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Zhang S, Chen Q, Zhang L, Li J, Hu X, Xie D. Dynamics studies for the multi-well and multi-channel reaction of OH with C 2H 2 on a full-dimensional global potential energy surface. Phys Chem Chem Phys 2024; 26:7351-7362. [PMID: 38375620 DOI: 10.1039/d3cp05811e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2024]
Abstract
The C2H2 + OH reaction is an important acetylene oxidation pathway in the combustion process, as well as a typical multi-well and multi-channel reaction. Here, we report an accurate full-dimensional machine learning-based potential energy surface (PES) for the C2H2 + OH reaction at the UCCSD(T)-F12b/cc-pVTZ-F12 level, based on about 475 000 ab initio points. Extensive quasi-classical trajectory (QCT) calculations were performed on the newly developed PES to obtain detailed dynamic data and analyze reaction mechanisms. Below 1000 K, the C2H2 + OH reaction produces H + OCCH2 and CO + CH3. With increasing temperature, the product channels H2O + C2H and H + HCCOH are accessible and the former dominates above 1900 K. It is found that the formation of H2O + C2H is dominated by a direct reaction process, while other channels belong to the indirect mechanism involving long-lived intermediates along the reaction pathways. At low temperatures, the C2H2 + OH reaction behaves like an unimolecular reaction due to the unique PES topographic features, of which the dynamic features are similar to the decomposition of energy-rich complexes formed by C2H2 + OH collision. The classification of trajectories that undergo different reaction pathways to generate each product and their product energy distributions were also reported in this work. This dynamic information may provide a deep understanding of the C2H2 + OH reaction.
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Affiliation(s)
- Shuwen Zhang
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Qixin Chen
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Lidong Zhang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, China; State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, China.
| | - Jun Li
- School of Chemistry and Chemical Engineering & Chongqing Key Laboratory of Theoretical and Computational Chemistry, Chongqing University, Chongqing 401331, China.
| | - Xixi Hu
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China.
- Hefei National Laboratory, Hefei 230088, China
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- Hefei National Laboratory, Hefei 230088, China
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2
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Dmitriev A, Osipova KN, Knyazkov DA, Shmakov AG. Propylene Oxide Addition Effect on the Chemical Speciation of a Fuel-Rich Premixed n-Heptane/Toluene Flame. ACS OMEGA 2022; 7:46900-46914. [PMID: 36570235 PMCID: PMC9774339 DOI: 10.1021/acsomega.2c05999] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
1,2-Propylene oxide (PO, C3H6O) is considered as a promising agent for improving fuel. In this work, the effect of PO additives on the species pool in a premixed burner-stabilized fuel-rich (ϕ = 1.6) flame fueled by n-heptane/toluene mixture (7/3 by volume of liquids) at atmospheric pressure is studied by the flame-sampling molecular beam mass spectrometry and numerical modeling in order to get insight into the chemical aspects of the influence of oxygenates with an epoxy group on the formation of abundant intermediates (including PAH precursors) during combustion of fossil fuels. The flames with various loadings of PO in the fuel blend (from 0 to 16.3% in mole basis) are examined, and detailed kinetic mechanisms available in the literature are validated against the measurements of mole fraction profiles of reactants, major products, and many intermediate species. A higher reactivity of the fresh mixture and a reduction in the peak mole fractions of intermediates playing an important role in PAH formation (benzene, styrene, ethylbenzene, phenol, acetylene, diacetylene, etc.) are observed when PO is added. This was found to be due to simultaneously two factors: the partial replacement of "sooting" fuel (toluene, which is the main precursor of these species) with oxygenated additive, and the changes in the flame radical pool caused by PO addition. Propylene oxide additive was found to change the ratio between H, OH, O, and CH3 toward an increase in the proportion of O and CH3. The detailed kinetic mechanisms considered in the work are found to overpredict the peak mole fraction of acetylene, a key species playing a crucial role in PAH growth. Its chemistry is revisited in order to provide a better prediction of C2H2 and, as a result, PAHs.
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3
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Shojaei SR, Shiroudi A, Abdel-Rahman MA. Computational studies on thermo-kinetics aspects of pyrolysis of isopropyl acetate and its methyl, bromide and hydroxyl derivatives. Heliyon 2022; 8:e11274. [PMID: 36339763 PMCID: PMC9626549 DOI: 10.1016/j.heliyon.2022.e11274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 10/05/2022] [Accepted: 10/21/2022] [Indexed: 11/17/2022] Open
Abstract
The gas-phase decomposition kinetics of isopropyl acetate (IPA) and its methyl, bromide and hydroxyl derivatives into the corresponding acid and propene were investigated using density functional theory (DFT) with the ωB97XD and M06–2x functionals, as well as the benchmark CBS-QB3 composite method. Transition state theory (TST) and RRKM theory calculations of rate constants under atmospheric pressure and in the fall-off regime were used to supplement the measured energy profiles. The results show that the formation of propene and bromoacetic acid is the most dominant pathway at the CBS-QB3 composite method, both kinetically and thermodynamically. There was a good agreement with experimental results. Pressures greater than 0.01 bar, corresponding to larger barrier heights are insufficient to ensure saturation of the measured rate coefficient when compared to the RRKM kinetic rates. Natural bond orbitals (NBO) charges, bond orders, bond indices, and synchronicity parameters all point to the considered pathways taking place via a homogenous, first-order concerted, as well as an asynchronous mechanism involving a non-planar cyclic six-membered transition state. The calculated data exhibit that the elongation of the Cα−O bond length and subsequent polarization of the Cα+δ…O−δ bond is the rate-determining step of the considered reactions in the cyclic transition state, which appears to be involved in this type of reaction.
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Affiliation(s)
- S.H. Reza Shojaei
- Department of Physics, Faculty of Science, Sahand University of Technology, Tabriz, 51335-1996, Iran
- X-LAB, Hasselt University, Agoralaan, Diepenbeek, 3590, Belgium
| | | | - Mohamed A. Abdel-Rahman
- Chemistry Department, Faculty of Science, Suez University, Suez, 43518, Egypt
- Corresponding author.
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4
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Hu X, Yu X, Hou H, Wang B. Theoretical Investigations on the Hydroxyl-Initialized Oxidation of Hexafluoro-2-butyne in the Presence of Oxygen. J Phys Chem A 2022; 126:1994-2006. [PMID: 35298178 DOI: 10.1021/acs.jpca.2c00613] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hexafluoro-2-butyne (C4F6) is a potential eco-friendly alternative gas in plasma, refrigerants, and electrical insulation applications. Mechanisms for the reactions of C4F6 with OH/O2 have been revealed in detail using various theoretical methods including ROCBS-Q, RCCSD(T), multireference RS2C, and extrapolations to the complete basis-set limit with Aug-cc-pVnZ (n = T, Q, 5) basis sets. Rate coefficients and product branching ratios were predicted for a wide range of temperatures and pressures using the solution of master equations. The vibrationally adiabatic ground-state barrier for the initial C4F6 + OH association was best estimated to be 1.53-2.26 kcal/mol. Energetically preferable decomposition paths for the conformation-dependent C4F6OH adducts include six-center HF elimination, four-center proton migration, and C-C bond cleavage, but the collisional deactivation is dominant under ambient conditions. The subsequent oxidation of C4F6OH by O2 bifurcates in two orientations and proceeds without any well-defined barrier followed by the successive isomerization/elimination steps, forming perfluorobiacetyl to regenerate OH radicals or trifluoroacetic acid with trifluoroacetyl radicals. The OH-recycling path accounts for a branching ratio of 70% under ambient conditions. Theoretical rate coefficients are in good agreement with the available experimental results. The effect of fluorination on the reactivity of alkynes toward OH/O2 is discussed.
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Affiliation(s)
- Xiaoyi Hu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China
| | - Xiaojuan Yu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China
| | - Hua Hou
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China
| | - Baoshan Wang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People's Republic of China
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5
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Bowman MC, Burke AD, Turney JM, Schaefer III HF. Conclusive determination of ethynyl radical hydrogen abstraction energetics and kinetics*. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1769214] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Michael C. Bowman
- Center for Computational Quantum Chemistry, University of Georgia, Athens, GA, USA
- Department of Chemistry and Biochemistry, Taylor University, Upland, IN, USA
| | - Alexandra D. Burke
- Center for Computational Quantum Chemistry, University of Georgia, Athens, GA, USA
| | - Justin M. Turney
- Center for Computational Quantum Chemistry, University of Georgia, Athens, GA, USA
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6
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Miar M, Shiroudi A, Pourshamsian K, Oliaey AR, Hatamjafari F. Theoretical investigations on the HOMO–LUMO gap and global reactivity descriptor studies, natural bond orbital, and nucleus-independent chemical shifts analyses of 3-phenylbenzo[d]thiazole-2(3H)-imine and its para-substituted derivatives: Solvent and substituent effects. JOURNAL OF CHEMICAL RESEARCH 2020. [DOI: 10.1177/1747519820932091] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Natural bond orbital analysis, salvation, and substituent effects of electron-releasing (–CH3, –OH) and electron-withdrawing (–Cl, –NO2, –CF3) groups at para positions on the molecular structure of synthesized 3-phenylbenzo[ d]thiazole-2(3 H)-imine and its derivatives in selected solvents (acetone, toluene, and ethanol) and in the gas phase by employing the polarizable continuum method model are studied using the M06-2x method and 6-311++G(d,p) basis set. The relative stability of the studied compounds is influenced by the possibility of intramolecular interactions between substituents and the electron donor–acceptor centers of the thiazole ring. Furthermore, atomic charges, electron density, chemical thermodynamics, energetic properties, dipole moments, and nucleus-independent chemical shifts of the studied compounds and their relative stability are considered. The dipole moment values and the highest occupied molecular orbital–lowest unoccupied molecular orbital energy gaps reveal different charge-transfer possibilities within the considered molecules. Finally, natural bond orbital analysis is carried out to picture the charge transfer between the localized bonds and lone pairs.
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Affiliation(s)
- Marzieh Miar
- Department of Chemistry, Islamic Azad University, Tonekabon, Iran
| | - Abolfazl Shiroudi
- Young Researchers and Elite Club, Islamic Azad University, Tehran, Iran
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7
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A theoretical investigation on the mechanism and kinetics of the thermal isomerization of Trimethylsilylcyclopropane using CBS-QB3. REACTION KINETICS MECHANISMS AND CATALYSIS 2020. [DOI: 10.1007/s11144-020-01775-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Aceta Y, Hapiot P, Leroux YR. Investigation of Protective Properties of Organic Layers toward Reactive Oxygen Species. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16210-16216. [PMID: 31697088 DOI: 10.1021/acs.langmuir.9b02991] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The antioxidant protective properties of polyaromatic organic layers were evaluated toward reactive oxygen species (ROS) using scanning electrochemical microscopy in a foot-printing strategy. The layers were prepared by electrografting of aryldiazonium salts. Where p-(methyl)phenyl films show only weak protective properties toward ROS, p-(ethynyl)phenyl films evidence efficient protection of the covered surfaces. Applied potentials and electrolytes used during oxygen reduction reaction are critical parameters to control, prevent, or reduce the influence of ROS production and hence enhance the device lifetime.
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Affiliation(s)
- Yara Aceta
- Univ Rennes, CNRS, ISCR-UMR 6226 , F-35000 Rennes , France
| | | | - Yann R Leroux
- Univ Rennes, CNRS, ISCR-UMR 6226 , F-35000 Rennes , France
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9
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Middaugh JE, Buras ZJ, Matrat M, Chu TC, Kim YS, Alecu IM, Vasiliou AK, Goldsmith CF, Green WH. A combined photoionization time-of-flight mass spectrometry and laser absorption spectrometry flash photolysis apparatus for simultaneous determination of reaction rates and product branching. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:074102. [PMID: 30068092 DOI: 10.1063/1.5024399] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 07/04/2018] [Indexed: 06/08/2023]
Abstract
In recent years, predictions of product branching for reactions of consequence to both combustion and atmospheric chemistry have outpaced validating experiments. An apparatus is described that aims to fill this void by combining several well-known experimental techniques into one: flash photolysis for radical generation, multiple-pass laser absorption spectrometry (LAS) for overall kinetics measurements, and time-resolved photoionization time-of-flight mass spectrometry (PI TOF-MS) for product branching quantification. The sensitivity of both the LAS and PI TOF-MS detection techniques is shown to be suitable for experiments with initial photolytically generated radical concentrations of ∼1 × 1012 molecules cm-3. As it is fast (μs time resolution) and non-intrusive, LAS is preferred for accurate kinetics (time-dependence) measurements. By contrast, PI TOF-MS is preferred for product quantification because it provides a near-complete picture of the reactor composition in a single mass spectrum. The value of simultaneous LAS and PI TOF-MS detection is demonstrated for the chemically interesting phenyl radical + propene system.
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Affiliation(s)
- Joshua E Middaugh
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Zachary J Buras
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Mickael Matrat
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Te-Chun Chu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Young-Seok Kim
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Ionut M Alecu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - AnGayle K Vasiliou
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - C Franklin Goldsmith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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10
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Kawade MN, Srinivas D, Upadhyaya HP. Gas Phase OH Radical Reaction with 2‐Chloroethyl Vinyl Ether in the 256–333 K Temperature Range: A Combined LP‐LIF and Computational Study. ChemistrySelect 2018. [DOI: 10.1002/slct.201800885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Monali N. Kawade
- Radiation & Photochemistry DivisionBhabha Atomic Research Centre, HBNI, Trombay Mumbai – 400 085 India
| | - Doddipatla Srinivas
- Radiation & Photochemistry DivisionBhabha Atomic Research Centre, HBNI, Trombay Mumbai – 400 085 India
| | - Hari P. Upadhyaya
- Radiation & Photochemistry DivisionBhabha Atomic Research Centre, HBNI, Trombay Mumbai – 400 085 India
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11
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Bakkum T, van Leeuwen T, Sarris AJC, van Elsland DM, Poulcharidis D, Overkleeft HS, van Kasteren SI. Quantification of Bioorthogonal Stability in Immune Phagocytes Using Flow Cytometry Reveals Rapid Degradation of Strained Alkynes. ACS Chem Biol 2018; 13:1173-1179. [PMID: 29693370 PMCID: PMC5962927 DOI: 10.1021/acschembio.8b00355] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
One of the areas
in which bioorthogonal chemistry—chemistry
performed inside a cell or organism—has become of pivotal importance
is in the study of host–pathogen interactions. The incorporation
of bioorthogonal groups into the cell wall or proteome of intracellular
pathogens has allowed study within the endolysosomal system. However,
for the approach to be successful, the incorporated bioorthogonal
groups must be stable to chemical conditions found within these organelles,
which are some of the harshest found in metazoans: the groups are
exposed to oxidizing species, acidic conditions, and reactive thiols.
Here we present an assay that allows the assessment of the stability
of bioorthogonal groups within host cell phagosomes. Using a flow
cytometry-based assay, we have quantified the relative label stability
inside dendritic cell phagosomes of strained and unstrained alkynes.
We show that groups that were shown to be stable in other systems
were degraded by as much as 79% after maturation of the phagosome.
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Affiliation(s)
- Thomas Bakkum
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Tyrza van Leeuwen
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Alexi J. C. Sarris
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Daphne M. van Elsland
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Dimitrios Poulcharidis
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Herman S. Overkleeft
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Sander I. van Kasteren
- Leiden Institute of Chemistry and The Institute for Chemical Immunology, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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12
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Gudiyella S, Buras ZJ, Chu TC, Lengyel I, Pannala S, Green WH. Modeling Study of High Temperature Pyrolysis of Natural Gas. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.8b00758] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Soumya Gudiyella
- Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Zachary J. Buras
- Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Te-Chun Chu
- Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Istvan Lengyel
- SABIC Technology
Center, 1600 Industrial Boulevard, Sugar Land, Texas 77478, United States
| | - Sreekanth Pannala
- SABIC Technology
Center, 1600 Industrial Boulevard, Sugar Land, Texas 77478, United States
| | - William H. Green
- Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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13
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Estep ML, Morgan WJ, Winkles AT, Abbott AS, Villegas-Escobar N, Mullinax JW, Turner WE, Wang X, Turney JM, Schaefer HF. Radicals derived from acetaldehyde and vinyl alcohol. Phys Chem Chem Phys 2017; 19:27275-27287. [PMID: 28868538 DOI: 10.1039/c7cp04671e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vinyl alcohol and acetaldehyde are isoelectronic products of incomplete butanol combustion. Along with the radicals resulting from the removal of atomic hydrogen or the hydroxyl radical, these species are studied here using ab initio methods as complete as coupled cluster theory with single, double, triple, and perturbative quadruple excitations [CCSDT(Q)], with basis sets as large as cc-pV5Z. The relative energies provided herein are further refined by including corrections for relativistic effects, the frozen core approximation, and the Born-Oppenheimer approximation. The effects of anharmonic zero-point vibrational energies are also treated. The syn conformer of vinyl alcohol is predicted to be lower in energy than the anti conformer by 1.1 kcal mol-1. The alcoholic hydrogen of syn-vinyl alcohol is found to be the easiest to remove, requiring 84.4 kcal mol-1. Five other radicals are also carefully considered, with four conformers investigated for the 1-hydroxyvinyl radical. Beyond energetics, we have conducted an overhaul of the spectroscopic literature for these species. Our results also provide predictions for fundamental modes yet to be reported experimentally. To our knowledge, the ν3 (3076 cm-1) and ν4 (2999 cm-1) C-H stretches for syn-vinyl alcohol and all but one of the vibrational modes for anti-vinyl alcohol (ν1-ν14) are yet to be observed experimentally. For the acetyl radical, ν6 (1035 cm-1), ν11 (944 cm-1), ν12 (97 cm-1), and accounting for our changes to the assignment of the 1419.9 cm-1 experimental mode, ν10 (1441 cm-1), are yet to be observed. We have predicted these unobserved fundamentals and reassigned the experimental 1419.9 cm-1 frequency in the acetyl radical to ν4 rather than to ν10. Our work also strongly supports reassignment of the ν10 and ν11 fundamentals of the vinoxy radical. We suggest that the bands assigned to the overtones of these fundamentals were in fact combination bands. Our findings may be useful in constructing improved combustion models of butanol and in spectroscopically characterizing these molecules further.
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Affiliation(s)
- Marissa L Estep
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA.
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14
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Blitz MA, Salter RJ, Heard DE, Seakins PW. An Experimental Study of the Kinetics of OH/OD(v = 1,2,3) + SO 2: The Limiting High-Pressure Rate Coefficients as a Function of Temperature. J Phys Chem A 2017; 121:3175-3183. [PMID: 28363245 DOI: 10.1021/acs.jpca.7b01294] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics of the reaction OH/OD(v = 1,2,3) + SO2 were studied using a photolysis/laser-induced fluorescence technique. The rate coefficients OH/OD(v = 1,2,3) + SO2, k1, over the temperature range of 295-810 K were used to determine the limiting high-pressure limit k1∞. This method is usually applicable if the reaction samples the potential well of the adduct HOSO2 and if intramolecular vibrational relaxation is fast. In the present case, however, the rate coefficients showed an additional fast removal contribution as evidenced by the increase in k1 with vibrational level; this behavior together with its temperature dependence is consistent with the existence of a weakly bound complex on the potential energy surface prior to adduct formation. The data were analyzed using a composite mechanism that incoporates energy-transfer mechanisms via both the adduct and the complex, and yielded a value of k1∞(295 K) equal to (7.2 ± 3.3) × 10-13 cm3 molecule-1 s-1 (errors at 1σ), a factor of between 2 and 3 smaller than the current recommended IUPAC and JPL values of (2.0-1.0+2.0) and (1.6 ± 0.4) × 10-12 cm3 molecule-1 s-1 at 298 K, respectively, although the error bars do overlap. k1∞ was observed to only depend weakly on temperature. Further evidence for a smaller k1∞ is presented in the companion paper.
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Affiliation(s)
| | - Robert J Salter
- Deloitee MCS , 3 Rivergate, Temple Quay, Bristol BR1 6GD, U.K
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15
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Gimenez-Lopez J, Rasmussen CT, Hashemi H, Alzueta MU, Gao Y, Marshall P, Goldsmith CF, Glarborg P. Experimental and Kinetic Modeling Study of C2H2Oxidation at High Pressure. INT J CHEM KINET 2016. [DOI: 10.1002/kin.21028] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jorge Gimenez-Lopez
- Department of Chemical and Biochemical Engineering; Technical University of Denmark; DK-2800 Kgs. Lyngby Denmark
- Department of Chemical and Environmental Engineering; University of Zaragoza; 50018 Zaragoza Spain
| | - Christian Tihic Rasmussen
- Department of Chemical and Biochemical Engineering; Technical University of Denmark; DK-2800 Kgs. Lyngby Denmark
| | - Hamid Hashemi
- Department of Chemical and Biochemical Engineering; Technical University of Denmark; DK-2800 Kgs. Lyngby Denmark
| | - Maria U. Alzueta
- Department of Chemical and Environmental Engineering; University of Zaragoza; 50018 Zaragoza Spain
| | - Yide Gao
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling; University of North Texas; 1155 Union Circle #305070 Denton Texas 76203-5017
| | - Paul Marshall
- Department of Chemistry and Center for Advanced Scientific Computing and Modeling; University of North Texas; 1155 Union Circle #305070 Denton Texas 76203-5017
| | | | - Peter Glarborg
- Department of Chemical and Biochemical Engineering; Technical University of Denmark; DK-2800 Kgs. Lyngby Denmark
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16
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Sato S. Empirical rate equation for association reactions and ion–molecule reactions. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2016.02.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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17
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Adamson SO. Reactions C2H2 + OH and C2 + H2O: Ab initio study of the potential energy surfaces. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2016. [DOI: 10.1134/s1990793116010012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Jung SH, Jang SC, Kim JW, Kim JW, Choi JH. Theoretical Investigation of the Radical-Radical Reaction of O((3)P) + C2H3 and Comparison with Gas-Phase Crossed-Beam Experiments. J Phys Chem A 2015; 119:11761-71. [PMID: 26562486 DOI: 10.1021/acs.jpca.5b09191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Herein, we present an ab initio study of the prototypal radical-radical reactions of ground-state atomic oxygen [O((3)P)] with the vinyl (C2H3) radical using density functional theory and a complete basis set model. Two distinctive pathways on the lowest doublet potential energy surfaces (PESs) were predicted to be in competition: addition and abstraction. The barrierless addition of O((3)P) to the hydrocarbon radicals leads to energy-rich intermediate formation followed by subsequent isomerization and decomposition to yield various products: CH2CO (ketene) + H, CO + CH3, C2HOH (acetylenol) + H, (3,1)CCHOH + H, H2O + C2H, (3,1)CH2 + HCO, H2CO (formaldehyde) + CH, C2H2 (acetylene) + OH, and (3,1)CCH2 + OH. The competing but minor H-atom abstraction mechanisms produce C2H2 + OH and (1,3)CCH2 + OH. The optimized structures of the reactants, products, intermediates, and transition states and the reaction mechanisms were obtained on the lowest doublet PESs. The major pathway was predicted to be the formation of CH2CO + H through the low-barrier, single-step cleavages of the addition intermediates. The Levine-Bernstein prior method, statistical surprisal approach, and microcanonical Rice-Ramsperger-Kassel-Marcus theory were applied to deduce the energy distributions of H atoms and OH products and quantitative rate constants. On the basis of the statistical theory and the population analysis, the predicted energy distributions were compared to the kinetic energy release of H and the preferential population of the Π(A') component of OH products reported in recent gas-phase crossed-beam investigations (Park, M. J.; Jang, S. C.; Choi, J. H. J. Chem. Phys. 2012, 137, 204311), and their kinetic and dynamic characteristics were discussed.
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Affiliation(s)
- Se-Hee Jung
- Department of Chemistry, Research Institute for Natural Sciences, Korea University , Anam-dong, Seoul 136-701, Republic of Korea
| | - Su-Chan Jang
- Department of Chemistry, Research Institute for Natural Sciences, Korea University , Anam-dong, Seoul 136-701, Republic of Korea
| | - Jin-Wook Kim
- Department of Chemistry, Research Institute for Natural Sciences, Korea University , Anam-dong, Seoul 136-701, Republic of Korea
| | - Jang-Woon Kim
- Department of Chemistry, Research Institute for Natural Sciences, Korea University , Anam-dong, Seoul 136-701, Republic of Korea
| | - Jong-Ho Choi
- Department of Chemistry, Research Institute for Natural Sciences, Korea University , Anam-dong, Seoul 136-701, Republic of Korea
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19
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Maranzana A, Ghigo G, Tonachini G. Combustive, Postcombustive, and Tropospheric Butadiyne Oxidation by O 2, Following Initial HO Attack. Theoretical Study. J Phys Chem A 2015; 119:10172-80. [DOI: 10.1021/acs.jpca.5b06548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Andrea Maranzana
- Dipartimento di Chimica, Università di Torino, via Pietro
Giuria, 7, I-10125 Torino, Italy
| | - Giovanni Ghigo
- Dipartimento di Chimica, Università di Torino, via Pietro
Giuria, 7, I-10125 Torino, Italy
| | - Glauco Tonachini
- Dipartimento di Chimica, Università di Torino, via Pietro
Giuria, 7, I-10125 Torino, Italy
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20
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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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21
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Jang SC, Choi JH. Probing the kinetic energy-release dynamics of H-atom products from the gas-phase reaction of O(3P) with vinyl radical C2H3. Phys Chem Chem Phys 2014; 16:23679-85. [PMID: 25272025 DOI: 10.1039/c4cp03046j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The gas-phase radical-radical reaction dynamics of ground-state atomic oxygen O((3)P) with vinyl radicals C2H3 has been studied by combining the results of vacuum-ultraviolet laser-induced fluorescence spectroscopy in a crossed beam configuration with ab initio calculations. The two radical reactants O((3)P) and C2H3 were produced by photolysis of NO2 and supersonic flash pyrolysis of C2H3I, respectively. Doppler profile analysis of the kinetic energy release of the nascent H-atom products from the title reaction O((3)P) + C2H3→ H((2)S) + CH2CO (ketene) revealed that the average translational energy of the products and the average fraction of the total available energy were 7.03 ± 0.30 kcal mol(-1) and 7.2%. The empirical data combined with CBS-QB3 level ab initio theory and statistical calculations demonstrated that the title oxygen-hydrogen exchange reaction is a major reaction channel, through an addition-elimination mechanism involving the formation of a short-lived, dynamical complex on the doublet potential energy surface. On the basis of systematic comparison with several exchange reactions of hydrocarbon radicals, the observed kinetic energy release can be explained in terms of the weak impulse at the moment of decomposition in the loose transition state with a product-like geometry and a small reverse barrier along the exit channel.
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Affiliation(s)
- Su-Chan Jang
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 1, Anam-dong, Seoul 136-701, Korea.
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22
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Zhang Y, Sun J, Zhang W, Tang Y, Wang R. Theoretical study on the gas phase reaction of propargyl alcohol with hydroxyl radical. J Comput Chem 2014; 35:1646-56. [PMID: 24995629 DOI: 10.1002/jcc.23670] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/03/2014] [Accepted: 06/08/2014] [Indexed: 11/11/2022]
Abstract
The reaction of propargyl alcohol with hydroxyl radical has been studied extensively at CCSD(T)/aug-cc-pVTZ//MP2/cc-pVTZ level. This is the first time to gain a conclusive insight into the reaction mechanism and kinetics for this important reaction in detail. Two reaction mechanisms were revealed, namely addition/elimination and hydrogen abstraction mechanism. The reaction mechanism confirms that OH addition to C≡C triple bond forms the chemically activated adducts, IM1 (·CHCOHCH2OH) and IM2 (CHOH·CCH2OH), and the hydrogen abstraction pathways (-CH2OH bonded to the carbon atom and alcohol hydrogen) may occur via low barriers. Harmonic model of Rice-Ramsperger-Kassel-Marcus theory and variational transition state theory are used to calculate the overall and individual rate constants over a wide range of temperatures and pressures. The calculated rate constants are in good agreement with the experimental data. At atmospheric pressure with Ar as bath gas, IM1 (·CHCOHCH2OH) and IM2 (CHOH·CCH2OH) formed by collisional stabilization are dominant in the low temperature range. The production of CHCCHOH + H2O via hydrogen abstraction becomes dominate at higher temperature. The fraction of IM3 (CH2COHCH2·O) is very significant over the moderate temperature range.
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Affiliation(s)
- Yunju Zhang
- Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Renmin Road 5268, Changchun, Jilin, 130024, People's Republic of China
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23
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Jasper AW, Miller JA, Klippenstein SJ. Collision Efficiency of Water in the Unimolecular Reaction CH4 (+H2O) ⇆ CH3 + H (+H2O): One-Dimensional and Two-Dimensional Solutions of the Low-Pressure-Limit Master Equation. J Phys Chem A 2013; 117:12243-55. [DOI: 10.1021/jp409086w] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ahren W. Jasper
- Combustion
Research Facility, Sandia National Laboratories, P.O. Box 969, Livermore, California 94551-0969, United States
| | - James A. Miller
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Stephen J. Klippenstein
- Chemical
Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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24
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A Hierarchical and Comparative Kinetic Modeling Study of C1
− C2
Hydrocarbon and Oxygenated Fuels. INT J CHEM KINET 2013. [DOI: 10.1002/kin.20802] [Citation(s) in RCA: 773] [Impact Index Per Article: 70.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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25
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Miller JA, Klippenstein SJ. Dissociation of Propyl Radicals and Other Reactions on a C3H7 Potential. J Phys Chem A 2013; 117:2718-27. [DOI: 10.1021/jp312712p] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James A. Miller
- Chemical Sciences and Engineering
Division, Argonne National Laboratory,
9700 South Cass Avenue,
Argonne, Illinois 60439, United States
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering
Division, Argonne National Laboratory,
9700 South Cass Avenue,
Argonne, Illinois 60439, United States
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26
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Park MJ, Jang SC, Choi JH. A combined crossed-beam and theoretical study of the reaction dynamics of O(3P) + C2H3 → C2H2 + OH: analysis of the nascent OH products with the preferential population of the Π(A') component. J Chem Phys 2012. [PMID: 23206007 DOI: 10.1063/1.4767772] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The gas-phase reaction dynamics of ground-state atomic oxygen [O((3)P) from the photo-dissociation of NO(2)] with vinyl radicals [C(2)H(3) from the supersonic flash pyrolysis of vinyl iodide, C(2)H(3)I] has been investigated using a combination of high-resolution laser-induced fluorescence spectroscopy in a crossed-beam configuration and ab initio calculations. Unlike the previous gas-phase bulk kinetic experiments by Baulch et al. [J. Phys. Chem. Ref. Data 34, 757 (2005)], a new exothermic channel of O((3)P) + C(2)H(3) → C(2)H(2) + OH (X (2)Π: υ" = 0) has been identified for the first time, and the population analysis shows bimodal nascent rotational distributions of OH products with low- and high-N" components with a ratio of 2.4:1. No spin-orbit propensities were observed, and the averaged ratios of Π(A('))∕Π(A") were determined to be 1.66 ± 0.27. On the basis of computations at the CBS-QB3 theory level and comparison with prior theory, the microscopic mechanisms responsible for the nascent populations can be understood in terms of two competing dynamical pathways: a direct abstraction process in the low-N" regime as the major pathway and an addition-complex forming process in the high-N" regime as the minor pathway. Particularly, during the bond cleavage process of the weakly bound van der Waals complex C(2)H(2)-OH, the characteristic pathway from the low dihedral-angle geometry was consistent with the observed preferential population of the Π(A') component in the nascent OH products. A molecular-level discussion of the reactivity, mechanism, and dynamical features of the title reaction are presented together with a comparison to gas-phase oxidation reactions of a series of prototypical hydrocarbon radicals.
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Affiliation(s)
- Min-Jin Park
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 1, Anam-dong, Seoul 136-701, Korea
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27
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Glowacki DR, Lockhart J, Blitz MA, Klippenstein SJ, Pilling MJ, Robertson SH, Seakins PW. Interception of excited vibrational quantum states by O2 in atmospheric association reactions. Science 2012; 337:1066-9. [PMID: 22936771 DOI: 10.1126/science.1224106] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Bimolecular reactions in Earth's atmosphere are generally assumed to proceed between reactants whose internal quantum states are fully thermally relaxed. Here, we highlight a dramatic role for vibrationally excited bimolecular reactants in the oxidation of acetylene. The reaction proceeds by preliminary adduct formation between the alkyne and OH radical, with subsequent O(2) addition. Using a detailed theoretical model, we show that the product-branching ratio is determined by the excited vibrational quantum-state distribution of the adduct at the moment it reacts with O(2). Experimentally, we found that under the simulated atmospheric conditions O(2) intercepts ~25% of the excited adducts before their vibrational quantum states have fully relaxed. Analogous interception of excited-state radicals by O(2) is likely common to a range of atmospheric reactions that proceed through peroxy complexes.
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28
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Zhang W, Du B. Quantum chemical study of the mechanism for OH-initiated atmospheric oxidation reaction of (Z)-CF3CFCHF. COMPUT THEOR CHEM 2012. [DOI: 10.1016/j.comptc.2012.03.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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29
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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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30
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Ali MA, Rajakumar B. Computational study on OH radical reaction with CHF2CHFCHF2(HFC-245ea) between 200 and 400 K. INT J CHEM KINET 2011. [DOI: 10.1002/kin.20569] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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31
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Carr SA, Glowacki DR, Liang CH, Baeza-Romero MT, Blitz MA, Pilling MJ, Seakins PW. Experimental and Modeling Studies of the Pressure and Temperature Dependences of the Kinetics and the OH Yields in the Acetyl + O2 Reaction. J Phys Chem A 2011; 115:1069-85. [DOI: 10.1021/jp1099199] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Scott A. Carr
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - David R. Glowacki
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Chi-Hsiu Liang
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - M. Teresa Baeza-Romero
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Mark A. Blitz
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Michael J. Pilling
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Paul W. Seakins
- School of Chemistry and ‡School of Earth and Environment, University of Leeds, Leeds LS2 9JT, United Kingdom
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32
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Yang X, Jasper AW, Giri BR, Kiefer JH, Tranter RS. A shock tube and theoretical study on the pyrolysis of 1,4-dioxane. Phys Chem Chem Phys 2011; 13:3686-700. [DOI: 10.1039/c0cp01541e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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33
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Murakami Y, Oguchi T, Hashimoto K, Nosaka Y. Density Functional Study of the High-Temperature Oxidation of o-, m- and p-Xylyl Radicals. J Phys Chem A 2009; 113:10652-66. [DOI: 10.1021/jp902204a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yoshinori Murakami
- Department of Materials Engineering, Nagaoka National College of Technology, Nishikatagai, Nagaoka, 940-8532 Japan, Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi, 441-8580 Japan, Honda R&D Co. Ltd. Fundamental Technology Research Center,1-4-1 Chuo, Wako-shi, Saitama, 351-0193 Japan, and Department of Chemistry, Nagaoka University of Technology, Kamitomioka, Nagaoka, 940-2188 Japan
| | - Tatsuo Oguchi
- Department of Materials Engineering, Nagaoka National College of Technology, Nishikatagai, Nagaoka, 940-8532 Japan, Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi, 441-8580 Japan, Honda R&D Co. Ltd. Fundamental Technology Research Center,1-4-1 Chuo, Wako-shi, Saitama, 351-0193 Japan, and Department of Chemistry, Nagaoka University of Technology, Kamitomioka, Nagaoka, 940-2188 Japan
| | - Kohtaro Hashimoto
- Department of Materials Engineering, Nagaoka National College of Technology, Nishikatagai, Nagaoka, 940-8532 Japan, Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi, 441-8580 Japan, Honda R&D Co. Ltd. Fundamental Technology Research Center,1-4-1 Chuo, Wako-shi, Saitama, 351-0193 Japan, and Department of Chemistry, Nagaoka University of Technology, Kamitomioka, Nagaoka, 940-2188 Japan
| | - Yoshio Nosaka
- Department of Materials Engineering, Nagaoka National College of Technology, Nishikatagai, Nagaoka, 940-8532 Japan, Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi, 441-8580 Japan, Honda R&D Co. Ltd. Fundamental Technology Research Center,1-4-1 Chuo, Wako-shi, Saitama, 351-0193 Japan, and Department of Chemistry, Nagaoka University of Technology, Kamitomioka, Nagaoka, 940-2188 Japan
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34
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Klippenstein SJ, Harding LB, Ruscic B, Sivaramakrishnan R, Srinivasan NK, Su MC, Michael JV. Thermal Decomposition of NH2OH and Subsequent Reactions: Ab Initio Transition State Theory and Reflected Shock Tube Experiments. J Phys Chem A 2009; 113:10241-59. [PMID: 19722533 DOI: 10.1021/jp905454k] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- S. J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - L. B. Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - B. Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - R. Sivaramakrishnan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - N. K. Srinivasan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - M.-C. Su
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J. V. Michael
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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35
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Gao H, Liu JY, Sun CC. Theoretical and kinetic studies of the reactions of CF2HCFHCF2H and CF3CFHCFH2 with hydroxyl radicals. J Chem Phys 2009; 130:224301. [DOI: 10.1063/1.3147464] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Maranzana A, Ghigo G, Tonachini G, Barker JR. Tropospheric Oxidation of Ethyne and But-2-yne. 1. Theoretical Mechanistic Study. J Phys Chem A 2008; 112:3656-65. [DOI: 10.1021/jp077174o] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Andrea Maranzana
- Dipartimento di Chimica Generale e Chimica Organica, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy, and Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan 48109-2143
| | - Giovanni Ghigo
- Dipartimento di Chimica Generale e Chimica Organica, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy, and Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan 48109-2143
| | - Glauco Tonachini
- Dipartimento di Chimica Generale e Chimica Organica, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy, and Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan 48109-2143
| | - John R. Barker
- Dipartimento di Chimica Generale e Chimica Organica, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy, and Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan 48109-2143
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37
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Maranzana A, Barker JR, Tonachini G. Oxidation of Ethyne and But-2-yne. 2. Master Equation Simulations. J Phys Chem A 2008; 112:3666-75. [DOI: 10.1021/jp077180k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrea Maranzana
- Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan, 48109-2143, and Dipartimento di Chimica Generale ed Organica Applicata, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy
| | - John R. Barker
- Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan, 48109-2143, and Dipartimento di Chimica Generale ed Organica Applicata, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy
| | - Glauco Tonachini
- Department of Atmospheric, Oceanic, and Space Sciences, 1520 Space Research Building, 2455 Hayward Street, University of Michigan, Ann Arbor, Michigan, 48109-2143, and Dipartimento di Chimica Generale ed Organica Applicata, Università di Torino, Corso Massimo D'Azeglio 48, I-10125 Torino, Italy
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38
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Pilling MJ. Interactions between theory and experiment in the investigation of elementary reactions of importance in combustion. Chem Soc Rev 2008; 37:676-85. [PMID: 18362976 DOI: 10.1039/b715767c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Elementary reactions are a central component of models of combustion processes. Rate constants and channel yields are needed for those models. Both experimental and theoretical methods used to determine such rate data are discussed in this tutorial review, which is of interest to reaction kinetics and combustion engineering communities. Applications to combustion present particular problems because the conditions required can be well outside the ranges of temperature and pressure accessible to experiment, and the rate data can show a complex dependence on conditions. Under these conditions, the interplay between theory and experiment becomes important.
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39
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Taylor SE, Goddard A, Blitz MA, Cleary PA, Heard DE. Pulsed Laval nozzle study of the kinetics of OH with unsaturated hydrocarbons at very low temperatures. Phys Chem Chem Phys 2008; 10:422-37. [DOI: 10.1039/b711411g] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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40
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Giri BR, Kiefer JH, Xu H, Klippenstein SJ, Tranter RS. An experimental and theoretical high temperature kinetic study of the thermal unimolecular dissociation of fluoroethane. Phys Chem Chem Phys 2008; 10:6266-73. [DOI: 10.1039/b808168a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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41
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Fan H, Pratt ST, Miller JA. Secondary decomposition of C3H5 radicals formed by the photodissociation of 2-bromopropene. J Chem Phys 2007; 127:144301. [DOI: 10.1063/1.2775445] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Miller JA, Klippenstein SJ. Master equation methods in gas phase chemical kinetics. J Phys Chem A 2007; 110:10528-44. [PMID: 16956234 DOI: 10.1021/jp062693x] [Citation(s) in RCA: 246] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this article, we discuss the application of master equation methods to problems in gas phase chemical kinetics. The focus is on reactions that take place over multiple, interconnected potential wells and on the dissociation of weakly bound free radicals. These problems are of paramount importance in combustion chemistry. To illustrate specific points, we draw on our experience with reactions we have studied previously.
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Affiliation(s)
- James A Miller
- Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA.
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43
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Senosiain JP, Klippenstein SJ, Miller JA. Reaction of ethylene with hydroxyl radicals: a theoretical study. J Phys Chem A 2007; 110:6960-70. [PMID: 16722710 DOI: 10.1021/jp0566820] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio calculations of portions of the C2H5O potential energy surface critical to the title reaction are presented. These calculations are based on QCISD geometries and frequencies and RQCISD(T) energies extrapolated to the complete-basis-set limit. Rate coefficients for the reaction of C2H4 with OH are calculated using this surface and the two transition-state model of Greenwald and co-workers [J. Phys. Chem. A 2005, 109, 6031] for the association of OH with C2H4. The present calculations reproduce most of the experimental data, including the temperature and pressure dependence of the rate coefficients, with only a small (0.4 kcal/mol) adjustment to the energy barrier for direct hydrogen abstraction. We confirm the importance of this channel above 800 K and find that a significant fraction of the total rate coefficient (approximately 10%) is due to the formation of vinyl alcohol above this temperature. Calculations of the vinyl alcohol channel are consistent with the recent observation of this molecule in low-pressure flames [Taatjes, C. A.; Hansen, N.; McIlroy, A.; Miller, J. A.; Senosiain, J. P.; Klippenstein, S. J.; Qi, F.; Sheng, L.; Zhang, Y.; Cool, T. A.; Wang, J.; Westmoreland, P. R.; Law, M. E.; Kasper, T.; Kohse-Höinghaus, K. Science 2005, 308, 1887] and suggest that this reaction should be included in hydrocarbon oxidation mechanisms.
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Affiliation(s)
- Juan P Senosiain
- Combustion Research Facility, Sandia National Laboratories, MS 9055, Livermore, California 94551-0969, USA.
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Gannon KL, Glowacki DR, Blitz MA, Hughes KJ, Pilling MJ, Seakins PW. H Atom Yields from the Reactions of CN Radicals with C2H2, C2H4, C3H6, trans-2-C4H8, and iso-C4H8. J Phys Chem A 2007; 111:6679-92. [PMID: 17536788 DOI: 10.1021/jp0689520] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics and H atom channel yield at both 298 and 195 K have been determined for reactions of CN radicals with C2H2 (1.00+/-0.21, 0.97+/-0.20), C2H4 (0.96+/-0.032, 1.04+/-0.042), C3H6 (pressure dependent), iso-C4H8 (pressure dependent), and trans-2-C4H8 (0.039+/-0.019, 0.029+/-0.047) where the first figure in each bracket is the H atom yield at 298 K and the second is that at 195 K. The kinetics of all reactions were studied by monitoring both CN decay and H atom growth by laser-induced fluorescence at 357.7 and 121.6 nm, respectively. The results are in good agreement with previous studies where available. The rate coefficients for the reaction of CN with trans-2-butene and iso-butene have been measured at 298 and 195 K for the first time, and the rate coefficients are as follows: k298K=(2.93+/-0.23)x10(-10) cm3 molecule(-1) s(-1), k195K=(3.58+/-0.43)x10(-10) cm3 molecule(-1) s(-1) and k298K=(3.17+/-0.10)x10(-10) cm3 molecule(-1) s(-1), k195K=(4.32+/-0.35)x10(-10) cm3 molecule(-1) s(-1), respectively, where the errors represent a combination of statistical uncertainty (2sigma) and an estimate of possible systematic errors. A potential energy surface for the CN+C3H6 reaction has been constructed using G3X//UB3LYP electronic structure calculations identifying a number of reaction channels leading to either H, CH3, or HCN elimination following the formation of initial addition complexes. Results from the potential energy surface calculations have been used to run master equation calculations with the ratio of primary:secondary addition, the average amount of downward energy transferred in a collision DeltaEd, and the difference in barrier heights between H atom elimination and an H atom 1, 2 migration as variable parameters. Excellent agreement is obtained with the experimental 298 K H atom yields with the following parameter values: secondary addition complex formation equal to 80%, DeltaEd=145 cm(-1), and the barrier height for H atom elimination set 5 kJ mol(-1) lower than the barrier for migration. Finally, very low temperature master equation simulations using the best fit parameters have been carried out in an increased precision environment utilizing quad-double and double-double arithmetic to predict H and CH3 yields for the CN+C3H6 reaction at temperatures and pressures relevant to Titan. The H and CH3 yields predicted by the master equation have been parametrized in a simple equation for use in modeling.
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Affiliation(s)
- Kelly L Gannon
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, United Kingdom
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Senosiain JP, Miller JA. The Reaction of n- and i-C4H5 Radicals with Acetylene. J Phys Chem A 2007; 111:3740-7. [PMID: 17408247 DOI: 10.1021/jp0675126] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this article, we discuss the reactions of i-C4H5 and n-C4H5 with acetylene. Both have been proposed as possible cyclization steps, forming benzene or fulvene, in rich flames burning aliphatic fuels. The relevant parts of the potential energy surface were determined from rQCISD(T) calculations extrapolated to the infinite-basis-set limit. Using this information in a Rice-Ramsperger-Kassel-Marcus-based master equation, we have calculated thermal rate coefficients and product distributions for both reactions as a function of temperature and pressure. The results are cast in forms that can be used in modeling, and the implications of the results for flame chemistry are discussed.
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Affiliation(s)
- Juan P Senosiain
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Avda. das Ciencias s/n, Santiago de Compostela 15782, Spain.
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McKee KW, Blitz MA, Cleary PA, Glowacki DR, Pilling MJ, Seakins PW, Wang L. Experimental and Master Equation Study of the Kinetics of OH + C2H2: Temperature Dependence of the Limiting High Pressure and Pressure Dependent Rate Coefficients. J Phys Chem A 2007; 111:4043-55. [PMID: 17397143 DOI: 10.1021/jp067594y] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The kinetics of the reaction OH + C2H2 have been studied using laser flash photolysis at 248 nm to generate OH radicals and laser-induced fluorescence to monitor OH removal. An attempt was made to use the rate coefficients OH (v = 1,2) + C2H2 to determine the limiting high-pressure rate coefficient, k(1a)(infinity), over the temperature range of 195-823 K. This method is usually applicable if the reaction samples the potential energy well of the adduct, HOC2H2, and if intramolecular vibrational relaxation is fast. In the present case, however, the rate coefficients for loss of the vibrationally excited states by reaction with C2H2 also contain a substantial contribution from nonreactive vibrational relaxation, which occurs via a mechanism that does not sample the adduct potential energy well but involves, at least at low temperatures, collisions that access a shallower, longer range van der Waals well. The data were analyzed using a composite mechanism that incorporates both reactive and nonreactive energy transfer mechanisms, which allows the determination of k(1a)(infinity)(T) for OH + C2H2 with satisfactory accuracy over the temperature range 195-823 K. The kinetics of the reaction OH (v = 0) + C2H2 were also studied in He over the range of conditions: 210-373 K and 5-760 Torr. A one-dimensional master equation (ME) analysis of the experimental data provided a further determination of k(1a)(infinity)(T) and also <DeltaE>(down) for He. Combining the two sets of results gives a consistent dataset for k(1a)(infinity) and the Arrhenius parameters A1ainfinity = 7.3 x 10(-12) cm(3) molecule(-1) s(-1) and E(1a)(infinity) = 5.3 kJ mol(-1), with <DeltaE>(down) = 150(T/300 K) cm(-1). Additional experiments were conducted at room temperature in N(2) and SF(6) by laser flash photolysis with cavity ring down spectroscopy, and ME calculations were then optimized for the pressure falloff in N(2) by varying the average downward energy transfer parameter (<DeltaE>(down)). The output from the best fit ME was parametrized using a modified Troe expression to provide rate data for use in atmospheric modeling.
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Affiliation(s)
- Kenneth W McKee
- School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
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Jasper AW, Klippenstein SJ, Harding LB, Ruscic B. Kinetics of the Reaction of Methyl Radical with Hydroxyl Radical and Methanol Decomposition. J Phys Chem A 2007; 111:3932-50. [PMID: 17388366 DOI: 10.1021/jp067585p] [Citation(s) in RCA: 170] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The CH3 + OH bimolecular reaction and the dissociation of methanol are studied theoretically at conditions relevant to combustion chemistry. Kinetics for the CH3 + OH barrierless association reaction and for the H + CH2OH and H + CH3O product channels are determined in the high-pressure limit using variable reaction coordinate transition state theory and multireference electronic structure calculations to evaluate the fragment interaction energies. The CH3 + OH --> 3CH2 + H2O abstraction reaction and the H2 + HCOH and H2 + H2CO product channels feature localized dynamical bottlenecks and are treated using variational transition state theory and QCISD(T) energies extrapolated to the complete basis set limit. The 1CH2 + H2O product channel has two dynamical regimes, featuring both an inner saddle point and an outer barrierless region, and it is shown that a microcanonical two-state model is necessary to properly describe the association rate for this reaction over a broad temperature range. Experimental channel energies for the methanol system are reevaluated using the Active Thermochemical Tables (ATcT) approach. Pressure dependent, phenomenological rate coefficients for the CH3 + OH bimolecular reaction and for methanol decomposition are determined via master equation simulations. The predicted results agree well with experimental results, including those from a companion high-temperature shock tube determination for the decomposition of methanol.
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Affiliation(s)
- Ahren W Jasper
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Schofield K, Steinberg M. CH and C2 Measurements Imply a Radical Pool within a Pool in Acetylene Flames. J Phys Chem A 2007; 111:2098-114. [PMID: 17388296 DOI: 10.1021/jp0667689] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Measured CH and C2 profiles show a striking resemblance as a function of time in a series of seven well-characterized fuel-rich (phi=1.2-2.0) non-sooting acetylene flames. This implied commonality and interrelationship are unexpected as these radicals have dissimilar chemical kinetic natures. As a result, a rigorous examination was undertaken of the behavior of each of the hydrocarbon species known to be present, C, CH, CH2, CH3, CH4, CHO, CHOH, CH2O, CH2OH, CH3O, CH3OH, C2, C2H, C2H2, CHCO, CH2CO, and C2O. This emphasized the main region where CH and C2 are observed (50-600 micros) and reduced the kinetic reactions to only those that operate efficiently and are dominant. It was immediately apparent that this region of the flame reflects the nature of a hydrogen flame heavily doped with CO and CO2 and containing traces of hydrocarbons. The radical species, H, OH, O, along with H2, H2O, and O2, form an important controlling radical pool that is in partial equilibrium, and the concentrations of each of the hydrocarbon radicals are minor to this, playing secondary roles. As a result, the dominant fast reactions are those between the hydrocarbons and the basic hydrogen/oxygen radicals. Hydrocarbon-hydrocarbon reactions are unimportant here at these equivalence ratios. CH and C2 are formed and destroyed on a sub-microsecond time scale so that their flame profiles are the reflection of a complex kinetically dynamic system. This is found to be the case for all of the hydrocarbon species examined. As might be expected, these rapidly form steady-state distributions. However, with the exceptions of C, CHO, CHOH, and CH2O, which are irreversibly being oxidized, the others all form an interconnected hydrocarbon pool that is under the control of the larger hydrogen radical pool. The hydrocarbon pool can rapidly adjust, and the CH and C2 decay together as the pool is drained. This is either by continuing oxidation in less rich mixtures, or in richer flames where this is negligible by the onset of hydrocarbon-hydrocarbon reactions. The implications of such a hydrocarbon pool are significant. It introduces a buffering effect on their distribution and provides the indirect connection between CH and C2. Moreover, because they are members of this radical pool, flame studies alone cannot answer questions concerning their specific importance in combustion other than their contributing role to this pool. The presence of such a pool modifies the exactness that is needed for kinetic mechanisms, and knowledge of every species in the system no longer is necessary. Furthermore, as rate constants become refined, it will allow for the calculation of the relative concentrations of the hydrocarbon species and facilitate reduced kinetic mechanisms. It provides an explanation for previous isotopically labeled experiments and illustrates the difficulty of exactly identifying in flames the role of individual species. It resolves the fact that differing kinetic models can show similar levels of accuracy and has implications for sensitivity analyses. It finally unveils the mechanism of the flame ionization detector and has implications for the differing interpretations of diamond formation mechanisms.
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Affiliation(s)
- Keith Schofield
- Materials Research Laboratory, University of California, Santa Barbara, California 93106-5121, USA.
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Ochando-Pardo M, Nebot-Gil I, González-Lafont A, Lluch JM. Methyl Vinyl Ketone+OH and Methacrolein+OH Oxidation Reactions: A Master Equation Analysis of the Pressure- and Temperature-Dependent Rate Constants. Chemistry 2007; 13:1180-90. [PMID: 17066494 DOI: 10.1002/chem.200600529] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
High-level electronic structure calculations and master equation analyses were carried out to obtain the pressure- and temperature-dependent rate constants of the methyl vinyl ketone+OH and methacrolein+OH reactions. The balance between the OH addition reactions at the high-pressure limit, the OH addition reactions in the fall-off region, and the pressure-independent hydrogen abstractions involved in these multiwell and multichannel systems, has been shown to be crucial to understand the pressure and temperature dependence of each global reaction. In particular, the fall-off region of the OH addition reactions contributes to the inverse temperature dependence of the rate constants in the Arrhenius plots, leading to pressure-dependent negative activation energies. The pressure dependence of the methyl vinyl ketone+OH reaction is clearly more important than in the case of the methacrolein+OH reaction owing to the weight of the hydrogen abstraction process in this second system. Comparison of the theoretical rate constants and the experimental measurements shows quite good agreement.
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Srinivasan NK, Su MC, Michael JV. Reflected shock tube studies of high-temperature rate constants for OH + C2H2 and OH + C2H4. Phys Chem Chem Phys 2007; 9:4155-63. [PMID: 17687465 DOI: 10.1039/b702267k] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reflected shock tube technique with multi-pass absorption spectrometric detection of OH-radicals at 308 nm (corresponding to a total path length of approximately 4.9 m) has been used to study the reactions, OH + C(2)H(2)--> products (1) and OH + C(2)H(4)--> C(2)H(3) + H(2)O (2). The present optical configuration gives a S/N ratio of approximately 1 at approximately 0.5-1.0 x 10(12) radicals cm(-3). Hence, kinetics experiments could be performed at [OH](0) = approximately 4-20 ppm thereby minimizing secondary reactions. OH was produced rapidly from the dissociations of either CH(3)OH or NH(2)OH (hydroxylamine). A mechanism was then used to obtain profile fits that agreed with the experiment to within <+/-5%. The derived Arrhenius expressions, in units of cm(3) molecule(-1) s(-1) are: k(1) = (1.03 +/- 0.24) x 10(-10) exp(-7212 +/- 417 K/T) for 1509-2362 K and k(2) = (10.2 +/- 5.8) x 10(-10) exp(-7411 +/- 871 K/T) for 1463-1931 K. The present study is the first ever direct measurement for reaction (1) at temperatures >1275 K while the present results extend the temperature range for (2) by approximately 700 K. These values are compared with earlier determinations and with recent theoretical calculations. The calculations agree with the present data for both reactions to within +/-10% over the entire T-range.
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Affiliation(s)
- N K Srinivasan
- Chemistry Division, Argonne National Laboratory, Argonne, IL 60439, USA
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