1
|
Alessandrini S, Melosso M, Bizzocchi L, Barone V, Puzzarini C. The Semiexperimental Approach at Work: Equilibrium Structure of Radical Species. J Phys Chem A 2024; 128:5833-5855. [PMID: 38991181 DOI: 10.1021/acs.jpca.4c01758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The so-called semiexperimental (SE) approach is a powerful technique for obtaining highly accurate equilibrium structures for isolated systems. This Featured Article describes its extension to open-shell species, thus providing the first systematic investigation on radical equilibrium geometries to be used for benchmarking purposes. The small yet significant database obtained demonstrates that there is no reduction in accuracy when moving from closed-shell species to radicals. We also provide an extension of the applicability of the SE approach to medium-/large-sized radicals by exploiting the so-called "Lego-brick" approach, which is based on the assumption that a molecular system can be seen as formed by smaller fragments for which the SE equilibrium structure is available. In this Featured Article we show that this model can be successfully applied also to open-shell species.
Collapse
Affiliation(s)
- Silvia Alessandrini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | - Mattia Melosso
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | - Luca Bizzocchi
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| | | | - Cristina Puzzarini
- Dipartimento di Chimica "Giacomo Ciamician", Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy
| |
Collapse
|
2
|
Moore B, Toh SY, Wong YTA, Bashiri T, McKinnon A, Wai Y, Alethea Lee KW, Ovchinnikov P, Chiang CY, Djuricanin P, Momose T. Hydrocarboxyl Radical as a Product of α-Alanine Ultraviolet Photolysis. J Phys Chem Lett 2021; 12:11992-11997. [PMID: 34889613 DOI: 10.1021/acs.jpclett.1c03104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
UV photodissociation of α-alanine was studied by parahydrogen matrix isolation infrared spectroscopy. The temporal behavior of Fourier transform infrared spectra revealed that UV irradiation at 213 nm yielded the HOCO radical as a direct photoproduct from the S2 excited state. The concentration of HOCO quickly approached a steady state due to secondary photodissociation of HOCO to produce CO2 + H or CO + OH. On the other hand, no photoproducts were detected by S1 excitation at 266 nm. Irradiation of fully deuterated α-alanine at 213 nm yielded ∼2 times more cis-DOCO radicals than the lower energy isomer trans-DOCO, indicating that the conformation of the hydroxyl group is fairly well-preserved upon photodissociation of α-alanine. The present study suggests that HOCO may be a good tracer species in the search for amino acids in interstellar space.
Collapse
Affiliation(s)
- Brendan Moore
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Shin Yi Toh
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Y T Angel Wong
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Termeh Bashiri
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Alexandra McKinnon
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Yonnie Wai
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Ka Wing Alethea Lee
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Polina Ovchinnikov
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Chih-Yu Chiang
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Pavle Djuricanin
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| | - Takamasa Momose
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
| |
Collapse
|
3
|
Zhao S, Yan S, Liu X, Yang L, Sun S, Zhang J. Effect of water on dynamics of HOCO radical. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
4
|
McCarthy MC, McGuire BA. Aromatics and Cyclic Molecules in Molecular Clouds: A New Dimension of Interstellar Organic Chemistry. J Phys Chem A 2021; 125:3231-3243. [DOI: 10.1021/acs.jpca.1c00129] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael C. McCarthy
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge Massachusetts 02138, United States
| | - Brett A. McGuire
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge Massachusetts 02138, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- National Radio Astronomy Observatory, Charlottesville, Virginia 22903, United States
| |
Collapse
|
5
|
Walton JC. Dissociations of free radicals to generate protons, electrophiles or nucleophiles: role in DNA strand breaks. Chem Soc Rev 2021; 50:7496-7512. [PMID: 34019058 DOI: 10.1039/d1cs00193k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The concept behind the research described in this article was that of marrying the 'soft' methods of radical generation with the effectiveness and flexibility of nucleophile/electrophile synthetic procedures. Classic studies with pulse radiolysis and laser flash photolysis had shown that free radicals could be more acidic than their closed shell counterparts. QM computations harmonised with this and helped to define which radical centres and which structural types were most effective. Radicals based on the sulfonic acid moiety and on the Meldrum's acid moiety (2,2-dimethyl-1,3-dioxane-4,6-dione) were found to be extreme examples in the superacid class. The ethyne unit could be used as a very effective spacer between the radical centre and the site of proton donation. The key factor in promoting acidity was understood to be the thermodynamic stabilisation of the conjugate anion-radicals released on deprotonation. Solvation played a key part in promoting this and theoretical microhydration studies provided notable support. A corollary was that heterolytic dissociations of free radicals to yield either electrophiles or nucleophiles were also enhanced relative to non-radical models. The most effective radical types for spontaneous releases of both these types of reagents were identified. Ethyne units were again effective as spacers. The enhancement of release of phosphate anions by adjacent radical centres was an important special case. Reactive oxygen species and also diradicals from endiyne antibiotics generate C4'-deoxyribose radicals from nucleotides. Radicals of these types spontaneously release phosphate and triphosphate and this is a contributor to DNA and RNA strand breaks.
Collapse
Affiliation(s)
- John C Walton
- EaStCHEM School of Chemistry, University of St. Andrews, St. Andrews, Fife KY16 9ST, UK.
| |
Collapse
|
6
|
Barker JR, Stanton JF, Nguyen TL. Semiclassical transition state theory/master equation kinetics of HO + CO: Performance evaluation. INT J CHEM KINET 2020. [DOI: 10.1002/kin.21420] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- John R. Barker
- Climate and Space Sciences & Engineering University of Michigan Ann Arbor Michigan
| | - John F. Stanton
- Quantum Theory Project Department of Chemistry University of Florida Gainesville Florida
| | - Thanh Lam Nguyen
- Quantum Theory Project Department of Chemistry University of Florida Gainesville Florida
| |
Collapse
|
7
|
Johansen SL, Martin-Drumel MA, Crabtree KN. Rotational Spectrum of the β-Cyanovinyl Radical: A Possible Astrophysical N-Heterocycle Precursor. J Phys Chem A 2019; 123:5171-5177. [PMID: 31135161 DOI: 10.1021/acs.jpca.9b03798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A fundamental question in the field of astrochemistry is whether the molecules essential to life originated in the interstellar medium (ISM), and, if so, how they were formed. Nitrogen-containing heterocycles are of particular interest because of their role in biology; however, to date, no N-heterocycle has been detected in the ISM, and it is unclear how and where such species might form. Recently, the β-cyanovinyl radical (HCCHCN) was implicated in the low-temperature gas-phase formation of pyridine. While neutral vinyl cyanide (H2CCHCN) has been rotationally characterized and detected in the ISM, HCCHCN has not. Here, we present the first theoretical study of all three cyanovinyl isomers at the CCSD(T)/ANO1 level of theory and the experimental rotational spectra of cis- and trans-HCCHCN, as well as those of their 15N isotopologues, from 5 to 75 GHz. The observed spectra are in good agreement with calculations and provide a basis for further laboratory and astronomical investigations of these radicals.
Collapse
Affiliation(s)
- Sommer L Johansen
- Department of Chemistry , University of California , Davis, One Shields Ave., Davis , California 95616 , United States
| | - Marie-Aline Martin-Drumel
- Institut des Sciences Moléculaires d'Orsay , CNRS, Univ. Paris-Sud, Université Paris-Saclay , F-91405 Orsay , France
| | - Kyle N Crabtree
- Department of Chemistry , University of California , Davis, One Shields Ave., Davis , California 95616 , United States
| |
Collapse
|
8
|
Kortyna A, Nesbitt DJ. High-resolution infrared spectroscopy of jet cooled trans-deuteroxycarbonyl (trans-DOCO) radical. J Chem Phys 2019; 150:194304. [PMID: 31117796 DOI: 10.1063/1.5092599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The rovibrational spectrum of jet cooled trans-deuteroxycarbonyl (trans-DOCO) radical has been explored at suppressed-Doppler resolution via direct infrared absorption spectroscopy. The trans-DOCO is produced in a supersonic slit discharge of rare-gas/CO mixture doped with D2O, whereby the OD forms an energized adduct with CO, cooling in the supersonic expansion and stabilizing DOCO in the trans well. Active laser-frequency stabilization and collisional quenching of Doppler broadening along the slit axis yield <10 MHz frequency precision, with the absorbance noise approaching the quantum shot-noise limit. The current high-resolution spectral results are in excellent agreement with recent studies of the trans-DOCO radical by infrared frequency comb spectroscopy under room temperature conditions [Bui et al., Mol. Phys. 116, 3710 (2018)]. Combined with previous microwave/millimeter wave rotational studies, the suppressed-Doppler infrared data permit characterization of the vibrational ground state, improved structural parameters for the OD stretch vibrational level, and trans-DOCO spin-rotation information in both ground and excited vibrational states. Additionally, the infrared data reveal a-type and much weaker b-type contributions to the spectrum, analysis of which yields orientation of the OD stretch transition dipole moment in the body fixed frame. Of dynamical interest is whether the nascent trans-DOCO complex formed in the entrance channel has sufficient time to convert into the cis-DOCO isomer, or whether this is quenched by rapid stabilization into the trans-DOCO well. Ab initio and Rice-Ramsperger-Kassel-Marcus analysis of the intrinsic reaction coordinate for trans-DOCO to cis-DOCO interconversion rates supports the latter scenario, which helps explain the failure of previous high resolution infrared efforts to detect cis-hydroxycarbonyl.
Collapse
Affiliation(s)
- A Kortyna
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| | - D J Nesbitt
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309, USA
| |
Collapse
|
9
|
|
10
|
Bui TQ, Changala PB, Bjork BJ, Yu Q, Wang Y, Stanton JF, Bowman J, Ye J. Spectral analyses of trans- and cis-DOCO transients via comb spectroscopy. Mol Phys 2018. [DOI: 10.1080/00268976.2018.1484949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Thinh Q. Bui
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO, USA
| | - P. Bryan Changala
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO, USA
| | - Bryce J. Bjork
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO, USA
| | - Qi Yu
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA, USA
| | - Yimin Wang
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA, USA
| | - John F. Stanton
- Department of Chemistry, University of Florida, Gainesville, FL, USA
| | - Joel Bowman
- Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, GA, USA
| | - Jun Ye
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO, USA
| |
Collapse
|
11
|
Microhydration and the Enhanced Acidity of Free Radicals. Molecules 2018; 23:molecules23020423. [PMID: 29443952 PMCID: PMC6017598 DOI: 10.3390/molecules23020423] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 02/09/2018] [Accepted: 02/14/2018] [Indexed: 12/02/2022] Open
Abstract
Recent theoretical research employing a continuum solvent model predicted that radical centers would enhance the acidity (RED-shift) of certain proton-donor molecules. Microhydration studies employing a DFT method are reported here with the aim of establishing the effect of the solvent micro-structure on the acidity of radicals with and without RED-shifts. Microhydration cluster structures were obtained for carboxyl, carboxy-ethynyl, carboxy-methyl, and hydroperoxyl radicals. The numbers of water molecules needed to induce spontaneous ionization were determined. The hydration clusters formed primarily round the CO2 units of the carboxylate-containing radicals. Only 4 or 5 water molecules were needed to induce ionization of carboxyl and carboxy-ethynyl radicals, thus corroborating their large RED-shifts.
Collapse
|
12
|
Bui TQ, Bjork BJ, Changala PB, Nguyen TL, Stanton JF, Okumura M, Ye J. Direct measurements of DOCO isomers in the kinetics of OD + CO. SCIENCE ADVANCES 2018; 4:eaao4777. [PMID: 29349298 PMCID: PMC5770171 DOI: 10.1126/sciadv.aao4777] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 12/07/2017] [Indexed: 05/14/2023]
Abstract
Quantitative and mechanistically detailed kinetics of the reaction of hydroxyl radical (OH) with carbon monoxide (CO) have been a longstanding goal of contemporary chemical kinetics. This fundamental prototype reaction plays an important role in atmospheric and combustion chemistry, motivating studies for accurate determination of the reaction rate coefficient and its pressure and temperature dependence at thermal reaction conditions. This intricate dependence can be traced directly to details of the underlying dynamics (formation, isomerization, and dissociation) involving the reactive intermediates cis- and trans-HOCO, which can only be observed transiently. Using time-resolved frequency comb spectroscopy, comprehensive mechanistic elucidation of the kinetics of the isotopic analog deuteroxyl radical (OD) with CO has been realized. By monitoring the concentrations of reactants, intermediates, and products in real time, the branching and isomerization kinetics and absolute yields of all species in the OD + CO reaction are quantified as a function of pressure and collision partner.
Collapse
Affiliation(s)
- Thinh Q. Bui
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Corresponding author. (T.Q.B.); (J.Y.)
| | - Bryce J. Bjork
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - P. Bryan Changala
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Thanh L. Nguyen
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - John F. Stanton
- Department of Chemistry, University of Florida, Gainesville, FL 32611, USA
| | - Mitchio Okumura
- Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA
| | - Jun Ye
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
- Corresponding author. (T.Q.B.); (J.Y.)
| |
Collapse
|
13
|
McCarthy MC, Lee KLK, Stanton JF. Detection and structural characterization of nitrosamide H 2NNO: A central intermediate in deNO x processes. J Chem Phys 2017; 147:134301. [PMID: 28987087 DOI: 10.1063/1.4992097] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The structure and bonding of H2NNO, the simplest N-nitrosamine, and a key intermediate in deNOx processes, have been precisely characterized using a combination of rotational spectroscopy of its more abundant isotopic species and high-level quantum chemical calculations. Isotopic spectroscopy provides compelling evidence that this species is formed promptly in our discharge expansion via the NH2 + NO reaction and is collisionally cooled prior to subsequent unimolecular rearrangement. H2NNO is found to possess an essentially planar geometry, an NNO angle of 113.67(5)°, and a N-N bond length of 1.342(3) Å; in combination with the derived nitrogen quadrupole coupling constants, its bonding is best described as an admixture of uncharged dipolar (H2N-N=O, single bond) and zwitterion (H2N+=N-O-, double bond) structures. At the CCSD(T) level, and extrapolating to the complete basis set limit, the planar geometry appears to represent the minimum of the potential surface, although the torsional potential of this molecule is extremely flat.
Collapse
Affiliation(s)
- Michael C McCarthy
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, Massachusetts 02138, USA
| | - Kin Long Kelvin Lee
- Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, 29 Oxford St., Cambridge, Massachusetts 02138, USA
| | - John F Stanton
- Department of Chemistry and Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA
| |
Collapse
|
14
|
Barreau L, Martinez O, Crabtree KN, Womack CC, Stanton JF, McCarthy MC. Oxygen-18 Isotopic Studies of HOOO and DOOO. J Phys Chem A 2017; 121:6296-6303. [DOI: 10.1021/acs.jpca.7b05380] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | - Caroline C. Womack
- Department
of Chemistry, MIT, Cambridge, Massachusetts 02138, United States
| | - John F. Stanton
- Department of Chemistry & Biochemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, United States
| | | |
Collapse
|
15
|
Ryazantsev SV, Feldman VI, Khriachtchev L. Conformational Switching of HOCO Radical: Selective Vibrational Excitation and Hydrogen-Atom Tunneling. J Am Chem Soc 2017. [DOI: 10.1021/jacs.7b02605] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sergey V. Ryazantsev
- Department
of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
- Department
of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FIN-00014, Finland
| | - Vladimir I. Feldman
- Department
of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Leonid Khriachtchev
- Department
of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FIN-00014, Finland
| |
Collapse
|
16
|
Zhang L, Yang L, Zhao Y, Zhang J, Feng D, Sun S. Effects of Water Molecule on CO Oxidation by OH: Reaction Pathways, Kinetic Barriers, and Rate Constants. J Phys Chem A 2017; 121:4868-4880. [DOI: 10.1021/acs.jpca.7b03704] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Linyao Zhang
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Li Yang
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Yijun Zhao
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Jiaxu Zhang
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Dongdong Feng
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| | - Shaozeng Sun
- School of Energy Science and Engineering and ‡School of Chemistry and Chemical
Engineering, Harbin Institute of Technology, Harbin 150001, People’s Republic of China
| |
Collapse
|
17
|
Porterfield JP, Bross DH, Ruscic B, Thorpe JH, Nguyen TL, Baraban JH, Stanton JF, Daily JW, Ellison GB. Thermal Decomposition of Potential Ester Biofuels. Part I: Methyl Acetate and Methyl Butanoate. J Phys Chem A 2017; 121:4658-4677. [PMID: 28517940 DOI: 10.1021/acs.jpca.7b02639] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two methyl esters were examined as models for the pyrolysis of biofuels. Dilute samples (0.06-0.13%) of methyl acetate (CH3COOCH3) and methyl butanoate (CH3CH2CH2COOCH3) were entrained in (He, Ar) carrier gas and decomposed in a set of flash-pyrolysis microreactors. The pyrolysis products resulting from the methyl esters were detected and identified by vacuum ultraviolet photoionization mass spectrometry. Complementary product identification was provided by matrix infrared absorption spectroscopy. Pyrolysis pressures in the pulsed microreactor were about 20 Torr and residence times through the reactors were roughly 25-150 μs. Reactor temperatures of 300-1600 K were explored. Decomposition of CH3COOCH3 commences at 1000 K, and the initial products are (CH2═C═O and CH3OH). As the microreactor is heated to 1300 K, a mixture of CH2═C═O and CH3OH, CH3, CH2═O, H, CO, and CO2 appears. The thermal cracking of CH3CH2CH2COOCH3 begins at 800 K with the formation of CH3CH2CH═C═O and CH3OH. By 1300 K, the pyrolysis of methyl butanoate yields a complex mixture of CH3CH2CH═C═O, CH3OH, CH3, CH2═O, CO, CO2, CH3CH═CH2, CH2CHCH2, CH2═C═CH2, HCCCH2, CH2═C═C═O, CH2═CH2, HC≡CH, and CH2═C═O. On the basis of the results from the thermal cracking of methyl acetate and methyl butanoate, we predict several important decomposition channels for the pyrolysis of fatty acid methyl esters, R-CH2-COOCH3. The lowest-energy fragmentation will be a 4-center elimination of methanol to form the ketene RCH═C═O. At higher temperatures, concerted fragmentation to radicals will ensue to produce a mixture of species: (RCH2 + CO2 + CH3) and (RCH2 + CO + CH2═O + H). Thermal cracking of the β C-C bond of the methyl ester will generate the radicals (R and H) as well as CH2═C═O + CH2═O. The thermochemistry of methyl acetate and its fragmentation products were obtained via the Active Thermochemical Tables (ATcT) approach, resulting in ΔfH298(CH3COOCH3) = -98.7 ± 0.2 kcal mol-1, ΔfH298(CH3CO2) = -45.7 ± 0.3 kcal mol-1, and ΔfH298(COOCH3) = -38.3 ± 0.4 kcal mol-1.
Collapse
Affiliation(s)
| | - David H Bross
- 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.,Computation Institute, The University of Chicago , Chicago, Illinois 60637, United States
| | - James H Thorpe
- Department of Chemistry, University of Texas , Austin, Texas 78712, United States
| | - Thanh Lam Nguyen
- Department of Chemistry, University of Texas , Austin, Texas 78712, United States
| | | | - John F Stanton
- Department of Chemistry, University of Texas , Austin, Texas 78712, United States.,Department of Chemistry, University of Florida , Gainesville, Florida 32611, United States
| | | | | |
Collapse
|
18
|
Carter S, Wang Y, Bowman JM. The Rovibrational Spectra of trans- and cis-HOCO, Calculated by MULTIMODE with ab Initio Potential Energy and Dipole Moment Surfaces. J Phys Chem A 2017; 121:1616-1626. [PMID: 28157298 DOI: 10.1021/acs.jpca.6b13013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The code MULTIMODE is used in its reaction path version, along with ab initio potential energy and dipole moment surfaces introduced earlier, to predict the infrared spectra of both trans and cis forms of HOCO at temperatures 296 and 15 K. All six fundamentals are isolated for each isomer and temperature, and their main features examined, paying particular attention to the OH stretch fundamental, whose spectrum has been reported experimentally for trans-HOCO. The current spectra for cis-HOCO, while not of "spectroscopic" accuracy, should be sufficient to aid in new experimental efforts to record the spectrum of this isomer.
Collapse
Affiliation(s)
- Stuart Carter
- Cherry L. Emerson Center for Scientific Computation, Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States
| | - Yimin Wang
- Cherry L. Emerson Center for Scientific Computation, Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States
| | - Joel M Bowman
- Cherry L. Emerson Center for Scientific Computation, Department of Chemistry, Emory University , Atlanta, Georgia 30322, United States
| |
Collapse
|
19
|
Bjork BJ, Bui TQ, Heckl OH, Changala PB, Spaun B, Heu P, Follman D, Deutsch C, Cole GD, Aspelmeyer M, Okumura M, Ye J. Direct frequency comb measurement of OD + CO -> DOCO kinetics. Science 2016; 354:444-448. [PMID: 27789837 DOI: 10.1126/science.aag1862] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/28/2016] [Indexed: 11/02/2022]
Affiliation(s)
- B J Bjork
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| | - T Q Bui
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - O H Heckl
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - P B Changala
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - B Spaun
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - P Heu
- Crystalline Mirror Solutions, 114 East Haley Street, Suite G, Santa Barbara, CA 93101, USA
| | - D Follman
- Crystalline Mirror Solutions, 114 East Haley Street, Suite G, Santa Barbara, CA 93101, USA
| | - C Deutsch
- Crystalline Mirror Solutions, Parkring 10, 1010 Vienna, Austria
| | - G D Cole
- Crystalline Mirror Solutions, 114 East Haley Street, Suite G, Santa Barbara, CA 93101, USA. Crystalline Mirror Solutions, Parkring 10, 1010 Vienna, Austria
| | - M Aspelmeyer
- Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, 1090 Vienna, Austria
| | - M Okumura
- Arthur Amos Noyes Laboratory of Chemical Physics, Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - J Ye
- JILA, National Institute of Standards and Technology and University of Colorado, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| |
Collapse
|