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Prozument K, Suleimanov YV, Buesser B, Oldham JM, Green WH, Suits AG, Field RW. A Signature of Roaming Dynamics in the Thermal Decomposition of Ethyl Nitrite: Chirped-Pulse Rotational Spectroscopy and Kinetic Modeling. J Phys Chem Lett 2014; 5:3641-3648. [PMID: 26278732 DOI: 10.1021/jz501758p] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chirped-pulse (CP) Fourier transform rotational spectroscopy is uniquely suited for near-universal quantitative detection and structural characterization of mixtures that contain multiple molecular and radical species. In this work, we employ CP spectroscopy to measure product branching and extract information about the reaction mechanism, guided by kinetic modeling. Pyrolysis of ethyl nitrite, CH3CH2ONO, is studied in a Chen type flash pyrolysis reactor at temperatures of 1000-1800 K. The branching between HNO, CH2O, and CH3CHO products is measured and compared to the kinetic models generated by the Reaction Mechanism Generator software. We find that roaming CH3CH2ONO → CH3CHO + HNO plays an important role in the thermal decomposition of ethyl nitrite, with its rate, at 1000 K, comparable to that of the radical elimination channel CH3CH2ONO → CH3CH2O + NO. HNO is a signature of roaming in this system.
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Affiliation(s)
| | | | - Beat Buesser
- §IBM Research, Smarter Cities Technology Centre, Dublin 15, Ireland
| | - James M Oldham
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | | | - Arthur G Suits
- ∥Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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Kidwell NM, Vaquero-Vara V, Ormond TK, Buckingham GT, Zhang D, Mehta-Hurt DN, McCaslin L, Nimlos MR, Daily JW, Dian BC, Stanton JF, Ellison GB, Zwier TS. Chirped-Pulse Fourier Transform Microwave Spectroscopy Coupled with a Flash Pyrolysis Microreactor: Structural Determination of the Reactive Intermediate Cyclopentadienone. J Phys Chem Lett 2014; 5:2201-2207. [PMID: 26279534 DOI: 10.1021/jz5010895] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Chirped-pulse Fourier transform microwave spectroscopy (CP-FTMW) is combined with a flash pyrolysis (hyperthermal) microreactor as a novel method to investigate the molecular structure of cyclopentadienone (C5H4═O), a key reactive intermediate in biomass decomposition and aromatic oxidation. Samples of C5H4═O were generated cleanly from the pyrolysis of o-phenylene sulfite and cooled in a supersonic expansion. The (13)C isotopic species were observed in natural abundance in both C5H4═O and in C5D4═O samples, allowing precise measurement of the heavy atom positions in C5H4═O. The eight isotopomers include: C5H4═O, C5D4═O, and the singly (13)C isotopomers with (13)C substitution at the C1, C2, and C3 positions. Microwave spectra were interpreted by CCSD(T) ab initio electronic structure calculations and an re molecular structure for C5H4═O was found. Comparisons of the structure of this "anti-aromatic" molecule are made with those of comparable organic molecules, and it is concluded that the disfavoring of the "anti-aromatic" zwitterionic resonance structure is consistent with a more pronounced C═C/C-C bond alternation.
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Affiliation(s)
- Nathanael M Kidwell
- †Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Vanesa Vaquero-Vara
- †Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Thomas K Ormond
- ‡National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
- ∥Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Grant T Buckingham
- ‡National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
- ∥Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Di Zhang
- †Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Deepali N Mehta-Hurt
- †Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - Laura McCaslin
- ¶Institute of Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - Mark R Nimlos
- ‡National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, United States
| | - John W Daily
- ⊥Center for Combustion and Environmental Research, Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309-0427, United States
| | - Brian C Dian
- †Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
| | - John F Stanton
- ¶Institute of Theoretical Chemistry, Department of Chemistry, University of Texas, Austin, Texas 78712, United States
| | - G Barney Ellison
- ∥Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, United States
| | - Timothy S Zwier
- †Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States
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