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Shi Z, Lele AD, Jasper AW, Klippenstein SJ, Ju Y. Quasi-Classical Trajectory Calculation of Rate Constants Using an Ab Initio Trained Machine Learning Model (aML-MD) with Multifidelity Data. J Phys Chem A 2024; 128:3449-3457. [PMID: 38642065 DOI: 10.1021/acs.jpca.4c00750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2024]
Abstract
Machine learning (ML) provides a great opportunity for the construction of models with improved accuracy in classical molecular dynamics (MD). However, the accuracy of a ML trained model is limited by the quality and quantity of the training data. Generating large sets of accurate ab initio training data can require significant computational resources. Furthermore, inconsistent or incompatible data with different accuracies obtained using different methods may lead to biased or unreliable ML models that do not accurately represent the underlying physics. Recently, transfer learning showed its potential for avoiding these problems as well as for improving the accuracy, efficiency, and generalization of ML models using multifidelity data. In this work, ab initio trained ML-based MD (aML-MD) models are developed through transfer learning using DFT and multireference data from multiple sources with varying accuracy within the Deep Potential MD framework. The accuracy of the force field is demonstrated by calculating rate constants for the H + HO2 → H2 + 3O2 reaction using quasi-classical trajectories. We show that the aML-MD model with transfer learning can accurately predict the rate constants while reducing the computational cost by more than five times compared to the use of more expensive quantum chemistry training data sets. Hence, the aML-MD model with transfer learning shows great potential in using multifidelity data to reduce the computational cost involved in generating the training set for these potentials.
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Affiliation(s)
- Zhiyu Shi
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Aditya Dilip Lele
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
| | - Ahren W Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Yiguang Ju
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, United States
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2
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Copan AV, Moore KB, Elliott SN, Mulvihill CR, Pratali Maffei L, Klippenstein SJ. Radical Stereochemistry: Accounting for Diastereomers in Kinetic Mechanism Development. J Phys Chem A 2024. [PMID: 38683599 DOI: 10.1021/acs.jpca.4c01060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2024]
Abstract
Recent work in combustion and atmospheric chemistry has revealed cases in which diastereomers must be distinguished to accurately model a reacting flow. This paper presents an open-source framework for introducing such stereoisomer resolution into a kinetic mechanism. We detail our definitions and algorithms for labeling and enumerating the stereoisomers of a molecule and then generalize our system to describe the transition state (TS) of a reaction. This allows for the stereospecific enumeration of reactants and products while accounting for "fleeting" stereochemistry that is unique to the TS. We also present the AutoMech Chemical Identifier (AMChI), an InChI-like string identifier that accounts for stereocenters omitted by InChI. This identifier is extended to describe the TSs of reactions, providing a universal lookup key for specific reaction channels. The final piece of our methodology is an analytic formula to remove redundancy from a stereoresolved mechanism when its enantiomers exist as a racemic mixture, making it as compact as possible while fully accounting for the differences between diastereomers. In applying our methodology to two subsets of the NUIGMech1.1 mechanism, we find that our approach reduces the extra species added for large-fuel oxidation from 2231 (133%, full expansion) to 694 (41%, nonredundant expansion). We also find that for pyrolysis more than a quarter of the species in the expanded mechanism cannot be properly described by an InChI string, requiring an AMChI string to communicate their identity. Finally, we find that roughly one-quarter of the large-fuel oxidation reactions and one-third of the pyrolysis reactions include fleeting TS stereochemistry, which may have relevant effects on their kinetics.
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Affiliation(s)
- Andreas V Copan
- College of Engineering, University of Georgia, Athens, Georgia 30602, United States
- Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - Kevin B Moore
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Clayton R Mulvihill
- Department of Mechanical Engineering, Baylor University, Waco, Texas 76798, United States
| | - Luna Pratali Maffei
- Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano, Milano 20133, Italy
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Qian Y, Roy TK, Jasper AW, Sojdak CA, Kozlowski MC, Klippenstein SJ, Lester MI. Isomer-resolved unimolecular dynamics of the hydroperoxyalkyl intermediate (•QOOH) in cyclohexane oxidation. Proc Natl Acad Sci U S A 2024; 121:e2401148121. [PMID: 38602914 PMCID: PMC11032462 DOI: 10.1073/pnas.2401148121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/08/2024] [Indexed: 04/13/2024] Open
Abstract
The oxidation of cycloalkanes is important in the combustion of transportation fuels and in atmospheric secondary organic aerosol formation. A transient carbon-centered radical intermediate (•QOOH) in the oxidation of cyclohexane is identified through its infrared fingerprint and time- and energy-resolved unimolecular dissociation dynamics to hydroxyl (OH) radical and bicyclic ether products. Although the cyclohexyl ring structure leads to three nearly degenerate •QOOH isomers (β-, γ-, and δ-QOOH), their transition state (TS) barriers to OH products are predicted to differ considerably. Selective characterization of the β-QOOH isomer is achieved at excitation energies associated with the lowest TS barrier, resulting in rapid unimolecular decay to OH products that are detected. A benchmarking approach is employed for the calculation of high-accuracy stationary point energies, in particular TS barriers, for cyclohexane oxidation (C6H11O2), building on higher-level reference calculations for the smaller ethane oxidation (C2H5O2) system. The isomer-specific characterization of β-QOOH is validated by comparison of experimental OH product appearance rates with computed statistical microcanonical rates, including significant heavy-atom tunneling, at energies in the vicinity of the TS barrier. Master-equation modeling is utilized to extend the results to thermal unimolecular decay rate constants at temperatures and pressures relevant to cyclohexane combustion.
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Affiliation(s)
- Yujie Qian
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA19104-6323
| | - Tarun Kumar Roy
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA19104-6323
| | - Ahren W. Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL60439
| | | | - Marisa C. Kozlowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA19104-6323
| | | | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA19104-6323
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Kidwell NM, Klippenstein SJ, Lehman JH, McCoy AB. Tribute to Marsha I. Lester. J Phys Chem A 2024; 128:501-502. [PMID: 38268456 DOI: 10.1021/acs.jpca.3c07803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2024]
Affiliation(s)
- Nathanael M Kidwell
- Department of Chemistry, The College of William and Mary, Williamsburg 23187-8795, Virginia, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont 60439, Illinois, United States
| | - Julia H Lehman
- School of Chemistry, University of Birmingham, Edgbaston B15 2TT, United Kingdom
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle 98195, Washington, United States
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Klippenstein SJ, Elliott SN. OH Roaming during the Ozonolysis of α-Pinene: A New Route to Highly Oxygenated Molecules? J Phys Chem A 2023; 127:10647-10662. [PMID: 38055299 DOI: 10.1021/acs.jpca.3c05179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
The formation of low-volatility organic compounds in the ozonolysis of α-pinene, the dominant atmospheric monoterpene, provides an important route to aerosol formation. In this work, we consider a previously unexplored set of pathways for the formation of highly oxygenated molecules in α-pinene ozonolysis. Pioneering, direct experimental observations of Lester and co-workers have demonstrated a significant production of hydroxycarbonyl products in the dissociation of Criegee intermediates. Theoretical analyses indicate that this production arises from OH roaming-induced pathways during the OO fission of the vinylhydroperoxides (VHPs), which in turn come from internal H transfers in the Criegee intermediates. Ab initio kinetics computations are used here to explore the OH roaming-induced channels that arise from the ozonolysis of α-pinene. For computational reasons, the calculations consider a surrogate for α-pinene, where two spectator methyl groups are replaced with H atoms. Multireference electronic structure calculations are used to illustrate a variety of energetically accessible OH roaming pathways for the four VHPs arising from the ozonolysis of this α-pinene surrogate. Ab initio transition-state theory-based master equation calculations indicate that for the dissociation of stabilized VHPs, these OH roaming pathways are kinetically significant with a branching that generally increases from ∼20% at room temperature up to ∼70% at lower temperatures representative of the troposphere. For one of the VHPs, this branching already exceeds 60% at room temperature. For the overall ozonolysis process, these branching ratios would be greatly reduced by a limited branching to the stabilized VHP, although there would also be some modest roaming fraction for the nonthermal VHP dissociation process. The strong exothermicities of the roaming-induced isomerizations/additions and abstractions suggest new routes to fission of the cyclobutane rings. Such ring fissions would facilitate further autoxidation reactions, thereby providing a new route for producing highly oxygenated nonvolatile precursors to aerosol formation.
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Affiliation(s)
- Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Cho J, Rösch D, Tao Y, Osborn DL, Klippenstein SJ, Sheps L, Sivaramakrishnan R. Modeling-Experiment-Theory Analysis of Reactions Initiated from Cl + Methyl Formate. J Phys Chem A 2023; 127:9804-9819. [PMID: 37937747 DOI: 10.1021/acs.jpca.3c05085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2023]
Abstract
Methyl formate (MF; CH3OCHO) is the smallest representative of esters, which are common components of biodiesel. The present study characterizes the thermal dissociation kinetics of the radicals formed by H atom abstraction from MF─CH3OCO and CH2OCHO─through a combination of modeling, experiment, and theory. For the experimental effort, excimer laser photolysis of Cl2 was used as a source of Cl atoms to initiate reactions with MF in the gas phase. Time-resolved species profiles of MF, Cl2, HCl, CO2, CH3, CH3Cl, CH2O, and CH2ClOCHO were measured and quantified using photoionization mass spectrometry at temperatures of 400-750 K and 10 Torr. The experimental data were simulated using a kinetic model, which was informed by ab initio-based theoretical kinetics calculations and included chlorine chemistry and secondary reactions of radical decomposition products. We calculated the rate coefficients for the H-abstraction reactions Cl + MF → HCl + CH3OCO (R1a) and Cl + MF → HCl + CH2OCHO (R1b): k1a,theory = 6.71 × 10-15·T1.14·exp(-606/T) cm3/molecule·s; k1b,theory = 4.67 × 10-18·T2.21·exp(-245/T) cm3/molecule·s over T = 200-2000 K. Electronic structure calculations indicate that the barriers to CH3OCO and CH2OCHO dissociation are 13.7 and 31.6 kcal/mol and lead to CH3 + CO2 (R3) and CH2O + HCO (R5), respectively. The master equation-based theoretical rate coefficients are k3,theory (P = ∞) = 2.94 × 109·T1.21·exp(-6209/T) s-1 and k5,theory (P = ∞) = 8.45 × 108·T1.39·exp(-15132/T) s-1 over T = 300-1500 K. The calculated branching fractions into R1a and R1b and the rate coefficient for R5 were validated by modeling of the experimental species time profiles and found to be in excellent agreement with theory. Additionally, we found that the bimolecular reactions CH2OCHO + Cl, CH2OCHO + Cl2, and CH3 + Cl2 were critical to accurately model the experimental data and constrain the kinetics of MF-radicals. Inclusion of the kinetic parameters determined in this study showed a significant impact on combustion simulations of larger methyl esters, which are considered as biodiesel surrogates.
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Affiliation(s)
- Jaeyoung Cho
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Daniel Rösch
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969, United States
| | - Yujie Tao
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969, United States
| | - Stephen J Klippenstein
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Leonid Sheps
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969, United States
| | - Raghu Sivaramakrishnan
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Mulvihill CR, Georgievskii Y, Klippenstein SJ. Quantum and anharmonic effects in non-adiabatic transition state theory. J Chem Phys 2023; 159:174104. [PMID: 37916591 DOI: 10.1063/5.0168612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
Quantitative descriptions of non-adiabatic transition rates at intermediate temperatures are challenging due to the simultaneous importance of quantum and anharmonic effects. In this paper, the interplay between quantum effects-for motion across or along the seam of crossing-and anharmonicity in the seam potential is considered within the weak coupling limit. The well-known expression for quantized 1-D motion across the seam (i.e., tunneling) in the linear terms approximation is derived in the thermal domain using the Lagrangian formalism, which is then applied to the case when tunneling is distributed along the seam of crossing (treating motion along the seam classically). For high-frequency quantum modes, a vibrationally adiabatic (VA) approach is developed that introduces to the non-adiabatic rate constant a factor associated with high-frequency wavefunction overlap; this approach treats the high-frequency motion along the seam quantum mechanically. To test these methodologies, the reaction N2O ↔ N2 + O(3P) was chosen. CCSD(T)-F12b/cc-pVTZ-F12 explorations of the 3A'-1A' seam of N2O revealed that seam anharmonicity has a strong effect on the rate constant (a factor of ∼20 at 2000 K). Several quantum effects were found to be significant at intermediate/lower temperatures, including the quantum N-N vibration that was coupled with seam anharmonicity using the VA approach. Finally, a 1-D approximation to non-adiabatic instanton theory is presented to estimate the validity limit of the linear terms model at low temperatures (∼250 K for N2O). We recommend that the assumptions built into many statistical theories for non-adiabatic reactions-harmonic behavior, classical motion, linear terms, and weak coupling-should be verified on a case-by-case basis.
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Affiliation(s)
- Clayton R Mulvihill
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
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Zou M, Liu T, Vansco MF, Sojdak CA, Markus CR, Almeida R, Au K, Sheps L, Osborn DL, Winiberg FAF, Percival CJ, Taatjes CA, Klippenstein SJ, Lester MI, Caravan RL. Bimolecular Reaction of Methyl-Ethyl-Substituted Criegee Intermediate with SO 2. J Phys Chem A 2023; 127:8994-9002. [PMID: 37870411 DOI: 10.1021/acs.jpca.3c04648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
Methyl-ethyl-substituted Criegee intermediate (MECI) is a four-carbon carbonyl oxide that is formed in the ozonolysis of some asymmetric alkenes. MECI is structurally similar to the isoprene-derived methyl vinyl ketone oxide (MVK-oxide) but lacks resonance stabilization, making it a promising candidate to help us unravel the effects of size, structure, and resonance stabilization that influence the reactivity of atmospherically important, highly functionalized Criegee intermediates. We present experimental and theoretical results from the first bimolecular study of MECI in its reaction with SO2, a reaction that shows significant sensitivity to the Criegee intermediate structure. Using multiplexed photoionization mass spectrometry, we obtain a rate coefficient of (1.3 ± 0.3) × 10-10 cm3 s-1 (95% confidence limits, 298 K, 10 Torr) and demonstrate the formation of SO3 under our experimental conditions. Through high-level theory, we explore the effect of Criegee intermediate structure on the minimum energy pathways for their reactions with SO2 and obtain modified Arrhenius fits to our predictions for the reaction of both syn and anti conformers of MECI with SO2 (ksyn = 4.42 × 1011 T-7.80exp(-1401/T) cm3 s-1 and kanti = 1.26 × 1011 T-7.55exp(-1397/T) cm3 s-1). Our experimental and theoretical rate coefficients (which are in reasonable agreement at 298 K) show that the reaction of MECI with SO2 is significantly faster than MVK-oxide + SO2, demonstrating the substantial effect of resonance stabilization on Criegee intermediate reactivity.
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Affiliation(s)
- Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Michael F Vansco
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Christopher A Sojdak
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Charles R Markus
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Raybel Almeida
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Kendrew Au
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Leonid Sheps
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - David L Osborn
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Frank A F Winiberg
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Carl J Percival
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Craig A Taatjes
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Rebecca L Caravan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Klippenstein SJ, Mulvihill CR, Glarborg P. Theoretical Kinetics Predictions for Reactions on the NH 2O Potential Energy Surface. J Phys Chem A 2023; 127:8650-8662. [PMID: 37812768 DOI: 10.1021/acs.jpca.3c05181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Recent modeling studies of ammonia oxidation, which are motivated by the prospective role of ammonia as a zero-carbon fuel, have indicated significant discrepancies among the existing literature mechanisms. In this study, high-level theoretical kinetics predictions have been obtained for reactions on the NH2O potential energy surface, including the NH2 + O, HNO + H, and NH + OH reactions. These reactions have previously been highlighted as important reactions in NH3 oxidation with high sensitivity and high uncertainty. The potential energy surface is explored with coupled cluster calculations, including large basis sets and high-level corrections to yield high-accuracy (∼0.2 kcal/mol 2σ uncertainty) estimates of the stationary point energies. Variational transition state theory is used to predict the microcanonical rate constants, which are then incorporated in master equation treatments of the temperature- and pressure-dependent kinetics. For radical-radical channels, the microcanonical rates are obtained from variable reaction coordinate transition state theory implementing directly evaluated multireference electronic energies. The analysis yields predictions for the total rate constants as well as the branching ratios. We find that the NO + H2 channel contributes 10% of the total NH2 + O flux at combustion temperatures, although this channel is not included in modern NH3 oxidation mechanisms. Modeling is used to illustrate the ramifications of these rate predictions on the kinetics of NH3 oxidation and NOx formation. The present results for NH2 + O are important for predicting the chain branching and formation of NO in the oxidation of NH3 and thermal DeNOx.
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Affiliation(s)
- Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Clayton R Mulvihill
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Peter Glarborg
- DTU Chemical Engineering, Technical University of Denmark, 2800 Lyngby, Denmark
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Liu T, Elliott SN, Zou M, Vansco MF, Sojdak CA, Markus CR, Almeida R, Au K, Sheps L, Osborn DL, Winiberg FAF, Percival CJ, Taatjes CA, Caravan RL, Klippenstein SJ, Lester MI. OH Roaming and Beyond in the Unimolecular Decay of the Methyl-Ethyl-Substituted Criegee Intermediate: Observations and Predictions. J Am Chem Soc 2023; 145:19405-19420. [PMID: 37623926 DOI: 10.1021/jacs.3c07126] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Alkene ozonolysis generates short-lived Criegee intermediates that are a significant source of hydroxyl (OH) radicals. This study demonstrates that roaming of the separating OH radicals can yield alternate hydroxycarbonyl products, thereby reducing the OH yield. Specifically, hydroxybutanone has been detected as a stable product arising from roaming in the unimolecular decay of the methyl-ethyl-substituted Criegee intermediate (MECI) under thermal flow cell conditions. The dynamical features of this novel multistage dissociation plus a roaming unimolecular decay process have also been examined with ab initio kinetics calculations. Experimentally, hydroxybutanone isomers are distinguished from the isomeric MECI by their higher ionization threshold and distinctive photoionization spectra. Moreover, the exponential rise of the hydroxybutanone kinetic time profile matches that for the unimolecular decay of MECI. A weaker methyl vinyl ketone (MVK) photoionization signal is also attributed to OH roaming. Complementary multireference electronic structure calculations have been utilized to map the unimolecular decay pathways for MECI, starting with 1,4 H atom transfer from a methyl or methylene group to the terminal oxygen, followed by roaming of the separating OH and butanonyl radicals in the long-range region of the potential. Roaming via reorientation and the addition of OH to the vinyl group of butanonyl is shown to yield hydroxybutanone, and subsequent C-O elongation and H-transfer can lead to MVK. A comprehensive theoretical kinetic analysis has been conducted to evaluate rate constants and branching yields (ca. 10-11%) for thermal unimolecular decay of MECI to conventional and roaming products under laboratory and atmospheric conditions, consistent with the estimated experimental yield (ca. 7%).
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Affiliation(s)
- Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Michael F Vansco
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Christopher A Sojdak
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Charles R Markus
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Raybel Almeida
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Kendrew Au
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Leonid Sheps
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - David L Osborn
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
- Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Frank A F Winiberg
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Carl J Percival
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Craig A Taatjes
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Rebecca L Caravan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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Klippenstein SJ, Kohse-Höinghaus K. Combustion in a Sustainable World: From Molecules to Processes. J Phys Chem A 2023; 127:3737-3742. [PMID: 37139614 DOI: 10.1021/acs.jpca.3c02016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Selby TM, Goulay F, Soorkia S, Ray A, Jasper AW, Klippenstein SJ, Morozov AN, Mebel AM, Savee JD, Taatjes CA, Osborn DL. Radical-Radical Reactions in Molecular Weight Growth: The Phenyl + Propargyl Reaction. J Phys Chem A 2023; 127:2577-2590. [PMID: 36905386 DOI: 10.1021/acs.jpca.2c08121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
The mechanism for hydrocarbon ring growth in sooting environments is still the subject of considerable debate. The reaction of phenyl radical (C6H5) with propargyl radical (H2CCCH) provides an important prototype for radical-radical ring-growth pathways. We studied this reaction experimentally over the temperature range of 300-1000 K and pressure range of 4-10 Torr using time-resolved multiplexed photoionization mass spectrometry. We detect both the C9H8 and C9H7 + H product channels and report experimental isomer-resolved product branching fractions for the C9H8 product. We compare these experiments to theoretical kinetics predictions from a recently published study augmented by new calculations. These ab initio transition state theory-based master equation calculations employ high-quality potential energy surfaces, conventional transition state theory for the tight transition states, and direct CASPT2-based variable reaction coordinate transition state theory (VRC-TST) for the barrierless channels. At 300 K only the direct adducts from radical-radical addition are observed, with good agreement between experimental and theoretical branching fractions, supporting the VRC-TST calculations of the barrierless entrance channel. As the temperature is increased to 1000 K we observe two additional isomers, including indene, a two-ring polycyclic aromatic hydrocarbon, and a small amount of bimolecular products C9H7 + H. Our calculated branching fractions for the phenyl + propargyl reaction predict significantly less indene than observed experimentally. We present further calculations and experimental evidence that the most likely cause of this discrepancy is the contribution of H atom reactions, both H + indenyl (C9H7) recombination to indene and H-assisted isomerization that converts less stable C9H8 isomers into indene. Especially at low pressures typical of laboratory investigations, H-atom-assisted isomerization needs to be considered. Regardless, the experimental observation of indene demonstrates that the title reaction leads, either directly or indirectly, to the formation of the second ring in polycyclic aromatic hydrocarbons.
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Affiliation(s)
- Talitha M Selby
- Department of Mathematics and Natural Sciences, University of Wisconsin-Milwaukee, West Bend, Wisconsin 53095, United States
| | - Fabien Goulay
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Satchin Soorkia
- Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay, CNRS, F-91405 Orsay, France
| | - Amelia Ray
- Department of Chemistry, University of Wisconsin-Parkside, Kenosha, Wisconsin 53144, United States
| | - Ahren W Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - John D Savee
- KLA Corporation, Milpitas, California 95035, United States
| | - Craig A Taatjes
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551, United States
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551, United States
- Department of Chemical Engineering, University of California, Davis, Davis, California 95616, United States
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13
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Elliott SN, Keçeli M, Ghosh MK, Somers KP, Curran HJ, Klippenstein SJ. High-Accuracy Heats of Formation for Alkane Oxidation: From Small to Large via the Automated CBH-ANL Method. J Phys Chem A 2023; 127:1512-1531. [PMID: 36695527 DOI: 10.1021/acs.jpca.2c07248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
It is generally challenging to obtain high-accuracy predictions for the heat of formation for species with more than a handful of heavy atoms, such as those of importance in standard combustion mechanisms. To this end, we construct the CBH-ANL approach and illustrate that, for a set of 194 alkane oxidation species, it can be used to produce ΔHf(0 K) values with 2σ uncertainties of 0.2-0.5 kcal mol-1. This set includes the alkanes, hydroperoxides, and alkyl, peroxy, and hydroperoxyalkyl radicals for 17 representative hydrocarbon fuels containing up to 10 heavy atoms with various degrees of branching in the alkane backbone. The CBH-ANL approach, automated in the QTC and AutoMech software suites, builds balanced chemical equations for the calculation of ΔHf(0 K), in which the reference species may be up to five heavy atoms. The high-level ANL0 and ANL1 reference ΔHf(0 K) values are further refined for even the largest of these reference species with a novel laddering approach. We perform a comprehensive quantification of the uncertainties for both the individual reference species (the largest of which is 0.15 kcal mol-1) and the propagation of those uncertainties when used in the calculation of ΔHf(0 K) for the 194 target species. We examine the sensitivity of the predicted ΔHf(0 K) values to (i) electronic energies from various methods, including ωB97X-D/cc-pVTZ, B2PLYP-D3/cc-pVTZ, CCSD(T)-F12b/cc-pVDZ-F12//B2PLYP-D3/cc-pVTZ, and CCSD(T)-F12b/cc-pVTZ-F12//B2PLYP-D3/cc-pVTZ; (ii) the zero-point vibrational energies (ZPVEs), where we consider harmonic ZPVEs as well as two scaling-based estimates of the anharmonic ZPVEs, all implemented for both ωB97X-D/cc-pVTZ and B2PLYP-D3/cc-pVTZ calculations; (iii) the particular CBH-ANL scheme employed; and (iv) the procedure for choosing the reference conformer for the analyses. The discussion concludes with a summary of the estimated overall uncertainty in the predictions and a validation of the predictions for the alkane subset.
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Affiliation(s)
- Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
| | - Murat Keçeli
- Computational Science Division, Argonne National Laboratory, Lemont, Illinois60439, United States
| | - Manik K Ghosh
- Combustion Chemistry Centre, School of Chemistry, Ryan Institute, MaREI, National University of Ireland, GalwayH91 TK33, Ireland
| | - Kieran P Somers
- Combustion Chemistry Centre, School of Chemistry, Ryan Institute, MaREI, National University of Ireland, GalwayH91 TK33, Ireland
| | - Henry J Curran
- Combustion Chemistry Centre, School of Chemistry, Ryan Institute, MaREI, National University of Ireland, GalwayH91 TK33, Ireland
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois60439, United States
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14
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Cho J, Mulvihill CR, Klippenstein SJ, Sivaramakrishnan R. Bimolecular Peroxy Radical (RO 2) Reactions and Their Relevance in Radical Initiated Oxidation of Hydrocarbons. J Phys Chem A 2023; 127:300-315. [PMID: 36562763 DOI: 10.1021/acs.jpca.2c06960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The kinetics of peroxy radical (RO2) reactions have been of long-standing interest in atmospheric and combustion chemistry. Nevertheless, the lack of kinetic studies at higher temperatures for their reactions with other radicals such as OH has precluded the inclusion of this class of reactions in detailed kinetics models developed for combustion applications. In this work, guided by the limited room-temperature experimental studies on selected alkyl-peroxy radicals and literature theoretical kinetics on the prototypical CH3O2 + OH system, we have performed parametric studies on the effect of uncertainties in the rate coefficients and branching ratios to potential product channels for RO2 + OH reactions at higher temperatures. Literature kinetics models were used to simulate autoignition delays, laminar flame speeds, and speciation profiles in flow and stirred reactors for a variety of common combustion-relevant fuels. Inclusion of RO2 + OH reactions was found to retard autoignition in fuel-lean (φ = 0.5) mixtures of ethane and dimethyl ether in air. The observed effects were noticeably more pronounced in ozone-enriched combustion of ethane and dimethyl ether. The simulations also examined the influence of ozone doping levels, pressures, and equivalence ratios for both ethane and dimethyl ether oxidation. Sensitivity and flux analyses revealed that the RO2 + OH reaction is a significant sink of RO2 radicals at the early stage of autoignition, affecting fuel oxidation through RO2 ↔ QOOH, RO2 ↔ alkene + HO2, or RO2 + HO2 ↔ ROOH + O2. Additionally, the kinetic stability of the trioxide formed from RO2 + OH reactions was investigated using master equation analyses. Last, we discuss other bimolecular reactions that are missing in literature kinetics models but are relevant to hydrocarbon oxidation initiated by external radical sources (plasma-enhanced, ozone-enriched combustion, etc.). The present simulations provide a strong motivation for better characterizing the bimolecular kinetics of peroxy radicals.
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Affiliation(s)
- Jaeyoung Cho
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Clayton R Mulvihill
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Raghu Sivaramakrishnan
- Chemical Sciences & Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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15
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Babikov D, Burke MP, Casavecchia P, Green WH, Grinberg Dana A, Guo H, Heard DE, Heathcote D, Hochlaf M, Jasper AW, Klippenstein SJ, Lester MI, Martí C, Mebel AM, Mullin AS, Nguyen TL, Olzmann M, Orr-Ewing AJ, Osborn DL, Robertson PA, Robinson MS, Shannon RJ, Shiels OJ, Suits AG, Taatjes CA, Troe J, Xu X, You X, Zhang F, Zhang RM, Zádor J. Collisional energy transfer: general discussion. Faraday Discuss 2022; 238:121-143. [PMID: 36200457 DOI: 10.1039/d2fd90048c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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16
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Hansen AS, Qian Y, Sojdak CA, Kozlowski MC, Esposito VJ, Francisco JS, Klippenstein SJ, Lester MI. Rapid Allylic 1,6 H-Atom Transfer in an Unsaturated Criegee Intermediate. J Am Chem Soc 2022; 144:5945-5955. [PMID: 35344666 DOI: 10.1021/jacs.2c00055] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A novel allylic 1,6 hydrogen-atom-transfer mechanism is established through infrared activation of the 2-butenal oxide Criegee intermediate, resulting in very rapid unimolecular decay to hydroxyl (OH) radical products. A new precursor, Z/E-1,3-diiodobut-1-ene, is synthesized and photolyzed in the presence of oxygen to generate a new four-carbon Criegee intermediate with extended conjugation across the vinyl and carbonyl oxide groups that facilitates rapid allylic 1,6 H-atom transfer. A low-energy reaction pathway involving isomerization of 2-butenal oxide from a lower-energy (tZZ) conformer to a higher-energy (cZZ) conformer followed by 1,6 hydrogen transfer via a seven-membered ring transition state is predicted theoretically and shown experimentally to yield OH products. The low-lying (tZZ) conformer of 2-butenal oxide is identified based on computed anharmonic frequencies and intensities of its conformers. Experimental IR action spectra recorded in the fundamental CH stretch region with OH product detection by UV laser-induced fluorescence reveal a distinctive IR transition of the low-lying (tZZ) conformer at 2996 cm-1 that results in rapid unimolecular decay to OH products. Statistical RRKM calculations involving a combination of conformational isomerization and unimolecular decay via 1,6 H-transfer yield an effective decay rate keff(E) on the order of 108 s-1 at ca. 3000 cm-1 in good accord with the experiment. Unimolecular decay proceeds with significant enhancement due to quantum mechanical tunneling. A rapid thermal decay rate of ca. 106 s-1 is predicted by master-equation modeling of 2-butenal oxide at 298 K, 1 bar. This novel unimolecular decay pathway is expected to increase the nonphotolytic production of OH radicals upon alkene ozonolysis in the troposphere.
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Affiliation(s)
- Anne S Hansen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
| | - Yujie Qian
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
| | - Christopher A Sojdak
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
| | - Marisa C Kozlowski
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
| | - Vincent J Esposito
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
| | - Joseph S Francisco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439 United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323 United States
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17
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Hansen AS, Bhagde T, Qian Y, Cavazos A, Huchmala RM, Boyer MA, Gavin-Hanner CF, Klippenstein SJ, McCoy AB, Lester MI. Infrared spectroscopic signature of a hydroperoxyalkyl radical (•QOOH). J Chem Phys 2022; 156:014301. [PMID: 34998315 DOI: 10.1063/5.0076505] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Infrared (IR) action spectroscopy is utilized to characterize a prototypical carbon-centered hydroperoxyalkyl radical (•QOOH) transiently formed in the oxidation of volatile organic compounds. The •QOOH radical formed in isobutane oxidation, 2-hydroperoxy-2-methylprop-1-yl, •CH2(CH3)2COOH, is generated in the laboratory by H-atom abstraction from tert-butyl hydroperoxide (TBHP). IR spectral features of jet-cooled and stabilized •QOOH radicals are observed from 2950 to 7050 cm-1 at energies that lie below and above the transition state barrier leading to OH radical and cyclic ether products. The observed •QOOH features include overtone OH and CH stretch transitions, combination bands involving OH or CH stretch and a lower frequency mode, and fundamental OH and CH stretch transitions. Most features arise from a single vibrational transition with band contours well simulated at a rotational temperature of 10 K. In each case, the OH products resulting from unimolecular decay of vibrationally activated •QOOH are detected by UV laser-induced fluorescence. Assignments of observed •QOOH IR transitions are guided by anharmonic frequencies computed using second order vibrational perturbation theory, a 2 + 1 model that focuses on the coupling of the OH stretch with two low-frequency torsions, as well as recently predicted statistical •QOOH unimolecular decay rates that include heavy-atom tunneling. Most of the observed vibrational transitions of •QOOH are readily distinguished from those of the TBHP precursor. The distinctive IR transitions of •QOOH, including the strong fundamental OH stretch, provide a general means for detection of •QOOH under controlled laboratory and real-world conditions.
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Affiliation(s)
- Anne S Hansen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Trisha Bhagde
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Yujie Qian
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Alyssa Cavazos
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Rachel M Huchmala
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | - Mark A Boyer
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | - Coire F Gavin-Hanner
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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18
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Aerssens J, Burke MP, Cavallotti C, Green NJB, Green WH, Guo H, Heard D, Hochlaf M, Jasper AW, Klippenstein SJ, Kuwata KT, Lawrence JE, Mebel AM, Mullin AS, Nguyen TL, Olzmann M, Osborn DL, Pfeifle M, Plane JMC, Robertson PA, Robertson SH, Salzburger M, Seakins PW, Shannon RJ, Shiels OJ, Trevitt AJ, Vallance C, Welz O, Xu X, Zádor J, Zhang RM. The master equation: general discussion. Faraday Discuss 2022; 238:529-574. [DOI: 10.1039/d2fd90050e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Bodi A, Burke MP, Butler AA, Douglas K, Eskola AJ, Green WH, Guo H, Heard DE, Heathcote D, Hochlaf M, Klippenstein SJ, Kuwata KT, Lawrence JE, Lester MI, Lourderaj U, Mebel A, Milesevic D, Mullin AS, Nguyen TL, Olzmann M, Orr-Ewing AJ, Osborn DL, Pazdera TM, Pfeifle M, Plane JMC, Pun R, Robertson PA, Robinson MS, Seakins PW, Shannon RJ, Taatjes CA, Troe J, Vallance C, Welz O, Zádor J, Zhang F. Impact of Lindemann and related theories: general discussion. Faraday Discuss 2022; 238:700-740. [DOI: 10.1039/d2fd90051c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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BHAGDE TRISHA, Hansen AS, Chen SG, Walsh P, Klippenstein SJ, Lester MI. Energy-resolved and time-dependent unimolecular dissociation of hydroperoxyalkyl radicals (•QOOH). Faraday Discuss 2022; 238:575-588. [DOI: 10.1039/d2fd00008c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydroperoxyalkyl radicals (•QOOH) are transient intermediates in the atmospheric oxidation of volatile organic compounds and combustion of hydrocarbon fuels in low temperature (< 1000 K) environments. The carbon-centered •QOOH radicals...
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21
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Burke MP, Casavecchia P, Cavallotti C, Clary DC, Doner A, Green WH, Grinberg Dana A, Guo H, Heathcote D, Hochlaf M, Klippenstein SJ, Kuwata KT, Lawrence JE, Lourderaj U, Mebel AM, Milesevic D, Mullin AS, Nguyen TL, Olzmann M, Orr-Ewing AJ, Osborn DL, Pazdera TM, Robertson PA, Robinson MS, Rotavera B, Seakins PW, Shannon RJ, Shiels OJ, Suits AG, Trevitt AJ, Troe J, Vallance C, Welz O, Zhang F, Zádor J. The reaction step: general discussion. Faraday Discuss 2022; 238:320-354. [DOI: 10.1039/d2fd90049a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Klippenstein SJ. Spiers Memorial Lecture: theory of unimolecular reactions. Faraday Discuss 2022; 238:11-67. [DOI: 10.1039/d2fd00125j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
One hundred years ago, at an earlier Faraday Discussion meeting, Lindemann presented a mechanism that provides the foundation for contemplating the pressure dependence of unimolecular reactions. Since that time, our...
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23
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Vansco MF, Zou M, Antonov IO, Ramasesha K, Rotavera B, Osborn DL, Georgievskii Y, Percival CJ, Klippenstein SJ, Taatjes CA, Lester MI, Caravan RL. Dramatic Conformer-Dependent Reactivity of the Acetaldehyde Oxide Criegee Intermediate with Dimethylamine Via a 1,2-Insertion Mechanism. J Phys Chem A 2021; 126:710-719. [PMID: 34939803 DOI: 10.1021/acs.jpca.1c08941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactivity of carbonyl oxides has previously been shown to exhibit strong conformer and substituent dependencies. Through a combination of synchrotron-multiplexed photoionization mass spectrometry experiments (298 K and 4 Torr) and high-level theory [CCSD(T)-F12/cc-pVTZ-F12//B2PLYP-D3/cc-pVTZ with an added CCSDT(Q) correction], we explore the conformer dependence of the reaction of acetaldehyde oxide (CH3CHOO) with dimethylamine (DMA). The experimental data support the theoretically predicted 1,2-insertion mechanism and the formation of an amine-functionalized hydroperoxide reaction product. Tunable-vacuum ultraviolet photoionization probing of anti- or anti- + syn-CH3CHOO reveals a strong conformer dependence of the title reaction. The rate coefficient of DMA with anti-CH3CHOO is predicted to exceed that for the reaction with syn-CH3CHOO by a factor of ∼34,000, which is attributed to submerged barrier (syn) versus barrierless (anti) mechanisms for energetically downhill reactions.
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Affiliation(s)
- Michael F Vansco
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Ivan O Antonov
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois 60208-3112, United States.,Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Krupa Ramasesha
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Brandon Rotavera
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States.,School of Environmental, Civil, Agricultural, and Mechanical Engineering, University of Georgia, Athens, Georgia 30602, United States.,Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - David L Osborn
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States.,Department of Chemical Engineering, University of California, Davis, California 95616, United States
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Carl J Percival
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Craig A Taatjes
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Rebecca L Caravan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, California 94551, United States
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24
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Abstract
Diastereomers have historically been ignored when building kinetic mechanisms for combustion. Low-temperature oxidation kinetics, which continues to gain interest in both combustion and atmospheric communities, may be affected by the inclusion of diastereomers in radical chain-branching pathways. In this work, key intermediates and transition states lacking stereochemical specification in an existing diethyl ether low-temperature oxidation mechanism were replaced with their diastereomeric counterparts. Rate coefficients for reactions involving diastereomers were computed with ab initio transition state theory master equation calculations. The presence of diastereomers increased rate coefficients by factors of 1.2-1.6 across various temperatures and pressures. Ignition delay simulations incorporating these revised rate coefficients indicate that the diastereomers enhanced the overall reactivity of the mechanism by almost 15% and increased the peak ketohydroperoxide concentration by 30% in the negative temperature coefficient region at combustion-relevant pressures. These results provide an illustrative indication of the important role of stereomeric effects in oxidation kinetics.
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Affiliation(s)
- Aaron D Danilack
- Chemical and Environmental Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Clayton R Mulvihill
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - C Franklin Goldsmith
- Chemical and Environmental Engineering, School of Engineering, Brown University, Providence, Rhode Island 02912, United States
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25
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Hansen AS, Bhagde T, Moore KB, Moberg DR, Jasper AW, Georgievskii Y, Vansco MF, Klippenstein SJ, Lester MI. Watching a hydroperoxyalkyl radical (•QOOH) dissociate. Science 2021; 373:679-682. [PMID: 34353951 DOI: 10.1126/science.abj0412] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 06/22/2021] [Indexed: 11/02/2022]
Abstract
A prototypical hydroperoxyalkyl radical (•QOOH) intermediate, transiently formed in the oxidation of volatile organic compounds, was directly observed through its infrared fingerprint and energy-dependent unimolecular decay to hydroxyl radical and cyclic ether products. Direct time-domain measurements of •QOOH unimolecular dissociation rates over a wide range of energies were found to be in accord with those predicted theoretically using state-of-the-art electronic structure characterizations of the transition state barrier region. Unimolecular decay was enhanced by substantial heavy-atom tunneling involving O-O elongation and C-C-O angle contraction along the reaction pathway. Master equation modeling yielded a fully a priori prediction of the pressure-dependent thermal unimolecular dissociation rates for the •QOOH intermediate-again increased by heavy-atom tunneling-which are required for global models of atmospheric and combustion chemistry.
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Affiliation(s)
- Anne S Hansen
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Trisha Bhagde
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kevin B Moore
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Daniel R Moberg
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Ahren W Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, IL 60439, USA.
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
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26
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Abstract
The important, and often dominant, role of tunneling in low temperature kinetics has resulted in numerous theoretical explorations into the methodology for predicting it. Nevertheless, there are still key aspects of the derivations that are lacking, particularly for nonseparable systems in the low temperature regime, and further explorations of the physical factors affecting the tunneling rate are warranted. In this work we obtain a closed-form rate expression for the tunneling rate constant that is a direct analog of the rigid-rotor-harmonic-oscillator expression. This expression introduces a novel "entanglement factor" that modulates the reaction rate. Furthermore, we are able to extend this expression, which is valid for nonseparable systems at low temperatures, to properly account for the conservation of angular momentum. In contrast, previous calculations have considered only vibrational transverse modes and so effectively employ a decoupled rotational partition function for the orientational modes. We also suggest a simple theoretical model to describe the tunneling effects in the vicinity of the crossover temperature (the temperature where tunneling becomes the dominating mechanism). This model allows one to naturally classify, interpret, and predict experimental data. Among other things, it quantitatively explains in simple terms the so-called "quantum bobsled" effect, also known as the negative centrifugal effect, which is related to curvature of the reaction path. Taken together, the expressions obtained here allow one to predict the thermal and E-resolved rate constants over broad ranges of temperatures and energies.
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Affiliation(s)
- Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Vansco MF, Zuraski K, Winiberg FAF, Au K, Trongsiriwat N, Walsh PJ, Osborn DL, Percival CJ, Klippenstein SJ, Taatjes CA, Lester MI, Caravan RL. Functionalized Hydroperoxide Formation from the Reaction of Methacrolein-Oxide, an Isoprene-Derived Criegee Intermediate, with Formic Acid: Experiment and Theory. Molecules 2021; 26:3058. [PMID: 34065491 PMCID: PMC8161369 DOI: 10.3390/molecules26103058] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/11/2021] [Accepted: 05/13/2021] [Indexed: 11/16/2022] Open
Abstract
Methacrolein oxide (MACR-oxide) is a four-carbon, resonance-stabilized Criegee intermediate produced from isoprene ozonolysis, yet its reactivity is not well understood. This study identifies the functionalized hydroperoxide species, 1-hydroperoxy-2-methylallyl formate (HPMAF), generated from the reaction of MACR-oxide with formic acid using multiplexed photoionization mass spectrometry (MPIMS, 298 K = 25 °C, 10 torr = 13.3 hPa). Electronic structure calculations indicate the reaction proceeds via an energetically favorable 1,4-addition mechanism. The formation of HPMAF is observed by the rapid appearance of a fragment ion at m/z 99, consistent with the proposed mechanism and characteristic loss of HO2 upon photoionization of functional hydroperoxides. The identification of HPMAF is confirmed by comparison of the appearance energy of the fragment ion with theoretical predictions of its photoionization threshold. The results are compared to analogous studies on the reaction of formic acid with methyl vinyl ketone oxide (MVK-oxide), the other four-carbon Criegee intermediate in isoprene ozonolysis.
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Affiliation(s)
- Michael F. Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA; (M.F.V.); (N.T.); (P.J.W.)
- Argonne National Laboratory, Chemical Sciences and Engineering Division, Lemont, IL 60439, USA;
| | - Kristen Zuraski
- NASA Postdoctoral Program Fellow, NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA;
| | - Frank A. F. Winiberg
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA; (F.A.F.W.); (C.J.P.)
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Kendrew Au
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, CA 94551, USA; (K.A.); (D.L.O.)
| | - Nisalak Trongsiriwat
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA; (M.F.V.); (N.T.); (P.J.W.)
| | - Patrick J. Walsh
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA; (M.F.V.); (N.T.); (P.J.W.)
| | - David L. Osborn
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, CA 94551, USA; (K.A.); (D.L.O.)
- Department of Chemical Engineering, University of California, Davis, CA 95616, USA
| | - Carl J. Percival
- NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA; (F.A.F.W.); (C.J.P.)
| | - Stephen J. Klippenstein
- Argonne National Laboratory, Chemical Sciences and Engineering Division, Lemont, IL 60439, USA;
| | - Craig A. Taatjes
- Combustion Research Facility, Mailstop 9055, Sandia National Laboratories, Livermore, CA 94551, USA; (K.A.); (D.L.O.)
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA; (M.F.V.); (N.T.); (P.J.W.)
| | - Rebecca L. Caravan
- Argonne National Laboratory, Chemical Sciences and Engineering Division, Lemont, IL 60439, USA;
- NASA Postdoctoral Program Fellow, NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA;
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28
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Zaleski DP, Sivaramakrishnan R, Weller HR, Seifert NA, Bross DH, Ruscic B, Moore KB, Elliott SN, Copan AV, Harding LB, Klippenstein SJ, Field RW, Prozument K. Substitution Reactions in the Pyrolysis of Acetone Revealed through a Modeling, Experiment, Theory Paradigm. J Am Chem Soc 2021; 143:3124-3142. [PMID: 33615780 DOI: 10.1021/jacs.0c11677] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The development of high-fidelity mechanisms for chemically reactive systems is a challenging process that requires the compilation of rate descriptions for a large and somewhat ill-defined set of reactions. The present unified combination of modeling, experiment, and theory provides a paradigm for improving such mechanism development efforts. Here we combine broadband rotational spectroscopy with detailed chemical modeling based on rate constants obtained from automated ab initio transition state theory-based master equation calculations and high-level thermochemical parametrizations. Broadband rotational spectroscopy offers quantitative and isomer-specific detection by which branching ratios of polar reaction products may be obtained. Using this technique, we observe and characterize products arising from H atom substitution reactions in the flash pyrolysis of acetone (CH3C(O)CH3) at a nominal temperature of 1800 K. The major product observed is ketene (CH2CO). Minor products identified include acetaldehyde (CH3CHO), propyne (CH3CCH), propene (CH2CHCH3), and water (HDO). Literature mechanisms for the pyrolysis of acetone do not adequately describe the minor products. The inclusion of a variety of substitution reactions, with rate constants and thermochemistry obtained from automated ab initio kinetics predictions and Active Thermochemical Tables analyses, demonstrates an important role for such processes. The pathway to acetaldehyde is shown to be a direct result of substitution of acetone's methyl group by a free H atom, while propene formation arises from OH substitution in the enol form of acetone by a free H atom.
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Affiliation(s)
- Daniel P Zaleski
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemistry, Colgate University, Hamilton, New York 13346, United States
| | - Raghu Sivaramakrishnan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Hailey R Weller
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States.,Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Nathan A Seifert
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David H Bross
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Kevin B Moore
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Sarah N Elliott
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Andreas V Copan
- Emmanuel College, Natural Sciences Department, Franklin Springs, Georgia 30639, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Robert W Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Kirill Prozument
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
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29
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Vansco MF, Caravan RL, Pandit S, Zuraski K, Winiberg FAF, Au K, Bhagde T, Trongsiriwat N, Walsh PJ, Osborn DL, Percival CJ, Klippenstein SJ, Taatjes CA, Lester MI. Formic acid catalyzed isomerization and adduct formation of an isoprene-derived Criegee intermediate: experiment and theory. Phys Chem Chem Phys 2020; 22:26796-26805. [PMID: 33211784 DOI: 10.1039/d0cp05018k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Isoprene is the most abundant non-methane hydrocarbon emitted into the Earth's atmosphere. Ozonolysis is an important atmospheric sink for isoprene, which generates reactive carbonyl oxide species (R1R2C[double bond, length as m-dash]O+O-) known as Criegee intermediates. This study focuses on characterizing the catalyzed isomerization and adduct formation pathways for the reaction between formic acid and methyl vinyl ketone oxide (MVK-oxide), a four-carbon unsaturated Criegee intermediate generated from isoprene ozonolysis. syn-MVK-oxide undergoes intramolecular 1,4 H-atom transfer to form a substituted vinyl hydroperoxide intermediate, 2-hydroperoxybuta-1,3-diene (HPBD), which subsequently decomposes to hydroxyl and vinoxylic radical products. Here, we report direct observation of HPBD generated by formic acid catalyzed isomerization of MVK-oxide under thermal conditions (298 K, 10 torr) using multiplexed photoionization mass spectrometry. The acid catalyzed isomerization of MVK-oxide proceeds by a double hydrogen-bonded interaction followed by a concerted H-atom transfer via submerged barriers to produce HPBD and regenerate formic acid. The analogous isomerization pathway catalyzed with deuterated formic acid (D2-formic acid) enables migration of a D atom to yield partially deuterated HPBD (DPBD), which is identified by its distinct mass (m/z 87) and photoionization threshold. In addition, bimolecular reaction of MVK-oxide with D2-formic acid forms a functionalized hydroperoxide adduct, which is the dominant product channel, and is compared to a previous bimolecular reaction study with normal formic acid. Complementary high-level theoretical calculations are performed to further investigate the reaction pathways and kinetics.
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Affiliation(s)
- Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
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30
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Wu CH, Magers DB, Harding LB, Klippenstein SJ, Allen WD. Reaction Profiles and Kinetics for Radical-Radical Hydrogen Abstraction via Multireference Coupled Cluster Theory. J Chem Theory Comput 2020; 16:1511-1525. [PMID: 32073856 DOI: 10.1021/acs.jctc.9b00966] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Radical-radical abstractions in hydrocarbon oxidation chemistry are disproportionation reactions that are generally exothermic with little or no barrier yet are underappreciated and poorly studied. Such challenging multireference electronic structure problems are tackled here using the recently developed state-specific multireference coupled cluster methods Mk-MRCCSD and Mk-MRCCSD(T), as well as the companion perturbation theory Mk-MRPT2 and the established MRCISD, MRCISD+Q, and CASPT2 approaches. Reaction paths are investigated for five prototypes involving radical-radical hydrogen abstraction: H + BeH → H2+ Be, H + NH2 → H2 + NH, CH3 + C2H5 → CH4 + C2H4, H + C2H5 → H2 + C2H4, and H + HCO → H2 + CO. Full configuration interaction (FCI) benchmark computations for the H + BeH, H + NH2, and H + HCO reactions prove that Mk-MRCCSD(T) provides superior accuracy for the interaction energies in the entrance channel, with mean absolute errors less than 0.3 kcal mol-1 and percentage deviations less than 10% over the fragment separations of relevance to kinetics. To facilitate combustion studies, energetics for the CH3 + C2H5, H + C2H5, and H + HCO reactions were computed at each level of theory with correlation-consistent basis sets (cc-pVXZ, X = T, Q, 5) and extrapolated to the complete basis set (CBS) limit. These CBS energies were coupled with CASPT2 projected vibrational frequencies along a minimum energy path to obtain rate constants for these three reactions. The rigorous Mk-MRCCSD(T)/CBS results demonstrate unequivocally that these three reactions proceed with no barrier in the entrance channel, contrary to some earlier predictions. Mk-MRCCSD(T) also reveals that the economical CASPT2 method performs well for large interfragment separations but may deteriorate substantially at shorter distances.
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Affiliation(s)
- Chia-Hua Wu
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
| | - D Brandon Magers
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States.,Department of Chemistry and Physics, Belhaven University, Jackson, Mississippi 39202, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Wesley D Allen
- Center for Computational Quantum Chemistry and Department of Chemistry, University of Georgia, Athens, Georgia 30602, United States
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31
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Barber VP, Hansen AS, Georgievskii Y, Klippenstein SJ, Lester MI. Experimental and theoretical studies of the doubly substituted methyl-ethyl Criegee intermediate: Infrared action spectroscopy and unimolecular decay to OH radical products. J Chem Phys 2020; 152:094301. [PMID: 33480748 DOI: 10.1063/5.0002422] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The infrared (IR) action spectrum of the doubly substituted methyl-ethyl Criegee intermediate (MECI) is observed in the CH stretch overtone region with detection of OH products. The MECI exhibits four conformers, all of which undergo unimolecular decay via a 1,4 H-atom transfer mechanism, followed by the rapid release of OH products. Conformers with different orientations of the carbonyl oxide group with respect to the methyl and ethyl substituents (i.e., anti and syn) decay via distinct transition state barriers (16.1 kcal mol-1 and 15.4 kcal mol-1, respectively). The observed IR action spectrum is in good agreement with the predicted anharmonic IR absorption spectrum, but exhibits significant congestion, which is attributed to couplings between spectroscopic bright states and nearby dark states. Energy-dependent OH appearance rates are measured upon IR excitation of the strongest features in the IR action spectrum and are found to be on the order of 106-107 s-1. The experimental rates are in good agreement with computed Rice-Ramsperger-Kassel-Marcus rates for the unimolecular decay of MECI at these energies, which incorporate quantum mechanical tunneling and sophisticated hindered rotor treatments, as well as high-level theoretical calculations of the TS barrier heights, rovibrational properties, and torsional barriers associated with the MECI conformers. Master equation modeling is used to predict thermal rates for the unimolecular decay of anti- and syn-MECI of 473 s-1 and 660 s-1, respectively. Comparison with other previously studied Criegee intermediate systems provides insights into substituent effects on unimolecular decay under both energy-dependent and thermal conditions.
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Affiliation(s)
- Victoria P Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Anne S Hansen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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32
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Vansco MF, Marchetti B, Trongsiriwat N, Bhagde T, Wang G, Walsh PJ, Klippenstein SJ, Lester MI. Synthesis, Electronic Spectroscopy, and Photochemistry of Methacrolein Oxide: A Four-Carbon Unsaturated Criegee Intermediate from Isoprene Ozonolysis. J Am Chem Soc 2019; 141:15058-15069. [PMID: 31446755 DOI: 10.1021/jacs.9b05193] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the earth's atmosphere, generates the four-carbon unsaturated methacrolein oxide (MACR-oxide) Criegee intermediate. The first laboratory synthesis and direct detection of MACR-oxide is achieved through reaction of photolytically generated, resonance-stabilized iodoalkene radicals with oxygen. MACR-oxide is characterized on its first π* ← π electronic transition using a ground-state depletion method. MACR-oxide exhibits a broad UV-visible spectrum peaked at 380 nm with weak oscillatory structure at long wavelengths ascribed to vibrational resonances. Complementary theory predicts two strong π* ← π transitions arising from extended conjugation across MACR-oxide with overlapping contributions from its four conformers. Electronic promotion to the 11ππ* state agrees well with experiment, and results in nonadiabatic coupling and prompt release of O 1D products observed as anisotropic velocity-map images. This UV-visible detection scheme will enable study of its unimolecular and bimolecular reactions under thermal conditions of relevance to the atmosphere.
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Affiliation(s)
- Michael F Vansco
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Barbara Marchetti
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Nisalak Trongsiriwat
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Trisha Bhagde
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Guanghan Wang
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Patrick J Walsh
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division , Argonne National Laboratory , Lemont , Illinois 60439 , United States
| | - Marsha I Lester
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
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Abstract
Quasiclassical trajectories are used to compute nonthermal rate constants, k*, for abstraction reactions involving highly-excited methane CH4 * and the radicals H, O, OH, and O2. Several temperatures and internal energies of methane, Evib, are considered, and significant nonthermal rate enhancements for large Evib are found. Specifically, when CH4 * is internally excited close to its dissociation threshold (Evib ≈ D0 = 104 kcal/mol), its reactivity with H, O, and OH is shown to be collision-rate-limited and to approach that of comparably-sized radicals, such as CH3, with k* > 10-10 cm3 molecule-1 s-1. Rate constants this large are more typically associated with barrierless reactions, and at 1000 K, this represents a nonthermal rate enhancement, k*/k, of more than two orders of magnitude relative to thermal rate constants k. We show that large nonthermal rate constants persist even after significant internal cooling, with k*/k > 10 down to Evib ≈ D0/4. The competition between collisional cooling and nonthermal reactivity is studied using a simple model, and nonthermal reactions are shown to account for up to 35%-50% of the fate of the products of H + CH3 = CH4 * under conditions of practical relevance to combustion. Finally, the accuracy of an effective temperature model for estimating k* from k is quantified.
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Affiliation(s)
- Ahren W Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Raghu Sivaramakrishnan
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Barber VP, Pandit S, Green AM, Trongsiriwat N, Walsh PJ, Klippenstein SJ, Lester MI. Four-Carbon Criegee Intermediate from Isoprene Ozonolysis: Methyl Vinyl Ketone Oxide Synthesis, Infrared Spectrum, and OH Production. J Am Chem Soc 2018; 140:10866-10880. [PMID: 30074392 DOI: 10.1021/jacs.8b06010] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The reaction of ozone with isoprene, one of the most abundant volatile organic compounds in the atmosphere, produces three distinct carbonyl oxide species (RR'COO) known as Criegee intermediates: formaldehyde oxide (CH2OO), methyl vinyl ketone oxide (MVK-OO), and methacrolein oxide (MACR-OO). The nature of the substituents (R,R' = H, CH3, CH═CH2) and conformations of the Criegee intermediates control their subsequent chemistry in the atmosphere. In particular, unimolecular decay of MVK-OO is predicted to be the major source of hydroxyl radicals (OH) in isoprene ozonolysis. This study reports the initial laboratory synthesis and direct detection of MVK-OO through reaction of a photolytically generated, resonance-stabilized monoiodoalkene radical with O2. MVK-OO is characterized utilizing infrared (IR) action spectroscopy, in which IR activation of MVK-OO with two quanta of CH stretch at ca. 6000 cm-1 is coupled with ultraviolet detection of the resultant OH products. MVK-OO is identified by comparison of the experimentally observed IR spectral features with theoretically predicted IR absorption spectra. For syn-MVK-OO, the rate of appearance of OH products agrees with the unimolecular decay rate predicted using statistical theory with tunneling. This validates the hydrogen atom transfer mechanism and computed transition-state barrier (18.0 kcal mol-1) leading to OH products. Theoretical calculations reveal an additional roaming pathway between the separating radical fragments, which results in other products. Master equation modeling yields a thermal unimolecular decay rate for syn-MVK-OO of 33 s-1 (298 K, 1 atm). For anti-MVK-OO, theoretical exploration of several unimolecular decay pathways predicts that isomerization to dioxole is the most likely initial step to products.
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Affiliation(s)
- Victoria P Barber
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Shubhrangshu Pandit
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Amy M Green
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Nisalak Trongsiriwat
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Patrick J Walsh
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Marsha I Lester
- Department of Chemistry , University of Pennsylvania , Philadelphia , Pennsylvania 19104-6323 , United States
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35
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Pfeifle M, Ma YT, Jasper AW, Harding LB, Hase WL, Klippenstein SJ. Nascent energy distribution of the Criegee intermediate CH2OO from direct dynamics calculations of primary ozonide dissociation. J Chem Phys 2018; 148:174306. [DOI: 10.1063/1.5028117] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mark Pfeifle
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yong-Tao Ma
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
| | - Ahren W. Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Lawrence B. Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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36
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Pelucchi M, Cavallotti C, Faravelli T, Klippenstein SJ. H-Abstraction reactions by OH, HO 2, O, O 2 and benzyl radical addition to O 2 and their implications for kinetic modelling of toluene oxidation. Phys Chem Chem Phys 2018; 20:10607-10627. [PMID: 29387837 DOI: 10.1039/c7cp07779c] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Alkylated aromatics constitute a significant fraction of the components commonly found in commercial fuels. Toluene is typically considered as a reference fuel. Together with n-heptane and iso-octane, it allows for realistic emulations of the behavior of real fuels by the means of surrogate mixture formulations. Moreover, it is a key precursor for the formation of poly-aromatic hydrocarbons, which are of relevance to understanding soot growth and oxidation mechanisms. In this study the POLIMI kinetic model is first updated based on the literature and on recent kinetic modelling studies of toluene pyrolysis and oxidation. Then, important reaction pathways are investigated by means of high-level theoretical methods, thereby advancing the present knowledge on toluene oxidation. H-Abstraction reactions by OH, HO2, O and O2, and the reactivity on the multi well benzyl-oxygen (C6H5CH2 + O2) potential energy surface (PES) were investigated using electronic structure calculations, transition state theory in its conventional, variational, and variable reaction coordinate forms (VRC-TST), and master equation calculations. Exploration of the effect on POLIMI model performance of literature rate constants and of the present calculations provides valuable guidelines for implementation of the new rate parameters in existing toluene kinetic models.
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Affiliation(s)
- M Pelucchi
- Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano, Milan, Italy.
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37
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Abstract
Alkene ozonolysis is a primary oxidation pathway for anthropogenic and biogenic alkenes emitted into the troposphere. It is also an important source of atmospheric hydroxyl (OH) radicals, often called the atmosphere's detergent. Alkene ozonolysis takes place through a highly exothermic reaction pathway with multiple intermediates and barriers prior to releasing the OH radical products. This Account focuses on a key reaction intermediate with a carbonyl oxide functional group (-COO), known as the Criegee intermediate, which is formed along with a carbonyl coproduct in alkene ozonolysis reactions. Under atmospheric conditions, the initially energized Criegee intermediates may promptly decay to OH products or be collisionally stabilized prior to thermal decay to OH radicals and other products. Alternatively, the stabilized Criegee intermediates may undergo bimolecular reactions with atmospheric species, including water vapor and sulfur dioxide, which can lead to nucleation and growth of aerosols. The dimethyl-substituted Criegee intermediate, (CH3)2COO, is utilized in this Account to showcase recent efforts to experimentally measure and theoretically predict the rates for prompt and thermal unimolecular decay processes of prototypical Criegee intermediates under laboratory and atmospheric conditions. The experimental laboratory studies utilize an alternative synthesis method to efficiently generate Criegee intermediates via the reaction of iodoalkyl radicals with O2. Infrared excitation is then used to prepare the (CH3)2COO Criegee intermediates at specific energies in the vicinity of the transition state barrier or significantly below the barrier for 1,4-hydrogen transfer that leads to OH products. The rate of unimolecular decay is revealed through direct time-domain measurements of the appearance of OH products utilizing ultraviolet laser-induced fluorescence detection under collision-free conditions. Complementary high-level theoretical calculations are carried out to evaluate the transition state barrier and the energy-dependent unimolecular decay rates for (CH3)2COO using Rice-Ramsperger-Kassel-Marcus (RRKM) theory, which are in excellent accord with the experimental measurements. Quantum mechanical tunneling through the barrier, incorporated through Eckart and semiclassical transition state theory models, is shown to make a significant contribution to the unimolecular decay rates at energies in the vicinity of and much below the barrier. Master equation modeling is used to extend the energy-dependent unimolecular rates to thermal decay rates of (CH3)2COO under tropospheric conditions (high pressure limit), which agree well with recent laboratory measurements [ Smith et al. J. Phys. Chem. A 2016 , 120 , 4789 and Chhantyal-Pun et al. J. Phys. Chem. A 2017 , 121 , 4 - 15 ]. Again, tunneling is shown to enhance the thermal decay rate by orders of magnitude. The experimentally validated unimolecular rates are also utilized in modeling the prompt and thermal unimolecular decay of chemically activated (CH3)2COO formed upon ozonolysis of 2,3-dimethyl-2-butene under atmospheric conditions [ Drozd et al. J. Phys. Chem. A 2017 , 121 , 6036 - 6045 ]. Future challenges lie in extension of these spectroscopic and dynamical methods to Criegee intermediates derived from more complex ozonolysis reactions involving biogenic alkenes.
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Affiliation(s)
- Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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38
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Jasper AW, Gruey ZB, Harding LB, Georgievskii Y, Klippenstein SJ, Wagner AF. Anharmonic Rovibrational Partition Functions for Fluxional Species at High Temperatures via Monte Carlo Phase Space Integrals. J Phys Chem A 2018; 122:1727-1740. [DOI: 10.1021/acs.jpca.7b11722] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ahren W. Jasper
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Zackery B. Gruey
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Lawrence B. Harding
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Yuri Georgievskii
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Albert F. Wagner
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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39
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Zaleski DP, Harding LB, Klippenstein SJ, Ruscic B, Prozument K. Time-Resolved Kinetic Chirped-Pulse Rotational Spectroscopy in a Room-Temperature Flow Reactor. J Phys Chem Lett 2017; 8:6180-6188. [PMID: 29193976 DOI: 10.1021/acs.jpclett.7b02864] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Chirped-pulse Fourier transform millimeter-wave spectroscopy is a potentially powerful tool for studying chemical reaction dynamics and kinetics. Branching ratios of multiple reaction products and intermediates can be measured with unprecedented chemical specificity; molecular isomers, conformers, and vibrational states have distinct rotational spectra. Here we demonstrate chirped-pulse spectroscopy of vinyl cyanide photoproducts in a flow tube reactor at ambient temperature of 295 K and pressures of 1-10 μbar. This in situ and time-resolved experiment illustrates the utility of this novel approach to investigating chemical reaction dynamics and kinetics. Following 193 nm photodissociation of CH2CHCN, we observe rotational relaxation of energized HCN, HNC, and HCCCN photoproducts with 10 μs time resolution and sample the vibrational population distribution of HCCCN. The experimental branching ratio HCN/HCCCN is compared with a model based on RRKM theory using high-level ab initio calculations, which were in turn validated by comparisons to Active Thermochemical Tables enthalpies.
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Affiliation(s)
- Daniel P Zaleski
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Lawrence B Harding
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Kirill Prozument
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
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40
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Green AM, Barber VP, Fang Y, Klippenstein SJ, Lester MI. Selective deuteration illuminates the importance of tunneling in the unimolecular decay of Criegee intermediates to hydroxyl radical products. Proc Natl Acad Sci U S A 2017; 114:12372-12377. [PMID: 29109292 PMCID: PMC5703325 DOI: 10.1073/pnas.1715014114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ozonolysis of alkenes, an important nonphotolytic source of hydroxyl (OH) radicals in the atmosphere, proceeds through unimolecular decay of Criegee intermediates. Here, we report a large kinetic isotope effect associated with the rate-limiting hydrogen-transfer step that releases OH radicals for a prototypical Criegee intermediate, CH3CHOO. IR excitation of selectively deuterated syn-CD3CHOO is shown to result in deuterium atom transfer and release OD radical products. Vibrational activation of syn-CD3CHOO is coupled with direct time-resolved detection of OD products to measure a 10-fold slower rate of unimolecular decay upon deuteration in the vicinity of the transition state barrier, which is confirmed by microcanonical statistical theory that incorporates quantum mechanical tunneling. The corresponding kinetic isotope effect of ∼10 is attributed primarily to the decreased probability of D-atom vs. H-atom transfer arising from tunneling. Master equation modeling is utilized to compute the thermal unimolecular decay rates for selectively and fully deuterated syn methyl-substituted Criegee intermediates under atmospheric conditions. At 298 K (1 atm), tunneling is predicted to enhance the thermal decay rate of syn-CH3CHOO compared with the deuterated species, giving rise to a significant kinetic isotope effect of ∼50.
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Affiliation(s)
- Amy M Green
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | - Victoria P Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | - Yi Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323;
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41
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Li Y, Klippenstein SJ, Zhou CW, Curran HJ. Theoretical Kinetics Analysis for Ḣ Atom Addition to 1,3-Butadiene and Related Reactions on the Ċ 4H 7 Potential Energy Surface. J Phys Chem A 2017; 121:7433-7445. [PMID: 28885843 DOI: 10.1021/acs.jpca.7b05996] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The oxidation chemistry of the simplest conjugated hydrocarbon, 1,3-butadiene, can provide a first step in understanding the role of polyunsaturated hydrocarbons in combustion and, in particular, an understanding of their contribution toward soot formation. On the basis of our previous work on propene and the butene isomers (1-, 2-, and isobutene), it was found that the reaction kinetics of Ḣ-atom addition to the C═C double bond plays a significant role in fuel consumption kinetics and influences the predictions of high-temperature ignition delay times, product species concentrations, and flame speed measurements. In this study, the rate constants and thermodynamic properties for Ḣ-atom addition to 1,3-butadiene and related reactions on the Ċ4H7 potential energy surface have been calculated using two different series of quantum chemical methods and two different kinetic codes. Excellent agreement is obtained between the two different kinetics codes. The calculated results including zero-point energies, single-point energies, rate constants, barrier heights, and thermochemistry are systematically compared among the two quantum chemical methods. 1-Methylallyl (Ċ4H71-3) and 3-buten-1-yl (Ċ4H71-4) radicals and C2H4 + Ċ2H3 are found to be the most important channels and reactivity-promoting products, respectively. We calculated that terminal addition is dominant (>80%) compared to internal Ḣ-atom addition at all temperatures in the range 298-2000 K. However, this dominance decreases with increasing temperature. The calculated rate constants for the bimolecular reaction C4H6 + Ḣ → products and C2H4 + Ċ2H3 → products are in excellent agreement with both experimental and theoretical results from the literature. For selected C4 species, the calculated thermochemical values are also in good agreement with literature data. In addition, the rate constants for H atom abstraction by Ḣ atoms have also been calculated, and it is found that abstraction from the central carbon atoms is the dominant channel (>70%) at temperatures in the range of 298-2000 K. Finally, by incorporating our calculated rate constants for both Ḣ atom addition and abstraction into our recently developed 1,3-butadiene model, we show that laminar flame speed predictions are significantly improved, emphasizing the value of this study.
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Affiliation(s)
- Yang Li
- Combustion Chemistry Centre, National University of Ireland , Galway, Ireland
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Chong-Wen Zhou
- School of Energy and Power Engineering, Beihang University , Beijing 100191, P. R. China
| | - Henry J Curran
- Combustion Chemistry Centre, National University of Ireland , Galway, Ireland
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Pfeifle M, Georgievskii Y, Jasper AW, Klippenstein SJ. Theoretical investigation of intersystem crossing in the cyanonitrene molecule, 1NCN → 3NCN. J Chem Phys 2017; 147:084310. [DOI: 10.1063/1.4999788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Mark Pfeifle
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Ahren W. Jasper
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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Klippenstein SJ, Harding LB, Ruscic B. Ab Initio Computations and Active Thermochemical Tables Hand in Hand: Heats of Formation of Core Combustion Species. J Phys Chem A 2017; 121:6580-6602. [DOI: 10.1021/acs.jpca.7b05945] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephen J. Klippenstein
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Lawrence B. Harding
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Branko Ruscic
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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44
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Burke MP, Klippenstein SJ. Ephemeral collision complexes mediate chemically termolecular transformations that affect system chemistry. Nat Chem 2017; 9:1078-1082. [DOI: 10.1038/nchem.2842] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 07/03/2017] [Indexed: 11/09/2022]
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45
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Harding LB, Georgievskii Y, Klippenstein SJ. Accurate Anharmonic Zero-Point Energies for Some Combustion-Related Species from Diffusion Monte Carlo. J Phys Chem A 2017; 121:4334-4340. [DOI: 10.1021/acs.jpca.7b03082] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lawrence B. Harding
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Yuri Georgievskii
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
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46
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Fang Y, Barber VP, Klippenstein SJ, McCoy AB, Lester MI. Tunneling effects in the unimolecular decay of (CH3)2COO Criegee intermediates to OH radical products. J Chem Phys 2017; 146:134307. [DOI: 10.1063/1.4979297] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yi Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323,
USA
| | - Victoria P. Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323,
USA
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division,
Argonne National Laboratory, Argonne, Illinois 60439,
USA
| | - Anne B. McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323,
USA
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47
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Cagnina S, Nicolle A, de Bruin T, Georgievskii Y, Klippenstein SJ. First-Principles Chemical Kinetic Modeling of Methyl trans-3-Hexenoate Epoxidation by HO 2. J Phys Chem A 2017; 121:1909-1915. [PMID: 28207262 DOI: 10.1021/acs.jpca.7b00519] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The design of innovative combustion processes relies on a comprehensive understanding of biodiesel oxidation kinetics. The present study aims at unraveling the reaction mechanism involved in the epoxidation of a realistic biodiesel surrogate, methyl trans-3-hexenoate, by hydroperoxy radicals using a bottom-up theoretical kinetics methodology. The obtained rate constants are in good agreement with experimental data for alkene epoxidation by HO2. The impact of temperature and pressure on epoxidation pathways involving H-bonded and non-H-bonded conformers was assessed. The obtained rate constant was finally implemented into a state-of-the-art detailed combustion mechanism, resulting in fairly good agreement with engine experiments.
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Affiliation(s)
- S Cagnina
- IFP Energies Nouvelles , Engine and Vehicle Modeling Department, 1 et 4 avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France.,Institut Carnot IFPEN Transports Energie , 1 et 4 avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - A Nicolle
- IFP Energies Nouvelles , Engine and Vehicle Modeling Department, 1 et 4 avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France.,Institut Carnot IFPEN Transports Energie , 1 et 4 avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - T de Bruin
- IFP Energies Nouvelles , Thermodynamics and Molecular Modeling Department, 1 et 4 avenue de Bois-Préau, 92852 Rueil-Malmaison Cedex, France
| | - Y Georgievskii
- Argonne National Laboratory , Chemical Sciences and Engineering Division, Argonne, Illinois 60439, United States
| | - S J Klippenstein
- Argonne National Laboratory , Chemical Sciences and Engineering Division, Argonne, Illinois 60439, United States
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48
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Fang Y, Liu F, Barber VP, Klippenstein SJ, McCoy AB, Lester MI. Deep tunneling in the unimolecular decay of CH3CHOO Criegee intermediates to OH radical products. J Chem Phys 2016; 145:234308. [DOI: 10.1063/1.4972015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yi Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Fang Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Victoria P. Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Anne B. McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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49
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Fang Y, Liu F, Klippenstein SJ, Lester MI. Direct observation of unimolecular decay of CH3CH2CHOO Criegee intermediates to OH radical products. J Chem Phys 2016; 145:044312. [DOI: 10.1063/1.4958992] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yi Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Fang Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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Fang Y, Liu F, Barber VP, Klippenstein SJ, McCoy AB, Lester MI. Communication: Real time observation of unimolecular decay of Criegee intermediates to OH radical products. J Chem Phys 2016; 144:061102. [PMID: 26874475 DOI: 10.1063/1.4941768] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In the atmosphere, a dominant loss process for carbonyl oxide intermediates produced from alkene ozonolysis is also an important source of hydroxyl radicals. The rate of appearance of OH radicals is revealed through direct time-domain measurements following vibrational activation of prototypical methyl-substituted Criegee intermediates under collision-free conditions. Complementary theoretical calculations predict the unimolecular decay rate for the Criegee intermediates in the vicinity of the barrier for 1,4 hydrogen transfer that leads to OH products. Both experiment and theory yield unimolecular decay rates of ca. 10(8) and 10(7) s(-1) for syn-CH3CHOO and (CH3)2COO, respectively, at energies near the barrier. Tunneling through the barrier, computed from high level electronic structure theory and experimentally validated, makes a significant contribution to the decay rate. Extension to thermally averaged unimolecular decay of stabilized Criegee intermediates under atmospheric conditions yields rates that are six orders of magnitude slower than those evaluated directly in the barrier region.
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Affiliation(s)
- Yi Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Fang Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Victoria P Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Anne B McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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