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Blázquez S, González D, Neeman EM, Ballesteros B, Agúndez M, Canosa A, Albaladejo J, Cernicharo J, Jiménez E. Gas-phase kinetics of CH 3CHO with OH radicals between 11.7 and 177.5 K. Phys Chem Chem Phys 2020; 22:20562-20572. [PMID: 32966434 PMCID: PMC7116299 DOI: 10.1039/d0cp03203d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas-phase reactions in the interstellar medium (ISM) are a source of molecules in this environment. The knowledge of the rate coefficient for neutral-neutral reactions as a function of temperature, k(T), is essential to improve astrochemical models. In this work, we have experimentally measured k(T) for the reaction between the OH radical and acetaldehyde, both present in many sources of the ISM. Laser techniques coupled to a CRESU system were used to perform the kinetic measurements. The obtained modified Arrhenius equation is k(T = 11.7-177.5 K) = (1.2 ± 0.2) × 10-11 (T/300 K)-(1.8±0.1) exp-{(28.7 ± 2.5)/T} cm3 molecule-1 s-1. The k(T) value of the title reaction has been measured for the first time below 60 K. No pressure dependence of k(T) was observed at ca. 21, 50, 64 and 106 K. Finally, a pure gas-phase model indicates that the title reaction could become the main CH3CO formation pathway in dark molecular clouds, assuming that CH3CO is the main reaction product at 10 K.
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Affiliation(s)
- Sergio Blázquez
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
| | - Daniel González
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
| | - Elias M Neeman
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
| | - Bernabé Ballesteros
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain. and Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, 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
| | - André Canosa
- CNRS, IPR (Institut de Physique de Rennes)-UMR 6251, Université de Rennes, F-35000 Rennes, France
| | - José Albaladejo
- Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain. and Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, Camino de Moledores s/n, 13071, Ciudad Real, 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, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain. and Instituto de Investigación en Combustión y Contaminación Atmosférica (ICCA), Universidad de Castilla-La Mancha, Camino de Moledores s/n, 13071, Ciudad Real, Spain
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Howes NUM, Lockhart JPA, Blitz MA, Carr SA, Baeza-Romero MT, Heard DE, Shannon RJ, Seakins PW, Varga T. Observation of a new channel, the production of CH 3, in the abstraction reaction of OH radicals with acetaldehyde. Phys Chem Chem Phys 2016; 18:26423-26433. [PMID: 27711478 DOI: 10.1039/c6cp03970g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using laser flash photolysis coupled to photo-ionization time-of-flight mass spectrometry (PIMS), methyl radicals (CH3) have been detected as primary products from the reaction of OH radicals with acetaldehyde (ethanal, CH3CHO) with a yield of ∼15% at 1-2 Torr of helium bath gas. Supporting measurements based on laser induced fluorescence studies of OH recycling in the OH/CH3CHO/O2 system are consistent with the PIMS study. Master equation calculations suggest that the origin of the methyl radicals is from prompt dissociation of chemically activated acetyl products and hence is consistent with previous studies which have shown that abstraction, rather than addition/elimination, is the sole route for the OH + acetaldehyde reaction. However, the observation of a significant methyl product yield suggests that energy partitioning in the reaction is different from the typical early barrier mechanism where reaction exothermicity is channeled preferentially into the newly formed bond. The master equation calculations predict atmospheric yields of methyl radicals of ∼9%. The implications of the observations in atmospheric and combustion chemistry are briefly discussed.
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Affiliation(s)
- Neil U M Howes
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
| | | | - Mark A Blitz
- National Centre for Atmospheric Science, University of Leeds, Leeds, LS2 9JT, UK
| | - Scott A Carr
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
| | | | - Dwayne E Heard
- National Centre for Atmospheric Science, University of Leeds, Leeds, LS2 9JT, UK
| | - Robin J Shannon
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
| | - Paul W Seakins
- National Centre for Atmospheric Science, University of Leeds, Leeds, LS2 9JT, UK
| | - T Varga
- School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
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Galano A, Alvarez-Idaboy JR. Branching Ratios of Aliphatic Amines + OH Gas-Phase Reactions: A Variational Transition-State Theory Study. J Chem Theory Comput 2015; 4:322-7. [PMID: 26620664 DOI: 10.1021/ct7002786] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A theoretical study on the mechanism of the OH + aliphatic amines reactions is presented. Geometry optimization and frequencies calculations have been performed at the BHandHLYP/6-311++G(2d,2p) level of theory for all stationary points. Energy values have been improved by single-point calculations at the above geometries using CCSD(T) and the same basis set. All the possible hydrogen abstraction channels have been modeled, involving the rupture of C-H and N-H bonds. It was found that as the temperature decreases the contributions of the channels involving NH sites to the overall reaction also decrease, suggesting that for upper layers in the troposphere these channels become less important. Their percentage contributions to the overall reaction, at 298 K, were found to be about 20%, 2%, and 48% for methylamine, ethlylamine, and dimethylamine, respectively.
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Affiliation(s)
- Annia Galano
- Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340 México D. F., México, and Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, México
| | - J Raul Alvarez-Idaboy
- Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340 México D. F., México, and Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, México
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Zavala-Oseguera C, Galano A, Merino G. Computational study on the kinetics and mechanism of the carbaryl + OH reaction. J Phys Chem A 2014; 118:7776-81. [PMID: 25142884 DOI: 10.1021/jp507244s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Carbaryl is released into the atmosphere as a spray drift immediately following the application. In order to evaluate its fate in the atmosphere, a computational study on the kinetics of the OH radical reaction with carbaryl is presented. Different reaction paths are studied at the M05-2X/6-311++G(d,p) level. A complex mechanism involving the formation of a stable reactant complex is proposed and the temperature dependence of the rate coefficients is studied in the 280-650 K temperature range. The principal degradation path is the hydroxyl radical addition to naphthalene, but hydrogen abstractions from the methyl group are identified as a secondary significant path. The rate coefficients, computed using the conventional transition state theory, reproduce quite well the scarce experimental data available.
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Affiliation(s)
- Claudia Zavala-Oseguera
- Departamento de Química, Universidad de Guanajuato , Noria Alta s/n C.P. 36050, Guanajuato, Guanajuato, México
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Di Palma TM, Bende A. Tautomerism and proton transfer in photoionized acetaldehyde and acetaldehyde-water clusters. JOURNAL OF MASS SPECTROMETRY : JMS 2014; 49:700-708. [PMID: 25044897 DOI: 10.1002/jms.3403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 05/16/2014] [Accepted: 05/22/2014] [Indexed: 06/03/2023]
Abstract
Understanding the gas-phase chemistry of acetaldehyde can be challenging because the molecule can assume several tautomeric forms, namely keto, enol and carbene. The two last forms are the most stable ionic forms. Here, insight into the gas-phase cluster ion chemistry of homogeneous acetaldehyde and mixed water-acetaldehyde clusters is provided by mass spectrometry/vacuum ultraviolet photoionization combined with density functional theory calculations. (AA)nH(+) clusters (AA = acetaldehyde) and mixed (AA)nH3O(+) clusters were detected using tunable vacuum ultraviolet photoionization. Barrierless proton transfers were observed during the geometry optimization of the most stable dimer structures and helped to explain the cluster ion chemistry induced by photoionization, namely the formation of deprotonated tautomers and protonated keto tautomers. Water was found to catalyze the keto-enol and keto-carbene isomerizations and facilitate the proton transfer from the ionized enol or carbene part of the cluster to the neutral keto part, resulting in protonated keto structures. The production of protonated keto structures was identified to be the main fragmentation channel following ionization of the homogeneous acetaldehyde cluster and a channel for ionized mixed clusters as well. These findings are significant for a broad range of fields, including current atmospheric models, because acetaldehyde is one of the most prominent organic species in the troposphere and ions play a crucial role in aerosol formation.
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Poutsma ML. Evolution of Structure–Reactivity Correlations for the Hydrogen Abstraction Reaction by Hydroxyl Radical and Comparison with That by Chlorine Atom. J Phys Chem A 2013; 117:6433-49. [DOI: 10.1021/jp404749z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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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Galano A, Raul Alvarez-Idaboy J, Francisco-Márquez M. Mechanism and Branching Ratios of Hydroxy Ethers + •OH Gas phase Reactions: Relevance of H Bond Interactions. J Phys Chem A 2010; 114:7525-36. [DOI: 10.1021/jp103575f] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Annia Galano
- Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México D. F. México
- Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, México
| | - J. Raul Alvarez-Idaboy
- Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México D. F. México
- Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, México
| | - Misaela Francisco-Márquez
- Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México D. F. México
- Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, México
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Chen SY, Lee YP. Transient infrared absorption of t-CH3C(O)OO, c-CH3C(O)OO, and alpha-lactone recorded in gaseous reactions of CH3CO and O2. J Chem Phys 2010; 132:114303. [PMID: 20331293 DOI: 10.1063/1.3352315] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient species produced in gaseous reactions of CH(3)CO and O(2); IR absorption spectra of CH(3)C(O)OO and alpha-lactone were observed. Absorption bands with origins at 1851+/-1, 1372+/-2, 1169+/-6, and 1102+/-3 cm(-1) are attributed to t-CH(3)C(O)OO, and those at 1862+/-3, 1142+/-4, and 1078+/-6 cm(-1) are assigned to c-CH(3)C(O)OO. A weak band near 1960 cm(-1) is assigned to alpha-lactone, cyc-CH(2)C(=O)O, a coproduct of OH. These observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters and dipole derivatives, and observed vibrational wavenumbers agree with harmonic vibrational wavenumbers predicted with B3LYP/aug-cc-pVDZ density-functional theory. The observed relative intensities indicate that t-CH(3)C(O)OO is more stable than c-CH(3)C(O)OO by 3+/-2 kJ mol(-1). Based on these observations, the branching ratio for the OH+alpha-lactone channel of the CH(3)CO+O(2) reaction is estimated to be 0.04+/-0.01 under 100 Torr of O(2) at 298 K. A simple kinetic model is employed to account for the decay of CH(3)C(O)OO.
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Affiliation(s)
- Sun-Yang Chen
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
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Vega-Rodriguez A, Alvarez-Idaboy JR. Quantum chemistry and TST study of the mechanisms and branching ratios for the reactions of OH with unsaturated aldehydes. Phys Chem Chem Phys 2010; 11:7649-58. [PMID: 19950504 DOI: 10.1039/b906692f] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A theoretical study is presented on the mechanism of OH reactions with three unsaturated aldehydes, relevant to atmospheric chemistry. Using acrolein as test molecule, several methods were tested in conjunction with the 6-311 ++ G(d,p) basis set. Based on the results from this study, the MPWB1K and M05-2X functionals were selected for the further study of acrolein, methacrolein and crotonaldehyde. All possible reaction channels have been modeled. Calculated overall rate coefficients at M05-2X/6-311 ++ G(d,p) are in excellent agreement with experimental data, supporting the proposed mechanisms. The previously proposed global mechanisms were confirmed, and specific mechanisms were identified. The causes of the mechanism for crotonaldehyde being different from the one of acrolein and methacrolein were clarified. The agreement between experiment and calculations validates the use of the chosen DFT methods for kinetic calculations, especially for large systems and cases in which spin contamination is an important issue.
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Affiliation(s)
- Aidee Vega-Rodriguez
- Facultad de Quimica, Departamento de Física y Química Teorica, Universidad Nacional Autonoma de Mexico, Mexico, DF, México
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Zavala-Oseguera C, Alvarez-Idaboy JR, Merino G, Galano A. OH Radical Gas Phase Reactions with Aliphatic Ethers: A Variational Transition State Theory Study. J Phys Chem A 2009; 113:13913-20. [DOI: 10.1021/jp906144d] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Claudia Zavala-Oseguera
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México, Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, and Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México
| | - Juan R. Alvarez-Idaboy
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México, Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, and Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México
| | - Gabriel Merino
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México, Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, and Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México
| | - Annia Galano
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México, Facultad de Química, Departamento de Física y Química Teórica, Universidad Nacional Autónoma de México, México DF 04510, and Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México
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Zavala-Oseguera C, Galano A. CBS-QB3 + VTST Study of Methyl N-Methylcarbamate + OH Gas-Phase Reaction: Mechanism, Kinetics, and Branching Ratios. J Chem Theory Comput 2009; 5:1295-303. [DOI: 10.1021/ct9000679] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Claudia Zavala-Oseguera
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México, and Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C.P. 09340, México, D. F. México
| | - Annia Galano
- Departamento de Química, Universidad de Guanajuato, Noria Alta s/n C.P. 36050, Guanajuato, Gto. México, and Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C.P. 09340, México, D. F. México
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Zhu L, Talukdar RK, Burkholder JB, Ravishankara AR. Rate coefficients for the OH + acetaldehyde (CH3CHO) reaction between 204 and 373 K. INT J CHEM KINET 2008. [DOI: 10.1002/kin.20346] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Rajakumar B, Gierczak T, Flad JE, Ravishankara A, Burkholder JB. The CH3CO quantum yield in the 248nm photolysis of acetone, methyl ethyl ketone, and biacetyl. J Photochem Photobiol A Chem 2008. [DOI: 10.1016/j.jphotochem.2008.06.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Iuga C, Galano A, Vivier‐Bunge A. Theoretical Investigation of the OH.‐Initiated Oxidation of Benzaldehyde in the Troposphere. Chemphyschem 2008; 9:1453-9. [DOI: 10.1002/cphc.200800144] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Jagiella S, Zabel F. Thermal stability of carbonyl radicals : Part II. Reactions of methylglyoxyl and methylglyoxylperoxy radicals at 1 bar in the temperature range 275–311 K. Phys Chem Chem Phys 2008; 10:1799-808. [DOI: 10.1039/b712312d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Atmospheric Reactions of Oxygenated Volatile Organic Compounds+OH Radicals: Role of Hydrogen-Bonded Intermediates and Transition States. ADVANCES IN QUANTUM CHEMISTRY 2008. [DOI: 10.1016/s0065-3276(07)00212-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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18
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Rajakumar B, Flad JE, Gierczak T, Ravishankara AR, Burkholder JB. Visible Absorption Spectrum of the CH3CO Radical. J Phys Chem A 2007; 111:8950-8. [PMID: 17705457 DOI: 10.1021/jp073339h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The visible absorption spectrum of the acetyl radical, CH(3)CO, was measured between 490 and 660 nm at 298 K using cavity ring-down spectroscopy. Gas-phase CH(3)CO radicals were produced using several methods including: (1) 248 nm pulsed laser photolysis of acetone (CH(3)C(O)CH(3)), methyl ethyl ketone (MEK, CH(3)C(O)CH(2)CH(3)), and biacetyl (CH(3)C(O)C(O)CH(3)), (2) Cl + CH(3)C(O)H --> CH(3)C(O) + HCl with Cl atoms produced via pulsed laser photolysis or in a discharge flow tube, and (3) OH + CH(3)C(O)H --> CH(3)CO + H(2)O with two different pulsed laser photolysis sources of OH radicals. The CH(3)CO absorption spectrum was assigned on the basis of the consistency of the spectra obtained from the different CH(3)CO sources and agreement of the measured rate coefficients for the reaction of the absorbing species with O(2) and O(3) with literature values for the CH(3)CO + O(2) + M and CH(3)CO + O(3) reactions. The CH(3)CO absorption spectrum between 490 and 660 nm has a broad peak centered near 535 nm and shows no discernible structure. The absorption cross section of CH(3)CO at 532 nm was measured to be (1.1 +/- 0.2) x 10(-19) cm(2) molecule(-1) (base e).
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Affiliation(s)
- B Rajakumar
- Earth System Research Laboratory, Chemical Sciences Division, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, Colorado 80305-3328, USA
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Hou H, Wang B. Ab initio study of the reaction of propionyl (C2H5CO) radical with oxygen (O2). J Chem Phys 2007; 127:054306. [PMID: 17688339 DOI: 10.1063/1.2756538] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The reaction of propionyl radical with oxygen has been studied using the full coupled cluster theory with the complete basis set. This is the first time to gain a conclusive insight into the reaction mechanism and kinetics for this important reaction in detail. The reaction takes place via a chemical activation mechanism. The barrierless association of propionyl with oxygen produces the propionylperoxy radical, which decomposes to form the hydroxyl radical and the three-center alpha-lactone predominantly or the four-center beta-propiolactone. The oxidation of propionyl radical to carbon monoxide or carbon dioxide is not straightforward rather via the secondary decomposition of alpha-lactone and beta-propiolactone. Kinetically, the overall rate constant is almost pressure independent and it approaches the high-pressure limit around tens of torr of helium. At temperatures below 600 K, the rate constant shows negative temperature dependence. The experimental yields of the hydroxyl radical can be well reproduced, with the average energy transferred per collision -DeltaE=20-25 cm(-1) at 213 and 295 K (helium bath gas). At low pressures, together with the hydroxy radical, alpha-lactone is the major product, while beta-propiolactone only accounts for about one-fifth of alpha-lactone. At the high-pressure limit, the production of the propionylperoxy radical is dominant together with a fraction of the isomers. The infrared spectroscopy or the mass spectroscopy techniques are suggested to be employed in the future experimental study of the C2H5CO+O2 reaction.
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Affiliation(s)
- Hua Hou
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, People's Republic of China
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Rosado-Reyes CM, Francisco JS. Atmospheric oxidation pathways of propane and its by-products: Acetone, acetaldehyde, and propionaldehyde. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd007566] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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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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Blitz MA, Goddard A, Ingham T, Pilling MJ. Time-of-flight mass spectrometry for time-resolved measurements. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2007; 78:034103. [PMID: 17411198 DOI: 10.1063/1.2712797] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A time-resolved time-of-flight mass spectrometer (TOF-MS) that can simultaneously monitor multiple species on the millisecond time scale has been constructed. A pulsed photolysis laser is used to initiate reaction, and then via a pinhole the reaction mixture is sampled by the TOF-MS. The ions are created by photoionization via either a discharge lamp or a pulsed laser. Comparison between the two ionization sources showed that the laser is at least an order of magnitude more efficient, based on the time to accumulate the data. Also, unlike the continuous lamp the pulsed laser is not mass limited. Frequency tripling the 355 nm output of a Nd:YAG laser provided a convenient laser ionization source. However, using a dye laser provided an equally intense laser ionization source with the ability to tune the vacuum ultraviolet (vuv) light. To show the versatility of the system the kinetics of the reaction of SO and ClSO radicals with NO(2) were simultaneously measured, and using the dye laser the vuv light was tuned to 114 nm in order to observe H(2)CO being formed from the reaction between CH(3)CO and O(2).
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Affiliation(s)
- Mark A Blitz
- School of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
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23
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Karunanandan R, Hölscher D, Dillon TJ, Horowitz A, Crowley JN, Vereecken L, Peeters J. Reaction of HO with Glycolaldehyde, HOCH2CHO: Rate Coefficients (240−362 K) and Mechanism. J Phys Chem A 2007; 111:897-908. [PMID: 17266231 DOI: 10.1021/jp0649504] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Absolute rate coefficients for the title reaction, HO+HOCH2CHO-->products (R1), were measured over the temperature range 240-362 K using the technique of pulsed laser photolytic generation of the HO radical coupled to detection by pulsed laser induced fluorescence. Within experimental error, the rate coefficient, k1, is independent of temperature over the range covered and is given by k1(240-362 K)=(8.0+/-0.8)x10(-12) cm3 molecule-1 s-1. The effects of the hydroxy substituent and hydrogen bonding on the rate coefficient are discussed based on theoretical calculations. The present results, which extend the database on the title reaction to a range of temperatures, indicate that R1 is the dominant loss process for HOCH2CHO throughout the troposphere. As part of this work, the absorption cross-section of HOCH2CHO at 184.9 nm was determined to be (3.85+/-0.2)x10(-18) cm2 molecule-1, and the quantum yield of HO formation from the photolysis of HOCH2CHO at 248 nm was found to be (7.0+/-1.5)x10(-2).
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Affiliation(s)
- Rosalin Karunanandan
- Max-Planck-Institut für Chemie, Division of Atmospheric Chemistry, 55020 Mainz, Germany
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Kovács G, Zádor J, Farkas E, Nádasdi R, Szilágyi I, Dóbé S, Bérces T, Márta F, Lendvay G. Kinetics and mechanism of the reactions of CH3CO and CH3C(O)CH2 radicals with O2. Low-pressure discharge flow experiments and quantum chemical computations. Phys Chem Chem Phys 2007; 9:4142-54. [PMID: 17687464 DOI: 10.1039/b706216h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactions CH(3)CO + O(2)--> products (1), CH(3)CO + O(2)--> OH +other products (1b) and CH(3)C(O)CH(2) + O(2)--> products (2) have been studied in isothermal discharge flow reactors with laser induced fluorescence monitoring of OH and CH(3)C(O)CH(2) radicals. The experiments have been performed at overall pressures between 1.33 and 10.91 mbar of helium and 298 +/- 1 K reaction temperature. OH formation has been found to be the dominant reaction channel for CH(3)CO + O(2): the branching ratio, Gamma(1b) = k(1b)/k(1), is close to unity at around 1 mbar, but decreases rapidly with increasing pressure. The rate constant of the overall reaction, k(2), has been found to be pressure dependent: the fall-off behaviour has been analysed in comparison with reported data. Electronic structure calculations have confirmed that at room temperature the reaction of CH(3)C(O)CH(2) with O(2) is essentially a recombination-type process. At high temperatures, the further reactions of the acetonyl-peroxyl adduct may yield OH radicals, but the most probable channel seems to be the O(2)-catalysed keto-enol transformation of acetonyl. Implications of the results for atmospheric modelling studies have been discussed.
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Affiliation(s)
- Gergely Kovács
- Chemical Research Center, Hungarian Academy of Sciences, Pusztaszeri út 59-67, H-1025 Budapest, Hungary
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Maranzana A, Barker JR, Tonachini G. Master equation simulations of competing unimolecular and bimolecular reactions: application to OH production in the reaction of acetyl radical with O2. Phys Chem Chem Phys 2007; 9:4129-41. [PMID: 17687463 DOI: 10.1039/b705116f] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Master equation calculations were carried out to simulate the production of hydroxyl free radicals initiated by the reaction of acetyl free radicals (CH3(C=O).) with molecular oxygen. In particular, the competition between the unimolecular reactions and bimolecular reactions of vibrationally excited intermediates was modeled by using a single master equation. The vibrationally excited intermediates (isomers of acetylperoxyl radicals) result from the initial reaction of acetyl free radical with O2. The bimolecular reactions were modeled using a novel pseudo-first-order microcanonical rate constant approach. Stationary points on the multi-well, multi-channel potential energy surface (PES) were calculated at the DFT(B3LYP)/6-311G(2df,p) level of theory. Some additional calculations were carried out at the CASPT2(7,5)/6-31G(d) level of theory to investigate barrierless reactions and other features of the PES. The master equation simulations are in excellent agreement with the experimental OH yields measured in N2 or He buffer gas near 300 K, but they do not explain a recent report that the OH yields are independent of pressure in nearly pure O2 buffer gas.
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Affiliation(s)
- Andrea Maranzana
- Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USA
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da Silva G, Bozzelli JW. Enthalpies of Formation, Bond Dissociation Energies, and Molecular Structures of the n-Aldehydes (Acetaldehyde, Propanal, Butanal, Pentanal, Hexanal, and Heptanal) and Their Radicals. J Phys Chem A 2006; 110:13058-67. [PMID: 17134166 DOI: 10.1021/jp063772b] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aldehydes are important intermediates and products in a variety of combustion and gas-phase oxidation processes, such as in low-temperature combustion, in the atmosphere, and in interstellar media. Despite their importance, the enthalpies of formation and bond dissociation energies (BDEs) for the aldehydes are not accurately known. We have determined enthalpies of formation for acetaldehyde, propanal, and butanal from thermodynamic cycles, using experimentally measured reaction and formation enthalpies. All enthalpy values used for reference molecules and reactions were first verified to be accurate to within around 1 kcal mol-1 using high-level ab initio calculations. Enthalpies of formation were found to be -39.72 +/- 0.16 kcal mol-1 for acetaldehyde, -45.18 +/- 1.1 kcal mol-1 for propanal, and -49.27 +/- 0.16 kcal mol-1 for butanal. Enthalpies of formation for these three aldehydes, as well as for pentanal, hexanal, and heptanal, were calculated using the G3, G3B3, and CBS-APNO theoretical methods, in conjunction with bond-isodesmic work reactions. On the basis of the results of our thermodynamic cycles, theoretical calculations using isodesmic work reactions, and existing experimental measurements, we suggest that the best available formation enthalpies for the aldehydes acetaldehyde, propanal, butanal, pentanal, hexanal, and heptanal are -39.72, -45.18, -50.0, -54.61, -59.37, and -64.2 kcal mol-1, respectively. Our calculations also identify that the literature enthalpy of formation of crotonaldehyde is in error by as much as 1 kcal mol-1, and we suggest a value of -25.1 kcal mol-1, which we calculate using isodesmic work reactions. Bond energies for each of the bonds in the aldehydes up to pentanal were calculated at the CBS-APNO level. Analysis of the BDEs reveals the R-CH(2)CH=O to be the weakest bond in all aldehydes larger than acetaldehyde, due to formation of the resonantly stabilized vinoxy radical (vinyloxy radical/formyl methyl radical). It is proposed that the vinoxy radical as well as the more commonly considered formyl and acetyl radicals are important products of aldehyde combustion and oxidation, and the reaction pathways of the vinoxy, formyl, and acetyl radicals are discussed. Group additivity values for the carbon-oxygen-hydrogen groups common to the aldehydes are also determined. Internal rotor profiles and electrostatic potential surfaces are used to study the dipole induced dipole-dipole interaction in the synperiplanar conformation of propanal. It is proposed that the loss of this dipole-dipole interaction in RC(.-)HCH(2)CH=O radicals causes a ca. 1-2 kcal mol-1 decrease in the aldehyde C-H and C-C bond energies corresponding to RC(.-)HCH(2)CH=O radical formation.
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Affiliation(s)
- Gabriel da Silva
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, USA
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Butkovskaya NI, Pouvesle N, Kukui A, Mu Y, Le Bras G. Mechanism of the OH-Initiated Oxidation of Hydroxyacetone over the Temperature Range 236−298 K. J Phys Chem A 2006; 110:6833-43. [PMID: 16722699 DOI: 10.1021/jp056345r] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The mechanism of the gas-phase reaction of OH radicals with hydroxyacetone (CH3C(O)CH2OH) was studied at 200 Torr over the temperature range 236-298 K in a turbulent flow reactor coupled to a chemical ionization mass-spectrometer. The product yields and kinetics were measured in the presence of O2 to simulate the atmospheric conditions. The major stable product at all temperatures is methylglyoxal. However, its yield decreases from 82% at 298 K to 49% at 236 K. Conversely, the yields of formic and acetic acids increase from about 8% to about 20%. Other observed products were formaldehyde, CO2 and peroxy radicals HO2 and CH3C(O)O2. A partial re-formation of OH radicals (by approximately 10% at 298 K) was found in the OH + hydroxyacetone + O2 chemical system along with a noticeable inverse secondary kinetic isotope effect (k(OH)/k(OD) = 0.78 +/- 0.10 at 298 K). The observed product yields are explained by the increasing role of the complex formed between the primary radical CH3C(O)CHOH and O2 at low temperature. The rate constant of the reaction CH3C(O)CHOH + O2 --> CH3C(O)CHO + HO2 at 298 K, (3.0 +/- 0.6) x 10(-12) cm3 molecule(-1) s(-1), was estimated by computer simulation of the concentration-time profiles of the CH3C(O)CHO product. The detailed mechanism of the OH-initiated oxidation of hydroxyacetone can help to better describe the atmospheric oxidation of isoprene, in particular, in the upper troposphere.
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Affiliation(s)
- Nadezhda I Butkovskaya
- CNRS, Laboratoire de Combustion et Systèmes Réactifs, 1C Av. de la Recherche Scientifique, 45071 Orléans Cedex 2, France
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Taylor PH, Yamada T, Marshall P. The reaction of OH with acetaldehyde and deuterated acetaldehyde: Further insight into the reaction mechanism at both low and elevated temperatures. INT J CHEM KINET 2006. [DOI: 10.1002/kin.20179] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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29
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Devolder P, Dusanter S, Lemoine B, Fittschen C. About the co-product of the OH radical in the reaction of acetyl with O2 below atmospheric pressure. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2005.09.114] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hou H, Li A, Hu H, Li Y, Li H, Wang B. Mechanistic and kinetic study of the CH3CO+O2 reaction. J Chem Phys 2005; 122:224304. [PMID: 15974665 DOI: 10.1063/1.1897375] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Potential-energy surface of the CH3CO + O2 reaction has been calculated by ab initio quantum chemistry methods. The geometries were optimized using the second-order Moller-Plesset theory (MP2) with the 6-311G(d,p) basis set and the coupled-cluster theory with single and double excitations (CCSD) with the correlation consistent polarized valence double zeta (cc-pVDZ) basis set. The relative energies were calculated using the Gaussian-3 second-order Moller-Plesset theory with the CCSD/cc-pVDZ geometries. Multireference self-consistent-field and MP2 methods were also employed using the 6-311G(d,p) and 6-311++G(3df,2p) basis sets. Both addition/elimination and direct abstraction mechanisms have been investigated. It was revealed that acetylperoxy radical [CH3C(O)OO] is the initial adduct and the formation of OH and alpha-lactone [CH2CO2(1A')] is the only energetically accessible decomposition channel. The other channels, e.g., abstraction, HO2 + CH2CO, O + CH3CO2, CO + CH3O2, and CO2 + CH3O, are negligible. Multichannel Rice-Ramsperger-Kassel-Marcus theory and transition state theory (E-resolved) were employed to calculate the overall and individual rate coefficients and the temperature and pressure dependences. Fairly good agreement between theory and experiments has been obtained without any adjustable parameters. It was concluded that at pressures below 3 Torr, OH and CH2CO2(1A') are the major nascent products of the oxidation of acetyl radicals, although CH2CO2(1A') might either undergo unimolecular decomposition to form the final products of CH2O + CO or react with OH and Cl to generate H2O and HCl. The acetylperoxy radicals formed by collisional stabilization are the major products at the elevated pressures. In atmosphere, the yield of acetylperoxy is nearly unity and the contribution of OH is only marginal.
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Affiliation(s)
- Hua Hou
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, People's Republic of China
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Kuwata KT, Hasson AS, Dickinson RV, Petersen EB, Valin LC. Quantum Chemical and Master Equation Simulations of the Oxidation and Isomerization of Vinoxy Radicals. J Phys Chem A 2005; 109:2514-24. [PMID: 16833553 DOI: 10.1021/jp047299i] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The vinoxy radical, a common intermediate in gas-phase alkene ozonolysis, reacts with O2 to form a chemically activated alpha-oxoperoxy species. We report CBS-QB3 energetics for O2 addition to the parent (*CH2CHO, 1a), 1-methylvinoxy (*CH2COCH3, 1b), and 2-methylvinoxy (CH3*CHCHO, 1c) radicals. CBS-QB3 predictions for peroxy radical formation agree with experimental data, while the G2 method systematically overestimates peroxy radical stability. RRKM/master equation simulations based on CBS-QB3 data are used to estimate the competition between prompt isomerization and thermalization for the peroxy radicals derived from 1a, 1b, and 1c. The lowest energy isomerization pathway for radicals 4a and 4c (derived from 1a and 1c, respectively) is a 1,4-shift of the acyl hydrogen requiring 19-20 kcal/mol. The resulting hydroperoxyacyl radical decomposes quantitatively to form *OH. The lowest energy isomerization pathway for radical 4b (derived from 1b) is a 1,5-shift of a methyl hydrogen requiring 26 kcal/mol. About 25% of 4a, but only approximately 5% of 4c, isomerizes promptly at 1 atm pressure. Isomerization of 4b is negligible at all pressures studied.
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Affiliation(s)
- Keith T Kuwata
- Department of Chemistry, Macalester College, Saint Paul, Minnesota 55105-1899, USA.
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32
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Espinosa-García J, Dóbé S. Theoretical enthalpies of formation for atmospheric hydroxycarbonyls. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/j.theochem.2004.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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