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Xu Q, Zhang J, Liu B, Wang H, Xu G, Gao J, Wang Z, Guan J. Probing the Reaction of Propargyl Radical with Molecular Oxygen by Synchrotron VUV Photoionization Mass Spectrometry. J Phys Chem A 2024; 128:7105-7113. [PMID: 39151122 DOI: 10.1021/acs.jpca.4c03294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2024]
Abstract
Self-reaction of propargyl (C3H3) radical is the main pathway to benzene, the formation of which is the rate-controlling step toward the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. Oxidation of C3H3 is a promising strategy to inhibit the formation of hazardous PAHs and soot. In the present study, we studied the C3H3 + O2 reaction from 650 to 1100 K in a laminar flow reactor and identified the intermediates and products by synchrotron VUV photoionization mass spectrometry. 2-Propynal, ethenone, formaldehyde, CO, CO2, C2H2, C2H4, and C3O2 were identified. Among them, 2-propynal, ethenone, and formaldehyde provided direct evidence for the branching reaction of C3H3 + O2 → HCCCHO + OH, C3H3 + O2 → H2CCO + CHO, and C3H3 + O2 → H2CO + CHCO, respectively. Potential energy surface calculation and mechanistic analysis of the C3O2 formations implied that C3H3 + O2 → CCCHO + H2O and C3H3 + O2 → HCCCO + H2O could occur, despite lacking direct observations of CCCHO and HCCCO radicals. The formation of ethenone and CO suggested the occurrence of the two CO elimination channels. We incorporated these validated reactions and the corresponding rate coefficients in the kinetic model of NUIGMech1.3, and the simulation showed obvious improvements toward the measured mole fractions of C3H3 and H2CCO, suggesting that the new C3H3 + O2 reaction channels were crucial in the overall combustion modeling of the important intermediate propyne (C3H4).
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Affiliation(s)
- Qiang Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
| | - Jinyang Zhang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
| | - Bingzhi Liu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
| | - Hong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
| | - Guangxian Xu
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
| | - Jiao Gao
- School of Pharmacy, Anhui Medical College, Hefei 230601, Anhui, P. R. China
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
- State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, Anhui, P. R. China
| | - Jiwen Guan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, P. R. China
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2
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Changala PB, McCarthy MC. Rotational Spectrum of the Phenoxy Radical. J Phys Chem Lett 2024:5063-5069. [PMID: 38701387 DOI: 10.1021/acs.jpclett.4c00962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
We report the hyperfine-resolved rotational spectrum of the gas-phase phenoxy radical in the 8-25 GHz frequency range using cavity Fourier transform microwave spectroscopy. A complete assignment of its complex but well-resolved fine and hyperfine splittings yielded a precisely determined set of rotational constants, spin-rotation parameters, and nuclear hyperfine coupling constants. These results are interpreted with support from high-level quantum chemical calculations to gain detailed insight into the distribution of the unpaired π electron in this prototypical resonance-stabilized radical. The accurate laboratory rest frequencies enable studies of the chemistry of phenoxy in both the laboratory and space. The prospects of extending the present experimental and theoretical techniques to investigate the rotational spectra of isotopic variants and structural isomers of phenoxy and other important gas-phase radical intermediates that are yet undetected at radio wavelengths are discussed.
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Affiliation(s)
- P Bryan Changala
- Center for Astrophysics | Harvard & Smithsonian Cambridge, Massachusetts 02138, United States
| | - Michael C McCarthy
- Center for Astrophysics | Harvard & Smithsonian Cambridge, Massachusetts 02138, United States
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3
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Biswas S, Paul D, Dias N, Lu W, Ahmed M, Pantoya ML, Kaiser RI. Efficient Oxidative Decomposition of Jet-Fuel exo-Tetrahydrodicyclopentadiene (JP-10) by Aluminum Nanoparticles in a Catalytic Microreactor: An Online Vacuum Ultraviolet Photoionization Study. J Phys Chem A 2024; 128:1665-1684. [PMID: 38383985 DOI: 10.1021/acs.jpca.3c08125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
The oxidation of gas-phase exo-tetrahydrodicyclopentadiene (JP-10, C10H16) over aluminum nanoparticles (AlNP) has been explored between a temperature range of 300 and 1250 K with a novel chemical microreactor. The results are compared with those obtained from chemical microreactor studies of helium-seeded JP-10 and of helium-oxygen-seeded JP-10 without AlNP to gauge the effects of molecular oxygen and AlNP, respectively. Vacuum ultraviolet (VUV) photoionization mass spectrometry reveals that oxidative decomposition of JP-10 in the presence of AlNP is lowered by 350 and 200 K with and without AlNP, respectively, in comparison with pyrolysis of the fuel. Overall, 63 nascent gas-phase products are identified through photoionization efficiency (PIE) curves; these can be categorized as oxygenated molecules and their radicals as well as closed-shell hydrocarbons along with hydrocarbon radicals. Quantitative branching ratios of the products reveal diminishing yields of oxidized species and enhanced branching ratios of hydrocarbon species with the increase in temperature. While in the low-temperature regime (300-1000 K), AlNP solely acts as an efficient heat transfer medium, in the higher-temperature regime (1000-1250 K), chemical reactivity is triggered, facilitating the primary decomposition of the parent JP-10 molecule. This enhanced reactivity of AlNP could plausibly be linked to the exposed reactive surface of the aluminum (Al) core generated upon the rupture of the alumina shell material above the melting point of the metal (Al).
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Affiliation(s)
- Souvick Biswas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Dababrata Paul
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Nureshan Dias
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Michelle L Pantoya
- Mechanical Engineering Department, Texas Tech University, Lubbock, Texas 79409, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
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4
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Chang AM, Meisner J, Xu R, Martínez TJ. Efficient Acceleration of Reaction Discovery in the Ab Initio Nanoreactor: Phenyl Radical Oxidation Chemistry. J Phys Chem A 2023; 127:9580-9589. [PMID: 37934692 DOI: 10.1021/acs.jpca.3c05484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Over the years, many computational strategies have been employed to elucidate reaction networks. One of these methods is accelerated molecular dynamics, which can circumvent the expense required in dynamics to find all reactants and products (local minima) and transition states (first-order saddle points) on a potential energy surface (PES) by using fictitious forces that promote reaction events. The ab initio nanoreactor uses these accelerating forces to study large chemical reaction networks from first-principles quantum mechanics. In the initial nanoreactor studies, this acceleration was done through a piston periodic compression potential, which pushes molecules together to induce entropically unfavorable bimolecular reactions. However, the piston is not effective for discovering intramolecular and dissociative reactions, such as those integral to the decomposition channels of phenyl radical oxidation. In fact, the choice of accelerating forces dictates not only the rate of reaction discovery but also the types of reactions discovered; thus, it is critical to understand the biases and efficacies of these forces. In this study, we examine forces using metadynamics, attractive potentials, and local thermostats for accelerating reaction discovery. For each force, we construct a separate phenyl radical combustion reaction network using solely that force in discovery trajectories. We elucidate the enthalpic and entropic trends of each accelerating force and highlight their efficiency in reaction discovery. Comparing the nanoreactor-constructed reaction networks with literature renditions of the phenyl radical combustion PES shows that a combination of accelerating forces is best suited for reaction discovery.
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Affiliation(s)
- Alexander M Chang
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Jan Meisner
- Department of Chemistry, Heinrich-Heine-Universität Düsseldorf, Düsseldorf 40225, Germany
| | - Rui Xu
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
| | - Todd J Martínez
- Department of Chemistry and The PULSE Institute, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States
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5
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Biswas S, Paul D, He C, Dias N, Ahmed M, Pantoya ML, Kaiser RI. Counterintuitive Catalytic Reactivity of the Aluminum Oxide "Passivation" Shell of Aluminum Nanoparticles Facilitating the Thermal Decomposition of exo-Tetrahydrodicyclopentadiene (JP-10). J Phys Chem Lett 2023; 14:9341-9350. [PMID: 37820371 DOI: 10.1021/acs.jpclett.3c02532] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
High energy density aluminum nanoparticles (AlNPs) have been at the center of attention as additives to hydrocarbon jet fuels like exo-tetrahydrodicyclopentadiene (JP-10, C10H16) aiming at the superior performance of volume-limited air-breathing propulsion systems. However, a fundamental understanding of the ignition and combustion chemistry of JP-10 in the presence of AlNPs has been elusive. Exploiting an isomer-selective comprehensive identification of the decomposition products in a newly designed high-temperature chemical microreactor coupled to vacuum ultraviolet photoionization, we reveal an active low-temperature heterogeneous surface chemistry commencing at 650 K involving the alumina (Al2O3) shell. Contrary to textbook knowledge of an "inactive alumina surface", this unconventional reactivity, where oxygen is transferred from alumina to JP-10, leads to generating cyclic, oxygenated organics like phenol (C6H5OH) and 2,4-cyclopentadiene-1-one (C5H4O)─key tracers of an alumina-mediated interfacial chemistry. This counterintuitive reactivity transforms our knowledge of the (catalytic) processes of alumina-coated AlNPs on the molecular level.
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Affiliation(s)
- Souvick Biswas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Dababrata Paul
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Nureshan Dias
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Michelle L Pantoya
- Mechanical Engineering Department, Texas Tech University, Lubbock, Texas 79409, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
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6
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Feng B, Sanov A. Microsolvation of Hot Ions: Spectroscopy and Statistical Mechanics of Phenide-Water Interactions. J Phys Chem A 2023; 127:6437-6446. [PMID: 37498135 DOI: 10.1021/acs.jpca.3c02737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Thermal excitation alters the spectroscopic signatures of solvated ions and affects their interactions with neighboring molecules. By analyzing the photoelectron spectra of microhydrated phenide (Ph-), the temperatures of the Ph-·H2O and Ph-·(H2O)2 clusters from a hot ion source were determined to be 560 and 520 K, respectively, vs 700 K for unsolvated Ph-. Compared to theory predictions for cold clusters, the high temperature of the environment significantly reduces the average hydration stabilization of the ions and the corresponding band shifts in their spectra. The results are discussed in terms of a statistical model that describes the energy content of the intermolecular (IM) degrees of freedom of the cluster, ⟨EIM⟩. We show that over the entire solvation energy range, the density of states associated with the IM modes of Ph-·H2O, of which there are only 6, is more than an order of magnitude greater than that associated with the 27 internal vibrations of the core anion. The results suggest that the observed cluster temperatures are not determined by the ion source but represent the intrinsic properties of the clusters. The energetics and statistical mechanics of microsolvation limit the excitation that the IM degrees of freedom can sustain without significant solvent evaporation on the timescale of the experiment. The limit is expressed as a characteristic solvation temperature (CST), which is the maximum canonical temperature of a stable cluster ensemble. Driven by evaporative cooling, the terminal cluster temperature from a hot ion source will always be close to the cluster's CST. Only if the source temperature is lower than CST will the observed cluster temperature be determined by the source conditions. An approximate rule is proposed for estimating the characteristic temperature of any cluster using the inflection point on the ⟨EIM⟩ vs T curve.
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Affiliation(s)
- Beverly Feng
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
| | - Andrei Sanov
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona 85721, United States
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7
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Ru B, Sanov A. Photoelectron Spectra of Hot Polyatomic Ions: A Statistical Treatment of Phenide. J Phys Chem A 2022; 126:9423-9439. [DOI: 10.1021/acs.jpca.2c07361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Beverly Ru
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona85721, United States
| | - Andrei Sanov
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona85721, United States
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8
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Fernholz C, Bodi A, Hemberger P. Threshold Photoelectron Spectrum of the Phenoxy Radical. J Phys Chem A 2022; 126:9022-9030. [DOI: 10.1021/acs.jpca.2c06670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christin Fernholz
- Laboratory for Synchtrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, CH-5232Villigen, Switzerland
| | - Andras Bodi
- Laboratory for Synchtrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, CH-5232Villigen, Switzerland
| | - Patrick Hemberger
- Laboratory for Synchtrotron Radiation and Femtochemistry, Paul Scherrer Institute, Forschungsstrasse 111, CH-5232Villigen, Switzerland
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9
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Altarawneh M. Temperature-dependent profiles of dioxin-like toxicants from combustion of brominated flame retardants. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126879. [PMID: 34411962 DOI: 10.1016/j.jhazmat.2021.126879] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/22/2021] [Accepted: 08/09/2021] [Indexed: 06/13/2023]
Abstract
Literature provides detailed mechanisms underpinning the formation of a wide array of bromine (Br)-containing molecules with a prime focus on dioxin-like compounds. However, from a more applied point of view, the practical deployment of attained thermo-kinetic parameters remains inadequate in the absence of a robust kinetic model that connects bromine transformation at the molecular level with pertinent experimental observations. Herein and to fill in this gap, this study constructs a chemical kinetic model to account for the "homogenous gas phase" emission of Br-aromatic pollutants from the oxidative thermal decomposition of a monobromobenzene molecule (MBZ). The latter serves as a model compound for brominated flame retardants (BFRs) present in e-waste. The model consists of sub-mechanisms (that include reaction rate constants and thermochemical T-dependent functions) for HBr oxidation, combustion mechanism of C1-C6 species, bromine transformation, and synthesis of Br dioxin-like compounds. Reaction rate parameters were obtained for a large array of reactions that constitute the core of the model. For instance, the obtained activation energies for the initial pathways in the formation of brominated biphenyls reside in the range of ~15-45 kJ/mol. Considering oxidation of 5000 ppm MBZ in a plug flow reactor, the model reasonably predicts the temperature-dependent profiles (between 500 and 1200 °C at atmospheric pressure) of a few PBDD/Fs (i.e., polybrominated dibenzo-p-dioxins) isomers in reference to limited corresponding experimental measurements. Most Br dioxin-like compounds appear in the narrow temperature window of 600-1000 °C and achieve their highest abundance at molar yields in the range of 1.0-15 mmol/mol MBZ. A high load (100-120 mmol/mol MBZ) of brominated environmentally persistent free radicals (Br-EPFR) emerges and shifts from bromophenoxy radicals to bromocyclopentadienyl radicals around 700 °C. Oxidation of a 2-bromophenol molecule results in the formation of higher yields of Br-toxicants when compared with that of MBZ. The assembled model provides an informed hazards assessment into the potential emission inventories of Br-compounds in the gas phase at conditions encountered in real scenarios, such as open burning and primitive treatment of e-waste. Via an atomic-base understanding of the complex bromine chemistry and speciation, the model allows the underlying operational conditions that reduce the emission of Br-notorious pollutants to be surveyed and fine-tuned.
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Affiliation(s)
- Mohammednoor Altarawneh
- United Arab Emirates University, Department of Chemical and Petroleum Engineering, Sheikh Khalifa bin Zayed Street, Al-Ain 15551, United Arab Emirates.
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10
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Liang Y, Li J, Xue Y, Tan T, Jiang Z, He Y, Shangguan W, Yang J, Pan Y. Benzene decomposition by non-thermal plasma: A detailed mechanism study by synchrotron radiation photoionization mass spectrometry and theoretical calculations. JOURNAL OF HAZARDOUS MATERIALS 2021; 420:126584. [PMID: 34273887 DOI: 10.1016/j.jhazmat.2021.126584] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/16/2021] [Accepted: 07/03/2021] [Indexed: 05/15/2023]
Abstract
Non-thermal Plasma (NTP) catalysis is considered as one of the most promising technologies to address a wide range of environmental needs, such as volatile organic compounds (VOCs) and NOx removal. To meet the updated environmental emission standard, the NTP catalysis reaction system needs to be better understood and further optimized. In this work, the degradation process of benzene in NTP, which is still regarded as a "black box" process, was explored by synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS). For the first time, we observed over 20 representative species by PIMS and identified their structures accurately by photoionization efficiency (PIE) spectra. Phenol, acetylene and acrolein were recognized as the three main products. More intriguingly, concentration profiles demonstrated that a large amount of acrolein and also several higher-order products, which were usually neglected in previous research, were produced during the NTP destruction process. The details of the benzene degradation reaction mechanism, were finally established by the combination of SVUV-PIMS results, thermochemistry and theoretical calculations. This work helps to complete the mechanistic picture of plasma chemistry, which may be helpful on raveling the more complicated NTP catalysis mechanism in the future therefore contributing to design of improved NTP system for environmental applications.
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Affiliation(s)
- Yuting Liang
- Research Center for Combustion and Environmental Technology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jiayi Li
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yingying Xue
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China
| | - Ting Tan
- Laboratory of Theoretical and Computational Nanoscience, CAS Key Laboratory of Nanophotonic Materials and Devices, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhi Jiang
- Research Center for Combustion and Environmental Technology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yaoyu He
- Research Center for Combustion and Environmental Technology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wenfeng Shangguan
- Research Center for Combustion and Environmental Technology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Jiuzhong Yang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China
| | - Yang Pan
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, China
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11
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Chemical insights into the atmospheric oxidation of thiophene by hydroperoxyl radical. Sci Rep 2021; 11:13049. [PMID: 34158534 PMCID: PMC8219665 DOI: 10.1038/s41598-021-92221-z] [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: 04/13/2021] [Accepted: 06/08/2021] [Indexed: 11/08/2022] Open
Abstract
The reaction mechanisms and kinetics of thiophene oxidation reactions initiated by hydroperoxyl radical, and decomposition of the related intermediates and complexes, have been considered herein by using high-level DFT and ab initio calculations. The main energetic parameters of all stationary points of the suggested potential energy surfaces have been computed at the BD(T) and CCSD(T) methods, based on the geometries optimized at the B3LYP/6-311 + g(d,p) level of theory. Rate constants of bimolecular reactions (high-pressure limit rate constants) at temperatures from 300 to 3000 K for the first steps of the title reaction have been obtained through the conventional transition state theory (TST), while the pressure dependent rate constants and the rate constants of the second and other steps have been calculated employing the Rice-Ramsperger-Kassel-Marcus/Master equation (RRKM/ME). The results show that the rate constants of addition to α and β carbons have positive temperature dependence and negative pressure dependence. It is found that the additions of HO2 to the α and β carbons of thiophene in the initial steps of the title reaction are the most favored pathways. Also, the addition to the sulfur atom has a minor contribution. But, all efforts for simulating hydrogen abstraction reactions have been unsuccessful. In this complex oxidation reaction, about 12 different products are obtained, including important isomers such as thiophene-epoxide, thiophene-ol, thiophene-oxide, oxathiane, and thiophenone. The calculated total rate constants for generation of all minimum stationary points show that the addition reactions to the α and β carbons are the fastest among all at temperatures below 1000 K, while the proposed multi-step parallel reactions are more competitive at temperatures above 1200 K. Furthermore, important inter-and intra-molecular interactions for some species have been investigated by two well-known quantum chemistry method, the NBO and AIM analyses. Thermochemical properties such as free energy, enthalpy, internal energy, and entropy for thiophene and hydroperoxyl radical and related species in the simulated reactions have been predicted using a combination of the B3LYP and BD(T) methods.
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12
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Morozov AN, Medvedkov IA, Azyazov VN, Mebel AM. Theoretical Study of the Phenoxy Radical Recombination with the O( 3P) Atom, Phenyl plus Molecular Oxygen Revisited. J Phys Chem A 2021; 125:3965-3977. [PMID: 33929861 DOI: 10.1021/acs.jpca.1c01545] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantum chemical calculations of the C6H5O2 potential energy surface (PES) were carried out to study the mechanism of the phenoxy + O(3P) and phenyl + O2 reactions. CASPT2(15e,13o)/CBS//CASSCF(15e,13o)/DZP multireference calculations were utilized to map out the minimum energy path for the entrance channels of the phenoxy + O(3P) reaction. Stationary points on the C6H5O2 PES were explored at the CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311++G** level for the species with a single-reference character of the wave function and at the CASPT2(15e,13o)/CBS//B3LYP/6-311++G** level of theory for the species with a multireference character of the wave function. Conventional, variational, and variable reaction coordinate transition-state theories were employed in Rice-Ramsperger-Kassel-Marcus master equation calculations to assess temperature- and pressure-dependent phenomenological rate constants and product branching ratios. The main bimolecular product channels of the phenoxy + O(3P) reaction are concluded to be para/ortho-benzoquinone + H, 2,4-cyclopentadienone + HCO and, at high temperatures, also phenyl + O2. The main bimolecular product channels of the phenyl + O2 reaction include 2,4-cyclopentadienone + HCO at lower temperatures and phenoxy + O(3P) at higher temperatures. For both the phenoxy + O(3P) and phenyl + O2 reactions, the collisional stabilization of peroxybenzene at low temperatures and high pressures competes with the bimolecular product channels.
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Affiliation(s)
- Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Iakov A Medvedkov
- Samara National Research University, Samara 443086, Russian Federation.,Lebedev Physical Institute, Samara 443011, Russian Federation
| | - Valeriy N Azyazov
- Samara National Research University, Samara 443086, Russian Federation.,Lebedev Physical Institute, Samara 443011, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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13
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Porfiriev DP, Azyazov VN, Mebel AM. Mechanism and kinetics of the oxidation of 1,3-butadien-1-yl ( n-C 4H 5): a theoretical study. Phys Chem Chem Phys 2021; 23:9198-9210. [PMID: 33885117 DOI: 10.1039/d1cp00567g] [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
Ab initio CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G(d,p) calculations of the C4H5O2 potential energy surface have been combined with Rice-Ramsperger-Kassel-Marcus Master Equation (RRKM-ME) calculations of temperature- and pressure-dependent rate constants and product branching ratios to unravel the mechanism and kinetics of the n-C4H5 + O2 reaction. The results indicate that the reaction is fast, with the total rate constant being in the range of 3.4-5.6 × 10-11 cm3 molecule-1 s-1. The main products include 1-oxo-n-butadienyl + O and acrolein + HCO, with their cumulative yield exceeding 90% at temperatures above 1500 K. Two conformers of 1-oxo-n-butadienyl + O are formed via a simple mechanism of O2 addition to the radical site of n-C4H5 followed by the cleavage of the O-O bond proceeding via a van der Waals C4H5OO complex. Alternatively, the pathways leading to acrolein + HCO involve significant reorganization of the heavy-atom skeleton either via formal migration of one O atom to the opposite end of the molecule or its insertion into the C1-C2 bond. Not counting thermal stabilization of the initial peroxy adducts, which prevails at low temperatures and high pressures, all other products share a minor yield of under 5%. Rate constants for the significant reaction channels have been fitted to modified Arrhenius expressions and are proposed for kinetic modeling of the oxidation of aromatic molecules and 1,3-butadiene. As a secondary reaction, n-C4H5 + O2 can be a source for the formation of acrolein observed experimentally in oxidation of the phenyl radical at low combustion temperatures, whereas another significant (secondary) product of the C6H5 + O2 reaction, furan, could be formed through unimolecular decomposition of 1-oxo-n-butadienyl. Both the n-C4H5 + O2 reaction and unimolecular decomposition of its 1-oxo-n-butadienyl primary product are shown not to be a substantial source of ketene.
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Affiliation(s)
- Denis P Porfiriev
- Samara National Research University, Samara 443086, Russian Federation.
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14
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Davis RJ, Liljestrand HM, Katz LE. Evidence for multiple removal pathways in low-temperature (200-400 °C) thermal treatment of pentachlorophenol-laden soils. JOURNAL OF HAZARDOUS MATERIALS 2020; 400:122870. [PMID: 32947725 DOI: 10.1016/j.jhazmat.2020.122870] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
Polychlorinated aromatic compounds (PCACs) pose significant remediation challenges, since their high soil affinities preclude mobile-phase partitioning and subsurface extraction. To enhance partitioning and desorption, subsurface temperatures are raised using a technique called thermal conduction heating-soil vapor extraction (TCH-SVE). While this technique improves PCAC partitioning, it can also promote several degradation reactions under temperatures typical of low-temperature TCH-SVE (200-400 °C). While these reactions are labile, the extent to which they occur in flow-through TCH-SVE is unclear. The current research used bench-scale, flow-through TCH-SVE to assess relative importance of three removal pathways: (1) target volatilization, (2) reductive dechlorination, and (3) oxidation via OH-addition. Pentachlorophenol was used as a representative PCAC, and pathway contributions, extents, and regioselectivity were examined as a function of temperature (225-375 °C) and gas-phase oxygen content (air vs. nitrogen). Across treatments, OH-addition and dechlorination occurred in parallel and accounted for significantly more removal than PCP volatilization. OH-addition byproducts had highest yields (regardless of oxygen content) and were consistent with surface-mediated OH production and ring addition. OH-addition increased with temperature while volatilization and dechlorination decreased. Notable exceptions occurred between 225 and 325 °C (where dechlorination dropped 10-fold) and 325 and 375 °C (where OH-addition fell 75%), signifying major mechanism shifts in these intervals.
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Affiliation(s)
- R Justin Davis
- Center for Water and the Environment, The University of Texas at Austin, Austin, TX, USA.
| | - Howard M Liljestrand
- Center for Water and the Environment, The University of Texas at Austin, Austin, TX, USA.
| | - Lynn E Katz
- Center for Water and the Environment, The University of Texas at Austin, Austin, TX, USA.
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15
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Kayanuma M, Suzuki S, Choe YK, Shimoi Y. Structure dependency of the reactivity of aromatic hydrocarbons involving the formation of oxygenated polycyclic aromatic hydrocarbons (OPAHs). Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137652] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Schönnenbeck C, Maryandyshev P, Trouvé G, Brillard A, Lyubov V, Brilhac JF. Combustion of hydrolysis lignin in a drop tube furnace and subsequent gaseous and particulate emissions. BIORESOURCE TECHNOLOGY 2019; 288:121498. [PMID: 31125933 DOI: 10.1016/j.biortech.2019.121498] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 06/09/2023]
Abstract
The aim of the study was to analyze the combustion of hydrolysis lignin in industrial plants which use pulverized combustible and which are characterized by very high heating rates (up to 105 K/min). Pulverized samples of hydrolysis lignin and of spruce bark or spruce trunk for comparison were injected in a drop tube furnace under an oxidative flow (synthetic air) and under an isothermal temperature (between 800 and 1200 °C) in the reaction zone. The gaseous and particulate emissions were analyzed. Ash was collected at the bottom of the drop tube furnace and analyzed. The fly ash were collected in an electrical low-pressure impactor and analyzed. Whatever the sample, the number of particles PM2.5 was sensitive to the temperature and a minimum was observed which is reached at 900 °C for hydrolysis lignin and spruce bark and at 1100 °C for spruce trunk.
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Affiliation(s)
- Cornelius Schönnenbeck
- Laboratoire Gestion des Risques et Environnement (EA 2334), Institut de Recherche Jean-Baptiste Donnet, Université de Haute-Alsace, 3bis, rue Alfred Werner, F-68093 Mulhouse Cedex, France
| | - Pavel Maryandyshev
- Department of Industrial Power Engineering, Higher School of Energy, Oil and Gas, Northern (Arctic) Federal University named after M.V. Lomonosov, 163002, Northern Dvina Embankment 17, Arkhangelsk, Russian Federation
| | - Gwenaëlle Trouvé
- Laboratoire Gestion des Risques et Environnement (EA 2334), Institut de Recherche Jean-Baptiste Donnet, Université de Haute-Alsace, 3bis, rue Alfred Werner, F-68093 Mulhouse Cedex, France
| | - Alain Brillard
- Laboratoire Gestion des Risques et Environnement (EA 2334), Institut de Recherche Jean-Baptiste Donnet, Université de Haute-Alsace, 3bis, rue Alfred Werner, F-68093 Mulhouse Cedex, France.
| | - Viktor Lyubov
- Department of Industrial Power Engineering, Higher School of Energy, Oil and Gas, Northern (Arctic) Federal University named after M.V. Lomonosov, 163002, Northern Dvina Embankment 17, Arkhangelsk, Russian Federation
| | - Jean-François Brilhac
- Laboratoire Gestion des Risques et Environnement (EA 2334), Institut de Recherche Jean-Baptiste Donnet, Université de Haute-Alsace, 3bis, rue Alfred Werner, F-68093 Mulhouse Cedex, France
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17
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Roohi H, Moghadam B. Decomposition mechanism of the phenylaminyl C6H5N H radical to propargyl and acetylene: A M06-2X, CBS-QB3 and G4 study. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.06.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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18
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Hernandez-Castillo AO, Abeysekera C, Stanton JF, Zwier TS. Structural Characterization of Phenoxy Radical with Mass-Correlated Broadband Microwave Spectroscopy. J Phys Chem Lett 2019; 10:2919-2923. [PMID: 31084013 DOI: 10.1021/acs.jpclett.9b00837] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A combination of broadband microwave spectroscopy and VUV photoionization time-of-flight mass spectra has been used to record rotational spectra of the prototypical phenoxy radical, its per-deuterated isotopomers, and the full set of singly 13C-substituted analogues. Rotational parameters associated with the fits to the full set of isotopomers produce a highly accurate r0 structure for the phenoxy radical. High-level ab initio calculations accurately reproduce the rotational constants and spin-rotation parameters. The structure of the phenoxy radical is distinctly quinoidal, with delocalization of the unpaired electron spin density on the oxygen and phenyl ring. The fitted Fermi contact terms for the 13C atoms reflect a weighting of resonance structures that is 27% on the O atom, 21.5% on each of the two ortho C's, and 30% on the para C, providing a quantitative measure of its sites for subsequent reactions that will control its abundances in combustion and atmospheric environments.
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Affiliation(s)
- A O Hernandez-Castillo
- Department of Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907-2084 , United States
| | - Chamara Abeysekera
- Department of Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907-2084 , United States
| | - John F Stanton
- Department of Chemistry , University of Florida , P.O. Box 117200, Gainesville , Florida 32611 , United States
| | - Timothy S Zwier
- Department of Chemistry , Purdue University , 560 Oval Drive , West Lafayette , Indiana 47907-2084 , United States
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19
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Quantum Chemical and Kinetic Study on Radical/Molecule Formation Mechanism of Pre-Intermediates for PCTA/PT/DT/DFs from 2-Chlorothiophenol and 2-Chlorophenol Precursors. Int J Mol Sci 2019; 20:ijms20071542. [PMID: 30934774 PMCID: PMC6480007 DOI: 10.3390/ijms20071542] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 03/16/2019] [Accepted: 03/22/2019] [Indexed: 12/31/2022] Open
Abstract
Polychlorinated phenoxathiins (PCPTs), polychlorinated dibenzothiophenes (PCDTs), and polychlorinated thianthrenes (PCTAs) are sulfur analogues of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/DFs). Chlorothiophenols (CTPs) and chlorophenols (CPs) are key precursors for the formation of PCTA/PT/DTs, which can react with H or OH to form chloro(thio)phenoxy radical, sulfydryl/hydroxyl-substituted phenyl radicals, and (thio)phenoxyl diradicals. However, previous radical/radical PCTA/DT formation mechanisms in the literature failed to explain the higher concentration of PCDTs than that of PCTAs under the pyrolysis or combustion conditions. In this work, a detailed thermodynamics and kinetic calculations were carried out to investigate the pre-intermediate formation for PCTA/PT/DTs from radical/molecule coupling of the 2-C(T)P with their key radical species. Our study showed that the radical/molecule coupling mechanism explains the gas-phase formation of PCTA/PT/DTs in both thermodynamic and kinetic perspectives. The S/C coupling modes to form thioether-(thio)enol intermediates are preferable over the O/C coupling modes to form ether-(thio)enol intermediates. Thus, although the radical/molecule coupling of chlorophenoxy radical with 2-C(T)P has no effect on the PCDD/PT formation, the radical/molecule coupling of chlorothiophenoxy radical with 2-C(T)P plays an important role in the PCTA/PT formation. Most importantly, the pre-PCDT intermediates formation pathways from the couplings of sulfydryl/hydroxyl-substituted phenyl radical with 2-C(T)P and (thio)phenoxyl diradicals with 2-C(T)P are more favorable than pre-PCTA/PT intermediates formation pathways from the coupling of chlorothiophenoxy radical with 2-C(T)P, which provides reasonable explanation for the high PCDT-to-PCTA ratio in the environment.
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20
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Zhao L, Prendergast M, Kaiser RI, Xu B, Ablikim U, Lu W, Ahmed M, Oleinikov AD, Azyazov VN, Howlader AH, Wnuk SF, Mebel AM. How to add a five-membered ring to polycyclic aromatic hydrocarbons (PAHs) – molecular mass growth of the 2-naphthyl radical (C10H7) to benzindenes (C13H10) as a case study. Phys Chem Chem Phys 2019; 21:16737-16750. [DOI: 10.1039/c9cp02930c] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction of aryl radicals with allene/methylacetylene leads to five-membered ring addition in PAH growth processes.
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Affiliation(s)
- Long Zhao
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | | | - Ralf I. Kaiser
- Department of Chemistry
- University of Hawaii at Manoa
- Honolulu
- USA
| | - Bo Xu
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Utuq Ablikim
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Wenchao Lu
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Musahid Ahmed
- Chemical Sciences Division
- Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | | | | | - A. Hasan Howlader
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
| | - Stanislaw F. Wnuk
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry
- Florida International University
- Miami
- USA
- Samara National Research University
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21
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Prendergast MB, Kirk BB, Savee JD, Osborn DL, Taatjes CA, Hemberger P, Blanksby SJ, da Silva G, Trevitt AJ. Product detection study of the gas-phase oxidation of methylphenyl radicals using synchrotron photoionisation mass spectrometry. Phys Chem Chem Phys 2019; 21:17939-17949. [DOI: 10.1039/c9cp01935a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions of ortho and meta-methylphenyl radicals with oxygen form products that depend acutely on the position of the methyl group.
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Affiliation(s)
| | | | - John D. Savee
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - David L. Osborn
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - Craig A. Taatjes
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - Patrick Hemberger
- Laboratory for Femtochemistry and Synchrotron Radiation
- Paul Scherrer Institut
- CH-5232 Villigen PSI
- Switzerland
| | - Stephen J. Blanksby
- Central Analytical Research Facility
- Queensland University of Technology
- Brisbane QLD 4001
- Australia
| | - Gabriel da Silva
- Department of Chemical Engineering
- The University of Melbourne
- Melbourne
- Australia
| | - Adam J. Trevitt
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
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22
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Komorek R, Xu B, Yao J, Ablikim U, Troy TP, Kostko O, Ahmed M, Yu XY. Enabling liquid vapor analysis using synchrotron VUV single photon ionization mass spectrometry with a microfluidic interface. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:115105. [PMID: 30501361 DOI: 10.1063/1.5048315] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/19/2018] [Indexed: 06/09/2023]
Abstract
Vacuum ultraviolet (VUV) single photon ionization mass spectrometry (SPI-MS) is a vacuum-based technique typically used for the analysis of gas phase and solid samples, but not for liquids due to the challenge in introducing volatile liquids in a vacuum. Here we present the first demonstration of in situ liquid analysis by integrating the System for Analysis at the Liquid Vacuum Interface (SALVI) microfluidic reactor into VUV SPI-MS. Four representative volatile organic compound (VOC) solutions were used to illustrate the feasibility of liquid analysis. Our results show the accurate mass identification of the VOC molecules and the reliable determination of appearance energy that is consistent with ionization energy for gaseous species in the literature as reported. This work validates that the vacuum-compatible SALVI microfluidic interface can be utilized at the synchrotron beamline and enable the in situ study of gas-phase molecules evaporating off the surface of a liquid, which holds importance in the study of condensed matter chemistry.
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Affiliation(s)
- R Komorek
- Atmospheric Sciences and Global Change Division, PNNL, Richland, Washington 99354, USA
| | - B Xu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - J Yao
- Atmospheric Sciences and Global Change Division, PNNL, Richland, Washington 99354, USA
| | - U Ablikim
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - T P Troy
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - O Kostko
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - M Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - X Y Yu
- Atmospheric Sciences and Global Change Division, PNNL, Richland, Washington 99354, USA
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23
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Zagidullin MV, Kaiser RI, Porfiriev DP, Zavershinskiy IP, Ahmed M, Azyazov VN, Mebel AM. Functional Relationships between Kinetic, Flow, and Geometrical Parameters in a High-Temperature Chemical Microreactor. J Phys Chem A 2018; 122:8819-8827. [PMID: 30345750 DOI: 10.1021/acs.jpca.8b06837] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Computational fluid dynamics (CFD) simulations and isothermal approximation were applied for the interpretation of experimental measurements of the C10H7Br pyrolysis efficiency in the high-temperature microreactor and of the pressure drop in the flow tube of the reactor. Applying isothermal approximation allows the derivation of analytical relationships between the kinetic, gas flow, and geometrical parameters of the microreactor, which, along with CFD simulations, accurately predict the experimental observations. On the basis of the obtained analytical relationships, a clear strategy for measuring rate coefficients of (pseudo) first-order bimolecular and unimolecular reactions using the microreactor was proposed. The pressure- and temperature-dependent rate coefficients for the C10H7Br pyrolysis calculated using variable reaction coordinate transition state theory were invoked to interpret the experimental data on the pyrolysis efficiency.
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Affiliation(s)
- M V Zagidullin
- Samara University , Samara 443086 , Russia.,Lebedev Physical Institute of RAS , Samara 443011 , Russia
| | - R I Kaiser
- Samara University , Samara 443086 , Russia.,University of Hawaii at Manoa , Honolulu , Hawaii 96822 , United States
| | - D P Porfiriev
- Samara University , Samara 443086 , Russia.,Lebedev Physical Institute of RAS , Samara 443011 , Russia
| | | | - M Ahmed
- Chemical Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - V N Azyazov
- Samara University , Samara 443086 , Russia.,Lebedev Physical Institute of RAS , Samara 443011 , Russia
| | - A M Mebel
- Samara University , Samara 443086 , Russia.,Florida International University , Miami , Florida 33199 , United States
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24
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Thomas AM, Lucas M, Zhao L, Liddiard J, Kaiser RI, Mebel AM. A combined crossed molecular beams and computational study on the formation of distinct resonantly stabilized C 5H 3 radicals via chemically activated C 5H 4 and C 6H 6 intermediates. Phys Chem Chem Phys 2018. [PMID: 29537029 DOI: 10.1039/c8cp00357b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crossed molecular beams technique was utilized to explore the formation of three isomers of resonantly stabilized (C5H3) radicals along with their d2-substituted counterparts via the bimolecular reactions of singlet/triplet dicarbon [C2(X1Σ+g/a3Πu)] with methylacetylene [CH3CCH(X1A1)], d3-methylacetylene [CD3CCH(X1A1)], and 1-butyne [C2H5CCH(X1A')] at collision energies up to 26 kJ mol-1via chemically activated singlet/triplet C5H4/C5D3H and C6H6 intermediates. These studies exploit a newly developed supersonic dicarbon [C2(X1Σ+g/a3Πu)] beam generated via photolysis of tetrachloroethylene [C2Cl4(X1Ag)] by excluding interference from carbon atoms, which represent the dominating (interfering) species in ablation-based dicarbon sources. We evaluated the performance of the dicarbon [C2(X1Σ+g/a3Πu)] beam in reactions with methylacetylene [CH3CCH(X1A1)] and d3-methylacetylene [CD3CCH(X1A1)]; the investigations demonstrate that the reaction dynamics match previous studies in our laboratory utilizing ablation-based dicarbon sources involving the synthesis of 1,4-pentadiynyl-3 [HCCCHCCH(X2B1)] and 2,4-pentadiynyl-1 [H2CCCCCH(X2B1)] radicals via hydrogen (deuterium) atom elimination. Considering the C2(X1Σ+g/a3Πu)-1-butyne [C2H5CCH(X1A')] reaction, the hitherto elusive methyl-loss pathway was detected. This channel forms the previously unknown resonantly stabilized penta-1-yn-3,4-dienyl-1 [H2CCCHCC(X2A)] radical along with the methyl radical [CH3(X2A2'')] and is open exclusively on the triplet surface with an overall reaction energy of -86 ± 10 kJ mol-1. The preferred reaction pathways proceed first by barrierless addition of triplet dicarbon to the π-electronic system of 1-butyne, either to both acetylenic carbon atoms or to the sterically more accessible carbon atom, to form the methyl-bearing triplet C6H6 intermediates [i41b] and [i81b], respectively, with the latter decomposing via a tight exit transition state to penta-1-yn-3,4-dienyl-1 [(H2CCCHCC(X2A)] plus the methyl radical [CH3(X2A2'')]. The successful unraveling of this methyl-loss channel - through collaborative experimental and computational efforts - underscores the viability of the photolytically generated dicarbon beam as an unprecedented tool to access reaction dynamics underlying the formation of resonantly stabilized free radicals (RSFR) that are vital to molecular mass growth processes that ultimately lead to polycyclic aromatic hydrocarbons (PAHs).
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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25
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Lucas M, Thomas AM, Zhao L, Kaiser RI, Kim GS, Mebel AM. Gas-Phase Synthesis of the Elusive Cyclooctatetraenyl Radical (C 8 H 7 ) via Triplet Aromatic Cyclooctatetraene (C 8 H 8 ) and Non-Aromatic Cyclooctatriene (C 8 H 8 ) Intermediates. Angew Chem Int Ed Engl 2017; 56:13655-13660. [PMID: 28887833 DOI: 10.1002/anie.201706861] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Indexed: 11/10/2022]
Abstract
The 1,2,4,7-cyclooctatetraenyl radical (C8 H7 ) has been synthesized for the very first time via the bimolecular gas-phase reaction of ground-state carbon atoms with 1,3,5-cycloheptatriene (C7 H8 ) on the triplet surface under single-collision conditions. The barrier-less route to the cyclic 1,2,4,7-cyclooctatetraenyl radical accesses exotic reaction intermediates on the triplet surface, which cannot be synthesized via classical organic chemistry methods: the triplet non-aromatic 2,4,6-cyclooctatriene (C8 H8 ) and the triplet aromatic 1,3,5,7-cyclooctatetraene (C8 H8 ). Our approach provides a clean gas-phase synthesis of this hitherto elusive cyclic radical species 1,2,4,7-cyclooctatetraenyl via a single-collision event and opens up a versatile, unconventional path to access this previously largely obscure class of cyclooctatetraenyl radicals, which have been impossible to access through classical synthetic methods.
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Affiliation(s)
- Michael Lucas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI, 96822, USA
| | - Gap-Sue Kim
- Dharma College, Dongguk University, Jung-gu, Seoul, 04620, Korea
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.,Samara National Research University, Samara, 443086, Russian Federation
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26
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Lucas M, Thomas AM, Zhao L, Kaiser RI, Kim G, Mebel AM. Gas‐Phase Synthesis of the Elusive Cyclooctatetraenyl Radical (C
8
H
7
) via Triplet Aromatic Cyclooctatetraene (C
8
H
8
) and Non‐Aromatic Cyclooctatriene (C
8
H
8
) Intermediates. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201706861] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Michael Lucas
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Aaron M. Thomas
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Long Zhao
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Ralf I. Kaiser
- Department of Chemistry University of Hawai'i at Manoa Honolulu HI 96822 USA
| | - Gap‐Sue Kim
- Dharma College Dongguk University Jung-gu Seoul 04620 Korea
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry Florida International University Miami FL 33199 USA
- Samara National Research University Samara 443086 Russian Federation
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27
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Mukhopadhyay A, Jacob L, Venkataramani S. Dehydro-oxazole, thiazole and imidazole radicals: insights into the electronic structure, stability and reactivity aspects. Phys Chem Chem Phys 2017; 19:394-407. [DOI: 10.1039/c6cp05677f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computations on the effect of heteroatoms in the structural, stability and reactivity aspects of the oxazole, thiazole and imidazole radicals.
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Affiliation(s)
- Anamika Mukhopadhyay
- Department of Chemical Sciences
- Indian Institute of Science Education and Research
- IISER Mohali
- Mohali
- India
| | - Lilit Jacob
- Department of Chemical Sciences
- Indian Institute of Science Education and Research
- IISER Mohali
- Mohali
- India
| | - Sugumar Venkataramani
- Department of Chemical Sciences
- Indian Institute of Science Education and Research
- IISER Mohali
- Mohali
- India
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28
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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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29
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Kostko O, Bandyopadhyay B, Ahmed M. Vacuum Ultraviolet Photoionization of Complex Chemical Systems. Annu Rev Phys Chem 2016; 67:19-40. [DOI: 10.1146/annurev-physchem-040215-112553] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Oleg Kostko
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720;
| | - Biswajit Bandyopadhyay
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720;
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720;
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30
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Prendergast MB, Kirk BB, Savee JD, Osborn DL, Taatjes CA, Masters KS, Blanksby SJ, da Silva G, Trevitt AJ. Formation and stability of gas-phase o-benzoquinone from oxidation of ortho-hydroxyphenyl: a combined neutral and distonic radical study. Phys Chem Chem Phys 2016; 18:4320-32. [DOI: 10.1039/c5cp02953h] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The o-hydroxyphenyl radical reacts with O2 to form o-benzoquinone + OH and cyclopentadienone is assigned as a secondary product.
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Affiliation(s)
| | | | - John D. Savee
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - David L. Osborn
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - Craig A. Taatjes
- Combustion Research Facility
- Sandia National Laboratories
- Livermore
- USA
| | - Kye-Simeon Masters
- School of Chemistry, Physics and Mechanical Engineering
- Faculty of Science and Engineering
- Queensland University of Technology
- Brisbane
- Australia
| | - Stephen J. Blanksby
- Central Analytical Research Facility
- Queensland University of Technology
- Brisbane
- Australia
| | - Gabriel da Silva
- Department of Chemical and Biomolecular Engineering
- The University of Melbourne
- Melbourne
- Australia
| | - Adam J. Trevitt
- School of Chemistry
- University of Wollongong
- Wollongong
- Australia
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31
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Hemberger P, da Silva G, Trevitt AJ, Gerber T, Bodi A. Are the three hydroxyphenyl radical isomers created equal?--The role of the phenoxy radical. Phys Chem Chem Phys 2015; 17:30076-83. [PMID: 26500055 DOI: 10.1039/c5cp05346c] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have investigated the thermal decomposition of the three hydroxyphenyl radicals (˙C6H4OH) in a heated microtubular reactor. Intermediates and products were identified isomer-selectively applying photoion mass-selected threshold photoelectron spectroscopy with vacuum ultraviolet synchrotron radiation. Similarly to the phenoxy radical (C6H5-O˙), hydroxyphenyl decomposition yields cyclopentadienyl (c-C5H5) radicals in a decarbonylation reaction at elevated temperatures. This finding suggests that all hydroxyphenyl isomers first rearrange to form phenoxy species, which subsequently decarbonylate, a mechanism which we also investigate computationally. Meta- and para-radicals were selectively produced and spectroscopically detectable, whereas the ortho isomer could not be traced due to its fast rethermalization and rapid decomposition in the reactor. A smaller barrier to isomerization to phenoxy was found to be the reason for this observation. Since hydroxyphenyl species may be present under typical sooting conditions in flames, the resonantly stabilized cyclopentadienyl radical adds to the hydrocarbon pool and can contribute to the formation of polycyclic aromatic hydrocarbons, which are precursors in soot formation.
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Affiliation(s)
- P Hemberger
- Molecular Dynamics Group, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
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32
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Ormond TK, Hemberger P, Troy TP, Ahmed M, Stanton JF, Ellison GB. The ionisation energy of cyclopentadienone: a photoelectron–photoion coincidence study. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1042936] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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33
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Singh RI, Mebel AM, Frenklach M. Oxidation of Graphene-Edge Six- and Five-Member Rings by Molecular Oxygen. J Phys Chem A 2015; 119:7528-47. [DOI: 10.1021/acs.jpca.5b00868] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ravi I. Singh
- Department
of Mechanical Engineering, University of California at Berkeley, Berkeley, California 94720-1740, United States
| | - Alexander M. Mebel
- Department
of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Michael Frenklach
- Department
of Mechanical Engineering, University of California at Berkeley, Berkeley, California 94720-1740, United States
- Environmental
Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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34
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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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