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Kuwata KT. Computational Modeling of the Conformation-Dependent Atmospheric Reactivity of Criegee Intermediates. J Phys Chem A 2024. [PMID: 39172159 DOI: 10.1021/acs.jpca.4c04517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
The impacts of Criegee intermediates (CIs) on atmospheric chemistry depend significantly on the CI conformation. In this Perspective, I highlight examples of how electronic structure and statistical rate theory calculations, in conjunction with experiment, have revealed conformation-dependent details of both CI ground-state reactivity and electronic excitation. Calculations using single-reference electronic structure methods and conventional transition state theory have predicted that CIs with syn-alkyl or syn-vinyl substituents isomerize rapidly to vinyl hydroperoxides (VHPs) or dioxoles, both of which can decompose rapidly under atmospheric conditions. Ongoing computational research on hydroxyl radical (OH) roaming initiated by VHP dissociation requires the application of multireference electronic structure methods and variational transition state theory. CIs that lack both syn-alkyl and syn-vinyl substituents undergo either bimolecular reaction or π* ← π electronic excitation in the atmosphere. Accurate predictions of CI ultraviolet-visible spectra require multireference calculations with large active spaces and at least a second-order perturbative treatment of dynamic electron correlation. The extent to which electronic spectra can be diagnostic of the presence of specific CI conformers varies significantly with CI chemical identity.
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Affiliation(s)
- Keith T Kuwata
- Department of Chemistry, Macalester College, Saint Paul, Minnesota 55105-1899, United States
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2
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Hewa Edirappulige DT, Kirby IJ, Beckett CK, Dibble TS. Atmospheric Chemistry of HOHg (II)O • Mimics That of a Hydroxyl Radical. J Phys Chem A 2023; 127:8392-8403. [PMID: 37769282 DOI: 10.1021/acs.jpca.3c04159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2023]
Abstract
HOHg(II)O•, formed from HOHg(I)• + O3, is a key intermediate in the OH-initiated oxidation of Hg(0) in the atmosphere. As no experimental data are available for HOHg(II)O•, we use computational chemistry (CCSD(T)//M06-2X/AVTZ) to characterize its reactions with atmospheric trace gases (NO, NO2, CH4, C2H4, CH2O and CO). In summary, HOHg(II)O•, like the analogous BrHg(II)O• radical, largely mimics the reactivity of •OH in reactions with NOx, alkanes, alkenes, and aldehydes. The rate constant for its reaction with methane (HOHg(II)O• + CH4 → Hg(II)(OH)2 + •CH3) is about four times higher than that of •OH at 298 K. All of these reactions maintain mercury as Hg(II), except for HOHg(II)O• + CO → HOHg(I)• + CO2. Considering only the six reactions studied here, we find that reduction by CO dominates the fate of HOHg(II)O• (79-93%) in many air masses (in the stratosphere and at ground level in rural, marine, and polluted urban regions) with only modest competition from HOHg(II)O• + CH4 (<15%). We expect that this work will help global modeling of atmospheric mercury chemistry.
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Affiliation(s)
- Darshi T Hewa Edirappulige
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
| | - Ilena J Kirby
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
| | - Camille K Beckett
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
| | - Theodore S Dibble
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, New York 13210, United States
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Lowe B, Cardona AL, Salas J, Bodi A, Mayer PM, Burgos Paci MA. Probing the pyrolysis of ethyl formate in the dilute gas phase by synchrotron radiation and theory. JOURNAL OF MASS SPECTROMETRY : JMS 2023; 58:e4901. [PMID: 36691327 DOI: 10.1002/jms.4901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 01/02/2023] [Indexed: 06/17/2023]
Abstract
The thermal decomposition of the atmospheric constituent ethyl formate was studied by coupling flash pyrolysis with imaging photoelectron photoion coincidence (iPEPICO) spectroscopy using synchrotron vacuum ultraviolet (VUV) radiation at the Swiss Light Source (SLS). iPEPICO allows photoion mass-selected threshold photoelectron spectra (ms-TPES) to be obtained for pyrolysis products. By threshold photoionization and ion imaging, parent ions of neutral pyrolysis products and dissociative photoionization products could be distinguished, and multiple spectral carriers could be identified in several ms-TPES. The TPES and mass-selected TPES for ethyl formate are reported for the first time and appear to correspond to ionization of the lowest energy conformer having a cis (eclipsed) configuration of the O=C(H)-O-C(H2 )-CH3 and trans (staggered) configuration of the O=C(H)-O-C(H2 )-CH3 dihedral angles. We observed the following ethyl formate pyrolysis products: CH3 CH2 OH, CH3 CHO, C2 H6 , C2 H4 , HC(O)OH, CH2 O, CO2 , and CO, with HC(O)OH and C2 H4 pyrolyzing further, forming CO + H2 O and C2 H2 + H2 . The reaction paths and energetics leading to these products, together with the products of two homolytic bond cleavage reactions, CH3 CH2 O + CHO and CH3 CH2 + HC(O)O, were studied computationally at the M06-2X-GD3/aug-cc-pVTZ and SVECV-f12 levels of theory, complemented by further theoretical methods for comparison. The calculated reaction pathways were used to derive Arrhenius parameters for each reaction. The reaction rate constants and branching ratios are discussed in terms of the residence time and newly suggest carbon monoxide as a competitive primary fragmentation product at high temperatures.
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Affiliation(s)
- Bethany Lowe
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - Alejandro L Cardona
- INFIQC - CONICET, Departamento fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Juana Salas
- INFIQC - CONICET, Departamento fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Paul M Mayer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada
| | - Maxi A Burgos Paci
- INFIQC - CONICET, Departamento fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
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Lowe B, Cardona AL, Salas J, Bodi A, Burgos Paci MA, Mayer PM. Probing the pyrolysis of methyl formate in the dilute gas phase by synchrotron radiation and theory. JOURNAL OF MASS SPECTROMETRY : JMS 2022; 57:e4868. [PMID: 35698788 DOI: 10.1002/jms.4868] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/22/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
The thermal dissociation of the atmospheric constituent methyl formate was probed by coupling pyrolysis with imaging photoelectron photoion coincidence spectroscopy (iPEPICO) using synchrotron VUV radiation at the Swiss Light Source (SLS). iPEPICO allows threshold photoelectron spectra to be obtained for pyrolysis products, distinguishing isomers and separating ionic and neutral dissociation pathways. In this work, the pyrolysis products of dilute methyl formate, CH3 OC(O)H, were elucidated to be CH3 OH + CO, 2 CH2 O and CH4 + CO2 as in part distinct from the dissociation of the radical cation (CH3 OH+• + CO and CH2 OH+ + HCO). Density functional theory, CCSD(T), and CBS-QB3 calculations were used to describe the experimentally observed reaction mechanisms, and the thermal decomposition kinetics and the competition between the reaction channels are addressed in a statistical model. One result of the theoretical model is that CH2 O formation was predicted to come directly from methyl formate at temperatures below 1200 K, while above 1800 K, it is formed primarily from the thermal decomposition of methanol.
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Affiliation(s)
- Bethany Lowe
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - Alejandro L Cardona
- INFIQC-CONICET, Departamento Fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Juana Salas
- INFIQC-CONICET, Departamento Fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, Villigen, Switzerland
| | - Maxi A Burgos Paci
- INFIQC-CONICET, Departamento Fisicoquímica, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Paul M Mayer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario, Canada
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Kuwata KT, DeVault MP, Claypool DJ. Improved Computational Modeling of the Kinetics of the Acetylperoxy + HO 2 Reaction. Faraday Discuss 2022; 238:589-618. [DOI: 10.1039/d2fd00030j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The acetylperoxy + HO2 reaction has multiple impacts on the troposphere, with a triplet pathway leading to peracetic acid + O2 (reaction 1a) competing with singlet pathways leading to acetic...
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Ghoshal S, Pramanik A, Sarkar P. Theoretical Investigations on the Possibility of Prebiotic HCN Formation via O-Addition Reactions. J Phys Chem A 2020; 124:4782-4792. [PMID: 32401514 DOI: 10.1021/acs.jpca.0c02538] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Until now, reactions between methane photolysis products (CH3•, CH2) and active N atom or reactive NO radical are proposed as routes of HCN formation in the prebiotic Earth. Scientists think that the reducing atmosphere of primitive Earth was made of H2, He, N2, NO, CH4, H2O, CO2, etc., and there was no molecular oxygen. However, it has been evident from experiments that the vacuum ultraviolet (VUV) photolysis of CO2 can produce atomic oxygen. Therefore, it can be presumed that atomic oxygen was likely present in early Earth's atmosphere. Was there any impact of atomic oxygen in production of early atmospheric HCN for the emergence of life? To hunt for the answer, we have employed computational methods to study the mechanism and kinetics of CH3NO + O(1D) and CH2NO• + O(3P) addition reactions. Current study suggests that the addition of O(1D) into nitrosomethane (CH3NO) and the addition of O(3P) into nitrosomethylene radical (CH2NO•) can efficiently produce HCN through an effectively barrierless pathway. At STP, Bartis-Widom phenomenological loss rate coefficients of O(1D) and O(3P) are obtained as 2.47 × 10-12 and 4.67 × 10-11 cm3 molecule-1 s-1, respectively. We propose that addition reactions of atomic oxygen with CH3NO and CH2NO• might act as a potential source for early atmospheric HCN.
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Affiliation(s)
- Sourav Ghoshal
- Department of Chemistry, Visva-Bharati University, Santiniketan-731235, India
| | - Anup Pramanik
- Department of Chemistry, Visva-Bharati University, Santiniketan-731235, India.,Department of Chemistry, Sidho-Kanho-Birsha University, Purulia-723104, India
| | - Pranab Sarkar
- Department of Chemistry, Visva-Bharati University, Santiniketan-731235, India
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Lam KT, Wilhelmsen CJ, Dibble TS. BrHgO• + C2H4 and BrHgO• + HCHO in Atmospheric Oxidation of Mercury: Determining Rate Constants of Reactions with Prereactive Complexes and Bifurcation. J Phys Chem A 2019; 123:6045-6055. [DOI: 10.1021/acs.jpca.9b05120] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Khoa T. Lam
- Department of Chemistry, State University of New York-College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, New York 13210, United States
| | - Curtis J. Wilhelmsen
- Department of Chemistry, State University of New York-College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, New York 13210, United States
| | - Theodore S. Dibble
- Department of Chemistry, State University of New York-College of Environmental Science and Forestry, 1 Forestry Dr., Syracuse, New York 13210, United States
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Shang Y, Ning H, Shi J, Wang H, Luo SN. Chemical kinetics of H-abstractions from dimethyl amine by H, CH3, OH, and HO2 radicals with multi-structural torsional anharmonicity. Phys Chem Chem Phys 2019; 21:12685-12696. [DOI: 10.1039/c9cp00709a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dimethyl amine (DMA) is identified as a promising nitrogen-containing fuel candidate.
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Affiliation(s)
- Yanlei Shang
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education, and Institute of Materials Dynamics
- Southwest Jiaotong University
- Chengdu
- P. R. China
| | - Hongbo Ning
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education, and Institute of Materials Dynamics
- Southwest Jiaotong University
- Chengdu
- P. R. China
| | - Jinchun Shi
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education, and Institute of Materials Dynamics
- Southwest Jiaotong University
- Chengdu
- P. R. China
| | - Hongyan Wang
- School of Physical Science and Technology, Southwest Jiaotong University
- Chengdu
- P. R. China
| | - Sheng-Nian Luo
- Key Laboratory of Advanced Technologies of Materials
- Ministry of Education, and Institute of Materials Dynamics
- Southwest Jiaotong University
- Chengdu
- P. R. China
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Kaur R, Vikas. Conflict in the Mechanism and Kinetics of the Barrierless Reaction between SH and NO 2 Radicals. J Phys Chem A 2018; 122:1926-1937. [PMID: 29457904 DOI: 10.1021/acs.jpca.7b06916] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
There are some unsettled issues regarding the mechanism and kinetics of an important atmospheric reaction of NO2 radical with the SH radical. The existing mechanism is based on the formation of HSO and NO radicals, both of which can result only along one barrierless channel. However, the detection of NO radical has never been reported though the formation of HSO radical has been followed in some studies to determine the rate constants. The latter are mainly obtained by monitoring the SH decay, but rate constants are reported to be highly conflicting among the existing studies reporting its value ranging from 10-10 to 10-12 cm3 molecule-1 sec-1. The present work attempts to resolve these issues by exploring various reaction pathways through the global reaction route mapping of the potential energy surface at the level of spin-unrestricted and spin-restricted coupled-cluster and density functional theories. The initial association of two radicals was found to proceed via two barrierless modes: (1) S-N association leading to HSNO2 and, (2) S-O association resulting in HSONO, in particular the cis-isomer. The kinetics of the barrierless pathways was investigated through rate constants computed using canonical variational transition state theory (CVTST) along with their temperature and pressure dependence investigated using the master equation. The rate constants calculated using spin-unrestricted methods are found to be in agreement with experimentally observed range of rate constant, and the formation of cis-HSONO (via mode 2) is observed to be the main contributing channel. Contrary to the results of spin-restricted calculations, the barrierless channel (mode 1) leading to the formation of HSNO2 is predicted to involve two bottlenecks when results using spin-unrestricted calculations were analyzed. Notably, the spin-unrestricted calculations predict a prereaction complex for the formation of S-N bond (via mode 1) which has been treated using Miller's unified transition state theory with a two transition state model. The fate of all the species involved in the reaction is critically evaluated in the present work, and the predictions made can be a subject of further experimental and theoretical studies involving radical-radical reactions.
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Affiliation(s)
- Ramanpreet Kaur
- Quantum Chemistry Group, Department of Chemistry & Centre of Advanced Studies in Chemistry, Panjab University , Chandigarh 160014, India
| | - Vikas
- Quantum Chemistry Group, Department of Chemistry & Centre of Advanced Studies in Chemistry, Panjab University , Chandigarh 160014, India
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Jiao Y, Dibble TS. First kinetic study of the atmospherically important reactions BrHg˙ + NO 2 and BrHg˙ + HOO. Phys Chem Chem Phys 2018; 19:1826-1838. [PMID: 28000816 DOI: 10.1039/c6cp06276h] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We use computational chemistry to determine the rate constants and product yields for the reactions of BrHg˙ with the atmospherically abundant radicals NO2 and HOO. The reactants, products, and well-defined transition states are characterized using CCSD(T) with large basis sets. The potential energy profiles for the barrierless addition of HOO and NO2 to BrHg˙ are characterized using CASPT2 and RHF-CCSDT, and the rate constants are computed as a function of temperature and pressure using variational transition state theory and master equation simulations. The calculated rate constant for the addition of NO2 to BrHg˙ is larger than that for the addition of HOO by a factor of up to two under atmospheric conditions. For the reaction of HOO with BrHg˙ the addition reaction entirely dominates competing HOO + BrHg˙ reaction channels. The addition of NO2 to BrHg˙ initially produces both BrHgNO2 and BrHgONO, but after a few seconds under atmospheric conditions the sole product is syn-BrHgONO. A previously unsuspected reaction channel for BrHg˙ + NO2 competes with the addition to yield Hg + BrNO2. This reaction reduces the mercury oxidation state in BrHg˙ from Hg(i) to Hg(0) and slows the atmospheric oxidation of Hg(0). While the rate constant for this reduction channel is not well-constrained by the present calculations, it may be as much as 18% as large as the oxidation channel under some atmospheric conditions. As no experimental kinetic or product yield data are available for the reactions studied here, this work will provide guidance for atmospheric modelers and experimental kineticists.
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Affiliation(s)
- Yuge Jiao
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Dr, Syracuse, NY 13210, USA.
| | - Theodore S Dibble
- Department of Chemistry, State University of New York, College of Environmental Science and Forestry, 1 Forestry Dr, Syracuse, NY 13210, USA.
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Shannon R, Glowacki DR. A Simple “Boxed Molecular Kinetics” Approach To Accelerate Rare Events in the Stochastic Kinetic Master Equation. J Phys Chem A 2018; 122:1531-1541. [DOI: 10.1021/acs.jpca.7b12521] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robin Shannon
- Mechanical Engineering, Stanford University, Stanford, California 94305, United States
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
| | - David R. Glowacki
- Mechanical Engineering, Stanford University, Stanford, California 94305, United States
- School of Chemistry, University of Bristol, Bristol, BS8 1TS, United Kingdom
- Department of Computer Science, University of Bristol, Bristol, BS8 1UB, United Kingdom
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