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Lucas M, Qin Y, Yang L, Sun G, Zhang J. Ultraviolet photochemistry of the 2-buten-2-yl radical. Phys Chem Chem Phys 2024. [PMID: 39421930 DOI: 10.1039/d4cp03076a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2024]
Abstract
The ultraviolet (UV) photodissociation dynamics of the 2-buten-2-yl (C4H7) radical were studied using the high-n Rydberg atom time-of-flight (HRTOF) technique in the photolysis region of 226-246 nm. 2-Buten-2-yl radicals were generated by 193 nm photodissociation of the precursor 2-chloro-2-butene. The H-atom photofragment yield (PFY) spectrum of 2-buten-2-yl is broad, peaking at 234 nm. Quantum chemistry calculations show that the UV absorption is due to the 3py and 3px Rydberg states (parallel to the plane of CC double bond). The translational energy distributions of the H-atom loss product channel, P(ET)'s, of 2-buten-2-yl show a bimodal distribution indicating two dissociation pathways. The major pathway peaks at ET ∼ 7 kcal mol-1 with a nearly constant fraction of average ET in the total excess energy, 〈fT〉, at ∼0.11-0.12. This main pathway has an isotropic product angular distribution with β ∼ 0, consistent with the unimolecular dissociation of a hot 2-buten-2-yl radical following internal conversion from the electronically excited state, resulting in the formation of 2-butyne + H (∼84%) and 1,2-butadiene + H (∼16%). Additionally, there is a minor non-statistical pathway with an isotropic angular distribution. The minor pathway peaks at ET ∼ 35 kcal mol-1 in the P(ET) distributions and exhibits a large 〈fT〉 of ∼0.40-0.46. This fast pathway suggests a direct dissociation of the methyl H-atom on a repulsive excited state surface or on the repulsive part of the ground state surface, forming 1,2-butadiene + H. The fast/slow pathway branching ratio is in the range of 0.03-0.08.
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Affiliation(s)
- Michael Lucas
- Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA.
| | - Yuan Qin
- Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA.
| | - Lei Yang
- Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA.
| | - Ge Sun
- Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA.
| | - Jingsong Zhang
- Department of Chemistry, University of California at Riverside, Riverside, CA 92521, USA.
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2
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Lucas M, Qin Y, Yang L, Sun G, Zhang J. Ultraviolet Photodissociation Dynamics of the 1-Methylallyl Radical. J Phys Chem A 2024; 128:5556-5566. [PMID: 38953902 DOI: 10.1021/acs.jpca.4c02535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
The ultraviolet (UV) photodissociation dynamics of the 1-methylallyl (1-MA) radical were studied using the high-n Rydberg atom time-of-flight (HRTOF) technique in the wavelength region of 226-244 nm. The 1-MA radicals were produced by 193 nm photodissociation of the 3-chloro-1-butene and 1-chloro-2-butene precursor. The 1 + 1 REMPI spectrum of 1-MA agrees with the previous UV absorption spectrum in this wavelength region. Quantum chemistry calculations show that the UV absorption is mainly attributed to the 3pz Rydberg state (perpendicular to the allyl plane). The H atom photofragment yield (PFY) spectrum of 1-MA from 3-chloro-1-butene displays a broad peak around 230 nm, while that from 1-chloro-2-butene peaks at ∼236 nm. The translational energy distributions of the H atom loss product channel, P (ET)'s, show a bimodal distribution indicating two dissociation pathways in 1-MA. The major pathway is isotropic in product angular distribution with β ∼ 0 and has a low fraction of average translational energy in the total excess energy, ⟨fT⟩, in the range of 0.13-0.17; this pathway corresponds to unimolecular dissociation of 1-MA after internal conversion to form 1,3-butadiene + H. The minor pathway is anisotropic with β ∼ -0.23 and has a large ⟨fT⟩ of ∼0.62-0.72. This fast pathway suggests a direct dissociation of the methyl H atom on a repulsive excited state surface or the repulsive part of the ground state surface to form 1,3-butadiene + H. The fast/slow pathway branching ratio is in the range of 0.03-0.08.
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Affiliation(s)
- Michael Lucas
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Yuan Qin
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Lei Yang
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Ge Sun
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
| | - Jingsong Zhang
- Department of Chemistry, University of California at Riverside, Riverside, California 92521, United States
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He C, Thomas AM, Galimova GR, Mebel AM, Kaiser RI. Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2Π) with Propylene (CH 3CHCH 2; X 1A'). J Phys Chem A 2019; 123:10543-10555. [PMID: 31718184 DOI: 10.1021/acs.jpca.9b09815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crossed molecular beam reactions of the methylidyne radical (CH; X2Π) with propylene (CH3CHCH2; X1A') along with (partially) substituted reactants were conducted at collision energies of 19.3 kJ mol-1. Combining our experimental data with ab initio electronic structure and statistical calculations, the methylidyne radical is revealed to add barrierlessly to the carbon-carbon double bond of propylene reactant resulting in a cyclic doublet C4H7 intermediate with a lifetime longer than its rotation period. These adducts undergo a nonstatistical unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming the cyclic products 1-methylcyclopropene and 3-methylcyclopropene with overall reaction exoergicities of 168 ± 25 kJ mol-1. These C4H6 isomers are predicted to exist even in low-temperature environments such as cold molecular clouds like TMC-1, since the reaction is barrierless and exoergic, all transition states are below the energy of the separated reactants, and both the methylidyne radical (CH; X2Π) and propylene reactant were detected in cold molecular clouds such as TMC-1.
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Affiliation(s)
- Chao He
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Aaron M Thomas
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States.,Samara National Research University , Samara 443086 , Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States
| | - Ralf I Kaiser
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
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Wang W, Feng W, Wang W, Li P. Theoretical Investigations on the Reactivity of Methylidyne Radical toward 2,3,7,8-Tetrachlorodibenzo- p-Dioxin: A DFT and Molecular Dynamics Study. Molecules 2018; 23:E2685. [PMID: 30340385 PMCID: PMC6222546 DOI: 10.3390/molecules23102685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 12/22/2022] Open
Abstract
To explore the potential reactivity of the methylidyne radical (CH) toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the reaction mechanism between them has been systematically investigated employing the density functional theory (DFT) and ab initio molecular dynamics simulations. The relevant thermodynamic and kinetic parameters in the possible reaction pathways have been discussed as well as the IR spectra and hyperfine coupling constants (hfcc's) of the major products. Different from the reaction of the CH radical with 2,3,7,8-tetrachlorodibenzofuran, CH radical can attack all the C-C bonds of TCDD to form an initial intermediate barrierlessly via the cycloaddition mechanism. After then, the introduced C-H bond can be further inserted into the C-C bond of TCDD, resulting in the formation of a seven-membered ring structure. The whole reactions are favorable thermodynamically and kinetically. Moreover, the major products have been verified by ab initio molecular dynamics simulations. The distinct IR spectra and hyperfine coupling constants of the major products can provide some help for their experimental detection and identification. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDDs has also been investigated. Hopefully, the present findings can provide new insights into the reactivity of the CH radical in the transformation of TCDD-like dioxins.
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Affiliation(s)
- Weihua Wang
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Wenling Feng
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Wenliang Wang
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China.
| | - Ping Li
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, China.
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Wei W, Wang W, Xu K, Feng W, Li X, Li P. Theoretical insights into the reaction mechanisms between 2,3,7,8-tetrachlorodibenzofuran and the methylidyne radical. RSC Adv 2018; 8:21150-21163. [PMID: 35539902 PMCID: PMC9080895 DOI: 10.1039/c8ra03046d] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 06/03/2018] [Indexed: 11/21/2022] Open
Abstract
To explore the potential role of the methylidyne radical (CH) in the transformation of 2,3,7,8-tetrachlorodibenzofuran (TCDF), in this study, the detailed reaction mechanisms between TCDF and CH radical have been systematically investigated employing the B3LYP method of density functional theory (DFT) in combination with the atoms in molecules (AIM) theory and ab initio molecular dynamics. It was found that the title reaction is a multi-channel reaction, i.e., the CH radical can attack the C-X (X = C, Cl, H, O) bonds of TCDF via the insertion modes, resulting in the formation of 13 products. Thermodynamically, the whole reaction processes are exothermic and spontaneous since all the enthalpy and Gibbs free energy changes are negative values in the formation processes. Moreover, the thermodynamic stability of the products is controlled by the distribution of the single unpaired electron. Kinetically, the most favorable reaction channel is the insertion of the CH radical into the C-C bond except for the C atoms attached to the chlorine atom. Moreover, the dominant products have been further confirmed by the molecular dynamics. Meanwhile, the IR spectra and hyperfine coupling constants of the dominant products have been investigated to provide helpful information for their identification experimentally. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDFs has also been investigated. Expectedly, the present findings can enable us to better understand the reactivity of the CH radical toward organic pollutants analogous to TCDF in the atmosphere.
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Affiliation(s)
- Wenjing Wei
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University Qufu 273165 P. R. China
| | - Weihua Wang
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University Qufu 273165 P. R. China
| | - Kaining Xu
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University Qufu 273165 P. R. China
| | - Wenling Feng
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University Qufu 273165 P. R. China
| | - Xiaoping Li
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University Qufu 273165 P. R. China
| | - Ping Li
- Key Laboratory of Life-Organic Analysis, School of Chemistry and Chemical Engineering, Qufu Normal University Qufu 273165 P. R. China
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Ribeiro JM, Mebel AM. Reaction Mechanism and Product Branching Ratios of the CH + C3H6 Reaction: A Theoretical Study. J Phys Chem A 2016; 120:1800-12. [DOI: 10.1021/acs.jpca.5b12588] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Joao Marcelo Ribeiro
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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Trevitt AJ, Goulay F. Insights into gas-phase reaction mechanisms of small carbon radicals using isomer-resolved product detection. Phys Chem Chem Phys 2016; 18:5867-82. [DOI: 10.1039/c5cp06389b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gas-phase radical reactions of CN and CH with small hydrocarbons are overviewed with emphasis on isomer-resolved product detection.
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Affiliation(s)
- Adam J. Trevitt
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
| | - Fabien Goulay
- Department of Chemistry
- West Virginia University
- Morgantown
- USA
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Nguyen HMT, Nguyen HT, Nguyen TN, Van Hoang H, Vereecken L. Theoretical Study on the Reaction of the Methylidyne Radical, CH(X2Π), with Formaldehyde, CH2O. J Phys Chem A 2014; 118:8861-71. [DOI: 10.1021/jp506175k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Hue Minh Thi Nguyen
- Faculty of Chemistry
and Center for Computational Science, Hanoi National University of Education, Hanoi, Vietnam
| | - Huu Tho Nguyen
- College of Education—Gia Lai, 126 Le Thanh Ton, Pleiku, Gia Lai, Vietnam
| | - Trong-Nghia Nguyen
- School of Chemical
Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Hung Van Hoang
- Faculty of Chemistry
and Center for Computational Science, Hanoi National University of Education, Hanoi, Vietnam
| | - Luc Vereecken
- Theoretical
Atmospheric Chemistry, Max Planck Institute for Chemistry, 55128 Mainz, Germany
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Trevitt AJ, Prendergast MB, Goulay F, Savee JD, Osborn DL, Taatjes CA, Leone SR. Product Branching Fractions of the CH + Propene Reaction from Synchrotron Photoionization Mass Spectrometry. J Phys Chem A 2013; 117:6450-7. [DOI: 10.1021/jp404965k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Adam J. Trevitt
- School of
Chemistry, University of Wollongong, NSW
2522 Australia
| | | | - Fabien Goulay
- Department
of Chemistry, West Virginia University,
Morgantown, West Virginia
26506, United States
| | - John D. Savee
- Combustion
Research Facility,
Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - David L. Osborn
- Combustion
Research Facility,
Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Craig A. Taatjes
- Combustion
Research Facility,
Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Stephen R. Leone
- Departments of Chemistry and Physics,
and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, United States
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Just GMP, Negru B, Park D, Neumark DM. Photodissociation of isobutene at 193 nm. Phys Chem Chem Phys 2012; 14:675-80. [PMID: 22120105 DOI: 10.1039/c1cp22651g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The collisionless photodissociation dynamics of isobutene (i-C(4)H(8)) at 193 nm via photofragment translational spectroscopy are reported. Two major photodissociation channels were identified: H + C(4)H(7) and CH(3) + CH(3)CCH(2). Translational energy distributions indicate that both channels result from statistical decay on the ground state surface. Although the CH(3) loss channel lies 13 kcal mol(-1) higher in energy, the CH(3):H branching ratio was found to be 1.7 (5), in reasonable agreement with RRKM calculations.
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Affiliation(s)
- Gabriel M P Just
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
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