1
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Nascimento JL, Junior ASL, Alves TV. The Interplay between the Temperature and Pressure on the Reaction Pathways of the Prenol Oxidation by Hydroxyl Radicals. Chemphyschem 2024; 25:e202400341. [PMID: 38878294 DOI: 10.1002/cphc.202400341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 05/03/2024] [Indexed: 07/16/2024]
Abstract
Despite prenol emerging as a next-generation biofuel, some questions about its mechanism still need to be adequately proposed to rationalize its consumption and evaluate its efficiency in spark-ignition (SI) engines. Here, we present new insights into the reaction mechanism of prenol (3-methyl-2-buten-1-ol) with OH radicals as a function of temperature and pressure. We have determined that the different temperature and pressure conditions control the preferred products. At combustion temperatures and low pressures, OH-addition adducts are suppressed, increasing the formation of α and δ allylic radicals responsible for the auto-ignition.
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Affiliation(s)
- Joel Leitão Nascimento
- Departamento de Físico-Química, Instituto de Química, Universidade Federal da Bahia - Salvador, Bahia, 40170-115, Brazil
| | - Adalberto S L Junior
- Departamento de Físico-Química, Instituto de Química, Universidade Federal da Bahia - Salvador, Bahia, 40170-115, Brazil
| | - Tiago Vinicius Alves
- Departamento de Físico-Química, Instituto de Química, Universidade Federal da Bahia - Salvador, Bahia, 40170-115, Brazil
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2
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Gao Q, Shen C, Zhang H, Long B, Truhlar DG. Quantitative kinetics reveal that reactions of HO 2 are a significant sink for aldehydes in the atmosphere and may initiate the formation of highly oxygenated molecules via autoxidation. Phys Chem Chem Phys 2024; 26:16160-16174. [PMID: 38787752 DOI: 10.1039/d4cp00693c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
Large aldehydes are widespread in the atmosphere and their oxidation leads to secondary organic aerosols. The current understanding of their chemical transformation processes is limited to hydroxyl radical (OH) oxidation during daytime and nitrate radical (NO3) oxidation during nighttime. Here, we report quantitative kinetics calculations of the reactions of hexanal (C5H11CHO), pentanal (C4H9CHO), and butanal (C3H7CHO) with hydroperoxyl radical (HO2) at atmospheric temperatures and pressures. We find that neither tunneling nor multistructural torsion anharmonicity should be neglected in computing these rate constants; strong anharmonicity at the transition states is also important. We find rate constants for the three reactions in the range 3.2-7.7 × 10-14 cm3 molecule-1 s-1 at 298 K and 1 atm, showing that the HO2 reactions can be competitive with OH and NO3 oxidation under some conditions relevant to the atmosphere. Our findings reveal that HO2-initiated oxidation of large aldehydes may be responsible for the formation of highly oxygenated molecules via autoxidation. We augment the theoretic studies with laboratory flow-tube experiments using an iodide-adduct time-of-flight chemical ionization mass spectrometer to confirm the theoretical predictions of peroxy radicals and the autoxidation pathway. We find that the adduct from HO2 + C5H11CHO undergoes a fast unimolecular 1,7-hydrogen shift with a rate constant of 0.45 s-1. We suggest that the HO2 reactions make significant contributions to the sink of aldehydes.
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Affiliation(s)
- Qiao Gao
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China.
| | - Chuanyang Shen
- Department of Chemistry, University of California, Riverside, California, 92507, USA.
| | - Haofei Zhang
- Department of Chemistry, University of California, Riverside, California, 92507, USA.
| | - Bo Long
- School of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China.
- College of Materials Science and Engineering, Guizhou Minzu university, Guiyang 550025, China
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
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3
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Zhang ZP, Wang SH, Shang YL, Liu JH, Luo SN. Theoretical Study on Ethylamine Dissociation Reactions Using VRC-VTST and SS-QRRK Methods. J Phys Chem A 2024; 128:2191-2199. [PMID: 38456900 DOI: 10.1021/acs.jpca.3c08373] [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
Barrierless bond dissociation reactions play an important role in fuel combustion. In this work, the pressure-dependent dissociation rate constants of ethylamine (EA) are accurately determined using variable-reaction-coordinate variational transition-state theory combined with the system-specific quantum Rice-Ramsperger-Kassel method. Before the kinetics calculations, the performances of four density functional theory methods in describing the bond dissociation of EA are evaluated against the benchmark method, FIC-MRCISD(T)+Q/cc-pVTZ, and the MN15-L/cc-pVTZ method is the best choice. By comparison of the Gibbs free energies and the rate constants for the bond dissociation reactions of EA, ethanol, and propane, the influence of functional groups on the reaction kinetics is discussed. The kinetics calculations show that the dissociation rate constants of EA are sensitive to pressure at low pressures and high temperatures, and the dominant channel is the reaction that yields C2H5 and NH2 radicals. A literature combustion model of EA is updated with our calculations, and the satisfactory agreement between the model predictions and reported ignition delay times of EA suggests the reliability of our calculations.
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Affiliation(s)
- Z P Zhang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
- Dynamic Materials Data Science Center, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
| | - S H Wang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
- Dynamic Materials Data Science Center, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
| | - Y L Shang
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
- Energy Research Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, Shandong 250014, P. R. China
- The Peac Institute of Multiscale Sciences, Chengdu, Sichuan 610027, P. R. China
- Dynamic Materials Data Science Center, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
| | - J H Liu
- Chengdu JiangDe Technology Co., Ltd, Chengdu, Sichuan 610100, P. R. China
| | - S N Luo
- Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
- Dynamic Materials Data Science Center, Southwest Jiaotong University, Chengdu, Sichuan 610031, P. R. China
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4
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Deng DD, Long B. Quantitative kinetics of the atmospheric reaction between isocyanic acid and hydroxyl radicals: post-CCSD(T) contribution, anharmonicity, recrossing effects, torsional anharmonicity, and tunneling. Phys Chem Chem Phys 2023; 26:485-492. [PMID: 38079149 DOI: 10.1039/d3cp04385a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Hydroxyl radicals (OH) are the most important atmospheric oxidant, initiating atmospheric reactions for the chemical transformation of volatile organic compounds. Here, we choose the HNCO + OH reaction as a prototype reaction because it contains the fundamental reaction processes for OH radicals: H-abstraction reaction by OH and OH addition reaction. However, its kinetics are unknown under atmospheric conditions. We investigate the reaction of HNCO with OH by using the GMM(P).L method close to the accuracy of single, double, triple, and quadruple excitations and noniterative quintuple excitations with a complete basis set (CCSDTQ(P)/CBS) as benchmark results and a dual-level strategy for kinetics calculations. The calculated rate constant of HNCO + OH is in good agreement with the experimental data available at the temperatures between 620 and 2500 K. We find that the rate constant cannot be correctly obtained by using experimental data to extrapolate the atmospheric temperature ranges. We find that the post-CCSD(T) contribution is very large for the barrier height with the value of -0.85 kcal mol-1 for the H-abstraction reaction, while the previous investigations were done up to the CCSD(T) level. Moreover, we also find that recrossing effects, tunneling, torsional anharmonicity, and anharmonicity are important for obtaining quantitative kinetics in the OH + HNCO reaction.
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Affiliation(s)
- Dai-Dan Deng
- College of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China.
| | - Bo Long
- College of Physics and Mechatronic Engineering, Guizhou Minzu University, Guiyang 550025, China.
- College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China
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5
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He Y, Xing L, Zhu Q, Lian L, Wang X, Liu M, Cheng Z. Theoretical Kinetic Study on Hydrogen Abstraction Reactions from n-Pentane by NO 2. J Phys Chem A 2023; 127:10243-10252. [PMID: 37983021 DOI: 10.1021/acs.jpca.3c05054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2023]
Abstract
The interaction of fuel with NOx chemistry is important for the construction of the reaction mechanism and engine application. In this work, the reaction pathways of nC5H12 + NO2 were studied by high-level electronic structure calculations (DLPNO-CCSD(T)-F12/cc-pVTZ-F12//B2PLYPD3/cc-pVTZ). The rate constants were calculated by using the multistructural canonical transition-state theory with the Eckart tunneling method (TST/MS-T/ET). The studied condition is in a wide temperature range of 298-2400 K. The influence of MS-T anharmonicity and tunneling effect will be clarified for these site-specific H-abstraction pathways. The result reflects the large deviation introduced by the treatment of MS-T anharmonicity, especially at a high temperature. For the same type of reactions, the rate constants of H-abstraction both occurring at the secondary carbon are not almost identical. The branching ratios show that abstraction from the secondary site forming cis-HONO (R2c) contributes 36-78% to nC5H12 consumption in the temperature range of 298-2400 K. The current results show that the multistructural torsional anharmonicity has a crucial influence on the accurate estimation of branching ratios.
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Affiliation(s)
- Yunrui He
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, PR China
| | - Lili Xing
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, PR China
| | - Qiongxuan Zhu
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, PR China
| | - Liuchao Lian
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, PR China
| | - Xuetao Wang
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, PR China
| | - Mengjie Liu
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, PR China
| | - Zhanjun Cheng
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, P. R. China
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6
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Crisci L, Di Grande S, Cavallotti C, Barone V. Toward an Accurate Black-Box Tool for the Kinetics of Gas-Phase Reactions Involving Barrier-less Elementary Steps. J Chem Theory Comput 2023; 19:7626-7639. [PMID: 37880932 PMCID: PMC10653117 DOI: 10.1021/acs.jctc.3c00857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/06/2023] [Accepted: 10/13/2023] [Indexed: 10/27/2023]
Abstract
An enhanced computational protocol has been devised for the accurate characterization of gas-phase barrier-less reactions in the framework of the reaction-path (RP) and variable reaction coordinate variational transition-state theory. In particular, the synergistic combination of density functional theory and Monte Carlo sampling to optimize reactive fluxes led to a reliable yet effective computational workflow. A black-box strategy has been developed for selecting the most suited density functional with reference to a high-level one-dimensional reference potential. At the same time, different descriptions of hindered rotations are automatically selected, depending on the corresponding harmonic frequencies along the RP. The performance of the new tool is investigated by means of two prototypical reactions involving different degrees of static and dynamic correlation, namely, H2S + Cl and CH3 + CH3. The remarkable agreement of the computed kinetic parameters with the available experimental data confirms the accuracy and robustness of the proposed approach. Together with their intrinsic interest, these results also pave the way toward systematic investigations of gas-phase reactions involving barrier-less elementary steps by a reliable, user-friendly tool, which can be confidently used also by nonspecialists.
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Affiliation(s)
- Luigi Crisci
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
- Department
of Chemical Sciences, University of Napoli
Federico II, Complesso Universitario di M.S. Angelo, via Cintia 21, I-80126 Napoli, Italy
| | - Silvia Di Grande
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
- Scuola
Superiore Meridionale, Largo San Marcellino 10, I-80138 Napoli, Italy
| | - Carlo Cavallotti
- Department
of Chemistry, Materials and Chemical Engineering “G. Natta”, Politecnico di Milano, I-20131 Milano, Italy
| | - Vincenzo Barone
- Scuola
Normale Superiore di Pisa, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
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7
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Reactions with criegee intermediates are the dominant gas-phase sink for formyl fluoride in the atmosphere. FUNDAMENTAL RESEARCH 2023. [DOI: 10.1016/j.fmre.2023.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
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8
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Long B, Xia Y, Truhlar DG. Quantitative Kinetics of HO 2 Reactions with Aldehydes in the Atmosphere: High-Order Dynamic Correlation, Anharmonicity, and Falloff Effects Are All Important. J Am Chem Soc 2022; 144:19910-19920. [PMID: 36264240 DOI: 10.1021/jacs.2c07994] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Kinetics provides the fundamental parameters for elucidating sources and sinks of key atmospheric species and for atmospheric modeling more generally. Obtaining quantitative kinetics in the laboratory for the full range of atmospheric temperatures and pressures is quite difficult. Here, we use computational chemistry to obtain quantitative rate constants for the reactions of HO2 with HCHO, CH3CHO, and CF3CHO. First, we calculate the high-pressure-limit rate constants by using a dual-level strategy that combines conventional transition state theory using a high level of electronic structure wave function theory with canonical variational transition state theory including small-curvature tunneling using density functional theory. The wave-function level is beyond-CCSD(T) for HCHO and CCSD(T)-F12a (Level-A) for XCHO (X = CH3, CF3), and the density functional (Level-B) is specifically validated for these reactions. Then, we calculate the pressure-dependent rate constants by using system-specific quantum RRK theory (SS-QRRK) and also by an energy-grained master equation. The two treatments of the pressure dependence agree well. We find that the Level-A//Level-B method gives good agreement with CCSDTQ(P)/CBS. We also find that anharmonicity is an important factor that increases the rate constants of all three reactions. We find that the HO2 + HCHO reaction has a significant dependence on pressure, but the HO2 + CF3CHO reaction is almost independent of pressure. Our findings show that the HO2 + HCHO reaction makes important contribution to the sink for HCHO, and the HO2 + CF3CHO reaction is the dominant sink for CF3CHO in the atmosphere.
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Affiliation(s)
- Bo Long
- College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China
| | - Yu Xia
- College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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9
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Xing L, Lian L, Wang Z, Cheng Z, He Y, Cui J, Truhlar DG. Lowering of Reaction Rates by Energetically Favorable Hydrogen Bonding in the Transition State. Degradation of Biofuel Ketohydroperoxides by OH. J Am Chem Soc 2022; 144:16984-16995. [PMID: 36069709 DOI: 10.1021/jacs.2c06124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ketohydroperoxides (KHPs) are oxygenates with carbonyl and hydroperoxy functional groups, and they are generated under combustion and atmospheric conditions. Their fate is crucial for secondary organic aerosol formation in the troposphere and for the ignition processes of biofuels in advanced combustion engines. We investigated the thermodynamics and kinetics of nine hydrogen abstraction reactions from four ether KHPs by OH. We find that the rate constants are strongly affected by entropic effects whose estimation requires a consideration of higher-energy conformers of the transition state. A density functional was selected for these reactions by comparison to coupled cluster calculations, and it was used for calculations by multistructural canonical transition-state theory with multidimensional tunneling over the temperature range of 200-2000 K. We find that the effect of multistructural torsional anharmonicity is very large and quite different for the various ether KHP reactions. A leading cause of the structural dependence is the dominance of entropic factors due to the lack of hydrogen bonding in some of the higher-energy conformers of the transition states. Four of the reactions involve abstraction from the α-carbon (the carbon vicinal to the hydroperoxide group); they exhibit nonmonotonic temperature dependence with complex fuel-specific dependence. The rate constants for abstraction from a non-α-carbon of a given KHP can be faster than the ones for abstraction from an α-carbon; in two cases, this is due to entropy, and in one case, the non-α-carbon abstraction has a lower energy barrier. Tunneling and recrossing effects are also found to be important.
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Affiliation(s)
- Lili Xing
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang 471003, Henan, China.,Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Liuchao Lian
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 230029, Anhui, China
| | - Zhanjun Cheng
- School of Environmental Science and Engineering, Tianjin University, Tianjin 300072, China
| | - Yunrui He
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Jintao Cui
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang 471003, Henan, China
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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10
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Xia Y, Long B, Lin S, Teng C, Bao JL, Truhlar DG. Large Pressure Effects Caused by Internal Rotation in the s-cis-syn-Acrolein Stabilized Criegee Intermediate at Tropospheric Temperature and Pressure. J Am Chem Soc 2022; 144:4828-4838. [PMID: 35262353 DOI: 10.1021/jacs.1c12324] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Criegee intermediates are important atmospheric oxidants, and quantitative kinetics for stabilized Criegee intermediates are key parameters for atmospheric modeling but are still limited. Here we report barriers and rate constants for unimolecular reactions of s-cis-syn-acrolein oxide (scsAO), in which the vinyl group makes it a prototype for Criegee intermediates produced in the ozonolysis of isoprene. We find that the MN15-L and M06-2X density functionals have CCSD(T)/CBS accuracy for the unimolecular cyclization and stereoisomerization of scsAO. We calculated high-pressure-limit rate constants by the dual-level strategy that combines (a) high-level wave function-based conventional transition-state theory (which includes coupled-cluster calculations with quasiperturbative inclusion of quadruple excitations because of the strongly multiconfigurational character of the electronic wave function) and (b) canonical variational transition-state theory with small-curvature tunneling based on a validated density functional. We calculated pressure-dependent rate constants both by system-specific quantum Rice-Ramsperger-Kassel theory and by solving the master equation. We report rate constants for unimolecular reactions of scsAO over the full range of atmospheric temperature and pressure. We found that the unimolecular reaction rates of this larger-than-previously studied Criegee intermediate depend significantly on pressure. Particularly, we found that falloff effects decrease the effective unimolecular cyclization rate constant of scsAO by about a factor of 3, but the unimolecular reaction is still the dominant atmospheric sink for scsAO at low altitudes. The large falloff caused by the inclusion of the stereoisomerization channel in the master equation calculations has broad implications for mechanistic analysis of reactions with competitive internal rotations that can produce stable rotamers.
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Affiliation(s)
- Yu Xia
- College of Mechanical and Electrical Engineering, Guizhou Minzu University, Guiyang 550025, China.,College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China
| | - Bo Long
- College of Mechanical and Electrical Engineering, Guizhou Minzu University, Guiyang 550025, China.,College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China
| | - Shiru Lin
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Chong Teng
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Junwei Lucas Bao
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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11
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Li Y, Guo X, Zhang RM, Zhang H, Zhang X, Xu X. Pressure-Dependent Kinetics of o-Xylene Reaction with OH Radical. Phys Chem Chem Phys 2022; 24:8672-8682. [DOI: 10.1039/d2cp00396a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OH-initiated oxidation reactions of o-xylene are widely concerned both in combustion and atmospheric chemistry. In this work, the kinetics of o-xylene reaction with OH radical has been studied systematically in...
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12
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Mohamed SY, Monge-Palacios M, Giri BR, Khaled F, Liu D, Farooq A, Sarathy SM. The Effect of Hydrogen Bonding on the Reactivity of OH Radicals with Prenol and Isoprenol: A Shock Tube and Multi-Structural Torsional Variational Transition State Theory Study. Phys Chem Chem Phys 2022; 24:12601-12620. [DOI: 10.1039/d2cp00737a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The presence of two functional groups (OH and double bond) in C5 methyl-substituted enols (i.e., isopentenols), such as 3-methyl-2-buten-1-ol (prenol) and 3-methyl-3-buten-1-ol (isoprenol), makes them excellent biofuel candidates as fuel...
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13
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Long B, Wang Y, Xia Y, He X, Bao JL, Truhlar DG. Atmospheric Kinetics: Bimolecular Reactions of Carbonyl Oxide by a Triple-Level Strategy. J Am Chem Soc 2021; 143:8402-8413. [PMID: 34029069 DOI: 10.1021/jacs.1c02029] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Criegee intermediates in the atmosphere serve as oxidizing agents to initiate aerosol formation, which are particularly important for atmospheric modeling, and understanding their kinetics is one of the current outstanding challenges in climate change modeling. Because experimental kinetics are still limited, we must rely on theory for the complete picture, but obtaining absolute rates from theory is a formidable task. Here, we report the bimolecular reaction kinetics of carbonyl oxide with ammonia, hydrogen sulfide, formaldehyde, and water dimer by designing a triple-level strategy that combines (i) benchmark results close to the complete-basis limit of coupled-cluster theory with the single, double, triple, and quadruple excitations (CCSDTQ/CBS), (ii) a new hybrid meta density functional (M06CR) specifically optimized for reactions of Criegee intermediates, and (iii) variational transition-state theory with both variable rection coordinates and optimized reaction paths, with multidimensional tunneling, and with pressure effects. For (i) we have found that quadruple excitations are required to obtain quantitative reaction barriers, and we designed new composite methods and strategies to reach CCSDTQ/CBS accuracy. The present findings show that (i) the CH2OO + HCHO reaction can make an important contribution to the sink of HCHO under wide atmospheric conditions in the gas phase and that (ii) CH2OO + (H2O)2 dominates over the CH2OO + H2O reaction below 10 km.
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Affiliation(s)
- Bo Long
- College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China.,Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Ying Wang
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.,The National and Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha 410006, China
| | - Yu Xia
- College of Materials Science and Engineering, Guizhou Minzu University, Guiyang 550025, China
| | - Xiao He
- Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.,NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai 200062, China
| | - Junwei Lucas Bao
- Department of Chemistry, Boston College, Chestnut Hill, Massachusetts 02467, United States
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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14
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Chavarrio Cañas JE, Monge-Palacios M, Grajales-González E, Sarathy SM. Early Chemistry of Nicotine Degradation in Heat-Not-Burn Smoking Devices and Conventional Cigarettes: Implications for Users and Second- and Third-Hand Smokers. J Phys Chem A 2021; 125:3177-3188. [PMID: 33834773 PMCID: PMC8154610 DOI: 10.1021/acs.jpca.1c01650] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nicotine exposure results in health risks not only for smokers but also for second- and third-hand smokers. Unraveling nicotine's degradation mechanism and the harmful chemicals that are produced under different conditions is vital to assess exposure risks. We performed a theoretical study to describe the early chemistry of nicotine degradation by investigating two important reactions that nicotine can undergo: hydrogen abstraction by hydroxyl radicals and unimolecular dissociation. The former contributes to the control of the degradation mechanism below 800 K due to a non-Arrhenius kinetics, which implies an enhancement of reactivity as temperature decreases. The latter becomes important at higher temperatures due to its larger activation energy. This change in the degradation mechanism is expected to affect the composition of vapors inhaled by smokers and room occupants. Conventional cigarettes, which operate at temperatures higher than 1000 K, are more prone to yield harmful pyridinyl radicals via nicotine dissociation, while nicotine in electronic cigarettes and vaporizers, with operating temperatures below 600 K, will be more likely degraded by hydroxyl radicals, resulting in a vapor with a different composition. Although low-temperature nicotine delivery devices have been claimed to be less harmful due to their nonburning operating conditions, the non-Arrhenius kinetics that we observed for the degradation mechanism below 873 K suggests that nicotine degradation may be more rapidly initiated as temperature is reduced, indicating that these devices may be more harmful than it is commonly assumed.
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Affiliation(s)
- Javier E Chavarrio Cañas
- Clean Combustion Research Center (CCRC), Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - M Monge-Palacios
- Clean Combustion Research Center (CCRC), Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - E Grajales-González
- Clean Combustion Research Center (CCRC), Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - S Mani Sarathy
- Clean Combustion Research Center (CCRC), Physical Science and Engineering (PSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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15
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Hasan G, Salo VT, Valiev RR, Kubečka J, Kurtén T. Comparing Reaction Routes for 3(RO···OR') Intermediates Formed in Peroxy Radical Self- and Cross-Reactions. J Phys Chem A 2020; 124:8305-8320. [PMID: 32902986 DOI: 10.1021/acs.jpca.0c05960] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Organic peroxy radicals (RO2) are key intermediates in the chemistry of the atmosphere. One of the main sink reactions of RO2 is the recombination reaction RO2 + R'O2, which has three main channels (all with O2 as a coproduct): (1) R-H═O + R'OH, (2) RO + R'O, and (3) ROOR'. The RO + R'O "alkoxy" channel promotes radical and oxidant recycling, while the ROOR' "dimer" channel leads to low-volatility products relevant to aerosol processes. The ROOR' channel has only recently been discovered to play a role in the gas phase. Recent computational studies indicate that all of these channels first go through an intermediate complex 1(RO···3O2···OR'). Here, 3O2 is very weakly bound and will likely evaporate from the system, giving a triplet cluster of two alkoxy radicals: 3(RO···OR'). In this study, we systematically investigate the three reaction channels for an atmospherically representative set of RO + R'O radicals formed in the corresponding RO2 + R'O2 reaction. First, we systematically sample the possible conformations of the RO···OR' clusters on the triplet potential energy surface. Next, we compute energetic parameters and attempt to estimate reaction rate coefficients for the three channels: evaporation/dissociation to RO + R'O, a hydrogen shift leading to the formation of R'-H═O + ROH, and "spin-flip" (intersystem crossing) leading to, or at least allowing, the formation of ROOR' dimers. While large uncertainties in the computed energetics prevent a quantitative comparison of reaction rates, all three channels were found to be very fast (with typical rates greater than 106 s-1). This qualitatively demonstrates that the computationally proposed novel RO2 + R'O2 reaction mechanism is compatible with experimental data showing non-negligible branching ratios for all three channels, at least for sufficiently complex RO2.
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Affiliation(s)
- Galib Hasan
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.,Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Vili-Taneli Salo
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.,Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Rashid R Valiev
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.,Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Jakub Kubečka
- Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
| | - Theo Kurtén
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.,Institute for Atmospheric and Earth System Research, Faculty of Science, University of Helsinki, FIN-00014 Helsinki, Finland
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16
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Matsugi A. Modeling Collisional Transitions in Thermal Unimolecular Reactions: Successive Trajectories and Two-Dimensional Master Equation for Trifluoromethane Decomposition in an Argon Bath. J Phys Chem A 2020; 124:6645-6659. [PMID: 32786667 DOI: 10.1021/acs.jpca.0c05906] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Collisional transition processes in thermal unimolecular reactions are modeled by collision frequency, Z, and probability distribution function, P(E, J; E', J'), which describes the probabilities of collisional transitions from the initial state specified by the total energy and angular momentum, (E', J'), to the final states, (E, J). The validity of the collisional transition model, consisting of Z and P(E, J; E', J'), is assessed here for the title reaction. The present model and its parameters are derived from the moments of transition probabilities calculated by classical trajectory simulations. The model explicitly accounts for coupling between the energy and angular momentum transfer and the dependence of transition probability on the initial state. The performance of the model is evaluated by comparing the rate constants calculated by solving the two-dimensional master equation with those obtained from the classical trajectory calculations of the sequence of successive collisions. The rate constants are also compared with available experimental data. The present collisional transition model is found to perform fairly well for predicting the pressure-dependent rate constants. The uncertainty in the prediction and sensitivities of the rate constants to the model parameters are discussed. A simplified version of the model is proposed, which performs as well as the full model. The simplifications and robust procedures for calculating the model parameters are described.
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Affiliation(s)
- Akira Matsugi
- National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
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17
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Grajales-González E, Monge-Palacios M, Sarathy SM. Collision Efficiency Parameter Influence on Pressure-Dependent Rate Constant Calculations Using the SS-QRRK Theory. J Phys Chem A 2020; 124:6277-6286. [PMID: 32663402 PMCID: PMC7458424 DOI: 10.1021/acs.jpca.0c02943] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The system-specific quantum Rice-Ramsperger-Kassel (SS-QRRK) theory (J. Am. Chem. Soc. 2016, 138, 2690) is suitable to determine rate constants below the high-pressure limit. Its current implementation allows incorporating variational effects, multidimensional tunneling, and multistructural torsional anharmonicity in rate constant calculations. Master equation solvers offer a more rigorous approach to compute pressure-dependent rate constants, but several implementations available in the literature do not incorporate the aforementioned effects. However, the SS-QRRK theory coupled with a formulation of the modified strong collision model underestimates the value of unimolecular pressure-dependent rate constants in the high-temperature regime for reactions involving large molecules. This underestimation is a consequence of the definition for collision efficiency, which is part of the energy transfer model. Selection of the energy transfer model and its parameters constitutes a common issue in pressure-dependent calculations. To overcome this underestimation problem, we evaluated and implemented in a bespoke Python code two alternative definitions for the collision efficiency using the SS-QRRK theory and tested their performance by comparing the pressure-dependent rate constants with the Rice-Ramsperger-Kassel-Marcus/Master Equation (RRKM/ME) results. The modeled systems were the tautomerization of propen-2-ol and the decomposition of 1-propyl, 1-butyl, and 1-pentyl radicals. One of the tested definitions, which Dean et al. explicitly derived (Z. Phys. Chem. 2000, 214, 1533), corrected the underestimation of the pressure-dependent rate constants and, in addition, qualitatively reproduced the trend of RRKM/ME data. Therefore, the used SS-QRRK theory with accurate definitions for the collision efficiency can yield results that are in agreement with those from more sophisticated methodologies such as RRKM/ME.
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Affiliation(s)
- E Grajales-González
- Physical Sciences and Engineering Division, Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal, Jeddah 23955-6900, Saudi Arabia
| | - M Monge-Palacios
- Physical Sciences and Engineering Division, Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal, Jeddah 23955-6900, Saudi Arabia
| | - S Mani Sarathy
- Physical Sciences and Engineering Division, Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal, Jeddah 23955-6900, Saudi Arabia
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18
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Xing L, Wang Z, Truhlar DG. Multistructural Anharmonicity Controls the Radical Generation Process in Biofuel Combustion. J Am Chem Soc 2019; 141:18531-18543. [PMID: 31637914 DOI: 10.1021/jacs.9b09194] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The OH radical plays an important role in combustion, and isopentanol (3-methylbutan-1-ol) is a promising sustainable fuel additive and second-generation biofuel. The abstractions of H atoms from fuel molecules are key initiation steps for chain branching in combustion chemistry. In comparison with the more frequently studied ethanol, isopentanol has a longer carbon chain that allows a greater number of products, and experimental work is unavailable for the branching fractions to the various products. However, the site-dependent kinetics of isopentanol with OH radicals are usually experimentally unavailable. Alcohol oxidation by OH is also important in the atmosphere, and in the present study we calculate the rate constants and branching fractions of the hydrogen abstraction reaction of isopentanol by OH radical in a broad temperature range of 298-2400 K, covering temperatures important for atmospheric chemistry and those important for combustion. The calculations are done by multipath variational transition state theory (MP-VTST). With a combination of electronic structure calculations, we determine previously missing thermochemical data. With MP-VTST, a multidimensional tunneling approximation, multiple-structure anharmonicity, and torsional potential anharmonicity, we carried out more realistic rate constant calculations than can be computed by conventional single-structure harmonic transition state theory or by the empirical relations that are currently used in atmospheric and combustion modeling. The roles of various factors in determining the rates are elucidated, and we show that recrossing, tunneling, and multiple structures are all essential for accurate work. We conclude that the multiple structure anharmonicity is the most important correction to conventional transition state theory for this reaction, although recrossing effects and tunneling are by no means insignificant and the tunneling depends significantly on the path. The thermodynamic and kinetics data determined in this work are indispensable for the gas-phase degradation of alcohols in the atmosphere and for the detailed understanding and prediction of ignition mechanisms of biofuels in combustion.
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Affiliation(s)
- Lili Xing
- Energy and Power Engineering Institute , Henan University of Science and Technology , Luoyang , Henan 471003 , China.,Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , Minnesota 55455-0431 , United States
| | - Zhandong Wang
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei , Anhui 230029 , PR China
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute , University of Minnesota , Minnesota 55455-0431 , United States
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19
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Xing L, Bao JL, Wang Z, Wang X, Truhlar DG. Relative Rates of Hydrogen Shift Isomerizations Depend Strongly on Multiple-Structure Anharmonicity. J Am Chem Soc 2018; 140:17556-17570. [DOI: 10.1021/jacs.8b09381] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Lili Xing
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, China
| | - Junwei Lucas Bao
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minnesota 55455-0431, United States
| | - Zhandong Wang
- Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Xuetao Wang
- Energy and Power Engineering Institute, Henan University of Science and Technology, Luoyang, Henan 471003, China
| | - Donald G. Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota, Minnesota 55455-0431, United States
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20
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Long B, Bao JL, Truhlar DG. Unimolecular reaction of acetone oxide and its reaction with water in the atmosphere. Proc Natl Acad Sci U S A 2018; 115:6135-6140. [PMID: 29844185 PMCID: PMC6004451 DOI: 10.1073/pnas.1804453115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Criegee intermediates (i.e., carbonyl oxides with two radical sites) are known to be important atmospheric reagents; however, our knowledge of their reaction kinetics is still limited. Although experimental methods have been developed to directly measure the reaction rate constants of stabilized Criegee intermediates, the experimental results cover limited temperature ranges and do not completely agree well with one another. Here we investigate the unimolecular reaction of acetone oxide [(CH3)2COO] and its bimolecular reaction with H2O to obtain rate constants with quantitative accuracy comparable to experimental accuracy. We do this by using CCSDT(Q)/CBS//CCSD(T)-F12a/DZ-F12 benchmark results to select and validate exchange-correlation functionals, which are then used for direct dynamics calculations by variational transition state theory with small-curvature tunneling and torsional and high-frequency anharmonicity. We find that tunneling is very significant in the unimolecular reaction of (CH3)2COO and its bimolecular reaction with H2O. We show that the atmospheric lifetimes of (CH3)2COO depend on temperature and that the unimolecular reaction of (CH3)2COO is the dominant decay mode above 240 K, while the (CH3)2COO + SO2 reaction can compete with the corresponding unimolecular reaction below 240 K when the SO2 concentration is 9 × 1010 molecules per cubic centimeter. We also find that experimental results may not be sufficiently accurate for the unimolecular reaction of (CH3)2COO above 310 K. Not only does the present investigation provide insights into the decay of (CH3)2COO in the atmosphere, but it also provides an illustration of how to use theoretical methods to predict quantitative rate constants of medium-sized Criegee intermediates.
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Affiliation(s)
- Bo Long
- College of Materials Science and Engineering, Guizhou Minzu University, 550025 Guiyang, China;
- Department of Chemistry, Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431
- Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Junwei Lucas Bao
- Department of Chemistry, Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431
- Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431;
- Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
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21
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Grajales-González E, Monge-Palacios M, Sarathy SM. Theoretical Kinetic Study of the Unimolecular Keto–Enol Tautomerism Propen-2-ol ↔ Acetone. Pressure Effects and Implications in the Pyrolysis of tert- and 2-Butanol. J Phys Chem A 2018; 122:3547-3555. [DOI: 10.1021/acs.jpca.8b00836] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- E. Grajales-González
- Clean Combustion Research Center, King Abdullah University of Science and Technology, Al Kindi Building 5, Thuwal 23955, Saudi Arabia
| | - M. Monge-Palacios
- Clean Combustion Research Center, King Abdullah University of Science and Technology, Al Kindi Building 5, Thuwal 23955, Saudi Arabia
| | - S. Mani Sarathy
- Clean Combustion Research Center, King Abdullah University of Science and Technology, Al Kindi Building 5, Thuwal 23955, Saudi Arabia
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22
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Bao JL, Truhlar DG. Effect of energy dependence of the density of states on pressure-dependent rate constants. Phys Chem Chem Phys 2018; 20:30475-30479. [DOI: 10.1039/c8cp05915b] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The rate of collisional energy transfer is slowed down by the increase in the density of states at higher energies.
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Affiliation(s)
- Junwei Lucas Bao
- Department of Chemistry
- Chemical Theory Center, and Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
| | - Donald G. Truhlar
- Department of Chemistry
- Chemical Theory Center, and Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
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23
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Zhang H, Zhang X, Truhlar DG, Xu X. Nonmonotonic Temperature Dependence of the Pressure-Dependent Reaction Rate Constant and Kinetic Isotope Effect of Hydrogen Radical Reaction with Benzene Calculated by Variational Transition-State Theory. J Phys Chem A 2017; 121:9033-9044. [PMID: 29095614 DOI: 10.1021/acs.jpca.7b09374] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction between H and benzene is a prototype for reactions of radicals with aromatic hydrocarbons. Here we report calculations of the reaction rate constants and the branching ratios of the two channels of the reaction (H addition and H abstraction) over a wide temperature and pressure range. Our calculations, obtained with an accurate potential energy surface, are based on variational transition-state theory for the high-pressure limit of the addition reaction and for the abstraction reaction and on system-specific quantum Rice-Ramsperger-Kassel theory calibrated by variational transition-state theory for pressure effects on the addition reaction. The latter is a very convenient way to include variational effects, corner-cutting tunneling, and anharmonicity in falloff calculations. Our results are in very good agreement with the limited experimental data and show the importance of including pressure effects in the temperature interval where the mechanism changes from addition to abstraction. We found a negative temperature effect of the total reaction rate constants at 1 atm pressure in the temperature region where experimental data are missing and accurate theoretical data were previously missing as well. We also calculated the H + C6H6/C6D6 and D + C6H6/C6D6 kinetic isotope effects, and we compared our H + C6H6 results to previous theoretical data for H + toluene. We report a very novel nonmonotonic dependence of the kinetic isotope effect on temperature. A particularly striking effect is the prediction of a negative temperature dependence of the total rate constant over 300-500 K wide temperature ranges, depending on the pressure but generally in the range from 600 to 1700 K, which includes the temperature range of ignition in gasoline engines, which is important because aromatics are important components of common fuels.
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Affiliation(s)
- Hui Zhang
- State Key Laboratory of Chemical Resource Engineering, Institute of Materia Medica, College of Science, Beijing University of Chemical Technology , Beijing 100029, P. R. China.,Center for Combustion Energy and Department of Thermal Engineering, Tsinghua University , Beijing 100084, P. R. China
| | - Xin Zhang
- State Key Laboratory of Chemical Resource Engineering, Institute of Materia Medica, College of Science, Beijing University of Chemical Technology , Beijing 100029, P. R. China
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States
| | - Xuefei Xu
- Center for Combustion Energy and Department of Thermal Engineering, Tsinghua University , Beijing 100084, P. R. China
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24
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Xing L, Bao JL, Wang Z, Zhang F, Truhlar DG. Degradation of Carbonyl Hydroperoxides in the Atmosphere and in Combustion. J Am Chem Soc 2017; 139:15821-15835. [PMID: 29022349 DOI: 10.1021/jacs.7b08297] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Oxygenates with carbonyl and hydroperoxy functional groups are important intermediates that are generated during the autoxidation of organic compounds in the atmosphere and during the autoignition of transport fuels. In the troposphere, the degradation of carbonyl hydroperoxides leads to low-vapor-pressure polyfunctional species that may precipitate in clouds and fog droplets or to the formation of secondary organic aerosols (SOAs). In combustion, the fate of carbonyl hydroperoxides is important for the performance of advanced combustion engines, especially for autoignition. A key fate of the carbonyl hydroperoxides is reaction with OH radicals, for which kinetics data are experimentally unavailable. Here, we study 4-hydroperoxy-2-pentanone (CH3C(═O)CH2CH(OOH)CH3) as a model compound to clarify the kinetics of OH reactions with carbonyl hydroperoxides, in particular H atom abstraction and OH addition reactions. With a combination of electronic structure calculations, we determine previously missing thermochemical data, and with multipath variational transition state theory (MP-VTST), a multidimensional tunneling (MT) approximation, multiple-structure anharmonicity, and torsional potential anharmonicity, we obtained much more accurate rate constants than the ones that can computed by conventional single-structure harmonic transition state theory (TST) and than the empirically estimated rate constants that are currently used in atmospheric and combustion modeling. The roles of various factors in determining the rates are elucidated. The pressure-dependent rate constants for the addition reaction are computed using system-specific quantum RRK theory. The calculated temperature range is 298-2400 K, and the pressure range is 0.01-100 atm. The accurate thermodynamic and kinetics data determined in this work are indispensable in the global modeling of SOAs in atmospheric science and in the detailed understanding and prediction of ignition properties of hydrocarbons and alternative fuels.
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Affiliation(s)
- Lili Xing
- National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, China.,Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota , Minnesota 55455-0431, United States
| | - Junwei Lucas Bao
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota , Minnesota 55455-0431, United States
| | - Zhandong Wang
- King Abdullah University of Science and Technology (KAUST) , Clean Combustion Research Center (CCRC), Thuwal, 23955-6900, Saudi Arabia
| | - Feng Zhang
- National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei, Anhui 230029, China
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Minnesota Supercomputing Institute, University of Minnesota , Minnesota 55455-0431, United States
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25
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Zhang L, Yang L, Zhao Y, Zhang J, Feng D, Sun S. Effects of Water Molecule on CO Oxidation by OH: Reaction Pathways, Kinetic Barriers, and Rate Constants. J Phys Chem A 2017; 121:4868-4880. [DOI: 10.1021/acs.jpca.7b03704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Linyao Zhang
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Li Yang
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Yijun Zhao
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Jiaxu Zhang
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Dongdong Feng
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Shaozeng Sun
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
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26
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Bao JL, Xing L, Truhlar DG. Dual-Level Method for Estimating Multistructural Partition Functions with Torsional Anharmonicity. J Chem Theory Comput 2017; 13:2511-2522. [DOI: 10.1021/acs.jctc.7b00232] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Junwei Lucas Bao
- Department of Chemistry, Chemical Theory
Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Lili Xing
- Department of Chemistry, Chemical Theory
Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
| | - Donald G. Truhlar
- Department of Chemistry, Chemical Theory
Center, and Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, United States
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27
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Bao JL, Truhlar DG. Variational transition state theory: theoretical framework and recent developments. Chem Soc Rev 2017; 46:7548-7596. [DOI: 10.1039/c7cs00602k] [Citation(s) in RCA: 207] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This article reviews the fundamentals of variational transition state theory (VTST), its recent theoretical development, and some modern applications.
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Affiliation(s)
- Junwei Lucas Bao
- Department of Chemistry
- Chemical Theory Center, and Minnesota Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
| | - Donald G. Truhlar
- Department of Chemistry
- Chemical Theory Center, and Minnesota Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
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28
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Abstract
We theoretically investigate the rate constantk(T,p) of the OH + SO2reaction with experimental accuracy.
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Affiliation(s)
- Bo Long
- College of Material Science and Engineering
- Guizhou Minzu University
- Guiyang
- China
- Department of Chemistry
| | - Junwei Lucas Bao
- Department of Chemistry
- Chemical Theory Center, and Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
| | - Donald G. Truhlar
- Department of Chemistry
- Chemical Theory Center, and Supercomputing Institute
- University of Minnesota
- Minneapolis
- USA
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29
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Barrierless association of CF2 and dissociation of C2F4 by variational transition-state theory and system-specific quantum Rice-Ramsperger-Kassel theory. Proc Natl Acad Sci U S A 2016; 113:13606-13611. [PMID: 27834727 DOI: 10.1073/pnas.1616208113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C2F4), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice-Ramsperger-Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements.
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30
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Long B, Bao JL, Truhlar DG. Atmospheric Chemistry of Criegee Intermediates: Unimolecular Reactions and Reactions with Water. J Am Chem Soc 2016; 138:14409-14422. [PMID: 27682870 DOI: 10.1021/jacs.6b08655] [Citation(s) in RCA: 200] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Criegee intermediates are produced in the ozonolysis of unsaturated hydrocarbons in the troposphere, and understanding their fate is a prerequisite to modeling climate-controlling atmospheric aerosol formation. Although some experimental and theoretical rate data are available, they are incomplete and partially inconsistent, and they do not cover the tropospheric temperature range. Here, we report quantum chemical rate constants for the reactions of stabilized formaldehyde oxide (CH2OO) and acetaldehyde oxide (syn-CH3CHOO and anti-CH3CHOO) with H2O and for their unimolecular reactions. Our results are obtained by combining post-CCSD(T) electronic structure benchmarks, validated density functional theory potential energy surfaces, and multipath variational transition state theory with multidimensional tunneling, coupled-torsions anharmonicity, and high-frequency anharmonicity. We consider two different types of reaction mechanisms for the bimolecular reactions, namely, (i) addition-coupled hydrogen transfer and (ii) double hydrogen atom transfer (DHAT). First, we show that the MN15-L exchange-correlation functional has kJ/mol accuracy for the CH2OO + H2O and syn-CH3CHOO + H2O reactions. Then we show that, due to tunneling, the DHAT mechanism is especially important in the syn-CH3CHOO + H2O reaction. We show that the dominant pathways for reactions of Criegee intermediates depend on altitude. The results we obtain eliminate the discrepancy between experiment and theory under those conditions where experimental results are available, and we make predictions for the full range of temperatures and pressures encountered in the troposphere and stratosphere. The present results are an important cog in clarifying the atmospheric fate and oxidation processes of Criegee intermediates, and they also show how theoretical methods can provide reliable rate data for complex atmospheric processes.
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Affiliation(s)
- Bo Long
- College of Information Engineering, Guizhou Minzu University , Guiyang 550025, China.,Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States
| | - Junwei Lucas Bao
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota , Minneapolis, Minnesota 55455-0431, United States
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