1
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Shiels OJ, Marlton SJP, Poad BLJ, Blanksby SJ, da Silva G, Trevitt AJ. Gas-Phase Phenyl Radical + O 2 Reacts via a Submerged Transition State. J Phys Chem A 2024; 128:413-419. [PMID: 38174881 DOI: 10.1021/acs.jpca.3c06878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
In the gas-phase chemistry of the atmosphere and automotive fuel combustion, peroxyl radical intermediates are formed following O2 addition to carbon-centered radicals which then initiate a complex network of radical reactions that govern the oxidative processing of hydrocarbons. The rapid association of the phenyl radical-a fundamental radical related to benzene-with O2 has hitherto been modeled as a barrierless process, a common assumption for peroxyl radical formation. Here, we provide an alternate explanation for the kinetics of this reaction by deploying double-hybrid density functional theory (DFT), at the DSD-PBEP86-D3(BJ)/aug-cc-pVTZ level of theory, and locate a submerged adiabatic transition state connected to a prereaction complex along the reaction entrance pathway. Using this potential energy scheme, experimental rate coefficients k(T) for the addition of O2 to the phenyl radical are accurately reproduced within a microcanonical kinetic model. This work highlights that purportedly barrierless radical oxidation reactions may instead be modeled using stationary points, which in turn provides insight into pressure and temperature dependence.
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Affiliation(s)
- Oisin J Shiels
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, Australia
| | - Samuel J P Marlton
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, Australia
| | - Berwyck L J Poad
- School of Chemistry and Physics and the Central Analytical Research Facility, Queensland University of Technology, Brisbane 4001, Australia
| | - Stephen J Blanksby
- School of Chemistry and Physics and the Central Analytical Research Facility, Queensland University of Technology, Brisbane 4001, Australia
| | - Gabriel da Silva
- Department of Chemical Engineering, the University of Melbourne, Melbourne 3010, Victoria, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong 2522, Australia
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2
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Komissarov L, Krep L, Schmalz F, Kopp WA, Leonhard K, Verstraelen T. A Reactive Molecular Dynamics Study of Chlorinated Organic Compounds. Part I: Force Field Development. Chemphyschem 2022; 24:e202200786. [PMID: 36585384 DOI: 10.1002/cphc.202200786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/23/2022] [Accepted: 12/28/2022] [Indexed: 01/01/2023]
Abstract
This work presents a novel parametrization for the ReaxFF formalism as a means to investigate reaction processes of chlorinated organic compounds. Force field parameters cover the chemical elements C, H, O, Cl and were obtained using a novel optimization approach involving relaxed potential energy surface scans as training targets. The resulting ReaxFF parametrization shows good transferability, as demonstrated on two independent ab initio validation sets. While this first part of our two-paper series focuses on force field parametrization, we apply our parameters to the simulation of chlorinated dibenzofuran formation and decomposition processes in Part II.
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Affiliation(s)
- Leonid Komissarov
- Center for Molecular Modeling (CMM), Ghent University, Technologiepark - Zwijnaarde 46, B-9052, Ghent, Belgium
| | - Lukas Krep
- Institute of Technical Thermodynamics, RWTH Aachen University, North Rhine - Westphalia, 52062, Aachen, Germany
| | - Felix Schmalz
- Institute of Technical Thermodynamics, RWTH Aachen University, North Rhine - Westphalia, 52062, Aachen, Germany
| | - Wassja A Kopp
- Institute of Technical Thermodynamics, RWTH Aachen University, North Rhine - Westphalia, 52062, Aachen, Germany
| | - Kai Leonhard
- Institute of Technical Thermodynamics, RWTH Aachen University, North Rhine - Westphalia, 52062, Aachen, Germany
| | - Toon Verstraelen
- Center for Molecular Modeling (CMM), Ghent University, Technologiepark - Zwijnaarde 46, B-9052, Ghent, Belgium
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3
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Shen J, Scholz W, He XC, Zhou P, Marie G, Wang M, Marten R, Surdu M, Rörup B, Baalbaki R, Amorim A, Ataei F, Bell DM, Bertozzi B, Brasseur Z, Caudillo L, Chen D, Chu B, Dada L, Duplissy J, Finkenzeller H, Granzin M, Guida R, Heinritzi M, Hofbauer V, Iyer S, Kemppainen D, Kong W, Krechmer JE, Kürten A, Lamkaddam H, Lee CP, Lopez B, Mahfouz NGA, Manninen HE, Massabò D, Mauldin RL, Mentler B, Müller T, Pfeifer J, Philippov M, Piedehierro AA, Roldin P, Schobesberger S, Simon M, Stolzenburg D, Tham YJ, Tomé A, Umo NS, Wang D, Wang Y, Weber SK, Welti A, Wollesen de Jonge R, Wu Y, Zauner-Wieczorek M, Zust F, Baltensperger U, Curtius J, Flagan RC, Hansel A, Möhler O, Petäjä T, Volkamer R, Kulmala M, Lehtipalo K, Rissanen M, Kirkby J, El-Haddad I, Bianchi F, Sipilä M, Donahue NM, Worsnop DR. High Gas-Phase Methanesulfonic Acid Production in the OH-Initiated Oxidation of Dimethyl Sulfide at Low Temperatures. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:13931-13944. [PMID: 36137236 PMCID: PMC9535848 DOI: 10.1021/acs.est.2c05154] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 09/01/2022] [Accepted: 09/02/2022] [Indexed: 06/16/2023]
Abstract
Dimethyl sulfide (DMS) influences climate via cloud condensation nuclei (CCN) formation resulting from its oxidation products (mainly methanesulfonic acid, MSA, and sulfuric acid, H2SO4). Despite their importance, accurate prediction of MSA and H2SO4 from DMS oxidation remains challenging. With comprehensive experiments carried out in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at CERN, we show that decreasing the temperature from +25 to -10 °C enhances the gas-phase MSA production by an order of magnitude from OH-initiated DMS oxidation, while H2SO4 production is modestly affected. This leads to a gas-phase H2SO4-to-MSA ratio (H2SO4/MSA) smaller than one at low temperatures, consistent with field observations in polar regions. With an updated DMS oxidation mechanism, we find that methanesulfinic acid, CH3S(O)OH, MSIA, forms large amounts of MSA. Overall, our results reveal that MSA yields are a factor of 2-10 higher than those predicted by the widely used Master Chemical Mechanism (MCMv3.3.1), and the NOx effect is less significant than that of temperature. Our updated mechanism explains the high MSA production rates observed in field observations, especially at low temperatures, thus, substantiating the greater importance of MSA in the natural sulfur cycle and natural CCN formation. Our mechanism will improve the interpretation of present-day and historical gas-phase H2SO4/MSA measurements.
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Affiliation(s)
- Jiali Shen
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Wiebke Scholz
- Institute
of Ion Physics and Applied Physics, University
of Innsbruck, 6020 Innsbruck, Austria
| | - Xu-Cheng He
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Putian Zhou
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Guillaume Marie
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Mingyi Wang
- Center
for Atmospheric Particle Studies, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Ruby Marten
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Mihnea Surdu
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Birte Rörup
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Rima Baalbaki
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Antonio Amorim
- CENTRA
and Faculdade de Ciências da Universidade de Lisboa, 1749-016 Campo
Grande, Lisboa, Portugal
| | - Farnoush Ataei
- Leibniz
Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany
| | - David M. Bell
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Barbara Bertozzi
- Institute
of Meteorology and Climate Research, Karlsruhe
Institute of Technology, 76344 Karlsruhe, Germany
| | - Zoé Brasseur
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Lucía Caudillo
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Dexian Chen
- Center
for Atmospheric Particle Studies, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Biwu Chu
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Lubna Dada
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Jonathan Duplissy
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
- Helsinki
Institute of Physics, University of Helsinki, 00014 Helsinki, Finland
| | - Henning Finkenzeller
- Department
of Chemistry and Cooperative Institute for Research in the Environmental
Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Manuel Granzin
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Roberto Guida
- CERN, the European Organization for Nuclear Research, CH-1211 Geneva
23, Switzerland
| | - Martin Heinritzi
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Victoria Hofbauer
- Center
for Atmospheric Particle Studies, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Siddharth Iyer
- Aerosol Physics
Laboratory, Physics Unit, Faculty of Engineering
and Natural Sciences, Tampere University, 33014 Tampere, Finland
| | - Deniz Kemppainen
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Weimeng Kong
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | | | - Andreas Kürten
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Houssni Lamkaddam
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Chuan Ping Lee
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Brandon Lopez
- Center
for Atmospheric Particle Studies, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Naser G. A. Mahfouz
- Atmospheric and Oceanic Sciences, Princeton
University, Princeton, New Jersey 08540, United States
| | - Hanna E. Manninen
- CERN, the European Organization for Nuclear Research, CH-1211 Geneva
23, Switzerland
| | - Dario Massabò
- Department
of Physics, University of Genoa & INFN, 16146 Genoa, Italy
| | - Roy L. Mauldin
- Department of Chemistry, Carnegie Mellon
University, Pittsburgh, Pennsylvania 15213, United States
- Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Bernhard Mentler
- Institute
of Ion Physics and Applied Physics, University
of Innsbruck, 6020 Innsbruck, Austria
| | - Tatjana Müller
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Joschka Pfeifer
- CERN, the European Organization for Nuclear Research, CH-1211 Geneva
23, Switzerland
| | - Maxim Philippov
- P.N. Lebedev Physical Institute of the Russian Academy of Sciences, 119991 Moscow, Russia
| | - Ana A. Piedehierro
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
| | - Pontus Roldin
- Division of Nuclear Physics, Lund University, 22100 Lund, Sweden
| | | | - Mario Simon
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Dominik Stolzenburg
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Yee Jun Tham
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
- School of Marine Sciences, Sun Yat-sen
University, 519082 Zhuhai, China
| | - António Tomé
- Institute Infante Dom Luíz, University
of Beira Interior, 6200-001 Covilhã, Portugal
| | - Nsikanabasi Silas Umo
- Institute
of Meteorology and Climate Research, Karlsruhe
Institute of Technology, 76344 Karlsruhe, Germany
| | - Dongyu Wang
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Yonghong Wang
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Stefan K. Weber
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
- CERN, the European Organization for Nuclear Research, CH-1211 Geneva
23, Switzerland
| | - André Welti
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
| | | | - Yusheng Wu
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Marcel Zauner-Wieczorek
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Felix Zust
- Institute
of Ion Physics and Applied Physics, University
of Innsbruck, 6020 Innsbruck, Austria
| | - Urs Baltensperger
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Joachim Curtius
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
| | - Richard C. Flagan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Armin Hansel
- Institute
of Ion Physics and Applied Physics, University
of Innsbruck, 6020 Innsbruck, Austria
| | - Ottmar Möhler
- Institute
of Meteorology and Climate Research, Karlsruhe
Institute of Technology, 76344 Karlsruhe, Germany
| | - Tuukka Petäjä
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Rainer Volkamer
- Department
of Chemistry and Cooperative Institute for Research in the Environmental
Sciences, University of Colorado Boulder, Boulder, Colorado 80309, United States
| | - Markku Kulmala
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
- Helsinki
Institute of Physics, University of Helsinki, 00014 Helsinki, Finland
- Joint
International Research Laboratory of Atmospheric and Earth System
Sciences, School of Atmospheric Sciences, Nanjing University, 210023 Nanjing, China
- Aerosol and Haze Laboratory, Beijing Advanced Innovation
Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, 100029 Beijing, China
| | - Katrianne Lehtipalo
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
- Finnish Meteorological Institute, Erik Palmenin aukio 1, 00560 Helsinki, Finland
| | - Matti Rissanen
- Aerosol Physics
Laboratory, Physics Unit, Faculty of Engineering
and Natural Sciences, Tampere University, 33014 Tampere, Finland
| | - Jasper Kirkby
- Institute
for Atmospheric and Environmental Sciences, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany
- CERN, the European Organization for Nuclear Research, CH-1211 Geneva
23, Switzerland
| | - Imad El-Haddad
- Laboratory
of Atmospheric Chemistry, Paul Scherrer
Institute, CH-5232 Villigen, Switzerland
| | - Federico Bianchi
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Mikko Sipilä
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
| | - Neil M. Donahue
- Center
for Atmospheric Particle Studies, Carnegie
Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Chemistry, Carnegie Mellon
University, Pittsburgh, Pennsylvania 15213, United States
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Douglas R. Worsnop
- Institute
for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, 00014 Helsinki, Finland
- Aerodyne Research, Inc., Billerica, Massachusetts 01821, United States
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4
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Qu HJ, Yuan L, Jia CX, Yu HT, Xu H. DFT Investigation of Hydrogen Atom Abstraction from NHC-Boranes by Methyl, Ethyl and Cyanomethyl Radicals-Composition and Correlation Analysis of Kinetic Barriers. Molecules 2020; 25:molecules25194509. [PMID: 33019654 PMCID: PMC7582687 DOI: 10.3390/molecules25194509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/21/2020] [Accepted: 09/29/2020] [Indexed: 11/20/2022] Open
Abstract
Understanding the hydrogen atom abstraction (HAA) reactions of N-heterocyclic carbene (NHC)-boranes is essential for extending the practical applications of boron chemistry. In this study, density functional theory (DFT) computations were performed for the HAA reactions of a series of NHC-boranes attacked by •CH2CN, Me• and Et• radicals. Using the computed data, we investigated the correlations of the activation and free energy barriers with their components, including the intrinsic barrier, the thermal contribution of the thermodynamic reaction energy to the kinetic barriers, the activation Gibbs free energy correction and the activation zero-point vibrational energy correction. Furthermore, to describe the dependence of the activation and free energy barriers on the thermodynamic reaction energy or reaction Gibbs free energy, we used a three-variable linear model, which was demonstrated to be more precise than the two-variable Evans–Polanyi linear free energy model and more succinct than the three-variable Marcus-theory-based nonlinear HAA model. The present work provides not only a more thorough understanding of the compositions of the barriers to the HAA reactions of NHC-boranes and the HAA reactivities of the substrates but also fresh insights into the suitability of various models for describing the relationships between the kinetic and thermodynamic physical quantities.
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Affiliation(s)
- Hong-jie Qu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
- College of Science, Heilongjiang Bayi Agricultural University, Daqing 163319, China
| | - Lang Yuan
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
| | - Cai-xin Jia
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
| | - Hai-tao Yu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
- Correspondence: (H.-t.Y.); (H.X.); Tel.: +86-451-86608616 (H.-t.Y.)
| | - Hui Xu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education) and School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China; (H.-j.Q.); (L.Y.); (C.-x.J.)
- Correspondence: (H.-t.Y.); (H.X.); Tel.: +86-451-86608616 (H.-t.Y.)
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5
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Qu HJ, Yuan L, Jia CX, Yu HT, Xu H. DFT investigation of hydrogen atom-abstraction reactions of NHC-boranes by various carbon-centered radicals: barriers and correlation analyses. RSC Adv 2020; 10:34752-34763. [PMID: 35514392 PMCID: PMC9057721 DOI: 10.1039/d0ra07638d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Accepted: 09/10/2020] [Indexed: 12/22/2022] Open
Abstract
In this study, we employed a quantum-mechanical computational method to investigate the hydrogen-atom abstraction reactions of two nitrogen heterocyclic carbene boranes (NHC-boranes), NHC-BH3 and NHC-BH2CN, by a series of carbon-centered radicals bearing various substituents. We explored the degree of correlation of the activation and free energy barriers to their components. Furthermore, we also investigated the effects of the radical and substituent sizes, nucleophilicity/electrophilicity indices, and the spin density distribution of the radical reactants on the three fundamental barriers and the thermal contribution of the reaction energy to the kinetic barrier. Using the generated data, we assessed the abilities of the various radical reactants to abstract the hydrogen atom from NHC-boranes. Further, we performed a similar analysis after dividing those radical reactants into four groups, which were classified based on the dominant factor affecting their electronic density distribution, which involves the inductive effect, conjugation, hyperconjugation, and the feedback of lone-pair electrons. The results and conclusions of this investigation not only provide insight into the relationships between some of the key kinetic and thermodynamic parameters, which is useful for understanding the dynamics of such hydrogen-abstraction reactions, but also provide information for selecting suitable radical reactants for further experimental investigations.
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Affiliation(s)
- Hong-Jie Qu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
- College of Science, Heilongjiang Bayi Agricultural University Daqing 163319 P. R. China
| | - Lang Yuan
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
| | - Cai-Xin Jia
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
| | - Hai-Tao Yu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
| | - Hui Xu
- Key Laboratory of Functional Inorganic Material Chemistry (Ministry of Education), School of Chemistry and Materials Science, Heilongjiang University Harbin 150080 P. R. China
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6
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Quintano MM, Rodrigues GLS, Chagas MA, Rocha WR. Revisiting the Tropospheric OH-Initiated Unimolecular Decomposition of Chlorpyrifos and Chlorpyrifos-Methyl: A Theoretical Perspective. J Phys Chem A 2020; 124:4280-4289. [PMID: 32374604 DOI: 10.1021/acs.jpca.0c02006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Based on density functional theory (DFT) electronic structure calculations with dispersion correction, we propose new reaction pathways in which no extra reaction step is necessary to account for the formation of 3,5,6-trichloro-2-pyridynol (TCP) within the process of tropospheric OH-initiated unimolecular decomposition of chlorpyrifos (CLP) and chlorpyrifos-methyl (CLPM). Chlorpyrifos and its analogous compound are among the most used organophosphorus pesticides worldwide, and their unimolecular decomposition in the troposphere is a dominant process of removal in the gas phase. The reaction pathways that we put forward have turned out to be the most exergonic ones among the three possible routes for the attack of the hydroxyl radical to the thiophosphoryl (P═S) bond of both CLP and CLPM. The results showed that the reaction is thermodynamically controlled with the formation of P-bonded adducts via a six-membered ring. The unimolecular decomposition of such reactive intermediates takes place with small energy barriers (less than 3 kcal mol-1) and is distinguished by hydrogen transfer to the nitrogen atom of the aromatic ring, resulting in the formation of 3,5,6-trichloro-2-pyridinol (TCP) and dialkyl phosphate radical (DAP·) product complexes in a single step.
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Affiliation(s)
- Mateus M Quintano
- Laboratory of Computational Studies on Molecular Systems, eCsMolab Department of Chemistry, ICEx, Federal University of Minas Gerais Pampulha, Belo Horizonte 31270-901, MG, Brazil
| | - Gabriel L S Rodrigues
- Laboratory of Computational Studies on Molecular Systems, eCsMolab Department of Chemistry, ICEx, Federal University of Minas Gerais Pampulha, Belo Horizonte 31270-901, MG, Brazil
| | - Marcelo A Chagas
- Laboratory of Computational Studies on Molecular Systems, eCsMolab Department of Chemistry, ICEx, Federal University of Minas Gerais Pampulha, Belo Horizonte 31270-901, MG, Brazil
| | - Willian R Rocha
- Laboratory of Computational Studies on Molecular Systems, eCsMolab Department of Chemistry, ICEx, Federal University of Minas Gerais Pampulha, Belo Horizonte 31270-901, MG, Brazil
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7
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Buchsteiner M, Martinez‐Rodriguez L, Jerabek P, Pozo I, Patzer M, Nöthling N, Lehmann CW, Fürstner A. Catalytic Asymmetric Fluorination of Copper Carbene Complexes: Preparative Advances and a Mechanistic Rationale. Chemistry 2020; 26:2509-2515. [PMID: 31916634 PMCID: PMC7065061 DOI: 10.1002/chem.202000081] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Indexed: 01/21/2023]
Abstract
The Cu-catalyzed reaction of substituted α-diazoesters with fluoride gives α-fluoroesters with ee values of up to 95 %, provided that chiral indane-derived bis(oxazoline) ligands are used that carry bulky benzyl substituents at the bridge and moderately bulky isopropyl groups on their core. The apparently homogeneous solution of CsF in C6 F6 /hexafluoroisopropanol (HFIP) is the best reaction medium, but CsF in the biphasic mixture CH2 Cl2 /HFIP also provides good results. DFT studies suggest that fluoride initially attacks the Cu- rather than the C-atom of the transient donor/acceptor carbene intermediate. This unusual step is followed by 1,2-fluoride shift; for this migratory insertion to occur, the carbene must rotate about the Cu-C bond to ensure orbital overlap. The directionality of this rotatory movement within the C2 -symmetric binding site determines the sense of induction. This model is in excellent accord with the absolute configuration of the resulting product as determined by X-ray diffraction using single crystals of this a priori wax-like material grown by capillary crystallization.
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Affiliation(s)
| | | | - Paul Jerabek
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
- Present Address: Nanotechnology DepartmentHelmholtz-Zentrum Geesthacht21502GeesthachtGermany
| | - Iago Pozo
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
| | - Michael Patzer
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
| | | | - Alois Fürstner
- Max-Planck-Institut für Kohlenforschung45470Mülheim/RuhrGermany
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Widjaja F, Max JP, Jin Z, Nash JJ, Kenttämaa HI. Gas-phase Reactivity of meta-Benzyne Analogs Toward Small Oligonucleotides of Differing Lengths. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:1392-1405. [PMID: 28456883 DOI: 10.1007/s13361-017-1655-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/05/2017] [Accepted: 03/06/2017] [Indexed: 06/07/2023]
Abstract
The gas-phase reactivity of two aromatic carbon-centered σ,σ-biradicals (meta-benzyne analogs) and a related monoradical towards small oligonucleotides of differing lengths was investigated in a Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer coupled with laser-induced acoustic desorption (LIAD). The mono- and biradicals were positively charged to allow for manipulation in the mass spectrometer. The oligonucleotides were evaporated into the gas phase as intact neutral molecules by using LIAD. One of the biradicals was found to be unreactive. The reactive biradical reacts with dinucleoside phosphates and trinucleoside diphosphates mainly by addition to a nucleobase moiety followed by cleavage of the glycosidic bond, leading to a nucleobase radical (e.g., base-H) abstraction. In some instances, after the initial cleavage, the unquenched radical site of the biradical abstracts a hydrogen atom from the neutral fragment, which results in a net nucleobase abstraction. In sharp contrast, the related monoradical mainly undergoes facile hydrogen atom abstraction from the sugar moiety. As the size of the oligonucleotides increases, the rate of hydrogen atom abstraction from the sugar moiety by the monoradical was found to increase due to the presence of more hydrogen atom donor sites, and it is the only reaction observed for tetranucleoside triphosphates. Hence, the monoradical only attacks sugar moieties in these substrates. The biradical also shows significant attack at the sugar moiety for tetranucleoside triphosphates. This drastic change in reactivity indicates that the size of the oligonucleotides plays a key role in the outcome of these reactions. This finding is attributed to more compact conformations in the gas phase for the tetranucleoside triphosphates than for the smaller oligonucleotides, which result from stronger stabilizing interactions between the nucleobases. Graphical Abstract ᅟ.
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Affiliation(s)
- Fanny Widjaja
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
- , 1 Makeway Ave #15-03, Singapore, 228598, Singapore
| | - Joann P Max
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
| | - Zhicheng Jin
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
- Northeast Ohio Medical University, 4209 OH-44, Rootstown, OH, 44272, USA
| | - John J Nash
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, IN, 47906, USA.
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9
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Mansell A, Theis Z, Gutierrez MG, Faza ON, Lopez CS, Bellert DJ. Submerged Barriers in the Ni(+) Assisted Decomposition of Propionaldehyde. J Phys Chem A 2016; 120:2275-84. [PMID: 27054589 DOI: 10.1021/acs.jpca.5b08444] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction dynamics of the Ni(+) mediated decarbonylation of propionaldehyde was assessed using the single photon initiated decomposition rearrangement reaction (SPIDRR) technique. The exothermic production of Ni(+)CO was temporally monitored and the associated rate constants, k(E), were extracted as a function of activating photon energy. In addition, the reaction potential energy surface was calculated at the UCCSD(T)/def2-TZVP//PBEPBE/cc-pVDZ level of theory to provide an atomistic description of the reaction profile. The decarbonylation of propionaldehyde can be understood as proceeding through parallel competitive reaction pathways that are initiated by Ni(+) insertion into either the C-C or C-H bond of the propionaldehyde carbonyl carbon. Both paths lead to the elimination of neutral ethane and are governed by submerged barriers. The lower energy sequence is a consecutive C-C/C-H addition process with a submerged barrier of 14 350 ± 600 cm(-1). The higher energy sequence is a consecutive C-H/C-C addition process with a submerged barrier of 15 400 ± 600 cm(-1). Both barriers were determined using RRKM calculations fit to the experimentally determined k(E) values. The measured energy difference between the two barriers agrees with the DFT computed difference in rate limiting transition-state energies, 18 413 and 19 495 cm(-1).
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Affiliation(s)
- A Mansell
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - Z Theis
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - M G Gutierrez
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
| | - O Nieto Faza
- Departamento de Quimica Organica, Universidad de Vigo , 36310, Vigo, Spain
| | - C Silva Lopez
- Departamento de Quimica Organica, Universidad de Vigo , 36310, Vigo, Spain
| | - D J Bellert
- Department of Chemistry and Biochemistry, Baylor University , Waco, Texas 76798, United States
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10
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Williams PE, Jankiewicz BJ, Yang L, Kenttämaa HI. Properties and reactivity of gaseous distonic radical ions with aryl radical sites. Chem Rev 2013; 113:6949-85. [PMID: 23987564 PMCID: PMC3889672 DOI: 10.1021/cr400121w] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Peggy E. Williams
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906
| | | | - Linan Yang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47906
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12
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Rypkema HA, Donahue NM, Anderson JG. Nature of the Chemical Bond in Transition: Dissection of Radical–Molecule Reactivity. J Phys Chem A 2012; 116:6303-11. [DOI: 10.1021/jp212023f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Heather A. Rypkema
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
02138, United States
| | - Neil M. Donahue
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
02138, United States
| | - James G. Anderson
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts
02138, United States
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Poutsma ML. Review of Rate Constants and Exploration of Correlations of the Halogen Transfer Reaction of Trisubstituted Carbon-Centered Radicals with Molecular Halogens. J Org Chem 2012; 77:2619-36. [DOI: 10.1021/jo2023075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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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14
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Varras PC, Zarkadis AK. Ground- and triplet excited-state properties correlation: a computational CASSCF/CASPT2 approach based on the photodissociation of allylsilanes. J Phys Chem A 2012; 116:1425-34. [PMID: 22208892 DOI: 10.1021/jp209583z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Excited-state properties, although extremely useful, are hardly accessible. One indirect way would be to derive them from relationships to ground-state properties which are usually more readily available. Herewith, we present quantitative correlations between triplet excited-state (T₁) properties (bond dissociation energy, D₀(T₁), homolytic activation energy, E(a)(T₁), and rate constant, k(r)) and the ground-state bond dissociation energy (D₀), taking as an example the photodissociation of the C-Si bond of simple substituted allylsilanes CH₂=CHC(R¹R²)-SiH₃ (R¹ and R² = H, Me, and Et). By applying the complete-active-space self-consistent field CASSCF(6,6) and CASPT2(6,6) quantum chemical methodologies, we have found that the consecutive introduction of Me/Et groups has little effect on the geometry and energy of the T₁ state; however, it reduces the magnitudes of D₀, D₀(T₁) and E(a)(T₁). Moreover, these energetic parameters have been plotted giving good linear correlations: D₀(T₁) = α₁ + β₁ · D₀, E(a)(T₁) = α₂ + β₂ · D₀(T₁), and E(a)(T₁) = α₃ + β₃ · D₀ (α and β being constants), while k(r) correlates very well to E(a)(T₁). The key factor behind these useful correlations is the validity of the Evans-Polanyi-Semenov relation (second equation) and its extended form (third equation) applied for excited systems. Additionally, the unexpectedly high values obtained for E(a)(T₁) demonstrate a new application of the principle of nonperfect synchronization (PNS) in excited-state chemistry issues.
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15
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Widjaja F, Jin Z, Nash JJ, Kenttämaa HI. Direct comparison of solution and gas-phase reactions of the three distonic isomers of the pyridine radical cation with methanol. J Am Chem Soc 2012; 134:2085-93. [PMID: 22148169 DOI: 10.1021/ja207899j] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To directly compare the reactivity of positively charged carbon-centered aromatic σ-radicals toward methanol in solution and in the gas phase, the 2-, 3-, and 4-dehydropyridinium cations (distonic isomers of the pyridine radical cation) were generated by ultraviolet photolysis of the corresponding iodo precursors in a mixture of water and methanol at varying pH. The reaction mixtures were analyzed by using liquid chromatography/mass spectrometry. Hydrogen atom abstraction was the only reaction observed for the 3- and 4-dehydropyridinium cations (and pyridines) in solution. This also was the major reaction observed earlier in the gas phase. Depending on the pH, the hydrogen atom can be abstracted from different molecules (i.e., methanol or water) and from different sites (in methanol) by the 3- and 4-dehydropyridinium cations/pyridines in solution. In the pH range 1-4, the methyl group of methanol is the main hydrogen atom donor site for both 3- and 4-dehydropyridinium cations (just like in the gas phase). At higher pH, the hydroxyl groups of water and methanol also act as hydrogen atom donors. This finding is rationalized by a greater abundance of the unprotonated radicals that preferentially abstract hydrogen atoms from the polar hydroxyl groups. The percentage yield of hydrogen atom abstraction by these radicals was found to increase with lowering the pH in the pH range 1.0-3.2. This pH effect is rationalized by polar effects: the lower the pH, the greater the fraction of protonated (more polar) radicals in the solution. This finding is consistent with previous results obtained in the gas phase and suggests that gas-phase studies can be used to predict solution reactivity, but only as long as the same reactive species is studied in both experiments. This was found not to be the case for the 2-iodopyridinium cation. Photolysis of this precursor in solution resulted in the formation of two major addition products, 2-hydroxy- and 2-methoxypyridinium cations, in addition to the hydrogen atom abstraction product. These addition products were not observed in the earlier gas-phase studies on 2-dehydropyridinium cation. Their observation in solution is explained by the formation of another reactive intermediate, the 2-pyridylcation, upon photolysis of 2-iodopyridinium cation (and 2-iodopyridine). The same intermediate was observed in the gas phase but it was removed before examining the reactions of the desired radical, 2-dehydropyridinium cation (which cannot be done in solution).
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Affiliation(s)
- Fanny Widjaja
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, USA
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Adeuya A, Nash JJ, Kenttämaa HI. Influence of hydrogen bonding on hydrogen-atom abstraction reactions of dehydropyridinium cations in the gas phase. J Phys Chem A 2010; 114:12851-7. [PMID: 21080694 PMCID: PMC3014263 DOI: 10.1021/jp107254k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The reactions of several substituted, positively charged dehydropyridinium cations with cyclohexane, methanol, and tetrahydrofuran have been examined in a Fourier-transform ion cyclotron resonance mass spectrometer. All of the charged monoradicals react with the neutral reagents exclusively via hydrogen atom abstraction. For cyclohexane, there is a good correlation between the reaction efficiencies and the calculated electron affinities at the radical sites; that is, the greater the electron affinity of the charged monoradical at the radical site, the faster the reaction. The reaction efficiencies with methanol and tetrahydrofuran, however, do not correlate with the calculated electron affinities. Density functional theory (DFT) calculations indicate that for these reagents a stabilizing hydrogen bonding interaction exists in the hydrogen atom abstraction transition states for some of the charged monoradicals but not for others. At both the MPW1K and G3MP2B3 levels of theory, there is a good correlation between the calculated activation enthalpies and the observed reaction efficiencies, although the G3MP2B3 method provides a slightly better correlation than the MPW1K method. The extent of enhancement in the reaction efficiencies caused by the hydrogen bonding interactions parallels the calculated hydrogen bond lengths in the transition states.
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Affiliation(s)
| | - John J. Nash
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
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17
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Chacon-Madrid HJ, Presto AA, Donahue NM. Functionalization vs. fragmentation: n-aldehyde oxidation mechanisms and secondary organic aerosol formation. Phys Chem Chem Phys 2010; 12:13975-82. [DOI: 10.1039/c0cp00200c] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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18
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Adeuya A, Price JM, Jankiewicz BJ, Nash JJ, Kenttämaa HI. Gas-phase reactivity of protonated 2-, 3-, and 4-dehydropyridine radicals toward organic reagents. J Phys Chem A 2009; 113:13663-74. [PMID: 19902945 PMCID: PMC2804851 DOI: 10.1021/jp901380y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
To explore the effects of the electronic nature of charged phenyl radicals on their reactivity, reactions of the three distonic isomers of n-dehydropyridinium cation (n = 2, 3, or 4) have been investigated in the gas phase by using Fourier-transform ion cyclotron resonance mass spectrometry. All three isomers react with cyclohexane, methanol, ethanol, and 1-pentanol exclusively via hydrogen atom abstraction and with allyl iodide mainly via iodine atom abstraction, with a reaction efficiency ordering of 2 > 3 > 4. The observed reactivity ordering correlates well with the calculated vertical electron affinities of the charged radicals (i.e., the higher the vertical electron affinity, the faster the reaction). Charged radicals 2 and 3 also react with tetrahydrofuran exclusively via hydrogen atom abstraction, but the reaction of 4 with tetrahydrofuran yields products arising from nonradical reactivity. The unusual reactivity of 4 is likely to result from the contribution of an ionized carbene-type resonance structure that facilitates nucleophilic addition to the most electrophilic carbon atom (C-4) in this charged radical. The influence of such a resonance structure on the reactivity of 2 is not obvious, and this may be due to stabilizing hydrogen-bonding interactions in the transition states for this molecule. Charged radicals 2 and 3 abstract a hydrogen atom from the substituent in both phenol and toluene, but 4 abstracts a hydrogen atom from the phenyl ring, a reaction that is unprecedented for phenyl radicals. Charged radical 4 reacts with tert-butyl isocyanide mainly by hydrogen cyanide (HCN) abstraction, whereas CN abstraction is the principal reaction for 2 and 3. The different reactivity observed for 4 (as compared to 2 and 3) is likely to result from different charge and spin distributions of the reaction intermediates for these charged radicals.
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Affiliation(s)
| | | | | | - John J. Nash
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907
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19
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Liu KH, Yang CF, Wang H, Wu WQ, Su HM. Time-Resolved FTIR Study on the Reaction of CHCl 2 with NO 2. CHINESE J CHEM PHYS 2009. [DOI: 10.1088/1674-0068/22/02/134-138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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20
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Gligorovski S, Rousse D, George CH, Herrmann H. Rate constants for the OH reactions with oxygenated organic compounds in aqueous solution. INT J CHEM KINET 2009. [DOI: 10.1002/kin.20405] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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21
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Nelson ED, Thompson GM, Yao Y, Flanagan HM, Harmon PA. Solvent Effects on the AIBN Forced Degradation of Cumene: Implications for Forced Degradation Practices. J Pharm Sci 2009; 98:959-69. [DOI: 10.1002/jps.21489] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Rissanen MP, Eskola AJ, Savina E, Timonen RS. Kinetics of the Reactions of CH3CH2, CH3CHCl, and CH3CCl2 Radicals with NO2 in the Temperature Range 221−363 K. J Phys Chem A 2009; 113:1753-9. [DOI: 10.1021/jp809193w] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matti P. Rissanen
- Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Finland
| | - Arkke J. Eskola
- Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Finland
| | - Elena Savina
- Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Finland
| | - Raimo S. Timonen
- Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 Finland
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23
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Jing L, Nash JJ, Kenttämaa HI. Correlation of hydrogen-atom abstraction reaction efficiencies for aryl radicals with their vertical electron affinities and the vertical ionization energies of the hydrogen-atom donors. J Am Chem Soc 2008; 130:17697-709. [PMID: 19061320 PMCID: PMC2682590 DOI: 10.1021/ja801707p] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The factors that control the reactivities of aryl radicals toward hydrogen-atom donors were studied by using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer. Hydrogen-atom abstraction reaction efficiencies for two substrates, cyclohexane and isopropyl alcohol, were measured for 23 structurally different, positively charged aryl radicals, which included dehydrobenzenes, dehydronaphthalenes, dehydropyridines, and dehydro(iso)quinolines. A logarithmic correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) vertical electron affinities (EA) of the aryl radicals. Transition state energies calculated for the reaction of three of the aryl radicals with isopropyl alcohol were found to correlate linearly with their (calculated) EAs. No correlation was found between the hydrogen-atom abstraction reaction efficiencies and the (calculated) enthalpy changes for the reactions. Measurement of the reaction efficiencies for the reactions of 15 different hydrogen-atom donors with two selected aryl radicals revealed a logarithmic correlation between the hydrogen-atom abstraction reaction efficiencies and the vertical ionization energies (IE) of the hydrogen-atom donors, but not the lowest homolytic X-H (X = heavy atom) bond dissociation energies of the hydrogen-atom donors. Examination of the hydrogen-atom abstraction reactions of 29 different aryl radicals and 18 different hydrogen-atom donors showed that the reaction efficiency increases (logarithmically) as the difference between the IE of the hydrogen-atom donor and the EA of the aryl radical decreases. This dependence is likely to result from the increasing polarization, and concomitant stabilization, of the transition state. Thus, the hydrogen-atom abstraction reaction efficiency for an aryl radical can be "tuned" by structural changes that influence either the vertical EA of the aryl radical or the vertical IE of the hydrogen atom donor.
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Affiliation(s)
| | - John J. Nash
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, E-mail:
| | - Hilkka I. Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, E-mail:
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24
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Foti MC, Daquino C, Mackie ID, DiLabio GA, Ingold KU. Reaction of Phenols with the 2,2-Diphenyl-1-picrylhydrazyl Radical. Kinetics and DFT Calculations Applied To Determine ArO-H Bond Dissociation Enthalpies and Reaction Mechanism. J Org Chem 2008; 73:9270-82. [DOI: 10.1021/jo8016555] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mario C. Foti
- Istituto di Chimica Biomolecolare del CNR, Via del Santuario 110, I-95028 Valverde (CT) Italy, National Institute for Nanotechnology, National Research Council of Canada 11421 Saskatchewan Drive, Edmonton, AB, Canada T6G 2M9, and National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6
| | - Carmelo Daquino
- Istituto di Chimica Biomolecolare del CNR, Via del Santuario 110, I-95028 Valverde (CT) Italy, National Institute for Nanotechnology, National Research Council of Canada 11421 Saskatchewan Drive, Edmonton, AB, Canada T6G 2M9, and National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6
| | - Iain D. Mackie
- Istituto di Chimica Biomolecolare del CNR, Via del Santuario 110, I-95028 Valverde (CT) Italy, National Institute for Nanotechnology, National Research Council of Canada 11421 Saskatchewan Drive, Edmonton, AB, Canada T6G 2M9, and National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6
| | - Gino A. DiLabio
- Istituto di Chimica Biomolecolare del CNR, Via del Santuario 110, I-95028 Valverde (CT) Italy, National Institute for Nanotechnology, National Research Council of Canada 11421 Saskatchewan Drive, Edmonton, AB, Canada T6G 2M9, and National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6
| | - K. U. Ingold
- Istituto di Chimica Biomolecolare del CNR, Via del Santuario 110, I-95028 Valverde (CT) Italy, National Institute for Nanotechnology, National Research Council of Canada 11421 Saskatchewan Drive, Edmonton, AB, Canada T6G 2M9, and National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6
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25
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Papadimitriou VC, Papanastasiou DK, Stefanopoulos VG, Zaras AM, Lazarou YG, Papagiannakopoulos P. Kinetic Study of the Reactions of Cl Atoms with CF3CH2CH2OH, CF3CF2CH2OH, CHF2CF2CH2OH, and CF3CHFCF2CH2OH. J Phys Chem A 2007; 111:11608-17. [DOI: 10.1021/jp074728e] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Vassileios C. Papadimitriou
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete, Greece
| | - Dimitrios K. Papanastasiou
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete, Greece
| | - Vassileios G. Stefanopoulos
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete, Greece
| | - Aristotelis M. Zaras
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete, Greece
| | - Yannis G. Lazarou
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete, Greece
| | - Panos Papagiannakopoulos
- Laboratory of Photochemistry and Kinetics, Department of Chemistry, University of Crete, 71003 Heraklion, Crete, Greece
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26
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Lee EPF, Dyke JM, Chow WK, Chau FT, Mok DKW. DFT and ab initio
calculations on two reactions between hydrogen atoms and the fire suppressants 2-H heptafluoropropane and CF3
Br. J Comput Chem 2007; 28:1582-1592. [PMID: 17340604 DOI: 10.1002/jcc.20695] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Reaction enthalpies and barrier heights of the reactions CF3Br+H-->CF3+HBr {reaction (1)} and CF3CHFCF3+H-->CF3CFCF3+H2 {reaction (2)} have been calculated at the near state-of-the-art ab initio level, and also by employing the B3LYP, BH&HLYP, BB1K, MPW1K, MPWB1K and TPSS1KCIS functionals. In addition, the integrated molecular orbital+molecular orbital (IMOMO) method has been used to study reaction (2). The ab initio benchmark values of the reaction enthalpy (298 K) and barrier height (0 K) of reaction (2) are reported for the first time {-(0.7+/-0.7) and 13.3+/-0.5 kcal/mole respectively}. When density functional theory (DFT) results are compared with ab initio benchmarks for both reactions (1) and (2), the MPWB1K functional is found to have the best performance of the six functionals used. The IMOMO method with the RCCSD/aug-cc-pVTZ and/or RCCSD(T)/aug-cc-pVTZ levels, as the high levels of calculation on the model system, gives reaction enthalpies and barrier heights of reaction (2), which agree with ab initio benchmark values to within 1 kcal/mole. Computed key geometrical parameters and imaginary vibrational frequencies of the transition state structures of reactions (1) and (2) obtained at different levels of calculation are compared. The magnitudes of the computed imaginary vibrational frequencies of the transition states of both reactions considered are found to be very sensitive to the levels of calculation used to obtain them. The heat of formation (298 K) of CF3CFCF3 calculated at the near state-of-the-art level has a value of -(318+/-3) kcal/mole.
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Affiliation(s)
- Edmond P F Lee
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
- School of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ United Kingdom
| | - John M Dyke
- School of Chemistry, University of Southampton, Highfield, Southampton, SO17 1BJ United Kingdom
| | - Wan-Ki Chow
- Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Foo-Tim Chau
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Daniel K W Mok
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Hong Kong
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Hansmann B, Abel B. Kinetics in Cold Laval Nozzle Expansions: From Atmospheric Chemistry to Oxidation of Biomolecules in the Gas Phase. Chemphyschem 2007; 8:343-56. [PMID: 17290359 DOI: 10.1002/cphc.200600646] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
New developments and recent applications of pulsed and miniaturised Laval nozzle technology allowing many gas-phase molecular processes to be studied at very low temperatures are highlighted. In the present Minireview we focus on molecular energy transfer and reactions of molecular radicals (e.g. OH) with neutral molecules. We show that with the combination of pulsed laser photolysis and sensitive laser-induced fluorescence detection a large number of fast reactions of radicals with more or less complex neutral molecules can be measured in Laval nozzle expansions nowadays. It is also demonstrated that collisional energy transfer of neutral molecules can be measured via kinetically controlled selective fluorescence (KCSF) excitation down to 58 Kelvin. Finally, we show that even the primary steps in the oxidation of biomolecules or biomolecular building blocks initiated by OH radicals can be followed at low temperatures. The temperature dependence of the measured rate constants is the key for an understanding of the underlying molecular mechanisms and the Laval nozzle expansion provides a unique environment for these measurements. The experimental finding that many reactions between radicals and neutral species can be rapid at low temperatures are discussed in terms of pre-reactive complexes formed in the overall complex forming bimolecular reactions.
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Affiliation(s)
- Björn Hansmann
- Institut für Physikalische Chemie der Universität Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
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28
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Aschmann SM, Atkinson R. Kinetic and Product Study of the Gas-Phase Reactions of OH Radicals, NO3 Radicals, and O3 with (C2H5O)2P(S)CH3 and (C2H5O)3PS. J Phys Chem A 2006; 110:13029-35. [PMID: 17134163 DOI: 10.1021/jp065382v] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rate constants for the reactions of OH radicals and NO3 radicals with O,O-diethyl methylphosphonothioate [(C(2)H(5)O)(2)P(S)CH(3); DEMPT] and O,O,O-triethyl phosphorothioate [(C(2)H(5)O)(3)PS; TEPT] have been measured using relative rate methods at atmospheric pressure of air over the temperature range 296-348 K for the OH radical reactions and at 296 +/- 2 K for the NO(3) radical reactions. At 296 +/- 2 K, the rate constants obtained for the OH radical reactions (in units of 10(-11) cm(3) molecule(-1) s(-1)) were 20.4 +/- 0.8 and 7.92 +/- 0.27 for DEMPT and TEPT, respectively, and those for the NO(3) radical reactions (in units of 10(-15) cm(3) molecule(-1) s(-1)) were 2.01 +/- 0.20 and 1.03 +/- 0.10, respectively. Upper limits to the rate constants for the reactions of O(3) with DEMPT and TEPT of <6 x 10(-20) cm(3) molecule(-1) s(-1) were determined in each case. Rate constants for the OH radical reactions, measured relative to k(OH + alpha-pinene) = 1.21 x 10(-11) e(436/T) cm(3) molecule(-1) s(-1), resulted in the Arrhenius expressions k(OH + DEMPT) = 1.08 x 10(-11) e(871+/-25)/T cm(3) molecule(-1) s(-1) and k(OH + TEPT) = 8.21 x 10(-13) e(1353+/-49)/T cm(3) molecule(-1) s(-1) over the temperature range 296-348 K, where the indicated errors are two least-squares standard deviations and do not include the uncertainties in the reference rate constant. Diethyl methylphosphonate was identified and quantified from the OH radical and NO(3) radical reactions with DEMPT, with formation yields of 21 +/- 4%, independent of temperature, from the OH radical reaction and 62 +/- 11% from the NO(3) radical reaction at 296 +/- 2 K. Similarly, triethyl phosphate was identified and quantified from the OH radical and NO(3) radical reactions with TEPT, with formation yields of 56 +/- 9%, independent of temperature, from the OH radical reaction and 78 +/- 15% from the NO(3) radical reaction at 296 +/- 2 K.
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Affiliation(s)
- Sara M Aschmann
- Air Pollution Research Center, Department of Environmental Sciences, and Department of Chemistry, University of California, Riverside, California 92521, USA
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29
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Eskola AJ, Wojcik-Pastuszka D, Ratajczak E, Timonen RS. Kinetics of the Reactions of CH2I, CH2Br, and CHBrCl Radicals with NO2 in the Temperature Range 220−360 K. J Phys Chem A 2006; 110:12177-83. [PMID: 17078613 DOI: 10.1021/jp064197e] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The kinetics of the CH2I + NO2, CH2Br + NO2, and CHBrCl + NO2 reactions have been studied at temperatures between 220 and 360 K using laser photolysis/photoionization mass spectrometry. Decays of radical concentrations have been monitored in time-resolved measurements to obtain reaction rate coefficients under pseudo-first-order conditions. The bimolecular rate coefficients of all three reactions are independent of the bath gas (He or N2) and pressure within the experimental range (2-6 Torr) and are found to depend on temperature as follows: k(CH2I + NO2) = (2.18 +/- 0.07) x 10(-11) (T / 300 K)(-1.45) (+/- 0.22) cm3 molecule(-1) s(-1) (220-363 K), k(CH2Br + NO2) = (1.76 +/- 0.03) x 10(-11) (T/300 K)(-0.86) (+/- 0.09) cm3 molecule(-1) s(-1) (221-363 K), and k(CHBrCl + NO2) = (8.81 +/- 0.28) x 10(-12) (T/300 K)(-1.55) (+/- 0.34) cm3 molecule(-1) s(-1) (267-363 K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are about +/-25%. In the CH2I + NO2 and CH2Br + NO2 reactions, the observed product is formaldehyde. For the CHBrCl + NO2 reaction, the product observed is CHClO. In addition, I atom and iodonitromethane (CH2INO2) or iodomethyl nitrite (CH2IONO) formations have been detected for the CH2I + NO2 reaction.
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Affiliation(s)
- Arkke J Eskola
- Laboratory of Physical Chemistry, PO Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
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30
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Aschmann SM, Long WD, Atkinson R. Temperature-Dependent Rate Constants for the Gas-Phase Reactions of OH Radicals with 1,3,5-Trimethylbenzene, Triethyl Phosphate, and a Series of Alkylphosphonates. J Phys Chem A 2006; 110:7393-400. [PMID: 16759127 DOI: 10.1021/jp061542r] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rate constants for the reactions of OH radicals with dimethyl methylphosphonate [DMMP, (CH3O)2P(O)CH3], dimethyl ethylphosphonate [DMEP, (CH3O)2P(O)C2H5], diethyl methylphosphonate [DEMP, (C2H5O)2P(O)CH3], diethyl ethylphosphonate [DEEP, (C2H5O)2P(O)C2H5], triethyl phosphate [TEP, (C2H5O)3PO] and 1,3,5-trimethylbenzene have been measured over the temperature range 278-348 K at atmospheric pressure of air using a relative rate method. alpha-Pinene (for DEMP, DEEP, TEP and 1,3,5-trimethylbenzene) and di-n-butyl ether (for DMMP and DMEP) were used as the reference compounds, and rate constants for the reaction of OH radicals with di-n-butyl ether were also measured over the same temperature range using alpha-pinene and n-decane as the reference compounds. The Arrhenius expressions obtained for these OH radical reactions (in cm3 molecule(-1) s(-1) units) are 8.00 x 10(-14)e(1470+/-132)/T for DMMP (296-348 K), 9.76 x 10(-14)e(1520+/-14)/T for DMEP (296-348 K), 4.20 x 10(-13)e(1456+/-227)/T for DEMP (296-348 K), 6.46 x 10(-13)e(1339+/-376)/T for DEEP (296-348 K), 4.29 x 10(-13)e(1428+/-219)/T for TEP (296-347 K), and 4.40 x 10(-12)e(738+/-176)/T for 1,3,5-trimethylbenzene (278-347 K), where the indicated errors are two least-squares standard deviations and do not include the uncertainties in the rate constants for the reference compounds. The measured rate constants for di-n-butyl ether are in good agreement with literature data over the temperature range studied (278-348 K).
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Affiliation(s)
- Sara M Aschmann
- Air Pollution Research Center, University of California, Riverside, California 92521, USA
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31
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Smith IWM, Sage AM, Donahue NM, Herbst E, Quan D. The temperature-dependence of rapid low temperature reactions: experiment, understanding and prediction. Faraday Discuss 2006; 133:137-56; discussion 191-230, 449-52. [PMID: 17191447 DOI: 10.1039/b600721j] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite the success of the CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme) method in measuring rate coefficients for neutral-neutral reactions of radicals down close to the very low temperatures prevalent in dense interstellar clouds (ISCs), there are still many reactions of potential importance in the chemistry of these objects for which there have been no measurements of low temperature rate coefficients. One important class of reactions is that between atomic and molecular free radicals and unsaturated hydrocarbons; that is, alkynes and alkenes. Based on semi-empirical arguments and correlations of 'room temperature' rate coefficients, k(298 K), for reactions of this type with the difference between the ionisation energy of the alkyne/alkene and the electron affinity of the radical, we suggest which reactions between the radicals, C(3P), O(3P), N(4S), CH, C2H and CN, and carbon chain molecules (Cn) and cyanopolyynes (HC2nCN and NCC2nCN) are likely to be fast at the temperature of dense ISCs. These reactions and rate coefficients have been incorporated into a purely gas-phase model (osu2005) of ISC chemistry. The results of these calculations are presented and discussed.
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Affiliation(s)
- Ian W M Smith
- University Chemical Laboratories, Lensfield Road, Cambridge, UK.
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32
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Sage AM, Donahue NM. Deconstructing experimental rate constant measurements: Obtaining intrinsic reaction parameters, kinetic isotope effects, and tunneling coefficients from kinetic data for OH+methane, ethane and cyclohexane. J Photochem Photobiol A Chem 2005. [DOI: 10.1016/j.jphotochem.2005.09.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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33
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Eskola AJ, Geppert WD, Rissanen MP, Timonen RS, Halonen L. Kinetics of the Reactions of Chlorinated Methyl Radicals (CH2Cl, CHCl2, and CCl3) with NO2 in the Temperature Range 220−360 K. J Phys Chem A 2005; 109:5376-81. [PMID: 16839062 DOI: 10.1021/jp050441a] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The kinetics of the reactions of chlorinated methyl radicals (CH2Cl, CHCl2, and CCl3) with NO2 have been studied in direct measurements at temperatures between 220 and 360 K using a tubular flow reactor coupled to a photoionization mass spectrometer. The radicals have been homogeneously generated at 193 or 248 nm by pulsed laser photolysis of appropriate precursors. Decays of radical concentrations have been monitored in time-resolved measurements to obtain the reaction rate coefficients under pseudo-first-order conditions with the amount of NO2 being in large excess over radical concentrations. The bimolecular rate coefficients of all three reactions are independent of the bath gas (He or N2) and pressure within the experimental range (1-6 Torr) and are found to depend on temperature as follows: k(CH2Cl + NO2) = (2.16 +/- 0.08) x 10(-11) (T/300 K)(-1.12+/-0.24) cm3 molecule(-1) s(-1) (220-363 K), k(CHCl2 + NO2) = (8.90 +/- 0.16) x 10(-12) (T/300 K)(-1.48+/-0.13) cm3 molecule(-1) s(-1) (220-363 K), and k(CCl3 + NO2) = (3.35 +/- 0.10) x 10(-12) (T/300 K)(-2.2+/-0.4) cm3 molecule(-1) s(-1) (298-363 K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are about +/-25%. In the reactions CH2Cl + NO2, CHCl2 + NO2, and CCl3 + NO2, the products observed are formaldehyde, CHClO, and phosgene (CCl2O), respectively. In addition, a weak signal for the HCl formation has been detected for the CHCl2 + NO2 reaction.
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Affiliation(s)
- Arkke J Eskola
- Laboratory of Physical Chemistry, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland
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34
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Hou XJ, Nguyen TL, Carl SA, Peeters J, Nguyen MT. Theoretical study of the kinetics of hydrogen abstraction in reactions of simple hydrogen compounds with triplet difluorocarbene. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2004.12.087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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35
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Donahue NM, Hartz KEH, Chuong B, Presto AA, Stanier CO, Rosenhørn T, Robinson AL, Pandis SN. Critical factors determining the variation in SOA yields from terpene ozonolysis: A combined experimental and computational study. Faraday Discuss 2005; 130:295-309; discussion 363-86, 519-24. [PMID: 16161790 DOI: 10.1039/b417369d] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A substantial fraction of the total ultrafine particulate mass is comprised of organic compounds. Of this fraction, a significant subfraction is secondary organic aerosol (SOA), meaning that the compounds are a by-product of chemistry in the atmosphere. However, our understanding of the kinetics and mechanisms leading to and following SOA formation is in its infancy. We lack a clear description of critical phenomena; we often don't know the key, rate limiting steps in SOA formation mechanisms. We know almost nothing about aerosol yields past the first generation of oxidation products. Most importantly, we know very little about the derivatives in these mechanisms; we do not understand how changing conditions, be they precursor levels, oxidant concentrations, co-reagent concentrations (i.e., the VOC/NOx ratio) or temperature will influence the yields of SOA. In this paper we explore the connections between fundamental details of physical chemistry and the multitude of steps associated with SOA formation, including the initial gas-phase reaction mechanisms leading to condensible products, the phase partitioning itself, and the continued oxidation of the condensed-phase organic products. We show that SOA yields in the alpha-pinene + ozone are highly sensitive to NOx, and that SOA yields from beta-caryophylene + ozone appear to increase with continued ozone exposure, even as aerosol hygroscopicity increases as well. We suggest that SOA yields are likely to increase substantially through several generations of oxidative processing of the semi-volatile products.
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Affiliation(s)
- Neil M Donahue
- Department of Chemistry and Chemical Engineering, Carnegie Mellon University, Pittsburgh PA 15213, USA.
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36
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Sun D, Schneider WF, Adams JB, Sengupta D. Molecular Origins of Selectivity in the Reduction of NOx by NH3. J Phys Chem A 2004. [DOI: 10.1021/jp049079a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Donghai Sun
- Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287, Physical and Environmental Sciences Department, Ford Motor Company, Mail Drop 3083/SRL, Dearborn, Michigan 48121-2053, and CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805
| | - William F. Schneider
- Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287, Physical and Environmental Sciences Department, Ford Motor Company, Mail Drop 3083/SRL, Dearborn, Michigan 48121-2053, and CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805
| | - James B. Adams
- Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287, Physical and Environmental Sciences Department, Ford Motor Company, Mail Drop 3083/SRL, Dearborn, Michigan 48121-2053, and CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805
| | - Debasis Sengupta
- Department of Chemical and Materials Engineering, Arizona State University, Tempe, Arizona 85287, Physical and Environmental Sciences Department, Ford Motor Company, Mail Drop 3083/SRL, Dearborn, Michigan 48121-2053, and CFD Research Corporation, 215 Wynn Drive, Huntsville, Alabama 35805
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37
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Su P, Song L, Wu W, Hiberty PC, Shaik S. Valence Bond Calculations of Hydrogen Transfer Reactions: A General Predictive Pattern Derived from Theory. J Am Chem Soc 2004; 126:13539-49. [PMID: 15479111 DOI: 10.1021/ja048105f] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrogen abstraction reactions of the type X(*) + H-H' --> X-H + H'(*) (X = F, Cl, Br, I) are studied by ab initio valence bond methods and the VB state correlation diagram (VBSCD) model. The reaction barriers and VB parameters of the VBSCD are computed by using the breathing orbital valence bond and valence bond configuration interaction methods. The combination of the VBSCD model and semiempirical VB theory leads to analytical expressions for the barriers and other VB quantities that match the ab initio VB calculations fairly well. The barriers are influenced by the endo- or exothermicity of the reaction, but the fundamental factor of the barrier is the average singlet-triplet gap of the bonds that are broken or formed in the reactions. Some further approximations lead to a simple formula that expresses the barrier for nonidentity and identity hydrogen abstraction reactions as a function of the bond strengths of reactants and products. The semiempirical expressions are shown to be useful not only for the model reactions that are studied in this work, but also for other nonidentity and identity hydrogen abstraction reactions that have been studied in previous articles.
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Affiliation(s)
- Peifeng Su
- Department of Chemistry, Xiamen University, Xiamen 361005, PR China
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Spangenberg T, Köhler S, Hansmann B, Wachsmuth U, Abel B, Smith MA. Low-Temperature Reactions of OH Radicals with Propene and Isoprene in Pulsed Laval Nozzle Expansions. J Phys Chem A 2004. [DOI: 10.1021/jp031228m] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tim Spangenberg
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstasse 6, D-37077 Göttingen, Germany
| | - Sven Köhler
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstasse 6, D-37077 Göttingen, Germany
| | - Björn Hansmann
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstasse 6, D-37077 Göttingen, Germany
| | - Uwe Wachsmuth
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstasse 6, D-37077 Göttingen, Germany
| | - Bernd Abel
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstasse 6, D-37077 Göttingen, Germany
| | - Mark A. Smith
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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Abstract
Proton-coupled electron transfer (PCET) reactions involve the concerted transfer of an electron and a proton. Such reactions play an important role in many areas of chemistry and biology. Concerted PCET is thermochemically more favorable than the first step in competing consecutive processes involving stepwise electron transfer (ET) and proton transfer (PT), often by >=1 eV. PCET reactions of the form X-H + Y X + H-Y can be termed hydrogen atom transfer (HAT). Another PCET class involves outersphere electron transfer concerted with deprotonation by another reagent, Y+ + XH-B Y + X-HB+. Many PCET/HAT rate constants are predicted well by the Marcus cross relation. The cross-relation calculation uses rate constants for self-exchange reactions to provide information on intrinsic barriers. Intrinsic barriers for PCET can be comparable to or larger than those for ET. These properties are discussed in light of recent theoretical treatments of PCET.
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Affiliation(s)
- James M Mayer
- Department of Chemistry, University of Washington, Campus Box 351700, Seattle, Washington 98195-1700, USA.
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