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Nikoobakht B. UV Absorption Spectroscopy of the Conformer-Dependent Reactivity of the Four Carbon Criegee Intermediate of Methyl Vinyl Ketone Oxide: An Ab initio Quantum Dynamics Study. J Phys Chem A 2023; 127:10091-10103. [PMID: 38012831 DOI: 10.1021/acs.jpca.3c05323] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
An extended theoretical analysis of the photodissociation dynamics of the four-carbon Criegee intermediate (CH2═CH(CH3)COO) or methyl vinyl ketone oxide, which has four conformers, following excitation to the B state, is presented. Our analysis relies on multireference electronic wave functions combined with a wavepacket propagation treatment for the two coupled B1A' and C1A' electronic states and two nuclear degrees of freedom. For each conformer, the 2D model depends on potential energy surfaces (PESs) along the O-O and C-O-O bending modes for the two lowest excited states, B1A' and C1A', and is sufficiently accurate to reproduce the experimental B1A' ← X1A' absorption spectrum with unprecedented accuracy. It is found that the roles of each conformer are essential in producing a cumulative spectrum, which is close to the recent experimental spectrum. The anti-trans and anti-cis conformers make contributions at the longer and shorter wavelengths of the cumulative spectrum, respectively, while the syn-cis and syn-trans conformers have contributions in the middle wavelength range of the cumulative spectrum of MVK-oxide. The existence of a deep well for each conformer on the PESs of the (diabatic) B state causes a considerable amount of the wavepacket to be reflected by the B state wells, which can explain the oscillatory structures appearing in the long wavelength range of 360-480 nm of the spectrum. The weakly avoided crossings between the B-state and C-state PESs of each conformer appearing within the range of 2.80-3.08 eV excitation energy cause considerable disturbance in the vibronic fine structure of the bands. The results give novel insight into the complex interactions governing this intriguing process.
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Affiliation(s)
- Behnam Nikoobakht
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, INF 229, D-69120 Heidelberg, Germany
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2
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Poirier CA, Guidry LM, Ratliff JM, Esposito VJ, Marchetti B, Karsili TNV. Modeling the Ground- and Excited-State Unimolecular Decay of the Simplest Fluorinated Criegee Intermediate, HFCOO, Formed from the Ozonolysis of Hydrofluoroolefin Refrigerants. J Phys Chem A 2023; 127:6377-6384. [PMID: 37523496 DOI: 10.1021/acs.jpca.3c01530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Hydrofluoroolefins (HFO) are fourth-generation refrigerants designed to function as efficient refrigerants with no ozone depletion potential and zero global warming potential. Despite extensive studies on their chemical and physical properties, the ground- and excited-state chemistry of their atmospheric oxidation products is less well understood. This study focuses on the ground- and excited-state chemistry of the simplest fluorinated Criegee intermediate (CI), fluoroformaldehyde oxide (HFCOO), which is the simplest fluorinated CI formed from the ozonolysis of HFOs. HFCOO contains syn- and anti-conformers, which have Boltzmann populations of, respectively, 87 and 13% at 298 K. For both conformers, the calculated ground-state reaction energy profiles associated with cyclization to form fluorodioxirane is lower than the equivalent unimolecular decay path in the simplest CI, H2COO, with anti-HFCOO returning a barrier height more than half of that of H2COO. The excited-state dynamics reveal that photoexcitation to the bright S2 state of syn-HFCOO and anti-HFCOO is expected to undergo a prompt O-O fission─with the former conformer expected to dissociate with an almost unity quantum yield and to form both O (1D) + HFCO (S0) and O (3P) + HFCO (T1) products. In contrast, photoexcitation of anti-HFCOO is expected to undergo an O-O bond fission with a non-unity quantum yield. The fraction of photoexcited anti-HFCOO that dissociates is predicted to exclusively form O (1D) + HFCO (S0) products, which is in sharp contrast to H2COO. The wider implications of our results are discussed from both physical and atmospheric chemistry perspectives.
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Affiliation(s)
- Courtney A Poirier
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
- Regional Application Center, NASA/University of Louisiana at Lafayette, Lafayette, Louisiana 70506, United States
| | - Lily M Guidry
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Jordyn M Ratliff
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Vincent J Esposito
- NASA Postdoctoral Program Fellow, NASA Ames Research Center, Moffett Field, California 94035-1000, United States
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70504, United States
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3
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Wang G, Liu T, Zou M, Karsili TNV, Lester MI. UV photodissociation dynamics of the acetone oxide Criegee intermediate: experiment and theory. Phys Chem Chem Phys 2023; 25:7453-7465. [PMID: 36848133 DOI: 10.1039/d3cp00207a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
The photodissociation dynamics of the dimethyl-substituted acetone oxide Criegee intermediate [(CH3)2COO] is characterized following electronic excitation to the bright 1ππ* state, which leads to O (1D) + acetone [(CH3)2CO, S0] products. The UV action spectrum of (CH3)2COO recorded with O (1D) detection under jet-cooled conditions is broad, unstructured, and essentially unchanged from the corresponding electronic absorption spectrum obtained using a UV-induced depletion method. This indicates that UV excitation of (CH3)2COO leads predominantly to the O (1D) product channel. A higher energy O (3P) + (CH3)2CO (T1) product channel is not observed, although it is energetically accessible. In addition, complementary MS-CASPT2 trajectory surface-hopping (TSH) simulations indicate minimal population leading to the O (3P) channel and non-unity overall probability for dissociation (within 100 fs). Velocity map imaging of the O (1D) products is utilized to reveal the total kinetic energy release (TKER) distribution upon photodissociation of (CH3)2COO at various UV excitation energies. Simulation of the TKER distributions is performed using a hybrid model that combines an impulsive model with a statistical component, the latter reflecting the longer-lived (>100 fs) trajectories identified in the TSH calculations. The impulsive model accounts for vibrational activation of (CH3)2CO arising from geometrical changes between the Criegee intermediate and the carbonyl product, indicating the importance of CO stretch, CCO bend, and CC stretch along with activation of hindered rotation and rock of the methyl groups in the (CH3)2CO product. Detailed comparison is also made with the TKER distribution arising from photodissociation dynamics of CH2OO upon UV excitation.
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Affiliation(s)
- Guanghan Wang
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, LA 70504, USA.
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
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Karsili TNV, Marchetti B, Lester MI, Ashfold MNR. Electronic Absorption Spectroscopy and Photochemistry of Criegee Intermediates. Photochem Photobiol 2023; 99:4-18. [PMID: 35713380 DOI: 10.1111/php.13665] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 06/14/2022] [Indexed: 01/26/2023]
Abstract
Interest in Criegee intermediates (CIs), often termed carbonyl oxides, and their role in tropospheric chemistry has grown massively since the demonstration of laboratory-based routes to their formation and characterization in the gas phase. This article reviews current knowledge regarding the electronic spectroscopy of atmospherically relevant CIs like CH2 OO, CH3 CHOO, (CH3 )2 COO and larger CIs like methyl vinyl ketone oxide and methacrolein oxide that are formed in the ozonolysis of isoprene, and of selected conjugated carbene-derived CIs of interest in the synthetic chemistry community. Of the aforementioned atmospherically relevant CIs, all except CH2 OO and (CH3 )2 COO exist in different conformers which, under tropospheric conditions, can display strikingly different thermal loss rates via unimolecular and bimolecular processes. Calculated photolysis rates based on their absorption properties suggest that solar photolysis will rarely be a significant contributor to the total loss rate for any CI under tropospheric conditions. Nonetheless, there is ever-growing interest in the absorption cross sections and primary photochemistry of CIs following excitation to the strongly absorbing 1 ππ* state, and how this varies with CI, with conformer and with excitation wavelength. The later part of this review surveys the photochemical data reported to date, including a range of studies that demonstrate prompt photo-induced fission of the terminal O-O bond, and speculates about possible alternate decay processes that could occur following non-adiabatic coupling to, and dissociation from, highly internally excited levels of the electronic ground state of a CI.
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Affiliation(s)
| | | | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA
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5
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Liu T, Zou M, Caracciolo A, Sojdak CA, Lester MI. Substituent Effects on the Electronic Spectroscopy of Four-Carbon Criegee Intermediates. J Phys Chem A 2022; 126:6734-6741. [DOI: 10.1021/acs.jpca.2c05502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Tianlin Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Meijun Zou
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Adriana Caracciolo
- 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
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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6
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Antwi E, Ratliff JM, Ashfold MNR, Karsili TNV. Comparing the Excited State Dynamics of CH 2OO, the Simplest Criegee Intermediate, Following Vertical versus Adiabatic Excitation. J Phys Chem A 2022; 126:6236-6243. [PMID: 36067494 DOI: 10.1021/acs.jpca.2c05118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ab initio molecular dynamics studies of CH2OO molecules following excitation to the minimum-energy geometry of the strongly absorbing S2 (1ππ*) state reveal a much richer range of behaviors than just the prompt O-O bond fission, with unity quantum yield and retention of overall planarity, identified in previous vertical excitation studies from the ground (S0) state. Trajectories propagated for 100 fs from the minimum-energy region of the S2 state show a high surface hopping (nonadiabatic coupling) probability between the near-degenerate S2 and S1 (1nπ*) states at geometries close to the S2 minimum, which enables population transfer to the optically dark S1 state. Greater than 80% of the excited population undergoes O-O bond fission on the S2 or S1 potential energy surfaces (PESs) within the analysis period, mostly from nonplanar geometries wherein the CH2 moiety is twisted relative to the COO plane. Trajectory analysis also reveals recurrences in the O-O stretch coordinate, consistent with the resonance structure observed at the red end of the parent S2-S0 absorption spectrum, and a small propensity for out-of-plane motion after nonadiabatic coupling to the S1 PES that enables access to a conical intersection between the S1 and S0 states and cyclization to dioxirane products.
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Affiliation(s)
- Ernest Antwi
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Jordyn M Ratliff
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Michael N R Ashfold
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, U.K
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
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Yang JN, Takahashi K, Lin JJM. Reaction Kinetics of Criegee Intermediates with Nitric Acid. J Phys Chem A 2022; 126:6160-6170. [PMID: 36044562 DOI: 10.1021/acs.jpca.2c04596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This work investigated the reaction kinetics of HNO3 with four Criegee intermediates (CIs): CH2OO, (CH3)2COO, methyl vinyl ketone oxide (MVKO), and methacrolein oxide (MACRO). Our results show that these reactions are extremely fast with rate coefficients of (1.51 ± 0.45) × 10-10, (3.54 ± 1.06) × 10-10, (3.93 ± 1.18) × 10-10, and (3.0 ± 1.0) × 10-10 cm3 s-1 for reactions of HNO3 with CH2OO, (CH3)2COO, syn-MVKO, and anti-MACRO, respectively. This is consistent with previous results for the reactions between CIs and carboxylic acids, but the rate coefficient of CH2OO + HNO3 in the literature [Foreman Angew. Chem. 2016, 128, 10575] was found to be overestimated by a factor of 3.6. In addition, we did not observe any significant pressure dependence in the HNO3 reactions with CH2OO and (CH3)2COO under 100-400 Torr. Our results indicate that in a dry area with severe NOx pollution, the reactions of CIs with HNO3 and their products may be worthy of attention, but these reactions may be insignificant under high-humidity conditions. However, CI reactions with HNO3 may not play an important role in the atmospheric removal processes of HNO3 because of the low concentrations of CIs.
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Affiliation(s)
- Jie-Ning Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kaito Takahashi
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
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Takahashi K. Wave Packet Calculation of Absolute UV Cross Section of Criegee Intermediates. J Phys Chem A 2022; 126:6080-6090. [PMID: 36041057 DOI: 10.1021/acs.jpca.2c04141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Criegee intermediates, R1R2COO, are reactive species formed in the atmosphere through the ozonolysis of alkenes. They have an intense ultraviolet (UV) adsorption between 300 to 400 nm. However, experimentally determining the absolute cross sections is not easy. We used wave packet propagation on an one-dimensional adiabatic potential energy curve (PEC) along the OO bond to simulate the UV spectra for various Criegee intermediates. Our results showed a very fast, ∼20 fs, decay out of the Franck-Condon region. This gives justification for using the semiclassical approach which was utilized in previous studies. From the comparison of various quantum chemistry methods, we found that multireference methods can give spectra with a width and cross section reproducing the experimental results, while single reference methods tend to give narrower skewed peaks with a larger cross section. From the test using wave packet propagation on various approximated PECs and transition moment functions, we show that the Gaussian approximation within the reflection method is valid. In addition, we found that we can obtain peak positions that reproduce the experimental results by shifting those obtained by MRCI+Q, CASSCF, EOMCCSD, and TDCAMB3LYP by -0.2, -1.0, -0.3, and -0.5 eV, respectively. The Gaussian approximation using peak position, oscillator strength, and peak width from MRCI+Q is a cost-effective way to simulate the UV spectra of Crigee intermediates for which experimental determination may be hard.
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Affiliation(s)
- Kaito Takahashi
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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9
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Antwi E, Bush RE, Marchetti B, Karsili TNV. A direct dynamics study of the exotic photochemistry of the simplest Criegee intermediate, CH 2OO. Phys Chem Chem Phys 2022; 24:16724-16731. [PMID: 35770704 DOI: 10.1039/d2cp01860h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Criegee intermediates are amongst the most fascinating molecules in modern-day chemistry. They are highly reactive intermediates that find vital roles that range from atmospheric chemistry to organic synthesis. Their excited state chemistry is exotic and complicated, and a myriad of electronic states can contribute to their photodissociation dynamics. This article reports a multi-state direct dynamics (full-dimensional) study of the photoinduced fragmentation of the simplest Criegee intermediate, CH2OO, using state-of-the-art MS-CASPT2 trajectory surface hopping. Following vertical excitation to the strongly absorbing S2(1ππ*) state, internal conversion, and thus changes in the electronic state character of the separating O + CH2O fragments, is observed between parent electronic states at separations that, traditionally, might be viewed as the classically asymptotic region of the potential energy surface. We suggest that such long-range internal conversion may account for the unusual and non-intuitive total kinetic energy distribution in the O(1D) + CH2O(S0) products observed following photoexcitation of CH2OO. The present results also reveal the interplay between seven singlet electronic states and dissociation to yield the experimentally observed O(1D) + CH2O(S0) and O(3P) + CH2O(T1) products. The former (singlet) products are favored, with a branching ratio of ca. 80%, quantifying the hitherto unknown product branching ratios observed in velocity map imaging experiments. To the best of our knowledge, such long-range internal conversions that lead to changes in the electronic state character of the fragment pairs originating from a common parent - at classically asymptotic separations - have not been recognized hitherto in the case of a molecular photodissociation.
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Affiliation(s)
- Ernest Antwi
- University of Louisiana at Lafayette, Lafayette, LA 70503, USA.
| | - Rachel E Bush
- University of Louisiana at Lafayette, Lafayette, LA 70503, USA.
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10
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Lin YH, Takahashi K, Lin JJM. Absolute photodissociation cross sections of thermalized methyl vinyl ketone oxide and methacrolein oxide. Phys Chem Chem Phys 2022; 24:10439-10450. [PMID: 35441630 DOI: 10.1039/d2cp00476c] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Methyl vinyl ketone oxide (MVKO) and methacrolein oxide (MACRO) are resonance-stabilized Criegee intermediates which are formed in the ozonolysis reaction of isoprene, the most abundant unsaturated hydrocarbon in the atmosphere. The absolute photodissociation cross sections of MVKO and MACRO were determined by measuring their laser depletion fraction at 352 nm, which was deduced from their time-resolved UV-visible absorption spectra. After calibrating the 352 nm laser fluence with the photodissociation of NO2, for which the absorption cross section and photodissociation quantum yield are well known, the photodissociation cross sections of thermalized (299 K) MVKO and MACRO at 352 nm were determined to be (3.02 ± 0.60) × 10-17 cm2 and (1.53 ± 0.29) × 10-17 cm2, respectively. Using their reported spectra and photodissociation quantum yields, their peak absorption cross sections were deduced to be (3.70 ± 0.74) × 10-17 cm2 (at 371 nm, MVKO) and (3.04 ± 0.58) × 10-17 cm2 (at 397 nm, MACRO). These values agree fairly with our theoretical predictions and are substantially larger than those of smaller, alkyl-substituted Criegee intermediates (CH2OO, syn-CH3CHOO, (CH3)2COO), revealing the effect of extended conjugation. With their cross sections, we also quantified the synthesis yields of MVKO and MACRO in the present experiment to be 0.22 ± 0.10 (at 299 K and 30-700 torr) and 0.043 ± 0.019 (at 299 K and 500 torr), respectively, relative to their photolyzed precursors. The lower yield of MACRO can be related to the high endothermicity of its formation channel.
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Affiliation(s)
- Yen-Hsiu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan. .,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kaito Takahashi
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
| | - Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan. .,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
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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] [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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12
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Peltola J, Seal P, Vuorio N, Heinonen P, Eskola A. Solving the discrepancy between the direct and relative-rate determinations of unimolecular reaction kinetics of dimethyl-substituted Criegee intermediate (CH 3) 2COO using a new photolytic precursor. Phys Chem Chem Phys 2022; 24:5211-5219. [PMID: 35167635 DOI: 10.1039/d1cp02270a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have performed direct kinetic measurements of the thermal unimolecular reaction of (CH3)2COO in the temperature range 243-340 K and pressure range 5-350 Torr using time-resolved UV-absorption spectroscopy. We have utilized a new photolytic precursor, 2-bromo-2-iodopropane ((CH3)2CIBr), which photolysis at 213 nm in the presence of O2 produces acetone oxide, (CH3)2COO. The results show that the thermal unimolecular reaction is even more important main loss process of (CH3)2COO in the atmosphere than direct kinetic studies have suggested hitherto. The current experiments show that the unimolecular reaction rate of (CH3)2COO at 296 K and atmospheric pressure is 899 ± 42 s-1. Probably more importantly, current measurements bring the direct and relative-rate measurements of thermal unimolecular reaction kinetics of (CH3)2COO into quantitative agreement.
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Affiliation(s)
- Jari Peltola
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), Helsinki, FI-00014, Finland.
| | - Prasenjit Seal
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), Helsinki, FI-00014, Finland.
| | - Niko Vuorio
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), Helsinki, FI-00014, Finland.
| | - Petri Heinonen
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), Helsinki, FI-00014, Finland.
| | - Arkke Eskola
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), Helsinki, FI-00014, Finland.
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13
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McCoy JC, Léger SJ, Frey CF, Vansco MF, Marchetti B, Karsili TNV. Modeling the Conformer-Dependent Electronic Absorption Spectra and Photolysis Rates of Methyl Vinyl Ketone Oxide and Methacrolein Oxide. J Phys Chem A 2022; 126:485-496. [PMID: 35049299 DOI: 10.1021/acs.jpca.1c08381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Criegee intermediates are important atmospheric oxidants, formed via the reaction of ozone with volatile alkenes emitted into the troposphere. Small Criegee intermediates (e.g., CH2OO and CH3CHOO) are highly reactive, and their removal via unimolecular decay or bimolecular chemistry dominates their atmospheric lifetimes. As the molecular complexity of Criegee intermediates increases, their electronic absorption spectra show a bathochromic shift within the solar spectrum relevant to the troposphere. In these cases, solar photolysis may become a competitive contributor to their atmospheric removal. In this article, we report the conformer-dependent simulated electronic absorption spectra of two four-carbon-centered Criegee intermediates, methyl vinyl ketone oxide (MVK-oxide) and methacrolein oxide (MACR-oxide). Both MVK-oxide and MACR-oxide contain four low-energy conformers, which are convoluted in the experimentally measured spectra. Here, we deconvolute each conformer and estimate contributions from each of the four conformers to the experimentally measured spectra. We also estimate the photolysis rates and predict that solar photolysis should be a more competitive removal process for MVK-oxide and MACR-oxide (cf. CH2OO and CH3CHOO).
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Affiliation(s)
- Julia C McCoy
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Spencer J Léger
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Conrad F Frey
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Michael F Vansco
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Barbara Marchetti
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
| | - Tolga N V Karsili
- Department of Chemistry, University of Louisiana at Lafayette, Louisiana, Louisiana 70503, United States
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14
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Esposito VJ, Werba O, Bush SA, Marchetti B, Karsili TNV. Insights into the Ultrafast Dynamics of CH 2 OO and CH 3 CHOO Following Excitation to the Bright 1 ππ* State: The Role of Singlet and Triplet States. Photochem Photobiol 2021; 98:763-772. [PMID: 34767632 DOI: 10.1111/php.13560] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 11/09/2021] [Indexed: 12/11/2022]
Abstract
Criegee intermediates make up a class of molecules that are of significant atmospheric importance. Understanding their electronically excited states guides experimental detection and provides insight into whether solar photolysis plays a role in their removal from the troposphere. The latter is particularly important for large and functionalized Criegee intermediates. In this study, the excited state chemistry of two small Criegee intermediates, formaldehyde oxide (CH2 OO) and acetaldehyde oxide (CH3 CHOO), was modeled to compare their specific dynamics and mechanisms following excitation to the bright ππ* state and to assess the involvement of triplet states to the excited state decay process. Following excitation to the bright ππ* state, the photoexcited population exclusively evolves to form oxygen plus aldehyde products without the involvement of triplet states. This occurs despite the presence of a more thermodynamically stable triplet path and several singlet/triplet energy crossings at the Franck-Condon geometry and contrasts with the photodynamics of related systems such as acetaldehyde and acetone. This work sets the foundations to study Criegee intermediates with greater molecular complexity, wherein a bathochromic shift in the electron absorption profiles may ensure greater removal via solar photolysis.
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Affiliation(s)
| | | | - Sarah A Bush
- University of Louisiana at Lafayette, Lafayette, LA
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15
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Lin Y, Lin JJ. A new approach to determine the absolute photodissociation cross section of molecules in a cell. J CHIN CHEM SOC-TAIP 2021. [DOI: 10.1002/jccs.202100336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yen‐Hsiu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica Taipei Taiwan
| | - Jim Jr‐Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica Taipei Taiwan
- Department of Chemistry National Taiwan University Taipei Taiwan
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16
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Kuo MT, Yang JN, Lin JJM, Takahashi K. Substituent Effect in the Reactions between Criegee Intermediates and 3-Aminopropanol. J Phys Chem A 2021; 125:6580-6590. [PMID: 34314585 DOI: 10.1021/acs.jpca.1c03737] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Via intramolecular H atom transfer, 3-aminopropanol is more reactive toward Criegee intermediates, in comparison with amines or alcohols. Here we accessed the substituent effect of Criegee intermediates in their reactions with 3-aminopropanol. Through real-time monitoring the concentrations of two Criegee intermediates with their strong UV absorption at 340 nm, the experimental rate coefficients at 298 K (100-300 Torr) were determined to be (1.52 ± 0.08) × 10-11 and (1.44 ± 0.22) × 10-13 cm3 s-1 for the reactions of 3-aminopropanol with (CH3)2COO (acetone oxide) and CH2CHC(CH3)OO (methyl vinyl ketone oxide), respectively. Compared to our previous experimental value for the reaction with syn-CH3CHOO, (1.24 ± 0.13) × 10-11 cm3 s-1, we can see that the methyl substitution at the anti position has little effect on the reactivity while the vinyl substitution causes a drastic decrease in the reactivity. Our theoretical calculations based on CCSD(T)-F12 energies reproduce this 2-order-of-magnitude decrease in the rate coefficient caused by the vinyl substitution. Using the activation strain model, we found that the interaction of Criegee intermediates with 3-aminopropanol is weaker for the case of vinyl substitution. This effect can be further rationalized by the delocalization of the lowest unoccupied molecular orbital for the vinyl-substituted Criegee intermediates. These results would help us better estimate the impact of similar reactions like the reactions of Criegee intermediates with water vapor, some of which could be difficult to measure experimentally but can be important in the atmosphere. We also found that the B2PLYP-D3BJ/aug-cc-pVTZ calculation can reproduce the CCSD(T)-F12 reaction barrier energies within ca. 1 kcal mol-1, indicating that the use of the B2PLYP-D3BJ method is promising for future predictions of the reactions of larger Criegee intermediates.
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Affiliation(s)
- Mei-Tsan Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Jie-Ning Yang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.,Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Kaito Takahashi
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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17
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McCoy JC, Marchetti B, Thodika M, Karsili TNV. A Simple and Efficient Method for Simulating the Electronic Absorption Spectra of Criegee Intermediates: Benchmarking on CH 2OO and CH 3CHOO. J Phys Chem A 2021; 125:4089-4097. [PMID: 33970629 DOI: 10.1021/acs.jpca.1c01074] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Criegee intermediates (CIs) play a vital role in the atmosphere-known most prominently for enhancing the oxidizing capacity of the troposphere. Knowledge of their electronic absorption spectra is of vital importance for two reasons: (1) to aid experimentalists in detecting CIs and (2) in deciding if their removal is affected by solar photolysis. In this article we report a simple and efficient method based on the nuclear ensemble method that may be effectively used to compute the electronic absorption spectra of Criegee intermediates without the need for extensive computation of preparing the initial configurations of the starting geometry. We use this method to benchmark several excited-state electronic structure methods and their efficacy in reproducing the electronic absorption spectra of two well-known cases of CI: CH2OO and CH3CHOO. The success and computational feasibility of the methodology are crucial for its applicability to CIs of increasing molecular complexity, which have no known experimentally measured electronic absorption spectra, allowing a guide for experimentalists. Application of the methodology to more complex CIs (e.g., those with extended conjugation or those derived from endocyclic alkenes) will also reveal if solar photolysis becomes a competitive removal process when compared to unimolecular decay or bimolecular chemistry.
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Affiliation(s)
- Julia C McCoy
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Barbara Marchetti
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
| | - Mushir Thodika
- Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Tolga N V Karsili
- University of Louisiana at Lafayette, Lafayette, Louisiana 70503, United States
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18
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Chhantyal-Pun R, Khan MAH, Taatjes CA, Percival CJ, Orr-Ewing AJ, Shallcross DE. Criegee intermediates: production, detection and reactivity. INT REV PHYS CHEM 2020. [DOI: 10.1080/0144235x.2020.1792104] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
| | | | - Craig A. Taatjes
- Combustion Research Facility, Sandia National Laboratories, Livermore, CA, USA
| | - Carl J. Percival
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
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19
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Affiliation(s)
- Carlos Cabezas
- Instituto de Física Fundamental (IFF-CSIC), Group of Molecular Astrophysics, Madrid, Spain
| | | | - Yasuki Endo
- Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan
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20
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Barber VP, Esposito VJ, Trabelsi T, Hansen AS, McHenry TA, Francisco JS, Lester MI. Experimental and computational investigation of vinoxy and 1-methylvinoxy radicals from the unimolecular decay of alkyl-substituted Criegee intermediates. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137478] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Hansen AS, Liu Z, Chen S, Schumer MG, Walsh PJ, Lester MI. Unraveling Conformer-Specific Sources of Hydroxyl Radical Production from an Isoprene-Derived Criegee Intermediate by Deuteration. J Phys Chem A 2020; 124:4929-4938. [PMID: 32449860 DOI: 10.1021/acs.jpca.0c02867] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ozonolysis of isoprene, the most abundant volatile organic compounds emitted into the Earth's troposphere after methane, yields three distinct Criegee intermediates. Among these, methyl vinyl ketone oxide (MVK-oxide) is predicted to be the major source of atmospheric hydroxyl radicals (OH) from isoprene ozonolysis. Previously, Barber et al. [ J. Am. Chem. Soc., 2018, 140, pp 10866-10880] demonstrated that syn-MVK-oxide conformers undergo unimolecular decay via 1,4-hydrogen (H) transfer from the methyl group to the adjacent terminal oxygen atom, followed by the prompt release of OH radical products. Here, we selectively deuterate the methyl group of MVK-oxide (d3-MVK-oxide) and record its IR action spectrum in the vinyl CH stretch overtone (2νCH) region. The resultant time-dependent appearance of OD radical products, detected by laser-induced fluorescence, demonstrates that a unimolecular decay of d3-MVK-oxide proceeds by an analogous 1,4-deuterium (D) atom transfer mechanism anticipated for syn conformers. The experimental spectral and temporal results are compared with the calculated IR absorption spectrum and unimolecular decay rates predicted by the Rice-Ramsperger-Kassel-Marcus (RRKM) theory for syn-d3-MVK-oxide, as well as the prior study on syn-MVK-oxide. The d3-MVK-oxide IR action spectrum is similar to that for MVK-oxide, yet exhibits notable changes as the overtone and combination transitions involving CD stretch shift to a lower frequency. The unimolecular decay rate for d3-MVK-oxide is predicted to be a factor of 40 times slower than that for MVK-oxide in the 2νCH region. Experimentally, the temporal profile of the OD products reflects the slower unimolecular decay of d3-MVK-oxide compared to that for MVK-oxide to OH products as well as experimental factors. Both experiment and theory demonstrate that quantum mechanical tunneling plays a very important role in the 1,4-H/D-transfer processes at energies in the vicinity of the transition-state barrier. The similarities of the IR action spectra and changes in the unimolecular decay dynamics upon deuteration indicate that syn conformers make the main contribution to the IR action spectra of MVK-oxide and d3-MVK-oxide.
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Affiliation(s)
- Anne S Hansen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Ziao Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Shuguang Chen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Mac G Schumer
- 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
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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22
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Peltola J, Seal P, Inkilä A, Eskola A. Time-resolved, broadband UV-absorption spectrometry measurements of Criegee intermediate kinetics using a new photolytic precursor: unimolecular decomposition of CH 2OO and its reaction with formic acid. Phys Chem Chem Phys 2020; 22:11797-11808. [PMID: 32347242 DOI: 10.1039/d0cp00302f] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present a time-resolved broadband cavity-enhanced UV-absorption spectrometer apparatus that we have constructed and utilized for temperature- and pressure-dependent kinetic measurements of formaldehyde oxide (CH2OO) reactions. We also introduce and utilize a new photolytic precursor, bromoiodomethane (CH2IBr), which photolysis at 213 nm in presence of O2 produces CH2OO. Importantly, this precursor appears to be free from secondary reactions that may regenerate CH2OO in kinetic experiments. The unimolecular decomposition rate coefficient of CH2OO has been measured over wide pressure (5-400 Torr) and temperature (296-600 K) ranges and master equation simulations of the decomposition kinetics have been performed using MESMER program. The MESMER simulations of the experimental data with the calculated zero-point energy corrected transition state energy 85.9 kJ mol-1 for decomposition required no adjustment and returned 〈ΔE〉down = 123.2 × (T/298 K)0.74 cm-1 for temperature-dependent exponential-down model of the collisional energy transfer in He. A very good agreement between results of simulations and experiments is obtained. The results are compared with the previously reported unimolecular decomposition study by Stone et al. (Phys. Chem. Chem. Phys., 2018, 20, 24940-24954). Current master equation simulations suggest about 61% decomposition yield for the predominant H2 + CO2 channel, whereas the yields of two other channels, H2O + CO, and HCO + OH, are sensitive on the parameters involved in the simulations. The kinetics of CH2OO reaction with formic acid has also been investigated as function of pressure (5-150 Torr) and temperature (296-458 K). The bimolecular rate coefficient for CH2OO + HCOOH reaction shows a negative temperature dependency, decreasing from (1.0 ± 0.03) × 10-10 cm3 molecule-1 s-1 at 296 K to (0.47 ± 0.05) × 10-10 cm3 molecule-1 s-1 at 458 K with an Arrhenius activation energy of -4.9 ± 1.6 kJ mol-1, where statistical uncertainties shown are 2σ. Estimated overall uncertainty in the measured rate coefficients is about ±20%. Current bimolecular rate coefficient at room temperature agrees with the previously reported rate coefficients from the direct kinetic experiments. The reaction is found to be pressure independent over the range between 5 and 150 Torr at 296 K in He.
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Affiliation(s)
- Jari Peltola
- Department of Chemistry, University of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FI-00014, Helsinki, Finland.
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23
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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] [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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24
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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] [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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25
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Vansco MF, Marchetti B, Lester MI. Electronic spectroscopy of methyl vinyl ketone oxide: A four-carbon unsaturated Criegee intermediate from isoprene ozonolysis. J Chem Phys 2019; 149:244309. [PMID: 30599734 DOI: 10.1063/1.5064716] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ozonolysis of isoprene, one of the most abundant volatile organic compounds in the atmosphere, proceeds through methyl vinyl ketone oxide (MVK-oxide), methacrolein oxide, and formaldehyde oxide (CH2OO) Criegee intermediates. The present study focuses on MVK-oxide, a four-carbon unsaturated carbonyl oxide intermediate, using vacuum ultraviolet photoionization at 118 nm and UV-visible induced depletion of the m/z = 86 mass channel to characterize its first π* ← π electronic transition. The electronic spectrum is broad and unstructured with its peak at 388 nm (3.2 eV). The MVK-oxide spectrum is shifted to a significantly longer wavelength than CH2OO and alkyl-substituted Criegee intermediates studied previously due to extended conjugation across the vinyl and carbonyl oxide groups. Electronic excitation results in rapid dissociation at λ ≤ 430 nm to methyl vinyl ketone and O 1D products, the latter detected by 2 + 1 resonance enhanced multiphoton ionization using velocity map imaging. Complementary electronic structure calculations (CASPT2(12,10)/AVDZ) predict two π* ← π transitions with significant oscillator strength for each of the four conformers of MVK-oxide with vertical excitation energies (and corresponding wavelengths) in the 3.1-3.6 eV (350-400 nm) and 4.5-5.5 eV (220-280 nm) regions. The computed electronic absorption profile of MVK-oxide, based on a Wigner distribution of ground state configurations and summed over the four conformers, is predicted to peak at 397 nm. UV-visible spectroscopy on the first π* ← π transition is shown by a combination of experiment and theory to provide a sensitive method for detection of the MVK-oxide Criegee intermediate that will enable further studies of its photochemistry and unimolecular and bimolecular reaction dynamics.
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Affiliation(s)
- Michael F Vansco
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Barbara Marchetti
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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26
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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] [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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27
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Long B, Bao JL, Truhlar DG. Unimolecular reaction of acetone oxide and its reaction with water in the atmosphere. Proc Natl Acad Sci U S A 2018; 115:6135-6140. [PMID: 29844185 PMCID: PMC6004451 DOI: 10.1073/pnas.1804453115] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Criegee intermediates (i.e., carbonyl oxides with two radical sites) are known to be important atmospheric reagents; however, our knowledge of their reaction kinetics is still limited. Although experimental methods have been developed to directly measure the reaction rate constants of stabilized Criegee intermediates, the experimental results cover limited temperature ranges and do not completely agree well with one another. Here we investigate the unimolecular reaction of acetone oxide [(CH3)2COO] and its bimolecular reaction with H2O to obtain rate constants with quantitative accuracy comparable to experimental accuracy. We do this by using CCSDT(Q)/CBS//CCSD(T)-F12a/DZ-F12 benchmark results to select and validate exchange-correlation functionals, which are then used for direct dynamics calculations by variational transition state theory with small-curvature tunneling and torsional and high-frequency anharmonicity. We find that tunneling is very significant in the unimolecular reaction of (CH3)2COO and its bimolecular reaction with H2O. We show that the atmospheric lifetimes of (CH3)2COO depend on temperature and that the unimolecular reaction of (CH3)2COO is the dominant decay mode above 240 K, while the (CH3)2COO + SO2 reaction can compete with the corresponding unimolecular reaction below 240 K when the SO2 concentration is 9 × 1010 molecules per cubic centimeter. We also find that experimental results may not be sufficiently accurate for the unimolecular reaction of (CH3)2COO above 310 K. Not only does the present investigation provide insights into the decay of (CH3)2COO in the atmosphere, but it also provides an illustration of how to use theoretical methods to predict quantitative rate constants of medium-sized Criegee intermediates.
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Affiliation(s)
- Bo Long
- College of Materials Science and Engineering, Guizhou Minzu University, 550025 Guiyang, China;
- Department of Chemistry, Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431
- Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Junwei Lucas Bao
- Department of Chemistry, Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431
- Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
| | - Donald G Truhlar
- Department of Chemistry, Chemical Theory Center, University of Minnesota, Minneapolis, MN 55455-0431;
- Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455-0431
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28
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Jr-Min Lin J, Chao W. Structure-dependent reactivity of Criegee intermediates studied with spectroscopic methods. Chem Soc Rev 2018; 46:7483-7497. [PMID: 28840926 DOI: 10.1039/c7cs00336f] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Criegee intermediates are very reactive carbonyl oxides that are formed in reactions of unsaturated hydrocarbons with ozone (ozonolysis). Recently, Criegee intermediates have gained significant attention since a new preparation method has been reported in 2012, which employs the reaction of iodoalkyl radical with molecular oxygen: for instance, CH2I + O2 → CH2OO + I. This new synthesis route can produce Criegee intermediates with a high number density, which allows direct detection of the Criegee intermediate via various spectroscopic tools, including vacuum UV photoionization mass spectrometry, absorption and action spectroscopy in the UV and IR regions, and microwave spectroscopy. Criegee intermediates have been thought to play important roles in atmospheric chemistry, such as in OH radical formation as well as oxidation of atmospheric gases such as SO2, NO2, volatile organic compounds, organic and inorganic acids, and even water. These reactions are relevant to acid rain and aerosol formation. Kinetics data including rate coefficients, product yields and their temperature and pressure dependences are important for understanding and modeling relevant atmospheric chemistry. In fundamental physical chemistry, Criegee intermediates have unique and interesting features, which have been partially revealed through spectroscopic, kinetic, and dynamic investigations. Although previous review articles have discussed Criegee intermediates, new data and knowledge on Criegee intermediates are still being accumulated. In this tutorial review, we have focused on structure-dependent reactivity of Criegee intermediates and various spectroscopic tools that have been utilized to probe the kinetics of Criegee intermediates.
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Affiliation(s)
- Jim Jr-Min Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
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Yin C, Takahashi K. How big is the substituent dependence of the solar photolysis rate of Criegee intermediates? Phys Chem Chem Phys 2018; 20:16247-16255. [DOI: 10.1039/c8cp02015a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Substituent dependence of the UV spectra of Criegee intermediates were calculated using multireference methods.
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Affiliation(s)
- Cangtao Yin
- Institute of Atomic and Molecular Sciences
- Academia Sinica
- Taipei 10617
- Taiwan
| | - Kaito Takahashi
- Institute of Atomic and Molecular Sciences
- Academia Sinica
- Taipei 10617
- Taiwan
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30
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Kapnas KM, Toulson BW, Foreman ES, Block SA, Hill JG, Murray C. UV photodissociation dynamics of CHI 2Cl and its role as a photolytic precursor for a chlorinated Criegee intermediate. Phys Chem Chem Phys 2017; 19:31039-31053. [PMID: 29160321 DOI: 10.1039/c7cp06532a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photolysis of geminal diiodoalkanes in the presence of molecular oxygen has become an established route to the laboratory production of several Criegee intermediates, and such compounds also have marine sources. Here, we explore the role that the trihaloalkane, chlorodiiodomethane (CHI2Cl), may play as a photolytic precursor for the chlorinated Criegee intermediate ClCHOO. CHI2Cl has been synthesized and its UV absorption spectrum measured; relative to that of CH2I2 the spectrum is shifted to longer wavelength and the photolysis lifetime is calculated to be less than two minutes. The photodissociation dynamics have been investigated using DC slice imaging, probing ground state I and spin-orbit excited I* atoms with 2 + 1 REMPI and single-photon VUV ionization. Total translational energy distributions are bimodal for I atoms and unimodal for I*, with around 72% of the available energy partitioned in to the internal degrees of freedom of the CHICl radical product, independent of photolysis wavelength. A bond dissociation energy of D0 = 1.73 ± 0.11 eV is inferred from the wavelength dependence of the translational energy release, which is slightly weaker than typical C-I bonds. Analysis of the photofragment angular distributions indicate dissociation is prompt and occurs primarily via transitions to states of A'' symmetry. Complementary high-level MRCI calculations, including spin-orbit coupling, have been performed to characterize the excited states and confirm that states of A'' symmetry with highly mixed singlet and triplet character are predominantly responsible for the absorption spectrum. Transient absorption spectroscopy has been used to measure the absorption spectrum of ClCHOO produced from the reaction of CHICl with O2 over the range 345-440 nm. The absorption spectrum, tentatively assigned to the syn conformer, is at shorter wavelengths relative to that of CH2OO and shows far weaker vibrational structure.
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Affiliation(s)
- Kara M Kapnas
- Department of Chemistry, University of California, Irvine, Irvine, CA 92697, USA.
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31
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Taatjes CA. Criegee Intermediates: What Direct Production and Detection Can Teach Us About Reactions of Carbonyl Oxides. Annu Rev Phys Chem 2017; 68:183-207. [DOI: 10.1146/annurev-physchem-052516-050739] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Craig A. Taatjes
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551-0969
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