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Carl SA, Vereecken L, Peeters J. Kinetic parameters for gas-phase reactions: experimental and theoretical challenges. Phys Chem Chem Phys 2007; 9:4071-84. [PMID: 17687459 DOI: 10.1039/b705505f] [Citation(s) in RCA: 16] [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
This article aims to illustrate the added value provided to experimental kinetics investigations by complementary theoretical kinetics studies, using as examples (i) reactions of two major hydrocarbon flame radicals, HCCO and C(2)H, and (ii) reactions of several oxygenated organic compounds with hydroxyl radicals of interest to atmospheric chemistry. The first part, on HCCO and C(2)H kinetics, does not attempt to give an extensive literature review, but rather addresses some major experimental techniques, mainly specific ones, that have allowed a great part of the available reactivity databases on these two species to be established. For several key reactions, it is shown how potential energy surfaces and statistical rate predictions based thereon have provided insight into the molecular mechanisms and have allowed estimates of product distributions as well as reliable extrapolations of experimental rate coefficients and branching ratios to higher temperatures. The second part addresses current issues in atmospheric chemistry relating mainly to hydroxyl radical reactions with oxygenated organics, and focuses on the experimental characterization of the often unusual temperature dependence of their rate coefficients and on the theoretical rationalization thereof, through the formation of hydrogen-bonded pre-reactive complexes and resulting tunnelling-enhanced H-abstraction. Finally, the development of general structure-activity relationships for OH reactions with organics, H-abstractions as well as OH-additions for unsaturated compounds, is briefly discussed.
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Affiliation(s)
- S A Carl
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium.
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Xie HB, Ding YH, Sun CC. Reaction of ketenyl radical with acetylene: a promising route for cyclopropenyl radical. J Phys Chem A 2006; 110:7262-7. [PMID: 16737278 DOI: 10.1021/jp061013n] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of the ketenyl radical (HCCO) with acetylene (C(2)H(2)) is very relevant to the oxygen-acetylene flames and fuel-rich combustion process for nitrogen-containing compounds. Unfortunately, except for several rate constant measurements, the mechanism is completely unknown for this reaction. In this paper, detailed theoretical investigations are performed for the HCCO + C(2)H(2) reaction at the G3B3 level using the B3LYP/6-31G(d), B3LYP/6-311++G(d,p), and QCISD/6-31G(d) geometries. The exclusive fragmentation channel is the formation of the cyclopropenyl radical (c-C(3)H(3)) and carbon monoxide (CO) via the chainlike OCCHCHCH and three-membered ring OC-cCHCHCH intermediates. Thus, the mass spectroscopic peak of C(3)H(3)(+) in a previous experiment can be explained. The calculated overall reaction barrier is 4.4, 4.4, and 5.3 kcal/mol at the G3B3//B3LYP/6-31G(d), G3B3//B3LYP/6-311++G(d,p), and G3B3//QCISD/6-31G(d) levels, respectively. The title reaction may provide an effective route for generating the long-sought cyclopropenyl radical in the laboratory, which has been the long-standing subject of numerous theoretical studies as the simplest cyclic conjugate radical, and its bulky derivatives were already known. Future experimental investigations for the HCCO + C(2)H(2) reaction are greatly desired to test the predicted fragmentation channel. The implication of the present study in combustion and interstellar processes is discussed.
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Affiliation(s)
- Hong-bin Xie
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun, People's Republic of China
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Vaghjiani GL. 248-nm Laser Photolysis of CHBr 3/O-Atom Mixtures: Kinetic Evidence for UV CO(A) Chemiluminescence in the Reaction of Methylidyne Radicals with Atomic Oxygen. J Phys Chem A 2005; 109:2197-206. [PMID: 16838991 DOI: 10.1021/jp046172q] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The 4th positive and Cameron band emissions from electronically excited CO have been observed for the first time in 248-nm pulsed laser photolysis of a trace amount of CHBr(3) vapor in an excess of O atoms. O atoms were produced by dissociation of N(2)O (or O(2)) in a cw-microwave discharge cavity in 2.0 Torr of He at 298 K. The CO emission intensity in these bands showed a quadratic dependence on the laser fluence employed. Temporal profiles of the CO(A) and other excited-state products that formed in the photoproduced precursor + O-atom reactions were measured by recording their time-resolved chemiluminescence in discrete vibronic bands. The CO 4th positive transition (A(1)Pi, v' = 0 --> X(1)Sigma(+), v' ' = 2) near 165.7 nm was monitored in this work to deduce the pseudo-first-order decay kinetics of the CO(A) chemiluminescence in the presence of various added substrates (CH(4), NO, N(2)O, H(2), and O(2)). From this, the second-order rate coefficient values were determined for reactions of these substrates with the photoproduced precursors. The measured reactivity trends suggest that the prominent precursors responsible for the CO(A) chemiluminescence are the methylidyne radicals, CH(X(2)Pi) and CH(a(4)Sigma(-)), whose production requires the absorption of at least 2 laser photons by the photolysis mixture. The O-atom reactions with brominated precursors (CBr, CHBr, and CBr(2)), which also form in the photolysis, are shown to play a minor role in the production of the CO(A or a) chemiluminescence. However, the CBr(2) + O-atom reaction was identified as a significant source for the 289.9-nm Br(2) chemiluminescence that was also observed in this work. The 282.2-nm OH and the 336.2-nm NH chemiluminescences were also monitored to deduce the kinetics of CH(X(2)Pi) and CH(a(4)Sigma(-)) reactions when excess O(2) and NO were present.
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Affiliation(s)
- Ghanshyam L Vaghjiani
- ERC, Inc., Air Force Research Laboratory, AFRL/PRSA, 10 E Saturn Blvd, Edwards AFB, California 93524, USA.
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Vaghjiani GL. Kinetics of CH radicals with O2: Evidence for CO chemiluminescence in the gas phase reaction. J Chem Phys 2003. [DOI: 10.1063/1.1599346] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Carl SA, Sun Q, Teugels L, Peeters J. Experimental determination of the temperature dependence of the absolute rate coefficients of the HCCO + NO2and HCCO + H2reactions. Phys Chem Chem Phys 2003. [DOI: 10.1039/b311684k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Carl SA, Sun Q, Vereecken L, Peeters J. Absolute Rate Coefficient of the HCCO + NO Reaction over the Range T = 297−802 K. J Phys Chem A 2002. [DOI: 10.1021/jp014135i] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- S. A. Carl
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Q. Sun
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - L. Vereecken
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - J. Peeters
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
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Metropoulos A, Mavridis A. Conditions conducive to the chemi-ionization reaction O(3P)+CH(X 2Π,a 4Σ−)→HCO+(X 1Σ+)+e−. J Chem Phys 2001. [DOI: 10.1063/1.1405007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Carl SA, Sun Q, Peeters J. Laser-induced fluorescence of nascent CH from ultraviolet photodissociation of HCCO and the absolute rate coefficient of the HCCO+O2 reaction over the range T=296–839 K. J Chem Phys 2001. [DOI: 10.1063/1.1370079] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Kalemos A, Mavridis A, Metropoulos A. An accurate description of the ground and excited states of CH. J Chem Phys 1999. [DOI: 10.1063/1.480285] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lee EPF, Wright TG. Methylcarbyne Radical [CH3C(X̃2A‘ ‘; ã4A2)] and the Chemiionization Reaction: CH3C + O → CH3CO+ + e-. J Phys Chem A 1999. [DOI: 10.1021/jp983236m] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Edmond P. F. Lee
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, and Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, U.K
| | - Timothy G. Wright
- Department of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ, U.K
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Boullart W, Devriendt K, Borms R, Peeters J. Identification of the Sequence CH(2Π) + C2H2 → C3H2 + H (and C3H + H2) Followed by C3H2 + O → C2H + HCO (or H + CO) as C2H Source in C2H2/O/H Atomic Flames. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp951995o] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Werner Boullart
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Katia Devriendt
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Ronny Borms
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Jozef Peeters
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
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Yarkony DR. Quenching of CH(a4Σ-) by CO(X1Σ+): Surfaces of Intersection, Spin−Orbit Interactions, and the Incorporation of Kramers' Degeneracy. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp961450+] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Hettema H, Yarkony DR. On the radiative lifetime of the (a 4Σ−,v,N,Fi) levels of the CH radical: An ab initio treatment. J Chem Phys 1994. [DOI: 10.1063/1.466703] [Citation(s) in RCA: 15] [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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Metropoulos A, Engels B, Peyerimhoff SD. The chemi-ionization reaction O+CH→HCO++e−. Collinear OCH approach. Chem Phys Lett 1993. [DOI: 10.1016/0009-2614(93)90018-v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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