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Gál DR, Papp D, Czakó G. Benchmark ab initio characterization of the multi-channel Cl + CH 3X [X = F, Cl, Br, I] reactive potential energy surfaces. Phys Chem Chem Phys 2024; 26:17695-17706. [PMID: 38869051 DOI: 10.1039/d4cp01578a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
We determine benchmark geometries and relative energies for the stationary points of the Cl + CH3X [X = F, Cl, Br, I] reactions. We consider four possible reaction pathways: hydrogen abstraction, hydrogen substitution, halogen abstraction, and halogen substitution, where the substitution processes can proceed via either Walden inversion or front-side attack. We perform geometry optimizations and obtain harmonic vibrational frequencies at the explicitly-correlated UCCSD(T)-F12b/aug-cc-pVTZ level of theory, followed by UCCSD(T)-F12b/aug-cc-pVQZ single-point computations to make finite-basis-set error negligible. To reach chemical (<1 kcal mol-1), or even subchemical (<0.5 kcal mol-1) accuracy, we include core-correlation, scalar relativistic, post-(T), spin-orbit-splitting and zero-point-energy contributions, as well, in the relative energies of all the stationary points. Our benchmark 0 K reaction enthalpies are compared to available experimental results and show good agreement. The stationary-point structures and energetics are interpreted in terms of Hammond's postulate and used to make predictions related to the dynamical behavior of these reactive systems.
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Affiliation(s)
- Dorina R Gál
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
| | - Dóra Papp
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
| | - Gábor Czakó
- MTA-SZTE Lendület Computational Reaction Dynamics Research Group, Interdisciplinary Excellence Centre and Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary.
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2
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Wada R, Tonokura K, Koba S, Imamura T, Nakai K, Ushiyama H, Yamashita K, Matsumi Y, Enami S, Seakins PW. Theoretical study on the enthalpies of adduct formation between alkyl iodides and chlorine atoms. Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2020.138140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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3
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Lin KC, Muthiah B, Chang HP, Kasai T, Chang YP. Halogen-related photodissociation in atmosphere: characterisation of atomic halogen, molecular halogen, and hydrogen halide. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1822590] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
| | | | - Hsiu-Pu Chang
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Toshio Kasai
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
| | - Yuan-Pin Chang
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan
- Aerosol Science Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan
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Larin IK, Spasskii AI, Trofimova EM, Proncheva NG. Measurement of the Rate Constant of a Reaction of Chlorine Atoms with CH3Br in a Temperature Range of 298–358 K Using the Resonance Fluorescence of Chlorine Atoms. KINETICS AND CATALYSIS 2018. [DOI: 10.1134/s002315841801007x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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5
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Kapnas KM, Toulson BW, Foreman ES, Block SA, Hill JG, Murray C. UV photodissociation dynamics of CHI 2Cl and its role as a photolytic precursor for a chlorinated Criegee intermediate. Phys Chem Chem Phys 2017; 19:31039-31053. [PMID: 29160321 DOI: 10.1039/c7cp06532a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photolysis of geminal diiodoalkanes in the presence of molecular oxygen has become an established route to the laboratory production of several Criegee intermediates, and such compounds also have marine sources. Here, we explore the role that the trihaloalkane, chlorodiiodomethane (CHI2Cl), may play as a photolytic precursor for the chlorinated Criegee intermediate ClCHOO. CHI2Cl has been synthesized and its UV absorption spectrum measured; relative to that of CH2I2 the spectrum is shifted to longer wavelength and the photolysis lifetime is calculated to be less than two minutes. The photodissociation dynamics have been investigated using DC slice imaging, probing ground state I and spin-orbit excited I* atoms with 2 + 1 REMPI and single-photon VUV ionization. Total translational energy distributions are bimodal for I atoms and unimodal for I*, with around 72% of the available energy partitioned in to the internal degrees of freedom of the CHICl radical product, independent of photolysis wavelength. A bond dissociation energy of D0 = 1.73 ± 0.11 eV is inferred from the wavelength dependence of the translational energy release, which is slightly weaker than typical C-I bonds. Analysis of the photofragment angular distributions indicate dissociation is prompt and occurs primarily via transitions to states of A'' symmetry. Complementary high-level MRCI calculations, including spin-orbit coupling, have been performed to characterize the excited states and confirm that states of A'' symmetry with highly mixed singlet and triplet character are predominantly responsible for the absorption spectrum. Transient absorption spectroscopy has been used to measure the absorption spectrum of ClCHOO produced from the reaction of CHICl with O2 over the range 345-440 nm. The absorption spectrum, tentatively assigned to the syn conformer, is at shorter wavelengths relative to that of CH2OO and shows far weaker vibrational structure.
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Affiliation(s)
- Kara M Kapnas
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA.
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6
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Lin KC, Tsai PY. Molecular halogen elimination from halogen-containing compounds in the atmosphere. Phys Chem Chem Phys 2014; 16:7184-98. [PMID: 24622955 DOI: 10.1039/c3cp54828g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atmospheric halogen chemistry has drawn much attention, because the halogen atom (X) playing a catalytic role may cause severe stratospheric ozone depletion. Atomic X elimination from X-containing hydrocarbons is recognized as the major primary dissociation process upon UV-light irradiation, whereas direct elimination of the X2 product has been seldom discussed or remained a controversial issue. This account is intended to review the detection of X2 primary products using cavity ring-down absorption spectroscopy in the photolysis at 248 nm of a variety of X-containing compounds, focusing on bromomethanes (CH2Br2, CF2Br2, CHBr2Cl, and CHBr3), dibromoethanes (1,1-C2H4Br2 and 1,2-C2H4Br2) and dibromoethylenes (1,1-C2H2Br2 and 1,2-C2H2Br2), diiodomethane (CH2I2), thionyl chloride (SOCl2), and sulfuryl chloride (SO2Cl2), along with a brief discussion on acyl bromides (BrCOCOBr and CH2BrCOBr). The optical spectra, quantum yields, and vibrational population distributions of the X2 fragments have been characterized, especially for Br2 and I2. With the aid of ab initio calculations of potential energies and rate constants, the detailed photodissociation mechanisms may be comprehended. Such studies are fundamentally important to gain insight into the dissociation dynamics and may also practically help to assess the halogen-related environmental variation.
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Affiliation(s)
- King-Chuen Lin
- Department of Chemistry, National Taiwan University, Taipei, and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan.
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7
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Sharma RC, Blitz M, Wada R, Seakins PW. HCl yield and chemical kinetics study of the reaction of Cl atoms with CH3I at the 298K temperature using the infra-red tunable diode laser absorption spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 128:176-182. [PMID: 24667422 DOI: 10.1016/j.saa.2014.02.065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2013] [Revised: 02/07/2014] [Accepted: 02/14/2014] [Indexed: 06/03/2023]
Abstract
Pulsed ArF excimer laser (193 nm)-CW infrared (IR) tunable diode laser Herriott type absorption spectroscopic technique has been made for the detection of product hydrochloric acid HCl. Absorption spectroscopic technique is used in the reaction chlorine atoms with methyl iodide (Cl+CH3I) to the study of kinetics on reaction Cl+CH3I and the yield of (HCl). The reaction of Cl+CH3I has been studied with the support of the reaction Cl+C4H10 (100% HCl) at temperature 298 K. In the reaction Cl+CH3I, the total pressure of He between 20 and 125 Torr at the constant concentration of [CH3I] 7.0×10(14) molecule cm(-3). In the present work, we estimated adduct formation is very important in the reaction Cl+CH3I and reversible processes as well and CH3I molecule photo-dissociated in the methyl [CH3] radical. The secondary chemistry has been studied as CH3+CH3ICl = product, and CH3I+CH3ICl = product2. The system has been modeled theoretically for secondary chemistry in the present work. The calculated and experimentally HCl yield nearly 65% at the concentration 1.00×10(14) molecule cm(-3) of [CH3I] and 24% at the concentration 4.0×10(15) molecule cm(-3) of [CH3I], at constant concentration 4.85×10(12) molecule cm(-3) of [CH3], and at 7.3×10(12) molecule cm(-3) of [Cl]. The pressure dependent also studied product of HCl at the constant [CH3], [Cl] and [CH3I]. The experimental results are also very good matching with the modelling work at the reaction CH3+CH3ICl = product (k = (2.75±0.35)×10(-10) s(-1)) and CH3I+CH3ICl = product2 (k = 1.90±0.15)×10(-12) s(-1). The rate coefficients of the reaction CH3+CH3ICl and CH3I+CH3ICl has been made in the present work. The experimental results has been studied by two method (1) phase locked and (2) burst mode.
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Affiliation(s)
- R C Sharma
- Lasers Laboratory, Department of Chemistry, The University of Leeds, Leeds LS 2 9JT, United Kingdom.
| | - M Blitz
- Lasers Laboratory, Department of Chemistry, The University of Leeds, Leeds LS 2 9JT, United Kingdom
| | - R Wada
- Lasers Laboratory, Department of Chemistry, The University of Leeds, Leeds LS 2 9JT, United Kingdom
| | - P W Seakins
- Lasers Laboratory, Department of Chemistry, The University of Leeds, Leeds LS 2 9JT, United Kingdom
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Šulka M, Šulková K, Louis F, Neogrády P, Černušák I. A Theoretical Study of the X-Abstraction Reactions (X = H, Br, or I) from CH2IBr by OH Radicals: Implications for Atmospheric Chemistry. Z PHYS CHEM 2013. [DOI: 10.1524/zpch.2013.0391] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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9
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Poutsma ML. Evolution of Structure–Reactivity Correlations for the Hydrogen Abstraction Reaction by Chlorine Atom. J Phys Chem A 2013; 117:687-703. [DOI: 10.1021/jp310970t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Marvin L. Poutsma
- Chemical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee
37831-6197, United States
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Fan H, Tsai PY, Lin KC, Lin CW, Yan CY, Yang SW, Chang AHH. Molecular elimination of Br2 in photodissociation of CH2BrC(O)Br at 248 nm using cavity ring-down absorption spectroscopy. J Chem Phys 2012; 137:214304. [DOI: 10.1063/1.4767346] [Citation(s) in RCA: 5] [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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11
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Larin IK, Spasskii AI, Trofimova EM. Measurement of the rate constants of the reactions of the chlorine atom with C3F7I and CF3I using the resonance fluorescence of chlorine atoms. KINETICS AND CATALYSIS 2012. [DOI: 10.1134/s0023158412010053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Sarzyński D, Gola AA, Brudnik K, Jodkowski JT. Kinetic study of the reactions of chlorine atoms with fluoromethane and D-fluoromethane in the gas phase. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2011.12.072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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13
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Saiz-Lopez A, Plane JMC, Baker AR, Carpenter LJ, von Glasow R, Gómez Martín JC, McFiggans G, Saunders RW. Atmospheric Chemistry of Iodine. Chem Rev 2011; 112:1773-804. [DOI: 10.1021/cr200029u] [Citation(s) in RCA: 383] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Alfonso Saiz-Lopez
- Laboratory for Atmospheric and Climate Science (CIAC), CSIC, Toledo, Spain
| | - John M. C. Plane
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Alex R. Baker
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Lucy J. Carpenter
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Roland von Glasow
- School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | | | - Gordon McFiggans
- School of Earth, Atmospheric & Environmental Sciences, University of Manchester, Manchester, M13 9PL, United Kingdom
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Sarzyński D, Gola AA, Brudnik K, Jodkowski JT. Kinetic study of the reaction of chlorine atoms with dichloromethane and D-dichloromethane in the gas phase. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.08.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Zhang S, Strekowski R, Bosland L, Monod A, Zetzsch C. Kinetic study of the reaction of OH with CH2I2. Phys Chem Chem Phys 2011; 13:11671-7. [DOI: 10.1039/c1cp20885c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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16
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Kinetic study of the reaction of chlorine atoms with bromomethane and D-bromomethane in the gas phase. Chem Phys Lett 2010. [DOI: 10.1016/j.cplett.2009.12.076] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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17
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Sakamoto Y, Yabushita A, Kawasaki M, Enami S. Direct Emission of I2 Molecule and IO Radical from the Heterogeneous Reactions of Gaseous Ozone with Aqueous Potassium Iodide Solution. J Phys Chem A 2009; 113:7707-13. [DOI: 10.1021/jp903486u] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yosuke Sakamoto
- Department of Molecular Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Akihiro Yabushita
- Department of Molecular Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Masahiro Kawasaki
- Department of Molecular Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Shinichi Enami
- W. M. Keck Laboratories, California Institute of Technology, Pasadena, California 91125
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Wada R, Sharma RC, Blitz MA, Seakins PW. Studies on the Cl + C2H5I reaction; site specific abstraction reactions and thermodynamics of adduct formation studied by observation of HCL product. Phys Chem Chem Phys 2009; 11:10417-26. [PMID: 19890528 DOI: 10.1039/b907793f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- R Wada
- School of Chemistry, University of Leeds, Leeds, UK LS2 9JT
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Enami S, Sakamoto Y, Yamanaka T, Hashimoto S, Kawasaki M, Tonokura K, Tachikawa H. Reaction Mechanisms of IO Radical Formation from the Reaction of CH3I with Cl Atom in the Presence of O2. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2008. [DOI: 10.1246/bcsj.81.1250] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Gravestock TJ, Blitz MA, Heard DE. A Kinetic and Spectroscopic Study of the CH3I−Cl and ICH2I−Cl Adducts. J Phys Chem A 2008; 112:9544-54. [DOI: 10.1021/jp800372c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
| | - M. A. Blitz
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, U.K
| | - D. E. Heard
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, U.K
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Dookwah-Roberts V, Nicovich JM, Wine PH. Spectroscopic and Kinetic Study of the Gas-Phase CH3I−Cl and C2H5I−Cl Adducts. J Phys Chem A 2008; 112:9535-43. [PMID: 18517179 DOI: 10.1021/jp800270r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- V. Dookwah-Roberts
- School of Earth and Atmospheric Sciences, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - J. M. Nicovich
- School of Earth and Atmospheric Sciences, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - P. H. Wine
- School of Earth and Atmospheric Sciences, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332
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Stefanopoulos VG, Papadimitriou VC, Lazarou YG, Papagiannakopoulos P. Absolute Rate Coefficient Determination and Reaction Mechanism Investigation for the Reaction of Cl Atoms with CH2I2and the Oxidation Mechanism of CH2I Radicals. J Phys Chem A 2008; 112:1526-35. [DOI: 10.1021/jp7096789] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Vassileios G. Stefanopoulos
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, Heraklion 710 03, Crete, Greece
| | - Vassileios C. Papadimitriou
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, Heraklion 710 03, Crete, Greece
| | - Yannis G. Lazarou
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, Heraklion 710 03, Crete, Greece
| | - Panos Papagiannakopoulos
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, Heraklion 710 03, Crete, Greece
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23
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Spectroscopy and kinetics of the gas phase addition complex of atomic chlorine with dimethyl sulfoxide. J Photochem Photobiol A Chem 2007. [DOI: 10.1016/j.jphotochem.2006.08.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Orlando JJ, Piety CA, Nicovich JM, McKee ML, Wine PH. Rates and Mechanisms for the Reactions of Chlorine Atoms with Iodoethane and 2-Iodopropane. J Phys Chem A 2005; 109:6659-75. [PMID: 16834018 DOI: 10.1021/jp051715x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The reaction of Cl atoms with iodoethane has been studied via a combination of laser flash photolysis/resonance fluorescence (LFP-RF), environmental chamber/Fourier transform (FT)IR, and quantum chemical techniques. Above 330 K, the flash photolysis data indicate that the reaction proceeds predominantly via hydrogen abstraction. The following Arrhenius expressions (in units of cm3 molecule(-1) s(-1)) apply over the temperature range 334-434 K for reaction of Cl with CH3CH2I (k4(H)) and CD3CD2I (k4(D)): k4(H) = (6.53 +/- 3.40) x 10(-11) exp[-(428 +/- 206)/T] and k4(D) = (2.21 +/- 0.44) x 10(-11) exp[-(317 +/- 76)/T]. At room temperature and below, the reaction proceeds both via hydrogen abstraction and via reversible formation of an iodoethane/Cl adduct. Analysis of the LFP-RF data yields a binding enthalpy (0 K) for CD3CD2I x Cl of 57 +/- 10 kJ mol(-1). Calculations using density functional theory show that the adduct is characterized by a C-I-Cl bond angle of 84.5 degrees; theoretical binding enthalpies of 38.2 kJ/mol, G2'[ECP(S)], and 59.0 kJ mol(-1), B3LYP/ECP, are reasonably consistent with the experimentally derived result. Product studies conducted in the environmental chamber show that hydrogen abstraction from both the -CH2I and -CH3 groups occur to a significant extent and also provide evidence for a reaction of the CH3CH2I x Cl adduct with CH3CH2I, leading to CH3CH2Cl formation. Complementary environmental chamber studies of the reaction of Cl atoms with 2-iodopropane, CH3CHICH3, are also presented. As determined by relative rate methods, the reaction proceeds with an effective rate coefficient, k6, of (5.0 +/- 0.6) x 10(-11) cm3 molecule(-1) s(-1) at 298 K. Product studies indicate that this reaction also occurs via two abstraction channels (from the CH3 groups and from the -CHI- group) and via reversible adduct formation.
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Affiliation(s)
- John J Orlando
- Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado 80305, USA
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Enami S, Yamanaka T, Hashimoto S, Kawasaki M, Tonokura K. Direct Observation of Adduct Formation of Alkyl and Aromatic Iodides with Cl Atoms Using Cavity Ring-Down Spectroscopy. J Phys Chem A 2005; 109:6066-70. [PMID: 16833942 DOI: 10.1021/jp0520188] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The reactions of Cl atoms with RI (R = n-C3H7, n-C4H9, cyclo-C6H11, C6H5, C6F5, and p-CH3C6H4) have been studied using cavity ring-down spectroscopy at a temperature range of 233-313 K and at 100 Torr total pressure of N2 diluent. Visible absorption spectra of the RI-Cl adducts were recorded at 440-520 nm at 263 K. The yields of the adducts were temperature-dependent. There was no discernible reaction of the adducts in the presence of 100 Torr of O2 at 263 K. Theoretical calculations were performed for C4H9I-Cl and C6H5I-Cl for quantitative explanation of the absorption spectra and the strength of the I-Cl bonds in the charge-transfer complexes. Evidence for the adduct formation following the reaction of Cl with C6H5Br was sought but not found at 440 and 520 nm.
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Affiliation(s)
- Shinichi Enami
- Department of Molecular Engineering and Graduate School of Global Environmental Studies, Kyoto University, Kyoto 615-8510, Japan
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