals derived from the atmospheric decomposition of 3-methyl-3-buten-1-ol (MBO331). Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2014.11.056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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11
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Nechab M, Mondal S, Bertrand MP. 1,n-Hydrogen-Atom Transfer (HAT) Reactions in Whichn≠5: An Updated Inventory. Chemistry 2014; 20:16034-59. [DOI: 10.1002/chem.201403951] [Citation(s) in RCA: 167] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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12
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A large source of low-volatility secondary organic aerosol. Nature 2014; 506:476-9. [PMID: 24572423 DOI: 10.1038/nature13032] [Citation(s) in RCA: 584] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 01/14/2014] [Indexed: 02/01/2023]
Abstract
Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth's radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally.
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13
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Chhantyal-Pun R, Chen MW, Miller TA. Laser induced fluorescence study of the - transition of FCH2CH2O. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2012.11.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Chhantyal-Pun R, Chen MW, Sun D, Miller TA. Detection and Characterization of Products from Photodissociation of XCH2CH2ONO (X = F, Cl, Br, OH). J Phys Chem A 2012. [PMID: 23185987 DOI: 10.1021/jp308428a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rabi Chhantyal-Pun
- Department of Chemistry, The Ohio State University, 120 West 18th Avenue, Columbus Ohio 43210,
United States
| | - Ming-Wei Chen
- Department of Chemistry, The Ohio State University, 120 West 18th Avenue, Columbus Ohio 43210,
United States
| | - Dianping Sun
- Department of Chemistry, The Ohio State University, 120 West 18th Avenue, Columbus Ohio 43210,
United States
| | - Terry A. Miller
- Department of Chemistry, The Ohio State University, 120 West 18th Avenue, Columbus Ohio 43210,
United States
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15
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Xing L, Borodin O. Oxidation induced decomposition of ethylene carbonate from DFT calculations – importance of explicitly treating surrounding solvent. Phys Chem Chem Phys 2012; 14:12838-43. [DOI: 10.1039/c2cp41103b] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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16
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Vereecken L, Francisco JS. Theoretical studies of atmospheric reaction mechanisms in the troposphere. Chem Soc Rev 2012; 41:6259-93. [DOI: 10.1039/c2cs35070j] [Citation(s) in RCA: 311] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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17
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Chen MW, Just GMP, Codd T, Miller TA. Spectroscopic studies of the ÖX̃ electronic spectrum of the β-hydroxyethylperoxy radical: Structure and dynamics. J Chem Phys 2011; 135:184304. [DOI: 10.1063/1.3656835] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Carr SA, Blitz MA, Seakins PW. Site-specific rate coefficients for reaction of OH with ethanol from 298 to 900 K. J Phys Chem A 2011; 115:3335-45. [PMID: 21443222 DOI: 10.1021/jp200186t] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The rate coefficients for reactions of OH with ethanol and partially deuterated ethanols have been measured by laser flash photolysis/laser-induced fluorescence over the temperature range 298-523 K and 5-100 Torr of helium bath gas. The rate coefficient, k(1.1), for reaction of OH with C(2)H(5)OH is given by the expression k(1.1) = 1.06 × 10(-22)T(3.58) exp(1126/T) cm(3) molecule(-1) s(-1), and the values are in good agreement with previous literature. Site-specific rate coefficients were determined from the measured kinetic isotope effects. Over the temperature region 298-523 K abstraction from the hydroxyl site is a minor channel. The reaction is dominated by abstraction of the α hydrogens (92 ± 8)% at 298 K decreasing to (76 ± 9)% with the balance being abstraction at the β position where the errors are 2σ. At higher temperatures decomposition of the CH(2)CH(2)OH product from β abstraction complicates the kinetics. From 575 to 650 K, biexponential decays were observed, allowing estimates to be made for k(1.1) and the fractional production of CH(2)CH(2)OH. Above 650 K, decomposition of the CH(2)CH(2)OH product was fast on the time scale of the measured kinetics and removal of OH corresponds to reaction at the α and OH sites. The kinetics agree (within ±20%) with previous measurements. Evidence suggests that reaction at the OH site is significant at our higher temperatures: 47-53% at 865 K.
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Affiliation(s)
- Scott A Carr
- School of Chemistry, University of Leeds, Leeds, United Kingdom
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19
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da Silva G. Kinetics and Mechanism of the Glyoxal + HO2 Reaction: Conversion of HO2 to OH by Carbonyls. J Phys Chem A 2010; 115:291-7. [DOI: 10.1021/jp108358y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriel da Silva
- Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville 3010, Victoria, Australia
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20
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Kuwata KT, Hermes MR, Carlson MJ, Zogg CK. Computational studies of the isomerization and hydration reactions of acetaldehyde oxide and methyl vinyl carbonyl oxide. J Phys Chem A 2010; 114:9192-204. [PMID: 20701322 DOI: 10.1021/jp105358v] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Alkene ozonolysis is a major source of hydroxyl radical (*OH), the most important oxidant in the troposphere. Previous experimental and computational work suggests that for many alkenes the measured *OH yields should be attributed to the combined impact of both chemically activated and thermalized syn-alkyl Criegee intermediates (CIs), even though the thermalized CI should be susceptible to trapping by molecules such as water. We have used RRKM/master equation and variational transition state theory calculations to quantify the competition between unimolecular isomerization and bimolecular hydration reactions for the syn and anti acetaldehyde oxide formed in trans-2-butene ozonolysis and for the CIs formed in isoprene ozonolysis possessing syn-methyl groups. Statistical rate theory calculations were based on quantum chemical data provided by the B3LYP, QCISD, and multicoefficient G3 methods, and thermal rate constants were corrected for tunneling effects using the Eckart method. At tropospheric temperatures and pressures, all thermalized CIs with syn-methyl groups are predicted to undergo 1,4-hydrogen shifts from 2 to 8 orders of magnitude faster than they react with water monomer at its saturation number density. For thermalized anti acetaldehyde oxide, the rates of dioxirane formation and hydration should be comparable.
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Affiliation(s)
- Keith T Kuwata
- Department of Chemistry, Macalester College, Saint Paul, Minnesota 55105-1899, USA.
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21
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da Silva G. Oxidation of Carboxylic Acids Regenerates Hydroxyl Radicals in the Unpolluted and Nighttime Troposphere. J Phys Chem A 2010; 114:6861-9. [DOI: 10.1021/jp101279p] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gabriel da Silva
- Department of Chemical and Biomolecular Engineering, The University of Melbourne. Parkville 3010, Victoria, Australia
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22
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da Silva G, Graham C, Wang ZF. Unimolecular beta-hydroxyperoxy radical decomposition with OH recycling in the photochemical oxidation of isoprene. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:250-256. [PMID: 19943615 DOI: 10.1021/es900924d] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A novel process in the photochemical oxidation of isoprene that recycles hydroxyl (OH) radicals has been identified using first-principles computational chemistry. Isoprene is the dominant biogenic volatile organic compound (VOC), and its oxidation controls chemistry in the forest boundary layer and is also thought to contribute to cloud formation in marine environments. The mechanism described here involves rapid unimolecular decomposition of the two major peroxy radicals (beta-hydroxyperoxy radicals) produced by OH-initiated isoprene oxidation. Peroxy radicals are well-known as key intermediates in VOC oxidation, but up to now were only thought to be destroyed in bimolecular reactions. The process described here leads to OH recycling with up to around 60% efficiency in environments with low levels of peroxy radicals and NO(x). In forested environments reaction of the beta-hydroxyperoxy radicals with HO2 is expected to dominate, with a small contribution from the mechanism described here. Peroxy radical decomposition will be more important in the unpolluted marine boundary layer, where lower levels of NO and HO2 are encountered.
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Affiliation(s)
- Gabriel da Silva
- Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville 3010, Victoria, Australia.
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23
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Ratkiewicz A, Bankiewicz B, Truong TN. Kinetics of thermoneutral intermolecular hydrogen migration in alkyl radicals. Phys Chem Chem Phys 2010; 12:10988-95. [PMID: 20664879 DOI: 10.1039/c0cp00293c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Artur Ratkiewicz
- Chemistry Institute, University of Bialystok, Hurtowa 1, 15-399 Bialystok, Poland
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24
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Peeters J, Nguyen TL, Vereecken L. HOx radical regeneration in the oxidation of isoprene. Phys Chem Chem Phys 2009; 11:5935-9. [PMID: 19588016 DOI: 10.1039/b908511d] [Citation(s) in RCA: 156] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We propose, and quantify from first principles, two novel HO(x)-regenerating unimolecular reactions in isoprene oxidation, which are estimated to yield in pristine tropical forest conditions about 0.7 HO(2) and 0.03 OH radicals per isoprene oxidized; it is further argued that the photolabile coproduct of HO(2) can be a major source of OH, with a yield of the order of 1. The newly proposed chemistry could provide a rationalization for the unexpectedly high OH concentrations often observed in forested environments, such as over the Amazon forest in the recent Gabriel campaign.
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Affiliation(s)
- J Peeters
- Department of Chemistry, K.U. Leuven, Celestijnenlaan 200F, B-3001, Leuven, Belgium.
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Sun W, Saeys M. first principles Study of the Reaction of Formic and Acetic Acids with Hydroxyl Radicals. J Phys Chem A 2008; 112:6918-28. [DOI: 10.1021/jp802017q] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Wenjie Sun
- Department of Chemical and Biomolecular Engineering, 4 Engineering Drive 4, National University of Singapore, Singapore 117576
| | - Mark Saeys
- Department of Chemical and Biomolecular Engineering, 4 Engineering Drive 4, National University of Singapore, Singapore 117576
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