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Demireva M, Au K, Hansen N, Sheps L. Time-resolved quantification of key species and mechanistic insights in low-temperature tetrahydrofuran oxidation. Phys Chem Chem Phys 2024; 26:10357-10368. [PMID: 38502092 DOI: 10.1039/d3cp06227a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
We investigate the kinetics and report the time-resolved concentrations of key chemical species in the oxidation of tetrahydrofuran (THF) at 7500 torr and 450-675 K. Experiments are carried out using high-pressure multiplexed photoionization mass spectrometry (MPIMS) combined with tunable vacuum ultraviolet radiation from the Berkely Lab Advanced Light Source. Intermediates and products are quantified using reference photoionization (PI) cross sections, when available, and constrained by a global carbon balance tracking approach at all experimental temperatures simultaneously for the species without reference cross sections. From carbon balancing, we determine time-resolved concentrations for the ROO˙ and ˙OOQOOH radical intermediates, butanedial, and the combined concentration of ketohydroperoxide (KHP) and unsaturated hydroperoxide (UHP) products stemming from the ˙QOOH + O2 reaction. Furthermore, we quantify a product that we tentatively assign as fumaraldehyde, which arises from UHP decomposition via H2O or ˙OH + H loss. The experimentally derived species concentrations are compared with model predictions using the most recent literature THF oxidation mechanism of Fenard et al., (Combust. Flame, 2018, 191, 252-269). Our results indicate that the literature mechanism significantly overestimates THF consumption and the UHP + KHP concentration at our conditions. The model predictions are sensitive to the rate coefficient for the ROO˙ isomerization to ˙QOOH, which is the gateway for radical chain propagating and branching pathways. Comparisons with our recent results for cyclopentane (Demireva et al., Combust. Flame, 2023, 257, 112506) provide insights into the effect of the ether group on reactivity and highlight the need to determine accurate rate coefficients of ROO˙ isomerization and subsequent reactions.
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Affiliation(s)
- Maria Demireva
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
| | - Kendrew Au
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
| | - Nils Hansen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
| | - Leonid Sheps
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
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Asatryan R, Hudzik J, Swihart M. Intramolecular Catalytic Hydrogen Atom Transfer (CHAT). J Phys Chem A 2024; 128:2169-2190. [PMID: 38451855 DOI: 10.1021/acs.jpca.3c06794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2024]
Abstract
Intramolecular catalysis (IntraCat) is the acceleration of a process at one site of a molecule catalyzed by a functional group in the same molecule; an external agent such as a solvent typically facilitates it. Here, we report a general first-principles-based IntraCat mechanism, which strictly occurs within a single molecule with no coreagent being involved─we call it intramolecular catalytic transfer of hydrogen atoms (CHAT). A reactive part of a molecule (chat catalyst moiety or chat agent, represented by -OOH, -COOH, -SH, -CH2OH, -HPO4, or another bifunctional H-donor/acceptor group) catalyzes an interconversion process, such as keto-enol or amino-imino tautomerization, and cyclization in the same molecule, while being regenerated in the process. It can thus be regarded as an intramolecular version of the intermolecular H atom transfer processes mediated by an external molecular catalyst, e.g., dihydrogen, water, or a carboxylic acid. Earlier, we proposed a general mechanistic systematization of intermolecular processes, illustrated in the simplest case of the H2-mediated reactions classified as dihydrogen catalysis [Asatryan, R.; et al. Catal. Rev.: Sci. Eng., 2014, 56, 403-475]. Following this systematization, the CHAT catalysis belongs to the category of relay transfer of H atoms, albeit in an intramolecular manner. A broader class of intramolecular processes includes all types of H-transfer reactions stimulated by an H-migration, which we call self-catalyzed H atom transfer (SC-HAT). The CHAT mechanism comprises a subset of SC-HAT in which the catalytic moiety is regenerated (i.e., acts as a true catalyst and not a reagent). We provide several characteristic examples of CHAT mechanism based on detailed analysis of the corresponding potential energy surfaces. All such cases showed a dramatically reduced activation barrier relative to the corresponding uncatalyzed H-transfer reactions. For example, we show that CHAT can facilitate long-range H-migration in larger molecules and can occur multiple times in one molecule with multiple interconverting groups. It also facilitates amino-imino tautomerization of unsaturated GABA-analogues and peptides, as well as intramolecular cyclization processes to form heterocycles, e.g., oxygenated rings. CHAT pathways may also explain the pH-dependent increase of mutarotation rate of glucose-6-phosphate demonstrated in pioneering experiments that introduced the classical IntraCat concept. In addition, we identify a ground electronic state CHAT pathway as an alternative to the UV-promoted long-range molecular crane keto-enol conversion with a remarkably low activation energy. To initially assess the possible impact of the new keto-enol conversion pathway on combustion of n-alkanes, we present a detailed kinetic analysis of isomerization and decomposition of pentane-2,4-ketohydroperoxide (2,4-KHP). The results are compared with key alternative reactions, including direct dissociation and Korcek channels (for which a new alkyl group migration channel is also identified), revealing the competitiveness of the CHAT pathway across a range of conditions. Taken together, this work provides insight into a general class of reaction pathways that has not previously being systematically considered and that may occur in a broad range of contexts from combustion to atmospheric chemistry to biochemistry.
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Affiliation(s)
- Rubik Asatryan
- Department of Chemical and Biological Engineering, and Center for Hybrid Rocket Exascale Simulation Technology (CHREST), University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Jason Hudzik
- Department of Chemical and Biological Engineering, and Center for Hybrid Rocket Exascale Simulation Technology (CHREST), University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Mark Swihart
- Department of Chemical and Biological Engineering, and Center for Hybrid Rocket Exascale Simulation Technology (CHREST), University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
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He C, Kaiser RI, Lu W, Ahmed M, Pivovarov PS, Kuznetsov OV, Zagidullin MV, Mebel AM. Unconventional Pathway in the Gas-Phase Synthesis of 9H-Fluorene (C 13 H 10 ) via the Radical-Radical Reaction of Benzyl (C 7 H 7 ) with Phenyl (C 6 H 5 ). Angew Chem Int Ed Engl 2023; 62:e202216972. [PMID: 36524679 DOI: 10.1002/anie.202216972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/16/2022] [Accepted: 12/16/2022] [Indexed: 12/23/2022]
Abstract
The simplest polycyclic aromatic hydrocarbon (PAH) carrying a five-membered ring-9H-fluorene (C13 H10 )-is produced isomer-specifically in the gas phase by reacting benzyl (C7 H7 ⋅) with phenyl (C6 H5 ⋅) radicals in a pyrolytic reactor coupled with single photon ionization mass spectrometry. The unconventional mechanism of reaction is supported by theoretical calculations, which first produces diphenylmethane and unexpected 1-(6-methylenecyclohexa-2,4-dienyl)benzene intermediates (C13 H12 ) accessed via addition of the phenyl radical to the ortho position of the benzyl radical. These findings offer convincing evidence for molecular mass growth processes defying conventional wisdom that radical-radical reactions are initiated through recombination at their radical centers. The structure of 9H-fluorene acts as a molecular building block for complex curved nanostructures like fullerenes and nanobowls providing fundamental insights into the hydrocarbon evolution in high temperature settings.
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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
| | - Pavel S Pivovarov
- Samara National Research University, Samara, 443086, Russian Federation
| | - Oleg V Kuznetsov
- Samara National Research University, Samara, 443086, Russian Federation
| | | | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL-33199, USA
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Kang S, Liao W, Chu Z, Yang B. A rapid compression machine coupled with time-resolved molecular beam mass spectrometry for gas-phase kinetics studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:084103. [PMID: 34470393 DOI: 10.1063/5.0055585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 07/25/2021] [Indexed: 06/13/2023]
Abstract
Rapid compression machines (RCMs) are used to simulate a single stroke of an internal combustion engine. After a high-speed compression process, a high-pressure and low-to-intermediate temperature condition can be obtained, under which ignition processes are usually studied. With the help of different diagnostic methods, the detailed speciation information of the ignition process can be quantified. In this study, the molecular beam mass spectrometry (MBMS) diagnostic method was applied on an RCM to realize time-resolved concentration profile measurements. To realize the combination between RCM and MBMS, particle dampers were adopted to suppress the vibrations of the RCM, and a novel flexible interface was designed to maintain a high vacuum, which ensured the safe and effective operation of a high-repetition-rate time-of-flight mass spectrometer (HRR-TOF-MS). The detailed configuration of this diagnostic method is presented, and the data acquisition system and data analysis method are described. The arrangement was validated through the investigation of the well-studied decomposition of 1,3,5-trioxane at temperatures between 697 and 777 K at 10 bars. The measured concentration profiles of 1,3,5-trioxane and formaldehyde were in good agreement with previous experimental and theoretical calculation results. The experimental results showed that the newly developed RCM coupled with the HRR-TOF-MS has advantages in time-resolved speciation measurements at low-to-intermediate temperatures and high pressures, and it can be applied in low-temperature combustion chemical kinetics studies.
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Affiliation(s)
- Shiqing Kang
- Center for Combustion Energy and Key Laboratory for Thermal Science and Power Engineering of MOE, Tsinghua University, Beijing 100084, China
| | - Wanxiong Liao
- Center for Combustion Energy and Key Laboratory for Thermal Science and Power Engineering of MOE, Tsinghua University, Beijing 100084, China
| | - Zhaohan Chu
- Center for Combustion Energy and Key Laboratory for Thermal Science and Power Engineering of MOE, Tsinghua University, Beijing 100084, China
| | - Bin Yang
- Center for Combustion Energy and Key Laboratory for Thermal Science and Power Engineering of MOE, Tsinghua University, Beijing 100084, China
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Zhou B, Huang E, Almeida R, Gurses S, Ungar A, Zetterberg J, Kulkarni A, Kronawitter CX, Osborn DL, Hansen N, Frank JH. Near-Surface Imaging of the Multicomponent Gas Phase above a Silver Catalyst during Partial Oxidation of Methanol. ACS Catal 2020. [DOI: 10.1021/acscatal.0c04396] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Bo Zhou
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
- Department of Mechanics and Aerospace Engineering, Southern University of Science and Technology, Shenzhen 518055, P. R. China
| | - Erxiong Huang
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Raybel Almeida
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Sadi Gurses
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Alexander Ungar
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Johan Zetterberg
- Division of Combustion Physics, Lund University, Lund SE-221 00, Sweden
| | - Ambarish Kulkarni
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Coleman X. Kronawitter
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - David L. Osborn
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Nils Hansen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - Jonathan H. Frank
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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Rousso AC, Jasper AW, Ju Y, Hansen N. Extreme Low-Temperature Combustion Chemistry: Ozone-Initiated Oxidation of Methyl Hexanoate. J Phys Chem A 2020; 124:9897-9914. [PMID: 33174431 DOI: 10.1021/acs.jpca.0c07584] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The accelerating chemical effect of ozone addition on the oxidation chemistry of methyl hexanoate [CH3(CH2)4C(═O)OCH3] was investigated over a temperature range from 460 to 940 K. Using an externally heated jet-stirred reactor at p = 700 Torr (residence time τ = 1.3 s, stoichiometry φ = 0.5, 80% argon dilution), we explored the relevant chemical pathways by employing molecular-beam mass spectrometry with electron and single-photon ionization to trace the temperature dependencies of key intermediates, including many hydroperoxides. In the absence of ozone, reactivity is observed in the so-called low-temperature chemistry (LTC) regime between 550 and 700 K, which is governed by hydroperoxides formed from sequential O2 addition and isomerization reactions. At temperatures above 700 K, we observed the negative temperature coefficient (NTC) regime, in which the reactivity decreases with increasing temperatures, until near 800 K, where the reactivity increases again. Upon addition of ozone (1000 ppm), the overall reactivity of the system is dramatically changed due to the time scale of ozone decomposition in comparison to fuel oxidation time scales of the mixtures at different temperatures. While the LTC regime seems to be only slightly affected by the addition of ozone with respect to the identity and quantity of the observed intermediates, we observed an increased reactivity in the intermediate NTC temperature range. Furthermore, we observed experimental evidence for an additional oxidation regime in the range near 500 K, herein referred to as the extreme low-temperature chemistry (ELTC) regime. Experimental evidence and theoretical rate constant calculations indicate that this ELTC regime is likely to be initiated by H abstraction from methyl hexanoate via O atoms, which originate from thermal O3 decomposition. The theoretical calculations show that the rate constants for methyl ester initiation via abstraction by O atoms increase dramatically with the size of the methyl ester, suggesting that ELTC is likely not important for the smaller methyl esters. Experimental evidence is provided indicating that, similar to the LTC regime, the chemistry in the ELTC regime is dominated by hydroperoxide chemistry. However, mass spectra recorded at various reactor temperatures and at different photon energies provide experimental evidence of some differences in chemical species between the ELTC and the LTC temperature ranges.
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Affiliation(s)
- Aric C Rousso
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Ahren W Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Yiguang Ju
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Nils Hansen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
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Doner AC, Davis MM, Koritzke AL, Christianson MG, Turney JM, Schaefer HF, Sheps L, Osborn DL, Taatjes CA, Rotavera B. Isomer‐dependent reaction mechanisms of cyclic ether intermediates:cis‐2,3‐dimethyloxirane andtrans‐2,3‐dimethyloxirane. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21429] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Anna C. Doner
- Department of Chemistry University of Georgia Athens GA USA
| | - Matthew M. Davis
- Department of Chemistry University of Georgia Athens GA USA
- Center for Computational Quantum Chemistry University of Georgia Athens GA USA
| | | | | | - Justin M. Turney
- Center for Computational Quantum Chemistry University of Georgia Athens GA USA
| | - Henry F. Schaefer
- Department of Chemistry University of Georgia Athens GA USA
- Center for Computational Quantum Chemistry University of Georgia Athens GA USA
| | - Leonid Sheps
- Combustion Research Facility Sandia National Laboratories Livermore CA USA
| | - David L. Osborn
- Combustion Research Facility Sandia National Laboratories Livermore CA USA
| | - Craig A. Taatjes
- Combustion Research Facility Sandia National Laboratories Livermore CA USA
| | - Brandon Rotavera
- Department of Chemistry University of Georgia Athens GA USA
- College of Engineering University of Georgia Athens GA USA
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He X, Hansen N, Moshammer K. Molecular-Weight Growth in Ozone-Initiated Low-Temperature Oxidation of Methyl Crotonate. J Phys Chem A 2020; 124:7881-7892. [PMID: 32893634 DOI: 10.1021/acs.jpca.0c05684] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report experiments of ozone-initiated low-temperature oxidation of methyl crotonate (MC, CH3-CH═CH-C(O)OCH3) from 420 to 660 K in a near-atmospheric-pressure jet-stirred reactor using photoionization molecular-beam mass spectrometry as a sampling technique. In this temperature regime, no typical low-temperature combustion (LTC) reactions have been observed for MC when oxygen (O2) is used as the oxidizer. Upon ozone addition, significant oxidation of methyl crotonate is found. On the basis of experimentally observed energy-dependent mass peaks in combination with temperature-dependent mole fraction profiles and photoionization efficiency curves, we provide new insights into the methyl crotonate ozonolysis reaction network. The observed MC + O3 products, C5H8O5, are found to be related to the keto-hydroperoxides resulting from the isomerization of the primary ozonide. Evidence is also provided that molecular growth mainly results from cycloaddition reactions of the Criegee intermediate into aldehydes and alkenes as well as addition reactions of the Criegee intermediates to the double bond of methyl crotonate and sequential decomposition into ketones. Furthermore, species that contribute in large amounts to the low-temperature oxidation of methyl crotonate, like H2O2, CH3OOH, CH3OH, and HC(O)OH, are identified, and their mole fractions are reported. Additionally, preliminary modeling is performed which qualitatively captures the observed NTC behavior and reveals future research opportunities.
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Affiliation(s)
- X He
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany
| | - N Hansen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, United States
| | - K Moshammer
- Department of Physical Chemistry, Physikalisch-Technische Bundesanstalt (PTB), 38116 Braunschweig, Germany
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Christianson MG, Doner AC, Davis MM, Koritzke AL, Turney JM, Schaefer HF, Sheps L, Osborn DL, Taatjes CA, Rotavera B. Reaction mechanisms of a cyclic ether intermediate: Ethyloxirane. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21423] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Anna C. Doner
- Department of Chemistry University of Georgia Athens Georgia
| | - Matthew M. Davis
- Department of Chemistry University of Georgia Athens Georgia
- Center for Computational Quantum Chemistry University of Georgia Athens Georgia
| | | | - Justin M. Turney
- Center for Computational Quantum Chemistry University of Georgia Athens Georgia
| | - Henry F. Schaefer
- Department of Chemistry University of Georgia Athens Georgia
- Center for Computational Quantum Chemistry University of Georgia Athens Georgia
| | - Leonid Sheps
- Combustion Research Facility Sandia National Laboratories Livermore California
| | - David L. Osborn
- Combustion Research Facility Sandia National Laboratories Livermore California
| | - Craig A. Taatjes
- Combustion Research Facility Sandia National Laboratories Livermore California
| | - Brandon Rotavera
- Department of Chemistry University of Georgia Athens Georgia
- College of Engineering University of Georgia Athens Georgia
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