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Turner AM, Marks JH, Luo Y, Lechner JT, Klapötke TM, Sun R, Kaiser RI. Electron-Induced Decomposition of Solid 1,1-Diamino-2,2-dinitroethylene (FOX-7) at Cryogenic Temperatures. J Phys Chem A 2023; 127:3390-3401. [PMID: 37027514 DOI: 10.1021/acs.jpca.3c01035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
Abstract
Solid FOX-7 (1,1-diamino-2,2-dinitroethylene), an energetic material of interest due to its high stability and low shock/thermal sensitivity, was exposed to energetic electrons at 5 K to explore the fundamental mechanisms leading to decomposition products and provide a better understanding of the reaction pathways involved. As a result of the radiation exposure, infrared spectroscopy revealed carbon dioxide (CO2) and carbon monoxide (CO) trapped in the FOX-7 matrix, while these compounds along with water (H2O), nitrogen monoxide (NO), and cyanogen (C2N2) were detected exploiting quadrupole mass spectrometry both during irradiation and during the warming phase from 5 to 300 K. Photoionization reflectron time-of-flight mass spectrometry detected small molecules such as ammonia (NH3), nitrogen monoxide (NO), and nitrogen dioxide (NO2) as well as more complex molecules up to 96 amu. Potential reaction pathways are presented and assignments are discussed. Among the reaction mechanisms, the importance of an initial nitro-to-nitrite isomerization is highlighted by the observed decomposition products.
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Affiliation(s)
- Andrew M Turner
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Joshua H Marks
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Yuheng Luo
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Jasmin T Lechner
- Department of Chemistry, Ludwig-Maximilian University of Munich, München 81377, Germany
| | - Thomas M Klapötke
- Department of Chemistry, Ludwig-Maximilian University of Munich, München 81377, Germany
| | - Rui Sun
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
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Turner AM, Luo Y, Marks JH, Sun R, Lechner JT, Klapötke TM, Kaiser RI. Exploring the Photochemistry of Solid 1,1-Diamino-2,2-dinitroethylene (FOX-7) Spanning Simple Bond Ruptures, Nitro-to-Nitrite Isomerization, and Nonadiabatic Dynamics. J Phys Chem A 2022; 126:4747-4761. [PMID: 35852300 DOI: 10.1021/acs.jpca.2c02696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The UV photolysis of solid FOX-7 at 5 K with 355 and 532 nm photons was investigated to unravel initial isomerization and decomposition pathways. Isomer-selective single photon ionization coupled with reflectron time-of-flight mass spectrometry (ReTOF-MS) documented the nitric oxide (NO) loss channel at 355 nm along with a nitro-to-nitrite isomerization, which was observed by using infrared spectroscopy, representing the initial reaction pathway followed by O─NO bond rupture of the nitrite moiety. A residual gas analyzer detected molecular oxygen for the 355 and 532 nm photolysis at a ratio of 4.3 ± 0.3:1, which signifies FOX-7 as an energetic material that provides its own oxidant once the decomposition starts. Overall branching ratios for molecular oxygen versus nitric oxide were derived to be 700 ± 100:1 at 355 nm. It is notable that this is the first time that molecular oxygen was detected as a decomposition product of FOX-7. Computations show that atomic oxygen, which later combines to form molecular oxygen, is likely released from a nitro group involving conical intersections. The condensed phase potential energy profile computed at the CCSD(T) and CASPT2 level correlates well with the experiments and highlights the critical roles of conical intersections, nonadiabatic dynamics, and the encapsulated environment that dictate the mechanism of the reaction through intermolecular hydrogen bonds.
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Affiliation(s)
- Andrew M Turner
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Yuheng Luo
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Joshua H Marks
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Rui Sun
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
| | - Jasmin T Lechner
- Department of Chemistry, Ludwig-Maximilian University of Munich, 81377 München, Germany
| | - Thomas M Klapötke
- Department of Chemistry, Ludwig-Maximilian University of Munich, 81377 München, Germany
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii, Honolulu, Hawaii 96822, United States
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Klapötke TM, Krumm B, Lechner JT, Stierstorfer J. Investigation of deuterated FOX-7 - changes in structural behavior and energetic characteristics after deuteration under ambient conditions. Dalton Trans 2022; 51:5788-5791. [PMID: 35355028 DOI: 10.1039/d2dt00490a] [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
For an investigation of the deuterium effect of N-deuterated compounds on the structural and thermal behavior, 1,1-diamino-2,2-dinitroethylene (FOX-7) was deuterated by deprotonation in heavy water and subsequent acidification with D2SO4. The status of deuteration progress was monitored by infrared spectra analysis and the deuteration level was determined via1H q-NMR. The properties of FOX-7-D4 were studied by single crystal X-ray diffraction and differential thermal analysis. In addition, the activation energy of thermal decomposition was determined, and the heat of formation and zero-point energy were calculated.
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Affiliation(s)
- Thomas M Klapötke
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstr. 5-13(D), Munich 81377, Germany.
| | - Burkhard Krumm
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstr. 5-13(D), Munich 81377, Germany.
| | - Jasmin T Lechner
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstr. 5-13(D), Munich 81377, Germany.
| | - Jörg Stierstorfer
- Department of Chemistry, Ludwig Maximilian University of Munich, Butenandtstr. 5-13(D), Munich 81377, Germany.
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Chang P, Zhou P, Liu J, Yin S. Theoretical study on autocatalytic reaction in thermal decomposition of nitromethane. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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A vacuum ultraviolet photoionization study on the isomerization, decomposition, and molecular mass growth processes in solid nitromethane (CH3NO2). Chem Phys Lett 2021. [DOI: 10.1016/j.cplett.2021.138343] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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6
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Murga MS, Wiebe DS, Vasyunin AI, Varakin VN, Stolyarov AV. Experimental and theoretical studies of photoinduced reactions in the solid phase of the interstellar medium. RUSSIAN CHEMICAL REVIEWS 2020. [DOI: 10.1070/rcr4912] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Singh SK, La Jeunesse J, Vuppuluri V, Son SF, Sun B, Chen Y, Chang AHH, Mebel AM, Kaiser RI. The Elusive Ketene (H
2
CCO) Channel in the Infrared Multiphoton Dissociation of Solid 1,3,5‐Trinitro‐1,3,5‐Triazinane (RDX). Chemphyschem 2020; 21:837-842. [DOI: 10.1002/cphc.201901202] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/18/2020] [Indexed: 11/05/2022]
Affiliation(s)
- Santosh K. Singh
- Department of Chemistry W. M. Keck Research Laboratory in AstrochemistryUniversity of Hawaii Honolulu HI 96822 HI USA
| | - Jesse La Jeunesse
- Department of Chemistry W. M. Keck Research Laboratory in AstrochemistryUniversity of Hawaii Honolulu HI 96822 HI USA
| | - Vasant Vuppuluri
- Mechanical Engineering Purdue Energetics Research CenterPurdue University West Lafayette IN 47907 USA
| | - Steven F. Son
- Mechanical Engineering Purdue Energetics Research CenterPurdue University West Lafayette IN 47907 USA
| | - Bing‐Jian Sun
- Department of ChemistryNational Dong Hwa University Shoufeng, Hualien 974 Taiwan
| | - Yue‐Lin Chen
- Department of ChemistryNational Dong Hwa University Shoufeng, Hualien 974 Taiwan
| | - Agnes H. H. Chang
- Department of ChemistryNational Dong Hwa University Shoufeng, Hualien 974 Taiwan
| | - Alexander M. Mebel
- Department of Chemistry and BiochemistryFlorida International University Miami, Florida 33199 USA
| | - Ralf I. Kaiser
- Department of Chemistry W. M. Keck Research Laboratory in AstrochemistryUniversity of Hawaii Honolulu HI 96822 HI USA
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Singh SK, Zhu C, Vuppuluri V, Son SF, Kaiser RI. Probing the Reaction Mechanisms Involved in the Decomposition of Solid 1,3,5-Trinitro-1,3,5-triazinane by Energetic Electrons. J Phys Chem A 2019; 123:9479-9497. [PMID: 31589046 DOI: 10.1021/acs.jpca.9b08695] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The decomposition mechanisms of 1,3,5-trinitro-1,3,5-triazinane (RDX) have been explored over the past decades, but as of now, a complete picture on these pathways has not yet emerged, as evident from the discrepancies in proposed reaction mechanisms and the critical lack of products and intermediates observed experimentally. This study exploited a surface science machine to investigate the decomposition of solid-phase RDX by energetic electrons at a temperature of 5 K. The products formed during irradiation were monitored online and in situ via infrared and UV-vis spectroscopy, and products subliming in the temperature programmed desorption phase were probed with a reflectron time-of-flight mass spectrometer coupled with soft photoionization at 10.49 eV (ReTOF-MS-PI). Infrared spectroscopy revealed the formation of water (H2O), carbon dioxide (CO2), dinitrogen oxide (N2O), nitrogen monoxide (NO), formaldehyde (H2CO), nitrous acid (HONO), and nitrogen dioxide (NO2). ReTOF-MS-PI identified 38 cyclic and acyclic products arranged into, for example, dinitro, mononitro, mononitroso, nitro-nitroso, and amines species. Among these molecules, 21 products such as N-methylnitrous amide (CH4N2O), 1,3,5-triazinane (C3H9N3), and N-(aminomethyl)methanediamine (C2H9N3) were detected for the first time in laboratory experiments; mechanisms based on the gas phase and condensed phase calculations were exploited to rationalize the formation of the observed products. The present studies reveal a rich, unprecedented chemistry in the condensed phase decomposition of RDX, which is significantly more complex than the unimolecular gas phase decomposition of RDX, thus leading us closer to an understanding of the decomposition chemistry of nitramine-based explosives.
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Affiliation(s)
| | | | - Vasant Vuppuluri
- Mechanical Engineering, Purdue Energetics Research Center , Purdue University , 500 Allison Road , West Lafayette , Indiana 47907-2088 , United States
| | - Steven F Son
- Mechanical Engineering, Purdue Energetics Research Center , Purdue University , 500 Allison Road , West Lafayette , Indiana 47907-2088 , United States
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Abplanalp MJ, Kaiser RI. On the formation of complex organic molecules in the interstellar medium: untangling the chemical complexity of carbon monoxide-hydrocarbon containing ice analogues exposed to ionizing radiation via a combined infrared and reflectron time-of-flight analysis. Phys Chem Chem Phys 2019; 21:16949-16980. [PMID: 31339133 DOI: 10.1039/c9cp01793c] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recently, over 200 molecules have been detected in the interstellar medium (ISM), with about one third being complex organic molecules (COMs), molecules containing six or more atoms. Over the last few decades, astrophysical laboratory experiments have shown that several COMs are formed via interaction of ionizing radiation within ices deposited on interstellar dust particles at 10 K (H2O, CH3OH, CO, CO2, CH4, NH3). However, there is still a lack of understanding of the chemical complexity that is available through individual ice constituents. The present research investigates experimentally the synthesis of carbon, hydrogen, and oxygen bearing COMs from interstellar ice analogues containing carbon monoxide (CO) and methane (CH4), ethane (C2H6), ethylene (C2H4), or acetylene (C2H2) exposed to ionizing radiation. Utilizing online and in situ techniques, such as infrared spectroscopy and tunable photoionization reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), specific isomers produced could be characterized. A total of 12 chemically different groups were detected corresponding to C2HnO (n = 2, 4, 6), C3HnO (n = 2, 4, 6, 8), C4HnO (n = 4, 6, 8, 10), C5HnO (n = 4, 6, 8, 10), C6HnO (n = 4, 6, 8, 10, 12, 14), C2HnO2 (n = 2, 4), C3HnO2 (n = 4, 6, 8), C4HnO2 (n = 4, 6, 8, 10), C5HnO2 (n = 6, 8), C6HnO2 (n = 8, 10, 12), C4HnO3 (n = 4, 6, 8), and C5HnO3 (n = 6, 8). More than half of these isomer specifically identified molecules have been identified in the ISM, and the remaining COMs detected here can be utilized to guide future astronomical observations. Of these isomers, three groups - alcohols, aldehydes, and molecules containing two of these functional groups - displayed varying degrees of unsaturation. Also, the detection of 1-propanol, 2-propanol, 1-butanal, and 2-methyl-propanal has significant implications as the propyl and isopropyl moieties (C3H7), which have already been detected in the ISM via propyl cyanide and isopropyl cyanide, could be detected in our laboratory studies. General reaction mechanisms for their formation are also proposed, with distinct follow-up studies being imperative to elucidate the complexity of COMs synthesized in these ices.
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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. and Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Ralf I Kaiser
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA. and Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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10
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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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11
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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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Góbi S, Crandall PB, Maksyutenko P, Förstel M, Kaiser RI. Accessing the Nitromethane (CH3NO2) Potential Energy Surface in Methanol (CH3OH)–Nitrogen Monoxide (NO) Ices Exposed to Ionizing Radiation: An FTIR and PI-ReTOF-MS Investigation. J Phys Chem A 2018; 122:2329-2343. [DOI: 10.1021/acs.jpca.7b12235] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sándor Góbi
- Department of Chemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
- W. M. Keck Laboratory in Astrochemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Parker B. Crandall
- Department of Chemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
- W. M. Keck Laboratory in Astrochemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Pavlo Maksyutenko
- Department of Chemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
- W. M. Keck Laboratory in Astrochemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Marko Förstel
- Department of Chemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
- W. M. Keck Laboratory in Astrochemistry, 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
- W. M. Keck Laboratory in Astrochemistry, University of Hawai‘i at Ma̅noa, Honolulu, Hawaii 96822, United States
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13
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Maksyutenko P, Förstel M, Crandall P, Sun BJ, Wu MH, Chang AH, Kaiser RI. An isomer-specific study of solid nitromethane decomposition pathways – Detection of aci-nitromethane (H2CNO(OH)) and nitrosomethanol (HOCH2NO) intermediates. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Öberg KI. Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules. Chem Rev 2016; 116:9631-63. [DOI: 10.1021/acs.chemrev.5b00694] [Citation(s) in RCA: 255] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Karin I. Öberg
- Harvard-Smithsonian Center for Astrophysics, 60
Garden St., Cambridge, Massachusetts 02138, United States
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Turner AM, Abplanalp MJ, Kaiser RI. PROBING THE CARBON-PHOSPHORUS BOND COUPLING IN LOW-TEMPERATURE PHOSPHINE (PH 3)-METHANE (CH 4) INTERSTELLAR ICE ANALOGUES. THE ASTROPHYSICAL JOURNAL 2016; 819:97. [PMID: 30842683 PMCID: PMC6398962 DOI: 10.3847/0004-637x/819/2/97] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Phosphine, which has now been confirmed around the carbon-rich star IRC+10216, provides the first example of a phosphorus-containing single bond in interstellar or circumstellar media. While four compounds containing both phosphorus and carbon have been discovered, none contain a carbon-phosphorus single bond. Here, we show that this moiety is plausible from the reaction of phosphine with methane in electron-irradiated interstellar ice analogues. Fractional sublimation allows for detection of individual products at distinct temperatures using reflectron time-of-flight mass spectrometry (ReTOF) coupled with vacuum ultraviolet photoionization. This method produced phosphanes and methylphosphanes as large as P8H10 and CH3P8H9, which demonstrates that a phosphorus-carbon bond can readily form and that methylphosphanes sublime at 12-17 K higher temperatures than the non-organic phosphanes. Also, irradiated ices of phosphine with deuterated-methane untangle the reaction pathways through which these methylphosphanes were formed and identified radical recombination to be preferred over carbene/phosphinidene insertion reactions. In addition, these ReTOF results confirm that CH3PH2 and CH6P2 can form via insertion of carbene and phosphinidene and that the methylenediphosphine (PH2CH2PH2) isomer forms in the ices, although methylphosphine (CH3P2H3) is likely the more abundant isomer and that phosphanes and organophosphanes preferentially fragment via the loss of a phosphino group when photoionized. While the formation of methylphosphine is overall endoergic, the intermediates produced by interactions with energetic electrons proceed toward methylphosphine favorably and barrierlessly and provide plausible mechanisms toward hitherto unidentified interstellar compounds.
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Affiliation(s)
- Andrew M Turner
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Matthew J Abplanalp
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Ralf I Kaiser
- W. M. Keck Research Laboratory in Astrochemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
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Tsegaw YA, Sander W, Kaiser RI. Electron Paramagnetic Resonance Spectroscopic Study on Nonequilibrium Reaction Pathways in the Photolysis of Solid Nitromethane (CH3NO2) and D3-Nitromethane (CD3NO2). J Phys Chem A 2016; 120:1577-87. [PMID: 26863093 DOI: 10.1021/acs.jpca.5b12520] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thin films of nitromethane (CH3NO2) along with its isotopically labeled counterpart D3-nitromethane (CD3NO2) were photolyzed at discrete wavelength between 266 nm (4.7 eV) and 121 nm (10.2 eV) to explore the underlying mechanisms involved in the decomposition of model compounds of energetic materials in the condensed phase at 5 K. The chemical modifications of the ices were traced in situ via electron paramagnetic resonance, thus focusing on the detection of (hitherto elusive) reaction intermediates and products with unpaired electrons. These studies revealed the formation of two carbon-centered radicals [methyl (CH3), nitromethyl (CH2NO2)], one oxygen-centered radical [methoxy (CH3O)], two nitrogen-centered radicals [nitrogen monoxide (NO), nitrogen dioxide (NO2)], as well as atomic hydrogen (H). The decomposition products of these channels and the carbon-centered nitromethyl (CH2NO2) radical in particular represent crucial reaction intermediates leading via sequential molecular mass growth processes in the exposed nitromethane samples to complex organic molecules as predicted previously by dynamics calculations. The detection of the nitromethyl (CH2NO2) radical along with atomic hydrogen (H) demonstrated the existence of a high-energy decomposition pathway, which is closed under collisionless conditions in the gas phase.
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Affiliation(s)
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II, Ruhr-Universitat Bochum , 44801 Bochum, Germany
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
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Wei Y, Wang X, Wang X, Tao Z, Cui Y, Yang M. A theoretical study of the activation of nitromethane under applied electric fields. RSC Adv 2016. [DOI: 10.1039/c6ra00724d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
C–N activation is the key step of nitromethane decomposition.
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Affiliation(s)
- Yuan Wei
- Institute of Atomic and Molecular Physics
- Key Laboratory of High Energy Density
- Physics and Technology of Ministry of Education
- Sichuan University
- Chengdu
| | - Xinqin Wang
- Institute of Atomic and Molecular Physics
- Key Laboratory of High Energy Density
- Physics and Technology of Ministry of Education
- Sichuan University
- Chengdu
| | - Xin Wang
- College of Chemistry
- Sichuan University
- Chengdu
- China
| | - Zhiqiang Tao
- College of Chemistry
- Sichuan University
- Chengdu
- China
| | - Yingqi Cui
- Institute of Atomic and Molecular Physics
- Key Laboratory of High Energy Density
- Physics and Technology of Ministry of Education
- Sichuan University
- Chengdu
| | - Mingli Yang
- Institute of Atomic and Molecular Physics
- Key Laboratory of High Energy Density
- Physics and Technology of Ministry of Education
- Sichuan University
- Chengdu
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18
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Turner AM, Abplanalp MJ, Chen SY, Chen YT, Chang AHH, Kaiser RI. A photoionization mass spectroscopic study on the formation of phosphanes in low temperature phosphine ices. Phys Chem Chem Phys 2015; 17:27281-91. [PMID: 26242769 PMCID: PMC6340707 DOI: 10.1039/c5cp02835c] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Isovalency rationalizes fundamental chemical properties of elements in the same group, but often fails to account for differences in the molecular structure due to the distinct atomic sizes and electron-pair repulsion of the isovalent atoms. With respect to main group V, saturated hydrides of nitrogen are limited to ammonia (NH3) and hydrazine (N2H4) along with ionic and/or metal-bound triazene (N3H5) and potentially tetrazene (N4H6). Here, we present a novel approach for synthesizing and detecting phosphanes formed via non-classical synthesis exploiting irradiation of phosphine ices with energetic electrons, subliming the newly formed phosphanes via fractionated sublimation, and detecting these species via reflectron time-of-flight mass spectrometry (ReTOF) coupled with vacuum ultraviolet (VUV) single photon ionization. This approach is able to synthesize, to separate, and to detect phosphanes as large as octaphosphane (P8H10), which far out-performs the traditional analytical tools of infrared spectroscopy and residual gas analysis via mass spectrometry coupled with electron impact ionization that could barely detect triphosphane (P3H5) thus providing an unconventional tool to prepare complex inorganic compounds such as a homologues series of phosphanes, which are difficult to synthesize via classical synthetic methods.
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Affiliation(s)
- Andrew M. Turner
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA. ; Tel: +1-808-956-5731
| | - Matthew J. Abplanalp
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA. ; Tel: +1-808-956-5731
| | - Si Y. Chen
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
| | - Yu T. Chen
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
| | - Agnes H. H. Chang
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA. ; Tel: +1-808-956-5731
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Mahmood A, Teixeira ES, Longo RL. Understanding the Reactivity and Regioselectivity of Methylation of Nitronates [R(1)R(2)CNO2](-) by CH3I in the Gas Phase. J Org Chem 2015; 80:8198-205. [PMID: 26181145 DOI: 10.1021/acs.joc.5b01273] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methylation of [R(1)R(2)CNO2](-), where R(1) = R(2) = H (1), R(1) = CH3 and R(2) = H (2), R(1) = R(2) = CH3 (3), and R(1) + R(2) = c-(CH2)2 (4), by CH3I was studied by an ab initio MP2/CBS method, RRKM theory, and kinetic simulations. Contrary to a previous proposal for the reaction mechanism, C-methylation is the preferred pathway of thermodynamics and kinetics. This is corroborated by the agreement between the calculated and experimental reactivity trend 4 ≫ 3 > 2 > 1. The regioselectivity toward C-alkylation is explained by the much larger exothermicity of this reaction channel compared to that of O-alkylation. The increase in reactivity with an increase in the crowdedness of the central carbon atom is explained by differences in sp(3) character at this atom and the decrease in the vibrational frequency associated with pyramidalization around this carbon atom.
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Affiliation(s)
- Ayyaz Mahmood
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Erico Souza Teixeira
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Ricardo L Longo
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
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A mechanistical study on non-equilibrium reaction pathways in solid nitromethane (CH3NO2) and D3-nitromethane (CD3NO2) upon interaction with ionizing radiation. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.04.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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