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Wang CY, Zhao L, Kaiser RI. Gas-Phase Preparation of the 14π Hückel Polycyclic Aromatic Anthracene and Phenanthrene Isomers (C 14H 10) via the Propargyl Addition-BenzAnnulation (PABA) Mechanism. Chemphyschem 2024:e202400151. [PMID: 38635959 DOI: 10.1002/cphc.202400151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/11/2024] [Accepted: 04/12/2024] [Indexed: 04/20/2024]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) imply the missing link between resonantly stabilized free radicals and carbonaceous nanoparticles, commonly referred to as soot particles in combustion systems and interstellar grains in deep space. Whereas gas phase formation pathways to the simplest PAH - naphthalene (C10H8) - are beginning to emerge, reaction pathways leading to the synthesis of the 14π Hückel aromatic PAHs anthracene and phenanthrene (C14H10) are still incomplete. Here, by utilizing a chemical microreactor in conjunction with vacuum ultraviolet (VUV) photoionization (PI) of the products followed by detection of the ions in a reflectron time-of-flight mass spectrometer (ReTOF-MS), the reaction between the 1'- and 2'-methylnaphthyl radicals (C11H9⋅) with the propargyl radical (C3H3⋅) accesses anthracene (C14H10) and phenanthrene (C14H10) via the Propargyl Addition-BenzAnnulation (PABA) mechanism in conjunction with a hydrogen assisted isomerization. The preferential formation of the thermodynamically less stable anthracene isomer compared to phenanthrene suggests a kinetic, rather than a thermodynamics control of the reaction.
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Affiliation(s)
- Chang Yang Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, China
| | - Long Zhao
- School of Nuclear Science and Technology, Deep Space Exploration Laboratory, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96888, USA
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2
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Medvedkov IA, Nikolayev AA, Yang Z, Goettl SJ, Mebel AM, Kaiser RI. Elucidating the chemical dynamics of the elementary reactions of the 1-propynyl radical (CH 3CC; X 2A 1) with 2-methylpropene ((CH 3) 2CCH 2; X 1A 1). Phys Chem Chem Phys 2024; 26:6448-6457. [PMID: 38319693 DOI: 10.1039/d3cp05872g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Exploiting the crossed molecular beam technique, we studied the reaction of the 1-propynyl radical (CH3CC; X2A1) with 2-methylpropene (isobutylene; (CH3)2CCH2; X1A1) at a collision energy of 38 ± 3 kJ mol-1. The experimental results along with ab initio and statistical calculations revealed that the reaction has no entrance barrier and proceeds via indirect scattering dynamics involving C7H11 intermediates with lifetimes longer than their rotation period(s). The reaction is initiated by the addition of the 1-propynyl radical with its radical center to the π-electron density at the C1 and/or C2 position in 2-methylpropene. Further, the C7H11 intermediate formed from the C1 addition either emits atomic hydrogen or undergoes isomerization via [1,2-H] shift from the CH3 or CH2 group prior to atomic hydrogen loss preferentially leading to 1,2,4-trimethylvinylacetylene (2-methylhex-2-en-4-yne) as the dominant product. The molecular structures of the collisional complexes promote hydrogen atom loss channels. RRKM results show that hydrogen elimination channels dominate in this reaction, with a branching ratio exceeding 70%. Since the reaction of the 1-propynyl radical with 2-methylpropene has no entrance barrier, is exoergic, and all transition states involved are located below the energy of the separated reactants, bimolecular collisions are feasible to form trimethylsubstituted 1,3-enyne (p1) via a single collision event even at temperatures as low as 10 K prevailing in cold molecular clouds such as G+0.693. The formation of trimethylsubstituted vinylacetylene could serve as the starting point of fundamental molecular mass growth processes leading to di- and trimethylsubstituted naphthalenes via the HAVA mechanism.
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Affiliation(s)
- Iakov A Medvedkov
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
| | | | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
| | - Shane J Goettl
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
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He C, Kaiser RI, Lu W, Ahmed M, Krasnoukhov VS, Pivovarov PS, Zagidullin MV, Azyazov VN, Morozov AN, Mebel AM. Unconventional gas-phase preparation of the prototype polycyclic aromatic hydrocarbon naphthalene (C 10H 8) via the reaction of benzyl (C 7H 7) and propargyl (C 3H 3) radicals coupled with hydrogen-atom assisted isomerization. Chem Sci 2023; 14:5369-5378. [PMID: 37234886 PMCID: PMC10208037 DOI: 10.1039/d3sc00911d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 04/19/2023] [Indexed: 05/28/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the interstellar medium and in meteorites such as Murchison and Allende and signify the missing link between resonantly stabilized free radicals and carbonaceous nanoparticles (soot particles, interstellar grains). However, the predicted lifetime of interstellar PAHs of some 108 years imply that PAHs should not exist in extraterrestrial environments suggesting that key mechanisms of their formation are elusive. Exploiting a microchemical reactor and coupling these data with computational fluid dynamics (CFD) simulations and kinetic modeling, we reveal through an isomer selective product detection that the reaction of the resonantly stabilized benzyl and the propargyl radicals synthesizes the simplest representative of PAHs - the 10π Hückel aromatic naphthalene (C10H8) molecule - via the novel Propargyl Addition-BenzAnnulation (PABA) mechanism. The gas-phase preparation of naphthalene affords a versatile concept of the reaction of combustion and astronomically abundant propargyl radicals with aromatic radicals carrying the radical center at the methylene moiety as a previously passed over source of aromatics in high temperature environments thus bringing us closer to an understanding of the aromatic universe we live in.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Mānoa Honolulu HI 96822 USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa Honolulu HI 96822 USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Vladislav S Krasnoukhov
- Lebedev Physical Institute Samara 443011 Russian Federation
- Samara National Research University Samara 443086 Russian Federation
| | - Pavel S Pivovarov
- Samara National Research University Samara 443086 Russian Federation
| | | | | | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University Miami Florida 33199 USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University Miami Florida 33199 USA
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Lukianova MA, Feldman VI. Radiation-induced closure of the second aromatic ring: Possible way to PAH starting from a styrene-acetylene complex. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2021.109847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Zhang T, Mu G, Zhang S, Hou J. Formation pathways of polycyclic aromatic hydrocarbons (PAHs) in butane or butadiene flames. RSC Adv 2021; 11:5629-5642. [PMID: 35423086 PMCID: PMC8694769 DOI: 10.1039/d0ra08744k] [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: 10/14/2020] [Accepted: 01/17/2021] [Indexed: 12/18/2022] Open
Abstract
The reaction pathways from phenyl radicals to phenanthrene (A3) and pyrene (A4) via C2H3 and C4H4 additions were investigated using the G3(MP2, CC) method. Rate constants of elementary reactions were calculated. The influence of additions, H-abstraction ways and reactive sites on the reaction rates were considered. These polycyclic aromatic hydrocarbon (PAH) formation pathways were used to improve the combustion chemistry model for C4 fuels, and the results from the improved model and the original model were compared with experimental data. H atoms are important for PAH formation owing to their influential roles in the production of aromatic radicals and stable aromatic structures. C2H3 and C4H4 addition reactions can occur at low temperature, and need less energy than C2H2 addition. The PAH formation pathways determined from G3 calculations, which were used to improve the model, were effective in promoting PAH formations in this model. Comparison of PAH formation in butane and butadiene flames showed both the C2H3 and C4H4 addition pathways included in this work can improve the formation of PAHs in butadiene and butane flames. C4H4 addition pathways in a butane flame were better for PAH formation than C2H3 addition. The reaction pathways from phenyl radicals to phenanthrene (A3) and pyrene (A4) via C2H3 and C4H4 additions were investigated using the G3(MP2, CC) method.![]()
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Affiliation(s)
- Tingting Zhang
- School of Mechanical and Electrical Engineering, Shandong Agricultural University Taian 271018 P. R. China
| | - Guizhi Mu
- School of Mechanical and Electrical Engineering, Shandong Agricultural University Taian 271018 P. R. China
| | - Shourong Zhang
- Department of Traffic Engineering, Shandong Transport Vocational College Taian 271000 P. R. China
| | - Jialin Hou
- School of Mechanical and Electrical Engineering, Shandong Agricultural University Taian 271018 P. R. China
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Shiels OJ, Prendergast MB, Savee JD, Osborn DL, Taatjes CA, Blanksby SJ, da Silva G, Trevitt AJ. Five vs. six membered-ring PAH products from reaction of o-methylphenyl radical and two C 3H 4 isomers. Phys Chem Chem Phys 2021; 23:14913-14924. [PMID: 34223848 DOI: 10.1039/d1cp01764k] [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
Gas-phase reactions of the o-methylphenyl (o-CH3C6H4) radical with the C3H4 isomers allene (H2C[double bond, length as m-dash]C[double bond, length as m-dash]CH2) and propyne (HC[triple bond, length as m-dash]C-CH3) are studied at 600 K and 4 Torr (533 Pa) using VUV synchrotron photoionisation mass spectrometry, quantum chemical calculations and RRKM modelling. Two major dissociation product ions arise following C3H4 addition: m/z 116 (CH3 loss) and 130 (H loss). These products correspond to small polycyclic aromatic hydrocarbons (PAHs). The m/z 116 signal for both reactions is conclusively assigned to indene (C9H8) and is the dominant product for the propyne reaction. Signal at m/z 130 for the propyne case is attributed to isomers of bicyclic methylindene (C10H10) + H, which contains a newly-formed methylated five-membered ring. The m/z 130 signal for allene, however, is dominated by the 1,2-dihydronaphthalene isomer arising from a newly created six-membered ring. Our results show that new ring formation from C3H4 addition to the methylphenyl radical requires an ortho-CH3 group - similar to o-methylphenyl radical oxidation. These reactions characteristically lead to bicyclic aromatic products, but the structure of the C3H4 co-reactant dictates the structure of the PAH product, with allene preferentially leading to the formation of two six-membered ring bicyclics and propyne resulting in the formation of six and five-membered bicyclic structures.
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Affiliation(s)
- Oisin J Shiels
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, 2522, Australia.
| | - Matthew B Prendergast
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, 2522, Australia.
| | - John D Savee
- Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA
| | - Craig A Taatjes
- Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551-0969, USA
| | - Stephen J Blanksby
- Central Analytical Research Facility, Queensland University of Technology, Brisbane, 4001, Australia
| | - Gabriel da Silva
- Department of Chemical Engineering, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, 2522, Australia.
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7
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Zhao L, Prendergast MB, Kaiser RI, Xu B, Lu W, Ablikim U, Ahmed M, Oleinikov AD, Azyazov VN, Mebel AM, Howlader AH, Wnuk SF. Reactivity of the Indenyl Radical (C 9 H 7 ) with Acetylene (C 2 H 2 ) and Vinylacetylene (C 4 H 4 ). Chemphyschem 2019; 20:1437-1447. [PMID: 30938059 DOI: 10.1002/cphc.201900052] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/28/2019] [Indexed: 11/09/2022]
Abstract
The reactions of the indenyl radicals with acetylene (C2 H2 ) and vinylacetylene (C4 H4 ) is studied in a hot chemical reactor coupled to synchrotron based vacuum ultraviolet ionization mass spectrometry. These experimental results are combined with theory to reveal that the resonantly stabilized and thermodynamically most stable 1-indenyl radical (C9 H7 . ) is always formed in the pyrolysis of 1-, 2-, 6-, and 7-bromoindenes at 1500 K. The 1-indenyl radical reacts with acetylene yielding 1-ethynylindene plus atomic hydrogen, rather than adding a second acetylene molecule and leading to ring closure and formation of fluorene as observed in other reaction mechanisms such as the hydrogen abstraction acetylene addition or hydrogen abstraction vinylacetylene addition pathways. While this reaction mechanism is analogous to the bimolecular reaction between the phenyl radical (C6 H5 . ) and acetylene forming phenylacetylene (C6 H5 CCH), the 1-indenyl+acetylene→1-ethynylindene+hydrogen reaction is highly endoergic (114 kJ mol-1 ) and slow, contrary to the exoergic (-38 kJ mol-1 ) and faster phenyl+acetylene→phenylacetylene+hydrogen reaction. In a similar manner, no ring closure leading to fluorene formation was observed in the reaction of 1-indenyl radical with vinylacetylene. These experimental results are explained through rate constant calculations based on theoretically derived potential energy surfaces.
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Affiliation(s)
- Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA
| | - Matthew B Prendergast
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA
| | - Bo Xu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Utuq Ablikim
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | | | - Alexander M Mebel
- Samara National Research University, Samara, 443086, Russia.,Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - A Hasan Howlader
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Stanislaw F Wnuk
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
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8
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Abplanalp MJ, Góbi S, Kaiser RI. On the formation and the isomer specific detection of methylacetylene (CH 3CCH), propene (CH 3CHCH 2), cyclopropane (c-C 3H 6), vinylacetylene (CH 2CHCCH), and 1,3-butadiene (CH 2CHCHCH 2) from interstellar methane ice analogues. Phys Chem Chem Phys 2019; 21:5378-5393. [PMID: 30221272 DOI: 10.1039/c8cp03921f] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pure methane (CH4) ices processed by energetic electrons under ultra-high vacuum conditions to simulate secondary electrons formed via galactic cosmic rays (GCRs) penetrating interstellar ice mantles have been shown to produce an array of complex hydrocarbons with the general formulae: CnH2n+2 (n = 4-8), CnH2n (n = 3-9), CnH2n-2 (n = 3-9), CnH2n-4 (n = 4-9), and CnH2n-6 (n = 6-7). By monitoring the in situ chemical evolution of the ice combined with temperature programmed desorption (TPD) studies and tunable single photon ionization coupled to a reflectron time-of-flight mass spectrometer, specific isomers of C3H4, C3H6, C4H4, and C4H6 were probed. These experiments confirmed the synthesis of methylacetylene (CH3CCH), propene (CH3CHCH2), cyclopropane (c-C3H6), vinylacetylene (CH2CHCCH), 1-butyne (HCCC2H5), 2-butyne (CH3CCCH3), 1,2-butadiene (H2CCCH(CH3)), and 1,3-butadiene (CH2CHCHCH2) with yields of 2.17 ± 0.95 × 10-4, 3.7 ± 1.5 × 10-3, 1.23 ± 0.77 × 10-4, 1.28 ± 0.65 × 10-4, 4.01 ± 1.98 × 10-5, 1.97 ± 0.98 × 10-4, 1.90 ± 0.84 × 10-5, and 1.41 ± 0.72 × 10-4 molecules eV-1, respectively. Mechanistic studies exploring the formation routes of methylacetylene, propene, and vinylacetylene were also conducted, and revealed the additional formation of the 1,2,3-butatriene isomer. Several of the above isomers, methylacetylene, propene, vinylacetylene, and 1,3-butadiene, have repeatedly been shown to be important precursors in the formation of polycyclic aromatic hydrocarbons (PAHs), but until now their interstellar synthesis has remained elusive.
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Affiliation(s)
- Matthew J Abplanalp
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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Lucas M, Thomas AM, Kaiser RI, Bashkirov EK, Azyazov VN, Mebel AM. Combined Experimental and Computational Investigation of the Elementary Reaction of Ground State Atomic Carbon (C; 3Pj) with Pyridine (C5H5N; X1A1) via Ring Expansion and Ring Degradation Pathways. J Phys Chem A 2018. [DOI: 10.1021/acs.jpca.8b00756] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Michael Lucas
- 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
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | | | | | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
- Samara University, Samara, 443086, Russia
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Abplanalp MJ, Jones BM, Kaiser RI. Untangling the methane chemistry in interstellar and solar system ices toward ionizing radiation: a combined infrared and reflectron time-of-flight analysis. Phys Chem Chem Phys 2018; 20:5435-5468. [PMID: 28972622 DOI: 10.1039/c7cp05882a] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Pure methane (CH4/CD4) ices were exposed to three ionizing radiation sources at 5.5 K under ultrahigh vacuum conditions to compare the complex hydrocarbon spectrum produced across several interstellar environments. These irradiation sources consisted of energetic electrons to simulate secondary electrons formed in the track of galactic cosmic rays (GCRs), Lyman α (10.2 eV; 121.6 nm) photons simulated the internal VUV field in a dense cloud, and broadband (112.7-169.8 nm; 11.0-7.3 eV) photons which mimic the interstellar ultra-violet field. The in situ chemical evolution of the ices was monitored via Fourier transform infrared spectroscopy (FTIR) and during heating via mass spectrometry utilizing a quadrupole mass spectrometer with an electron impact ionization source (EI-QMS) and a reflectron time-of-flight mass spectrometer with a photoionization source (PI-ReTOF-MS). The FTIR analysis detected six small hydrocarbon products from the three different irradiation sources: propane [C3H8(C3D8)], ethane [C2H6(C2D6)], the ethyl radical [C2H5(C2D5)], ethylene [C2H4(C2D4)], acetylene [C2H2(C2D2)], and the methyl radical [CH3(CD3)]. The sensitive PI-ReTOF-MS analysis identified a complex array of products with different products being detected between experiments with general formulae: CnH2n+2 (n = 4-8), CnH2n (n = 3-9), CnH2n-2 (n = 3-9), CnH2n-4 (n = 4-9), and CnH2n-6 (n = 6-7) from electron irradiation and CnH2n+2 (n = 4-8), CnH2n (n = 3-10), CnH2n-2 (n = 3-11), CnH2n-4 (n = 4-11), CnH2n-6 (n = 5-11), and CnH2n-8 (n = 6-11) from broadband photolysis and Lyman α photolysis. These experiments show that even the simplest hydrocarbon can produce important complex hydrocarbons such as C3H4 and C4H6 isomers. Distinct isomers from these groups have been shown to be important reactants in the synthesis of polycyclic aromatic hydrocarbons like indene (C9H8) and naphthalene (C10H8) under interstellar conditions.
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Affiliation(s)
- Matthew J Abplanalp
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, Hawaii, HI 96822, USA.
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11
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Wei M, Zhang T, Chen X, Yan F, Guo G, Zhang D. Formation of bicyclic polycyclic aromatic hydrocarbons (PAHs) from the reaction of a phenyl radical with cis-3-penten-1-yne. RSC Adv 2018; 8:13226-13236. [PMID: 35542549 PMCID: PMC9079691 DOI: 10.1039/c8ra01449c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 03/21/2018] [Indexed: 11/21/2022] Open
Abstract
The formation of PAHs within 4-, 5-, 6- and 7-membered rings on the C6H5 + C5H6 potential energy surface.
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Affiliation(s)
- Mingrui Wei
- Hubei Key Laboratory of Advanced Technology for Automotive Components
- Hubei Collaborative Innovation Center for Automotive Components Technology
- Wuhan University of Technology
- Wuhan 430070
- PR China
| | - Tingting Zhang
- Hubei Key Laboratory of Advanced Technology for Automotive Components
- Hubei Collaborative Innovation Center for Automotive Components Technology
- Wuhan University of Technology
- Wuhan 430070
- PR China
| | - Xianfeng Chen
- School of Resources and Environmental Engineering
- Wuhan University of Technology
- Wuhan 430070
- China
| | - Fuwu Yan
- Hubei Key Laboratory of Advanced Technology for Automotive Components
- Hubei Collaborative Innovation Center for Automotive Components Technology
- Wuhan University of Technology
- Wuhan 430070
- PR China
| | - Guanlun Guo
- Hubei Key Laboratory of Advanced Technology for Automotive Components
- Hubei Collaborative Innovation Center for Automotive Components Technology
- Wuhan University of Technology
- Wuhan 430070
- PR China
| | - Dongju Zhang
- Key Lab of Colloid and Interface Chemistry
- Ministry of Education
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan 250000
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Wei M, Zhang T, Li S, Guo G, Zhang D. Naphthalene formation pathways from phenyl radical via vinyl radical (C2H3) and vinylacetylene (C4H4): computational studies on reaction mechanisms and kinetics. CAN J CHEM 2017. [DOI: 10.1139/cjc-2017-0090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The reaction mechanisms of PAH formation from phenyl radical (C6H5) to naphthalene via C2H3 (C2H3-Path) and C4H4 (C4H4-Path) were investigated by the G3(MP2, CC) method. The hydrogen abstraction, ring closure, cis–trans isomerization, and disproportionation reactions were considered, as well as their occurred sequence. The results showed that H-abstraction reactions occurred more easily than H-dissociation reactions. The cis–trans conversion reactions in sub-routes of C2H3-Path and C4H4-Path provided the largest barriers of 51, 53, and 36 kcal/mol along their routes, which illustrated that the cis–trans isomerization was energetically costly in the PAH formation process. The entrance barriers of C2H2-Path, C2H3-Path, and C4H4-Path are 6, 8, and 3 kcal/mol, respectively, which indicates that it is easier to add C4H4 to C6H5 compared with adding C2H2 to C2H3. C2H3 additions were highly exothermic with reaction energies greater than 110 kcal/mol, and compared with C2H2 additions, C2H3 additions were irreversible. However, C2H2-Path, C2H3-Path and C4H4-Path involved energy barriers of 20, 32, and 36 kcal/mol, respectively. Considering the high temperature in combustion and the approximate concentrations of C2H3 and C4H4, all three of these pathways could lead to naphthalene in some combustion flames.
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Affiliation(s)
- Mingrui Wei
- Hubei Key Laboratory of Advanced Technology for Automotive Components & Hubei Collaborative Innovation Center for Automotive Components Technology, Wuhan University of Technology, Wuhan 430070, P. R. China
| | - Tingting Zhang
- Hubei Key Laboratory of Advanced Technology for Automotive Components & Hubei Collaborative Innovation Center for Automotive Components Technology, Wuhan University of Technology, Wuhan 430070, P. R. China
| | - Shunxi Li
- Hubei Key Laboratory of Advanced Technology for Automotive Components & Hubei Collaborative Innovation Center for Automotive Components Technology, Wuhan University of Technology, Wuhan 430070, P. R. China
| | - Guanlun Guo
- Hubei Key Laboratory of Advanced Technology for Automotive Components & Hubei Collaborative Innovation Center for Automotive Components Technology, Wuhan University of Technology, Wuhan 430070, P. R. China
| | - Dongju Zhang
- Key Lab of Colloid and Interface Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250000, P. R. China
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Parker DSN, Kaiser RI. On the formation of nitrogen-substituted polycyclic aromatic hydrocarbons (NPAHs) in circumstellar and interstellar environments. Chem Soc Rev 2017; 46:452-463. [DOI: 10.1039/c6cs00714g] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The chemical evolution of extraterrestrial environments leads to the formation of nitrogen substituted polycyclic aromatic hydrocarbons (NPAHs) via gas phase radical mediated aromatization reactions.
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Affiliation(s)
| | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawai’i at Manoa
- Honolulu
- USA
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14
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Thomas AM, Yang T, Dangi BB, Kaiser RI, Kim GS, Mebel AM. Oxidation of the para-Tolyl Radical by Molecular Oxygen under Single-Collison Conditions: Formation of the para-Toloxy Radical. J Phys Chem Lett 2016; 7:5121-5127. [PMID: 27973866 DOI: 10.1021/acs.jpclett.6b02357] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Crossed molecular beam experiments were performed to elucidate the chemical dynamics of the para-tolyl (CH3C6H4) radical reaction with molecular oxygen (O2) at an average collision energy of 35.3 ± 1.4 kJ mol-1. Combined with theoretical calculations, the results show that para-tolyl is efficiently oxidized by molecular oxygen to para-toloxy (CH3C6H4O) plus ground-state atomic oxygen via a complex forming, overall exoergic reaction (experimental, -33 ± 16 kJ mol-1; computational, -42 ± 8 kJ mol-1). The reaction dynamics are analogous to those observed for the phenyl (C6H5) plus molecular oxygen system which suggests the methyl group is a spectator during para-tolyl oxidation and that application of phenyl thermochemistry and reaction rates to para-substituted aryls is likely a suitable approximation.
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Ma̅noa , Honolulu, Hawaii 96822, United States
| | - Tao Yang
- Department of Chemistry, University of Hawai'i at Ma̅noa , Honolulu, Hawaii 96822, United States
| | - Beni B Dangi
- Department of Chemistry, University of Hawai'i at Ma̅noa , Honolulu, Hawaii 96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Ma̅noa , Honolulu, Hawaii 96822, United States
| | - Gap-Sue Kim
- Dharma College, Dongguk University , 30, Pildong-ro 1-gil, Jung-gu, Seoul 04620, South Korea
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University , Miami, Florida 33199, United States
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15
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Parker DSN, Yang T, Dangi BB, Kaiser RI, Bera PP, Lee TJ. LOW TEMPERATURE FORMATION OF NITROGEN-SUBSTITUTED POLYCYCLIC AROMATIC HYDROCARBONS (PANHs)—BARRIERLESS ROUTES TO DIHYDRO(iso)QUINOLINES. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/0004-637x/815/2/115] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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Zhou W, Feng X, Yu S, Xia Z, Chen Y, Chen Z. An Efficient Synthesis of 2,4-Dichloro-3,5-Difluorobenzoic Acid. JOURNAL OF CHEMICAL RESEARCH 2015. [DOI: 10.3184/174751915x14358518790739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
2,4-Dichloro-3,5-difluorobenzoic acid was synthesised from the commercially available 4-chloro-3,5-difluorobenzonitrile in good yield by a reaction sequence involving nitration, selective reduction, diazotisation and chlorination.
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Affiliation(s)
- Weiyou Zhou
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou 213164, P.R. China
| | - Xiaohu Feng
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Shuitao Yu
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Zhengjun Xia
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Yang Chen
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Zaixin Chen
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
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17
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Yu S, Zhou W, Xia Z, Lin S, Chen Z. An Efficient Synthesis of 5-Chloro-2, 3, 4-Trifluorobenzoic Acid. JOURNAL OF CHEMICAL RESEARCH 2015. [DOI: 10.3184/174751915x14322269913981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
5-Chloro-2, 3, 4-trifluorobenzoic acid, a key intermediate for preparing quinolone-3-carboxylic acid derivatives, was synthesised from the commercially available 2, 3, 4, 5-trifluorobenzoic acid in excellent yield by a reaction sequence involving nitration, selective reduction, diazotisation and chlorination.
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Affiliation(s)
- Shuitao Yu
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Weiyou Zhou
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou 213164, P.R. China
| | - Zhengjun Xia
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Song Lin
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Zaixin Chen
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
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18
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Zhou W, Yu S, Xia Z, Zhang M, Lin S, Chen Z. An Efficient Synthesis of 2,4-Difluoro-3,5-Dichlorobenzoic Acid. JOURNAL OF CHEMICAL RESEARCH 2015. [DOI: 10.3184/174751915x14295255352061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
2,4-Difluoro-3,5-dichlorobenzoic acid, as a key intermediate for preparing quinolone-3-carboxylic acids, was synthesised from the commercially available 2,4-difluoro-3-chlorobenzoic acid in excellent yield by a reaction sequence involving nitration, selective reduction, diazotisation and chlorination.
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Affiliation(s)
- Weiyou Zhou
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Changzhou University, Changzhou 213164, P.R. China
| | - Shuitao Yu
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Zhengjun Xia
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Mingguang Zhang
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Song Lin
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
| | - Zaixin Chen
- Yabang Medical Research Institute, Changzhou 213145, P.R. China
- Jiangsu Novel Quinolone Antibacterial Drugs Engineering Research Center, Changzhou 213145, P.R. China
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19
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Kaiser RI, Parker DS, Mebel AM. Reaction Dynamics in Astrochemistry: Low-Temperature Pathways to Polycyclic Aromatic Hydrocarbons in the Interstellar Medium. Annu Rev Phys Chem 2015; 66:43-67. [DOI: 10.1146/annurev-physchem-040214-121502] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822;
| | - Dorian S.N. Parker
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822;
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199
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20
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Yang T, Parker DSN, Dangi BB, Kaiser RI, Mebel AM. Formation of 5- and 6-methyl-1H-indene (C10H10) via the reactions of the para-tolyl radical (C6H4CH3) with allene (H2CCCH2) and methylacetylene (HCCCH3) under single collision conditions. Phys Chem Chem Phys 2015; 17:10510-9. [DOI: 10.1039/c4cp04288c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Flux contour map for the reactions of the p-tolyl radical with allene-d4 and methylacetylene-d4 at collision energies of around 48 kJ mol−1.
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Affiliation(s)
- Tao Yang
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | | | - Beni B. Dangi
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
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21
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Muzangwa LG, Yang T, Parker DSN, Kaiser RI, Mebel AM, Jamal A, Ryazantsev M, Morokuma K. A crossed molecular beam and ab initio study on the formation of 5- and 6-methyl-1,4-dihydronaphthalene (C11H12) via the reaction of meta-tolyl (C7H7) with 1,3-butadiene (C4H6). Phys Chem Chem Phys 2015; 17:7699-706. [DOI: 10.1039/c5cp00311c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crossed molecular beam reactions of the meta-tolyl radical with 1,3-butadiene and D6-1,3-butadiene were conducted at collision energies of 48.5 kJ mol−1 and 51.7 kJ mol−1.
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Affiliation(s)
| | - Tao Yang
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | | | - Ralf. I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
| | - Adeel Jamal
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation
- Emory University
- Atlanta
- USA
| | - Mikhail Ryazantsev
- Biomolecular NMR Laboratory
- St. Petersburg State University
- St. Petersburg
- Russia
| | - Keiji Morokuma
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation
- Emory University
- Atlanta
- USA
- Fukui Institute for Fundamental Chemistry
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22
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Yang T, Muzangwa L, Parker DSN, Kaiser RI, Mebel AM. Formation of 2- and 1-methyl-1,4-dihydronaphthalene isomers via the crossed beam reactions of phenyl radicals (C6H5) with isoprene (CH2C(CH3)CHCH2) and 1,3-pentadiene (CH2CHCHCHCH3). Phys Chem Chem Phys 2015; 17:530-40. [DOI: 10.1039/c4cp04612a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Crossed molecular beam reactions were exploited to elucidate the chemical dynamics of the reactions of phenyl radicals with isoprene and with 1,3-pentadiene at a collision energy of 55 ± 4 kJ mol−1.
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Affiliation(s)
- Tao Yang
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Lloyd Muzangwa
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | | | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
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23
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Yang T, Muzangwa L, Kaiser RI, Jamal A, Morokuma K. A combined crossed molecular beam and theoretical investigation of the reaction of the meta-tolyl radical with vinylacetylene – toward the formation of methylnaphthalenes. Phys Chem Chem Phys 2015. [DOI: 10.1039/c5cp03285g] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Flux contour map for the reactive scattering channel of meta-tolyl radical with vinylacetylene.
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Affiliation(s)
- Tao Yang
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Lloyd Muzangwa
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Adeel Jamal
- Fukui Institute for Fundamental Chemistry
- Kyoto University
- Sakyo
- Japan
| | - Keiji Morokuma
- Fukui Institute for Fundamental Chemistry
- Kyoto University
- Sakyo
- Japan
- Department of Chemistry and Cherry L. Emerson Center for Scientific Computation
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24
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Parker DSN, Kaiser RI, Kostko O, Troy TP, Ahmed M, Sun BJ, Chen SH, Chang AHH. On the formation of pyridine in the interstellar medium. Phys Chem Chem Phys 2015; 17:32000-8. [DOI: 10.1039/c5cp02960k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The nitrogen bearing aromatic molecule pyridine (C5H5N) is revealed to form in high temperature environments simulating conditions in carbon-rich circumstellar envelopes via the reaction of the cyano vinyl radical with vinyl cyanide.
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Affiliation(s)
| | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Oleg Kostko
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Tyler P. Troy
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Musahid Ahmed
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Bing-Jian Sun
- Department of Chemistry
- National Dong Hwa University
- Shoufeng
- Taiwan
| | - Shih-Hua Chen
- Department of Chemistry
- National Dong Hwa University
- Shoufeng
- Taiwan
| | - A. H. H. Chang
- Department of Chemistry
- National Dong Hwa University
- Shoufeng
- Taiwan
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25
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Parker DSN, Dangi BB, Kaiser RI, Jamal A, Ryazantsev M, Morokuma K. Formation of 6-methyl-1,4-dihydronaphthalene in the reaction of the p-tolyl radical with 1,3-butadiene under single-collision conditions. J Phys Chem A 2014; 118:12111-9. [PMID: 25407848 DOI: 10.1021/jp509990u] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Crossed molecular beam reactions of p-tolyl (C7H7) plus 1,3-butadiene (C4H6), p-tolyl (C7H7) plus 1,3-butadiene-d6 (C4D6), and p-tolyl-d7 (C7D7) plus 1,3-butadiene (C4H6) were carried out under single-collision conditions at collision energies of about 55 kJ mol(-1). 6-Methyl-1,4-dihydronaphthalene was identified as the major reaction product formed at fractions of about 94% with the monocyclic isomer (trans-1-p-tolyl-1,3-butadiene) contributing only about 6%. The reaction is initiated by barrierless addition of the p-tolyl radical to the terminal carbon atom of the 1,3-butadiene via a van der Waals complex. The collision complex isomerizes via cyclization to a bicyclic intermediate, which then ejects a hydrogen atom from the bridging carbon to form 6-methyl-1,4-dihydronaphthalene through a tight exit transition state located about 27 kJ mol(-1) above the separated products. This is the dominant channel under the present experimental conditions. Alternatively, the collision complex can also undergo hydrogen ejection to form trans-1-p-tolyl-1,3-butadiene; this is a minor contributor to the present experiment. The de facto barrierless formation of a methyl-substituted aromatic hydrocarbons by dehydrogenation via a single event represents an important step in the formation of polycyclic aromatic hydrocarbons (PAHs) and their partially hydrogenated analogues in combustion flames and the interstellar medium.
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Affiliation(s)
- Dorian S N Parker
- Department of Chemistry, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
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Kaiser RI, Dangi BB, Yang T, Parker DSN, Mebel AM. Reaction dynamics of the 4-methylphenyl radical (p-tolyl) with 1,2-butadiene (1-methylallene): are methyl groups purely spectators? J Phys Chem A 2014; 118:6181-90. [PMID: 25084134 DOI: 10.1021/jp505868q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactions of the 4-tolyl radical (C6H4CH3) and of the D7-4-tolyl radical (C6D4CD3) with 1,2-butadiene (C4H6) have been probed in crossed molecular beams under single collision conditions at a collision energy of about 54 kJ mol(-1) and studied theoretically using ab initio G3(MP2,CC)//B3LYP/6-311G** and statistical RRKM calculations. The results show that the reaction proceeds via indirect scattering dynamics through the formation of a van-der-Waals complex followed by the addition of the radical center of the 4-tolyl radical to the C1 or C3 carbon atoms of 1,2-butadiene. The collision complexes then isomerize by migration of the tolyl group from the C1 (C3) to the C2 carbon atom of the 1,2-butadiene moiety. The resulting intermediate undergoes unimolecular decomposition via elimination of a hydrogen atom from the methyl group of the 1,2-butadiene moiety through a rather loose exit transition state leading to 2-para-tolyl-1,3-butadiene (p4), which likely presents the major reaction product. Our observation combined with theoretical calculations suggest that one methyl group (at the phenyl group) acts as a spectator in the reaction, whereas the other one (at the allene moiety) is actively engaged in the underlying chemical dynamics. On the contrary to the reaction of the phenyl radical with allene, which leads to the formation of indene, the substitution of a hydrogen atom by a methyl group in allene essentially eliminates the formation of bicyclic PAHs such as substituted indenes in the 4-tolyl plus 1,2-butadiene reaction.
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Affiliation(s)
- Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa , Honolulu, Hawaii 96822, United States
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