1
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González D, Canosa A, Martínez-Núñez E, Fernández-Ramos A, Ballesteros B, Agúndez M, Cernicharo J, Jiménez E. Effect of temperature on the gas-phase reaction of CH 3CN with OH radicals: experimental ( T = 11.7-177.5 K) and computational ( T = 10-400 K) kinetic study. Phys Chem Chem Phys 2024; 26:3632-3646. [PMID: 38224163 DOI: 10.1039/d3cp04944b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Acetonitrile (CH3CN) is present in the interstellar medium (ISM) in a variety of environments. However, at the ultracold temperatures of the ISM, radical-molecule reactions are not widely investigated because of the experimental handicap of getting organic molecules in the gas phase by conventional techniques. The CRESU (French acronym for Reaction Kinetics in a Uniform Supersonic Flow) technique solves this problem. For this reason, we present in this work the kinetic study of the gas-phase reaction of CH3CN with one of the most ubiquitous radicals, the hydroxyl (OH) radical, as a function of temperature (11.7-177.5 K). The kinetic technique employed to investigate the CH3CN + OH reaction was the pulsed laser photolysis-laser induced fluorescence. The rate coefficient for this reaction k(T) has been observed to drastically increase from 177.5 K to 107.0 K (about 2 orders of magnitude), while the increase in k(T) from 107.0 K to 11.7 K was milder (around 4 times). The temperature dependent expressions for k(T) are provided in the two distinct T-ranges, excluding the upper limit obtained for k(177.5 K): In addition, the rate coefficients estimated by the canonical competitive unified statistical (CCUS) theory show a similar behaviour to the experimental results, when evaluated within the high-pressure limit. This is consistent with the experimentally observed independence of k(T) with total gas density at selected temperatures. Astrochemical networks, such as the KIDA database or UMIST, do not include the CH3CN + OH reaction as a potential depletion process for acetonitrile in the ISM because the current studies predict very low rate coefficients at IS temperatures. According to the model (T = 10 K), the impact of the titled reaction on the abundances of CH3CN appears to be negligible in dark molecular clouds of the ISM (∼1% of the total depletion reactions included in UMIST network). With respect to the potential formation of the CH2CN radical in those environments, even in the most favourable scenario, where this radical could be formed in a 100% yield from the CH3CN + OH reaction, this route would only contribute around 2% to the current assumed formation routes by the UMIST network.
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Affiliation(s)
- Daniel González
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha (UCLM), Avda. Camilo José Cela 1B, 13071 Ciudad Real, Spain.
- Instituto de Investigación en Combustión y Contaminación Atmosférica, UCLM, Camino de Moledores s/n, 13071 Ciudad Real, Spain
| | - André Canosa
- Institut de Physique de Rennes-CNRS - UMR 6251, Université de Rennes, F-35000 Rennes, France
| | - Emilio Martínez-Núñez
- Departamento de Química Física, Facultade de Química, Campus Vida, Universidade de Santiago de Compostela, Avda. das Ciencias s/n, 15782, Santiago de Compostela, Spain.
| | - Antonio Fernández-Ramos
- Departamento de Química Física, Facultade de Química, Campus Vida, Universidade de Santiago de Compostela, Avda. das Ciencias s/n, 15782, Santiago de Compostela, Spain.
- Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Campus Vida, Universidade de Santiago de Compostela, C/Jenaro de la Fuente s/n, 15782, Santiago de Compostela, Spain
| | - Bernabé Ballesteros
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha (UCLM), Avda. Camilo José Cela 1B, 13071 Ciudad Real, Spain.
- Instituto de Investigación en Combustión y Contaminación Atmosférica, UCLM, Camino de Moledores s/n, 13071 Ciudad Real, Spain
| | - Marcelino Agúndez
- Molecular Astrophysics Group, Instituto de Física Fundamental (IFF-CSIC), Consejo Superior de Investigaciones Científicas, C/Serrano 123, 28006, Madrid, Spain
| | - José Cernicharo
- Molecular Astrophysics Group, Instituto de Física Fundamental (IFF-CSIC), Consejo Superior de Investigaciones Científicas, C/Serrano 123, 28006, Madrid, Spain
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha (UCLM), Avda. Camilo José Cela 1B, 13071 Ciudad Real, Spain.
- Instituto de Investigación en Combustión y Contaminación Atmosférica, UCLM, Camino de Moledores s/n, 13071 Ciudad Real, Spain
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2
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Dash MR, Muthiah B, Mishra SS, Annaraj B, Lin KC. Kinetic insights into ethynyl radical with isobutane and neopentane. Theor Chem Acc 2021. [DOI: 10.1007/s00214-021-02833-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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3
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Doddipatla S, Galimova GR, Wei H, Thomas AM, He C, Yang Z, Morozov AN, Shingledecker CN, Mebel AM, Kaiser RI. Low-temperature gas-phase formation of indene in the interstellar medium. SCIENCE ADVANCES 2021; 7:7/1/eabd4044. [PMID: 33523847 PMCID: PMC7775774 DOI: 10.1126/sciadv.abd4044] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/04/2020] [Indexed: 06/07/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are fundamental molecular building blocks of fullerenes and carbonaceous nanostructures in the interstellar medium and in combustion systems. However, an understanding of the formation of aromatic molecules carrying five-membered rings-the essential building block of nonplanar PAHs-is still in its infancy. Exploiting crossed molecular beam experiments augmented by electronic structure calculations and astrochemical modeling, we reveal an unusual pathway leading to the formation of indene (C9H8)-the prototype aromatic molecule with a five-membered ring-via a barrierless bimolecular reaction involving the simplest organic radical-methylidyne (CH)-and styrene (C6H5C2H3) through the hitherto elusive methylidyne addition-cyclization-aromatization (MACA) mechanism. Through extensive structural reorganization of the carbon backbone, the incorporation of a five-membered ring may eventually lead to three-dimensional PAHs such as corannulene (C20H10) along with fullerenes (C60, C70), thus offering a new concept on the low-temperature chemistry of carbon in our galaxy.
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Affiliation(s)
- Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
- Samara National Research University, Samara 443086, Russia
| | - Hongji Wei
- Department of Physics and Astronomy, Benedictine College, Atchison, KS 66002, USA
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Chao He
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | | | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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4
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Zhang Y, Sun Y. Theoretical investigation on atmospheric reaction of O(3P) with CH2CN. J PHYS ORG CHEM 2018. [DOI: 10.1002/poc.3913] [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)
- Yunju Zhang
- Key Laboratory of Photoinduced Functional MaterialsMianyang Normal University Mianyang China
- Beijing Key Laboratory of Flavor ChemistryBeijing Technology and Business University (BTBU) Beijing China
| | - Yuxi Sun
- Key Laboratory of Photoinduced Functional MaterialsMianyang Normal University Mianyang China
- Beijing Key Laboratory of Flavor ChemistryBeijing Technology and Business University (BTBU) Beijing China
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5
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Potapov A, Canosa A, Jiménez E, Rowe B. Chemie mit Überschall: 30 Jahre astrochemische Forschung und künftige Herausforderungen. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Alexey Potapov
- Laborastrophysikgruppe des Max-Planck-Instituts für Astronomie am Institut für Festkörperphysik; Friedrich-Schiller-Universität Jena; Helmholtzweg 3 07743 Jena Deutschland
| | - André Canosa
- Département de Physique Moléculaire; Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, Campus de Beaulieu; 263 Avenue du Général Leclerc 35042 Rennes Cedex Frankreich
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas; Universidad de Castilla-La Mancha; Avda. Camilo José Cela, 1B 13071 Ciudad Real Spanien
| | - Bertrand Rowe
- Rowe-consulting, 22 Chemin des Moines; 22750 Saint Jacut de la Mer Frankreich
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6
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Potapov A, Canosa A, Jiménez E, Rowe B. Uniform Supersonic Chemical Reactors: 30 Years of Astrochemical History and Future Challenges. Angew Chem Int Ed Engl 2017; 56:8618-8640. [DOI: 10.1002/anie.201611240] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/27/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Alexey Potapov
- Laborastrophysikgruppe des Max-Planck-Instituts für Astronomie am Institut für Festkörperphysik; Friedrich-Schiller-Universität Jena; Helmholtzweg 3 07743 Jena Germany
| | - André Canosa
- Département de Physique Moléculaire; Institut de Physique de Rennes, UMR CNRS-UR1 6251, Université de Rennes 1, Campus de Beaulieu; 263 Avenue du Général Leclerc 35042 Rennes Cedex France
| | - Elena Jiménez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas; Universidad de Castilla-La Mancha; Avda. Camilo José Cela, 1B 13071 Ciudad Real Spain
| | - Bertrand Rowe
- Rowe-consulting, 22 Chemin des Moines; 22750 Saint Jacut de la Mer France
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7
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Bourgalais J, Spencer M, Osborn DL, Goulay F, Le Picard SD. Reactions of Atomic Carbon with Butene Isomers: Implications for Molecular Growth in Carbon-Rich Environments. J Phys Chem A 2016; 120:9138-9150. [PMID: 27798961 DOI: 10.1021/acs.jpca.6b09785] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- J. Bourgalais
- Institut
de Physique de Rennes, Département de Physique Moléculaire, Astrophysique de Laboratoire, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
| | - Michael Spencer
- Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - David L. Osborn
- Combustion
Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - F. Goulay
- Department
of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - S. D. Le Picard
- Institut
de Physique de Rennes, Département de Physique Moléculaire, Astrophysique de Laboratoire, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex, France
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8
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Abstract
Transient diode laser absorption spectroscopy has been used to measure three strong vibronic bands in the near infrared spectrum of the C2H, ethynyl, radical not previously observed in the gas phase. The radical was produced by ultraviolet excimer laser photolysis of either acetylene or (1,1,1)-trifluoropropyne in a slowly flowing sample of the precursor diluted in inert gas, and the spectral resolution was Doppler-limited. The character of the upper states was determined from the rotational and fine structure in the observed spectra and assigned by measurement of ground state rotational combination differences. The upper states include a (2)Σ(+) state at 6696 cm(-1), a second (2)Σ(+) state at 7088 cm(-1), and a (2)Π state at 7110 cm(-1). By comparison with published calculations [R. Tarroni and S. Carter, J. Chem. Phys 119, 12878 (2003); Mol. Phys. 102, 2167 (2004)], the vibronic character of these levels was also assigned. The observed states contain both X(2)Σ(+) and A(2)Π electronic characters. Several local rotational level perturbations were observed in the excited states. Kinetic measurements of the time-evolution of the ground state populations following collisional relaxation and reactive loss of the radicals formed in a hot, non-thermal, population distribution were made using some of the strong rotational lines observed. The case of C2H may be a good place to investigate the behavior at intermediate pressures of inert colliders, where the competition between relaxation and reaction can be tuned and observed to compare with master equation models, rather than deliberately suppressed to measure thermal rate constants.
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Affiliation(s)
- Anh T Le
- Department of Energy and Photon Sciences, Division of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Gregory E Hall
- Department of Energy and Photon Sciences, Division of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Trevor J Sears
- Department of Energy and Photon Sciences, Division of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
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9
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Sleiman C, González S, Klippenstein SJ, Talbi D, El Dib G, Canosa A. Pressure dependent low temperature kinetics for CN + CH3CN: competition between chemical reaction and van der Waals complex formation. Phys Chem Chem Phys 2016; 18:15118-32. [DOI: 10.1039/c6cp01982j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The gas phase reaction between the CN radical and acetonitrile CH3CN was investigated experimentally with a CRESU apparatus and a slow flow reactor as well as theoretically to explore the temperature and pressure dependence of its rate coefficient from 354 K down to 23 K.
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Affiliation(s)
- Chantal Sleiman
- Département de Physique Moléculaire
- Institut de Physique de Rennes
- UMR 6251 du CNRS - Université de Rennes 1
- Bat. 11C
- Campus de Beaulieu
| | - Sergio González
- Departamento de Química Física
- Facultad de Ciencias y Tecnologías Químicas
- Universidad de Castilla La Mancha
- Campus Universitario
- 13071 Ciudad Real
| | | | - Dahbia Talbi
- Laboratoire Univers et Particules de Montpellier – UMR 5299 du CNRS - Université de Montpellier
- Campus Triolet
- 34095 Montpellier Cedex 05
- France
| | - Gisèle El Dib
- Département de Physique Moléculaire
- Institut de Physique de Rennes
- UMR 6251 du CNRS - Université de Rennes 1
- Bat. 11C
- Campus de Beaulieu
| | - André Canosa
- Département de Physique Moléculaire
- Institut de Physique de Rennes
- UMR 6251 du CNRS - Université de Rennes 1
- Bat. 11C
- Campus de Beaulieu
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10
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Parker DSN, Mebel AM, Kaiser RI. The role of isovalency in the reactions of the cyano (CN), boron monoxide (BO), silicon nitride (SiN), and ethynyl (C2H) radicals with unsaturated hydrocarbons acetylene (C2H2) and ethylene (C2H4). Chem Soc Rev 2014; 43:2701-13. [DOI: 10.1039/c3cs60328h] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The classification of chemical reactions based on shared characteristics is at the heart of the chemical sciences, and is well exemplified by Langmuir's concept of isovalency, in which ‘two molecular entities with the same number of valence electrons have similar chemistries’.
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Affiliation(s)
- D. S. N. Parker
- Department of Chemistry
- University of Hawai'i at Manoa
- Honolulu, USA
| | - A. M. Mebel
- Department of Chemistry and Biochemistry
- Florida International University
- Miami, USA
| | - R. I. Kaiser
- Department of Chemistry
- University of Hawai'i at Manoa
- Honolulu, USA
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11
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Bouwman J, Fournier M, Sims IR, Leone SR, Wilson KR. Reaction Rate and Isomer-Specific Product Branching Ratios of C2H + C4H8: 1-Butene, cis-2-Butene, trans-2-Butene, and Isobutene at 79 K. J Phys Chem A 2013; 117:5093-105. [DOI: 10.1021/jp403637t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jordy Bouwman
- Departments of Chemistry and
Physics, University of California, Berkeley,
California 94720, United States
| | - Martin Fournier
- Institut de Physique de Rennes,
UMR 6251 du CNRS, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042 Rennes Cedex,
France
| | - Ian R. Sims
- Institut de Physique de Rennes,
UMR 6251 du CNRS, Université de Rennes 1, 263 Avenue du Général Leclerc, 35042 Rennes Cedex,
France
| | - Stephen R. Leone
- Departments of Chemistry and
Physics, University of California, Berkeley,
California 94720, United States
- Chemical Sciences
Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
| | - Kevin R. Wilson
- Chemical Sciences
Division, Lawrence Berkeley National Laboratory, 1 Cyclotron
Road, Berkeley, California 94720, United States
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12
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Feng W, Hershberger JF. Experimental and Theoretical Study of the Product Channels of the C2H + NO Reaction. J Phys Chem A 2013; 117:3585-92. [DOI: 10.1021/jp401354x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wenhui Feng
- Department
of Chemistry and Biochemistry, Department 2735, North Dakota State University, P.O. Box 6050, Fargo,
North Dakota 58108-6050, United States
| | - John F. Hershberger
- Department
of Chemistry and Biochemistry, Department 2735, North Dakota State University, P.O. Box 6050, Fargo,
North Dakota 58108-6050, United States
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13
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Bouwman J, Goulay F, Leone SR, Wilson KR. Bimolecular rate constant and product branching ratio measurements for the reaction of C2H with ethene and propene at 79 K. J Phys Chem A 2012; 116:3907-17. [PMID: 22429068 DOI: 10.1021/jp301015b] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reactions of the ethynyl radical (C(2)H) with ethene (C(2)H(4)) and propene (C(3)H(6)) are studied under low temperature conditions (79 K) in a pulsed Laval nozzle apparatus. Ethynyl radicals are formed by 193 nm photolysis of acetylene (C(2)H(2)) and the reactions are studied in nitrogen as a carrier gas. Reaction products are sampled and subsequently photoionized by the tunable vacuum ultraviolet radiation of the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory. The product ions are detected mass selectively and time-resolved by a quadrupole mass spectrometer. Bimolecular rate coefficients are determined under pseudo-first-order conditions, yielding values in good agreement with previous measurements. Photoionization spectra are measured by scanning the ALS photon energy while detecting the ionized reaction products. Analysis of the photoionization spectra yields-for the first time-low temperature isomer resolved product branching ratios. The reaction between C(2)H and ethene is found to proceed by H-loss and yields 100% vinylacetylene. The reaction between C(2)H and propene results in (85 ± 10)% C(4)H(4) (m/z = 52) via CH(3)-loss and (15 ± 10)% C(5)H(6) (m/z = 66) by H-loss. The C(4)H(4) channel is found to consist of 100% vinylacetylene. For the C(5)H(6) channel, analysis of the photoionization spectrum reveals that (62 ± 16)% is in the form of 4-penten-1-yne, (27 ± 8)% is in the form of cis- and trans-3-penten-1-yne and (11 ± 10)% is in the form of 2-methyl-1-buten-3-yne.
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Affiliation(s)
- Jordy Bouwman
- Department of Chemistry, University of California Berkeley, Berkeley, California 94720, USA
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14
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Kaiser RI, Mebel AM. On the formation of polyacetylenes and cyanopolyacetylenes in Titan's atmosphere and their role in astrobiology. Chem Soc Rev 2012; 41:5490-501. [DOI: 10.1039/c2cs35068h] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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15
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Blitz MA, Seakins PW. Laboratory studies of photochemistry and gas phase radical reaction kinetics relevant to planetary atmospheres. Chem Soc Rev 2012; 41:6318-47. [DOI: 10.1039/c2cs35204d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Matsugi A, Suma K, Miyoshi A. Deuterium kinetic isotope effects on the gas-phase reactions of C2H with H2(D2) and CH4(CD4). Phys Chem Chem Phys 2011; 13:4022-31. [PMID: 21240398 DOI: 10.1039/c0cp02056g] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Kinetics of the ethynyl (C(2)H) radical reactions with H(2), D(2), CH(4) and CD(4) was studied over the temperature range of 295-396 K by a pulsed laser photolysis/chemiluminescence technique. The C(2)H radicals were generated by ArF excimer-laser photolysis of C(2)H(2) or CF(3)C(2)H and were monitored by the chemiluminescence of CH(A(2)Δ) produced by their reaction with O(2) or O((3)P). The measured absolute rate constants for H(2) and CH(4) agreed well with the available literature data. The primary kinetic isotope effects (KIEs) were determined to be k(H(2))/k(D(2)) = 2.48 ± 0.14 and k(CH(4))/k(CD(4)) = 2.45 ± 0.16 at room temperature. Both of the KIEs increased as the temperature was lowered. The KIEs were analyzed by using the variational transition state theory with semiclassical small-curvature tunneling corrections. With anharmonic corrections on the loose transitional vibrational modes of the transition states, the theoretical predictions satisfactorily reproduced the experimental KIEs for both C(2)H + H(2)(D(2)) and C(2)H + CH(4)(CD(4)) reactions.
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Affiliation(s)
- Akira Matsugi
- Department of Chemical Systems Engineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
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17
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Sharp-Williams EN, Roberts MA, Nesbitt DJ. High resolution slit-jet infrared spectroscopy of ethynyl radical: 2Π-2Σ+ vibronic bands with sub-Doppler resolution. J Chem Phys 2011; 134:064314. [PMID: 21322687 DOI: 10.1063/1.3532088] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
High resolution infrared spectra for four (2)Π-(2)Σ(+) bands of jet-cooled ethynyl radical (i.e., C(2)H) in the gas phase are reported. The combination of (i) slit-jet cooling (T(rot) ≈ 12 K) and (ii) sub-Doppler resolution (≈ 60 MHz) permits satellite branches in each (2)Π-(2)Σ(+) band to be observed and resolved for the first time as well as help clarify a systematic parity misassignment from previous studies. The observed lines in each band are least squares fit to a Hamiltonian model containing rotational, spin-rotational, spin-orbit, and lambda-doubling contributions for the (2)Π state, from which we report revised excited state constants and band origins for the observed bands. Three of the four bands fit extremely well within a conventional (2)Π model (i.e., σ < 20 MHz), while one band exhibits a local perturbation due to an avoided crossing with a near resonant dark state. Vibronic assignments are given for the observed bands, with the dark state clearly identified as a highly excited stretch and bending overtone level X̃ (1,2(2),0) by comparison with high level ab initio efforts.
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18
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Sharp-Williams EN, Roberts MA, Nesbitt DJ. Dark state vibronic coupling in the Ã(2Π) ←X̃(2Σ+) band of ethynyl radical via high resolution infrared absorption spectroscopy. Phys Chem Chem Phys 2011; 13:17474-83. [DOI: 10.1039/c1cp21523j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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19
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Abstract
Polycyclic aromatic hydrocarbons and related species have been suggested to play a key role in the astrochemical evolution of the interstellar medium, but the formation mechanism of even their simplest building block--the aromatic benzene molecule--has remained elusive for decades. Here we demonstrate in crossed molecular beam experiments combined with electronic structure and statistical calculations that benzene (C(6)H(6)) can be synthesized via the barrierless, exoergic reaction of the ethynyl radical and 1,3-butadiene, C(2)H + H(2)CCHCHCH(2) → C(6)H(6) + H, under single collision conditions. This reaction portrays the simplest representative of a reaction class in which aromatic molecules with a benzene core can be formed from acyclic precursors via barrierless reactions of ethynyl radicals with substituted 1,3-butadiene molecules. Unique gas-grain astrochemical models imply that this low-temperature route controls the synthesis of the very first aromatic ring from acyclic precursors in cold molecular clouds, such as in the Taurus Molecular Cloud. Rapid, subsequent barrierless reactions of benzene with ethynyl radicals can lead to naphthalene-like structures thus effectively propagating the ethynyl-radical mediated formation of aromatic molecules in the interstellar medium.
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Soorkia S, Trevitt AJ, Selby TM, Osborn DL, Taatjes CA, Wilson KR, Leone SR. Reaction of the C2H Radical with 1-Butyne (C4H6): Low-Temperature Kinetics and Isomer-Specific Product Detection. J Phys Chem A 2010; 114:3340-54. [DOI: 10.1021/jp911132r] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Satchin Soorkia
- Departments of Chemistry and Physics, University of California, Berkeley, California 94720
| | - Adam J. Trevitt
- School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Talitha M. Selby
- Department of Chemistry, University of Wisconsin—Washington County, West Bend, Wisconsin 53095
| | - David L. Osborn
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969
| | - Craig A. Taatjes
- Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969
| | - Kevin R. Wilson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720
| | - Stephen R. Leone
- Departments of Chemistry and Physics, University of California, Berkeley, California 94720 and Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720
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21
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Berteloite C, Le Picard SD, Balucani N, Canosa A, Sims IR. Low temperature rate coefficients for reactions of the butadiynyl radical, C4H, with various hydrocarbons. Part I: reactions with alkanes (CH4, C2H6, C3H8, C4H10). Phys Chem Chem Phys 2010; 12:3666-76. [DOI: 10.1039/b907154g] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Soorkia S, Taatjes CA, Osborn DL, Selby TM, Trevitt AJ, Wilson KR, Leone SR. Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction. Phys Chem Chem Phys 2010; 12:8750-8. [DOI: 10.1039/c002135k] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Costes M, Naulin C. Integral and differential cross sections of reactions relevant to astrochemistry. Phys Chem Chem Phys 2010; 12:9154-64. [DOI: 10.1039/c003656k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Berteloite C, Le Picard SD, Balucani N, Canosa A, Sims IR. Low temperature rate coefficients for reactions of the butadiynyl radical, C4H, with various hydrocarbons. Part II: reactions with alkenes (ethylene, propene, 1-butene), dienes (allene, 1,3-butadiene) and alkynes (acetylene, propyne and 1-butyne). Phys Chem Chem Phys 2010; 12:3677-89. [DOI: 10.1039/b923867k] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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25
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Hébrard E, Dobrijevic M, Pernot P, Carrasco N, Bergeat A, Hickson KM, Canosa A, Le Picard SD, Sims IR. How Measurements of Rate Coefficients at Low Temperature Increase the Predictivity of Photochemical Models of Titan’s Atmosphere. J Phys Chem A 2009; 113:11227-37. [DOI: 10.1021/jp905524e] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | - P. Pernot
- Laboratoire de Chimie Physique, UMR 8000, CNRS-Université Paris-Sud 11, Bât. 349, Orsay, F-91405, France
| | - N. Carrasco
- Laboratoire Atmosphères, Milieux, Observations Spatiales, UMR 8190, CNRS-IPSL-Université de Versailles Saint Quentin, BP 3, Verrières le Buisson, F-91371, France
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Balucani N. Elementary reactions and their role in gas-phase prebiotic chemistry. Int J Mol Sci 2009; 10:2304-2335. [PMID: 19564951 PMCID: PMC2695279 DOI: 10.3390/ijms10052304] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Revised: 05/13/2009] [Accepted: 05/15/2009] [Indexed: 11/23/2022] Open
Abstract
The formation of complex organic molecules in a reactor filled with gaseous mixtures possibly reproducing the primitive terrestrial atmosphere and ocean demonstrated more than 50 years ago that inorganic synthesis of prebiotic molecules is possible, provided that some form of energy is provided to the system. After that groundbreaking experiment, gas-phase prebiotic molecules have been observed in a wide variety of extraterrestrial objects (including interstellar clouds, comets and planetary atmospheres) where the physical conditions vary widely. A thorough characterization of the chemical evolution of those objects relies on a multi-disciplinary approach: 1) observations allow us to identify the molecules and their number densities as they are nowadays; 2) the chemistry which lies behind their formation starting from atoms and simple molecules is accounted for by complex reaction networks; 3) for a realistic modeling of such networks, a number of experimental parameters are needed and, therefore, the relevant molecular processes should be fully characterized in laboratory experiments. A survey of the available literature reveals, however, that much information is still lacking if it is true that only a small percentage of the elementary reactions considered in the models have been characterized in laboratory experiments. New experimental approaches to characterize the relevant elementary reactions in laboratory are presented and the implications of the results are discussed.
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Affiliation(s)
- Nadia Balucani
- Dipartimento di Chimica, Università degli Studi di Perugia, 06123 Perugia, Italy; E-Mail:
; Tel. +39-075-585-5513; Fax: +39-075-585-5606
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27
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Zhang F, Kim S, Kaiser RI. A crossed molecular beams study of the reaction of the ethynyl radical (C2H(X2Sigma+)) with allene (H2CCCH2(X1A1)). Phys Chem Chem Phys 2009; 11:4707-14. [PMID: 19492123 DOI: 10.1039/b822366a] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The crossed beams reaction of ground state ethynyl radicals, C(2)H(X(2)Sigma(+)), with allene, H(2)CCCH(2)(X(1)A(1)), was conducted under single collision conditions at a collision energy of 22.0 +/- 0.4 kJ mol(-1). The center-of-mass functions were combined with earlier ab initio calculations and revealed that the reaction was barrier-less, proceeded via indirect reaction dynamics through an addition of the ethynyl radical to the terminal carbon atom of the allene molecule, and was terminated by atomic hydrogen emission via a tight exit transition state to form the ethynylallene product. The overall reaction was found to be exoergic by 93 +/- 15 kJ mol(-1). Since the reaction is barrier-less, exoergic, and all transition states involved are located below the energy level of the separated reactants, the formation of ethynylallene is predicted to take place in low temperature atmospheres of planets and their satellites such as Titan and also in cold molecular clouds via the neutral-neutral reaction of ethynyl radicals with allene. Implications to interstellar chemistry and a comparison with the chemistry of the isoelectronic cyano radical, CN(X(2)Sigma(+)), are also presented.
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Affiliation(s)
- Fangtong Zhang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA
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28
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Loison JC, Bergeat A. Rate constants and the H atom branching ratio of the reactions of the methylidyne CH(X2Π) radical with C2H2, C2H4, C3H4(methylacetylene and allene), C3H6(propene) and C4H8(trans-butene). Phys Chem Chem Phys 2009; 11:655-64. [DOI: 10.1039/b812810c] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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29
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Sun J, Tang Y, Sun H, Jia X, Pan X, Wang R. Theoretical and kinetic study of the H + C2H5CN reaction. J Comput Chem 2009; 31:1126-34. [DOI: 10.1002/jcc.21397] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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30
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Sun J, Tang Y, Sun H, Pan Y, Jia X, Pan X, Wang R. Mechanistic and kinetic study of the OH+C2H5CN reaction. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.08.055] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Zhao ZX, Liu JY, Wang L, Zhang HX, Hou CY, Sun CC. A study of the hydrogen abstraction reactions of C2H radical with CH3CN, C2H5CN, and C3H7CN by dual-level generalized transition state theory. J Phys Chem A 2008; 112:8455-63. [PMID: 18710195 DOI: 10.1021/jp804010t] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The hydrogen abstraction reactions C2H + CH3CN --> products (R1), C2H + CH3CH2CN --> products (R2), and C2H + CH3CH2CH2CN --> products (R3) have been investigated by dual-level generalized transition state theory. Optimized geometries and frequencies of all the stationary points and extra points along the minimum-energy path (MEP) are performed at the BH&H-LYP and MP2 methods with the 6-311G(d, p) basis set, and the energy profiles are further refined at the MC-QCISD level of theory. The rate constants are evaluated using canonical variational transition state theory (CVT) with a small-curvature tunneling correction (SCT) over a wide temperature range 104-2000 K. The calculated CVT/SCT rate constants are in good agreement with the available experimental values. Our calculations show that for reaction R2, the alpha-hydrogen abstraction channel and beta-hydrogen abstraction channel are competitive over the whole temperature range. For reaction R3, the gamma-hydrogen abstraction channel is preferred at lower temperatures, while the contribution of beta-hydrogen abstraction will become more significant with a temperature increase. The branching ratio to the alpha-hydrogen abstraction channel is found negligible over the whole temperature range.
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Affiliation(s)
- Zeng-Xia Zhao
- Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, People's Republic of China
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32
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H elimination and metastable lifetimes in the UV photoexcitation of diacetylene. Proc Natl Acad Sci U S A 2008; 105:12713-8. [PMID: 18697925 DOI: 10.1073/pnas.0801180105] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present an experimental investigation of the UV photochemistry of diacetylene under collisionless conditions. The H loss channel is studied using DC slice ion imaging with two-color reduced-Doppler detection at 243 nm and 212 nm. The photochemistry is further studied deep in the vacuum UV, that is, at Lyman-alpha (121.6 nm). Translational energy distributions for the H + C(4)H product arising from dissociation of C(4)H(2) after excitation at 243, 212, and 121.6 nm show an isotropic angular distribution and characteristic translational energy profile suggesting statistical dissociation from the ground state or possibly from a low-lying triplet state. From these distributions, a two-photon dissociation process is inferred at 243 nm and 212 nm, whereas at 121.6 nm, a one-photon dissociation process prevails. The results are interpreted with the aid of ab initio calculations on the reaction pathways and statistical calculations of the dissociation rates and product branching. In a second series of experiments, nanosecond time-resolved phototionization measurements yield a direct determination of the lifetime of metastable triplet diacetylene under collisionless conditions, as well as its dependence on excitation energy. The observed submicrosecond lifetimes suggest that reactions of metastable diacetylene are likely to be less important in Titan's atmosphere than previously believed.
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34
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Sun JY, Tang YZ, Sun H, Jia XJ, Pan XM, Pan YR, Wang RS. Theoretical study of the reaction of ethynyl radical with acetonitrile. Theor Chem Acc 2008. [DOI: 10.1007/s00214-008-0443-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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35
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Canosa A. Gas phase reaction kinetics at very low temperatures: recent advances on carbon chemistry using the CRESU technique. RUSSIAN CHEMICAL REVIEWS 2008. [DOI: 10.1070/rc2007v076n12abeh003733] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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36
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Sabbe MK, Reyniers MF, Van Speybroeck V, Waroquier M, Marin GB. Carbon-Centered Radical Addition and β-Scission Reactions: Modeling of Activation Energies and Pre-exponential Factors. Chemphyschem 2008; 9:124-40. [DOI: 10.1002/cphc.200700469] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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37
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Goulay F, Leone SR. Low-temperature rate coefficients for the reaction of ethynyl radical (C2H) with benzene. J Phys Chem A 2007; 110:1875-80. [PMID: 16451020 DOI: 10.1021/jp055637p] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction of the C2H radical with benzene is studied at low temperature using a pulsed Laval nozzle apparatus. The C2H radical is prepared by 193-nm photolysis of acetylene, and the C2H concentration is monitored using CH(A2Delta) chemiluminescence from the C2H + O2 reaction. Measurements at very low photolysis energy are performed using CF3C2H as the C2H precursor to study the influence of benzene photodissociation on the rate coefficient. Rate coefficients are obtained over a temperature range between 105 and 298 K. The average rate coefficient is found to be five times greater than the estimated value presently used in the photochemical modeling of Titan's atmosphere. The reaction exhibits a slight negative temperature dependence which can be fitted to the expression k(cm3 molecule(-1) s(-1)) = 3.28(+/-1.0) x 10(-10) (T/298)(-0.18(+/-0.18)). The results show that this reaction has no barrier and may play an important role in the formation of large molecules and aerosols at low temperature. Our results are consistent with the formation of a short lifetime intermediate that decomposes to give the final products.
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Affiliation(s)
- Fabien Goulay
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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38
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Abstract
The title unknown reaction is theoretically studied at various levels to probe the interaction mechanism between the ethynyl radical (HC triple bond C) and formaldehyde (H(2)C double bond O). The most feasible pathway is a barrier-free direct H-abstraction process leading to acetylene and formyl radical (C(2)H(2)+HCO) via a weakly bound complex, and then the product can take secondary dissociation to the final product C(2)H(2)+CO+H. The C-addition channel leading to propynal plus H-atom (HCCCHO+H) has the barrier of only 3.6, 2.9, and 2.1 kcal/mol at the CCSD(T)/6-311+G(3df,2p)MP2//6-311G(d,p)+ZPVE, CCSD(T)/6-311+G(3df,2p)//QCISD/6-311G(d,p)+ZPVE, and G3//MP2 levels, respectively [CCSD(T)--coupled cluster with single, double, and triple excitations; ZPVE--zero-point vibrational energy; QCISD--quadratic configuration interaction with single and double excitations; G3//MP2-Gaussian-3 based on Moller-Plesset geometry]. The O addition also leading to propynal plus H atom needs to overcome a higher barrier of 5.3, 8.7, and 3.0 kcalmol at the three corresponding levels. The title no-barrier reaction presents a new efficient route to remove the pollutant H(2)CO, and should be included in the combustion models of hydrocarbons. It may also represent the fastest radical-H(2)CO reaction among the available theoretical data. Moreover, it could play an important role in the interstellar chemistry where the zero- or minute-barrier reactions are generally favored. Discussions are also made on the possible formation of the intriguing propynal in space via the title reaction on ice surface.
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Affiliation(s)
- Hao Dong
- State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China
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39
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Quantum chemical study of hydrogen abstraction reactions of the ethynyl radical with hydrogen compounds (C2H+HX). ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.theochem.2005.07.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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40
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Elsamra RMI, Vranckx S, Carl SA. CH(A2Δ) Formation in Hydrocarbon Combustion: The Temperature Dependence of the Rate Constant of the Reaction C2H + O2 → CH(A2Δ) + CO2. J Phys Chem A 2005; 109:10287-93. [PMID: 16833323 DOI: 10.1021/jp053684b] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The temperature dependence of the rate constant of the chemiluminescence reaction C2H + O2 --> CH(A) + CO2, k1e, has been experimentally determined over the temperature range 316-837 K using pulsed laser photolysis techniques. The rate constant was found to have a pronounced positive temperature dependence given by k1e(T) = AT(4.4) exp(1150 +/- 150/T), where A = 1 x 10(-27) cm(3) s(-1). The preexponential factor for k1e, A, which is known only to within an order of magnitude, is based on a revised expression for the rate constant for the C2H + O(3P) --> CH(A) + CO reaction, k2b, of (1.0 +/- 0.5) x 10(-11) exp(-230 K/T) cm3 s(-1) [Devriendt, K.; Van Look, H.; Ceursters, B.; Peeters, J. Chem. Phys. Lett. 1996, 261, 450] and a k2b/k1e determination of this work of 1200 +/- 500 at 295 K. Using the temperature dependence of the rate constant k1e(T)/k1e(300 K), which is much more accurately and precisely determined than is A, we predict an increase in k(1e) of a factor 60 +/- 16 between 300 and 1500 K. The ratio of rate constants k2b/k1e is predicted to change from 1200 +/- 500 at 295 K to 40 +/- 25 at 1500 K. These results suggest that the reaction C2H + O2 --> CH(A) + CO2 contributes significantly to CH(A-->X) chemiluminescence in hot flames and especially under fuel-lean conditions where it probably dominates the reaction C2H + O(3P) --> CH(A) + CO.
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Affiliation(s)
- Rehab M I Elsamra
- University of Leuven, Department of Chemistry, Celestijnenlaan 200F, Leuven, Belgium
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41
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Mullen C, Smith MA. Temperature Dependence and Kinetic Isotope Effects for the OH + HBr Reaction and H/D Isotopic Variants at Low Temperatures (53−135 K) Measured Using a Pulsed Supersonic Laval Nozzle Flow Reactor. J Phys Chem A 2005; 109:3893-902. [PMID: 16833707 DOI: 10.1021/jp045540n] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The reactions of OH + HBr and all isotopic variants have been measured in a pulsed supersonic Laval nozzle flow reactor between 53 and 135 K, using a pulsed DC discharge to create the radical species and laser induced fluorescence on the A 2sigma <-- X 2pi (v' = 1 <-- v'' = 0) transition. All reactions are found to possess an inverse temperature dependence, in accord with previous work, and are fit to the form k = A(T/298)(-n), with k1 (OH + HBr) = (10.84 +/- 0.31) x 10(-12) (T/298)(-0.67+/-0.02) cm3/s, k2 (OD + HBr) = (6.43 +/- 2.60) x 10(-12) (T/298)(-1.19+/-0.26) cm3/s, k3 (OH + DBr) = (5.89 +/- 1.93) x 10(-12) (T/298)(-0.76+/-0.22) cm3/s, and k4 (OD + DBr) = (4.71 +/- 1.56) x 10(-12) (T/298)(-1.09+/-0.21) cm3/s. A global fit of k vs T over the temperature range 23-360 K, including the new OH + HBr data, yields kT = (1.06 +/- 0.02) x 10(-11) (T/298)(-0.90+/-0.11) cm3/s, and (0.96 +/- 0.02) x 10(-11) (T/298)(-0.90+/-0.03) exp((-2.88+/-1.82 K)/T) cm3/s, in accord with previous fits. In addition, the primary and secondary kinetic isotope effects are found to be independent of temperature within experimental error over the range investigated and take on the value of (kH/kD)(AVG) = 1.64 for the primary effect and (kH/kD)(AVG) = 0.87 for the secondary effect. These results are discussed within the context of current experimental and theoretical work.
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Affiliation(s)
- Christopher Mullen
- Department of Chemistry, University of Arizona, 1306 E. University Dr., Tucson, Arizona 85721, USA
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42
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Chikan V, Nizamov B, Leone SR. Product State Distributions of Vibrationally Excited CO(v) for the CH(X2Π) and CH(A2Δ) Channels of the C2H + O(3P) Reaction. J Phys Chem A 2004. [DOI: 10.1021/jp040317b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Viktor Chikan
- Departments of Chemistry and Physics, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460
| | - Boris Nizamov
- Departments of Chemistry and Physics, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460
| | - Stephen R. Leone
- Departments of Chemistry and Physics, and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720-1460
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