Formation of dimethylketene and methacrolein by reaction of the CH radical with acetone

Goulay, Fabien; Derakhshan, Adeeb; Maher, Eamonn; Trevitt, Adam J.; Savee, John David; Scheer, Adam M.; Osborn, David L.; Taatjes, Craig A.

doi:10.1039/c3cp43829e

Cited by 22 publications

(57 citation statements)

References 41 publications

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“…The signal at m / z 42 was assigned to ketene. Its literature PI spectrum reported by Goulay et al [ 47 ] matched well with the experimental data at m / z 42 at all temperatures ( Figure 3 ). The measured ionization energy of 9.56 ± 0.05 eV agreed with the reference adiabatic ionization energy (AIE) of 9.60 ± 0.01 eV [ 48 ].…”

Section: Resultssupporting

confidence: 81%

“…The ion signal starting at ~10.6 eV showed an artificial drop most likely due to an over-background subtraction of a very low signal-to-noise-ratio. The experimental ionization energy of 9.60 ± 0.05 eV matched the reference AIE of 9.62 ± 0.01 eV [ 47 ]. The product at m / z 72 was observed at all three temperatures and assigned to methylglyoxal based on the experimental ionization onset’s good agreement at 9.56 ± 0.01 eV with the literature AIE of 9.60 ± 0.05 eV [ 49 ] ( Figure 6 ).…”

Section: Resultsmentioning

confidence: 82%

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Study of the Synchrotron Photoionization Oxidation of Alpha-Angelica Lactone (AAL) Initiated by O(3P) at 298, 550, and 700 K

Rezaei

Meloni

2021

Molecules

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In recent years, biofuels have been receiving significant attention because of their potential for decreasing carbon emissions and providing a long-term renewable solution to unsustainable fossil fuels. Currently, lactones are some of the alternatives being produced. Many lactones occur in a range of natural substances and have many advantages over bioethanol. In this study, the oxidation of alpha-angelica lactone initiated by ground-state atomic oxygen, O(3P), was studied at 298, 550, and 700 K using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Lawrence Berkeley National Lab (LBNL). Photoionization spectra and kinetic time traces were measured to identify the primary products. Ketene, acetaldehyde, methyl vinyl ketone, methylglyoxal, dimethyl glyoxal, and 5-methyl-2,4-furandione were characterized as major reaction products, with ketene being the most abundant at all three temperatures. Possible reaction pathways for the formation of the observed primary products were computed using the CBS–QB3 composite method.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 82%

Study of the Synchrotron Photoionization Oxidation of Alpha-Angelica Lactone (AAL) Initiated by O(3P) at 298, 550, and 700 K

Rezaei

Meloni

2021

Molecules

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“…have also investigated the CH reaction with the carbonyl-containing species acetaldehyde 9 and acetone 10 as well as the cyclic nitrogen-containing species pyrrole. 11 Primarily, the isomer-resolved products detected in these studies can be rationalized by a reaction entrance channel characterized by CH addition to π-bond(s) of the co-reactant, although other processes, including insertion into C-H σ-bonds, could not be unequivocally ruled out.…”

Section: Introductionmentioning

confidence: 99%

Product Branching Fractions of the CH + Propene Reaction from Synchrotron Photoionization Mass Spectrometry

et al. 2013

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The CH(X2Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C4H6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C4H6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05), and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to C4H6 (m/z 54) + D and C4H5D (m/z 55) + H, formed at a ratio of 0.4 (m/z 54) to 1.0 (m/z 55). The D elimination channel forms almost exclusively 1,2-butadiene (0.97 ± 0.20) whereas the H elimination channel leads to the formation of deuterated 1,3-butadiene (0.89 ± 0.18) and 1-butyne (0.11 ± 0.02); photoionization spectra of undeuterated species are used in the fitting of the measured m/z 55 (C4H5D) spectrum. The results are generally consistent with a CH cycloaddition mechanism to the C═C bond of propene, forming 1-methylallyl followed by elimination of a H atom via several competing processes. The direct detection of 1,3-butadiene as a reaction product is an important validation of molecular weight growth schemes implicating the CH + propene reaction, for example, those reported recently for the formation of benzene in the interstellar medium ( Jones, B. M. Proc. Natl. Acad. Sci. U.S. A. 2011, 108, 452−457 ABSTRACTThe CH (X 2 Π) + propene reaction is studied in the gas phase at 298 K and 4 Torr (533.3 Pa) using VUV synchrotron photoionization mass spectrometry. The dominant product channel is the formation of C 4 H 6 (m/z 54) + H. By fitting experimental photoionization spectra to measured spectra of known C 4 H 6 isomers, the following relative branching fractions are obtained: 1,3-butadiene (0.63 ± 0.13), 1,2-butadiene (0.25 ± 0.05) and 1-butyne (0.12 ± 0.03) with no detectable contribution from 2-butyne. The CD + propene reaction is also studied and two product channels are observed that correspond to 2011, 108, 452-457).KEYWORDS: radical, gas-phase, photoionization, synchrotron, propene, methylidyne, mass spectrometry. 3 INTRODUCTIONThe highly reactive methylidyne (CH) radical affects the chemistry of energetic gasphase environments including combustion 1-3 , interplanetary atmospheres 4-6 and the interstellar medium. 7 In order to accurately model these systems, detailed chemical data are needed in the form of reaction rate coefficients and product branching fractions. Our purpose here is to determine total product branching fractions and provide mechanistic details for the CH (X 2 Π) + propene reaction. The present work builds on a series of previous product detection studies of the CH radical with small, unsaturated hydrocarbons: acetylene (C 2 H 2 ), ethylene (C 2 H 4 ), allene (C 3 H 4 , CH 2 CCH 2 ) and propyne (C 3 H 4 , CH 3 CCH). 8 Recent works have also investigated the CH reaction with the carbonyl-conta...

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“…At 248 nm the singlet CHBr carbene is expected to be formed in very low concentrations compared to the CH radical. 59 Its reaction with ammonia or the methyl-substituted amine reactants may form products through HBr-loss at the same m/z as the CH reaction products. There are no kinetic data available for the reactions of halocarbenes with amines.…”

Section: Resultsmentioning

confidence: 99%

Product Detection of the CH Radical Reactions with Ammonia and Methyl-Substituted Amines

et al. 2019

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Reactions of the methylidyne (CH) radical with ammonia (NH 3 ), methylamine (CH 3 NH 2 ), dimethylamine ((CH 3 ) 2 NH), and trimethylamine ((CH 3 ) 3 N), have been investigated under multiple collision conditions at 373 K and 4 Torr. The reaction products are detected using soft photoionization coupled to orthogonal acceleration time-of-flight mass spectrometry at the Advanced Light Source (ALS) synchrotron. Kinetic traces are employed to discriminate between CH reaction products and products from secondary or slower reactions. Branching ratios for isomers produced at a given mass and formed by a single reaction are obtained by fitting the observed photoionization spectra to linear combinations of pure compound spectra.The reaction of the CH radical with ammonia is found to form mainly imine, HN=CH 2 , in line with an addition-elimination mechanism. The singly methyl substituted imine is detected for the CH reactions with methylamine, dimethylamine, and trimethylamine. Dimethylimine isomers are formed by the reaction of CH with dimethylamine, while trimethylimine is formed by the CH reaction with trimethylamine. Overall, the temporal profiles of the products are not consistent with the formation of amino carbene products in the reaction flow tube. In the case of the reactions with methylamine and dimethylamine, product formation is assigned to an addition-elimination mechanism similar to that proposed for the CH reaction with ammonia.

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Formation of dimethylketene and methacrolein by reaction of the CH radical with acetone

Cited by 22 publications

References 41 publications

Study of the Synchrotron Photoionization Oxidation of Alpha-Angelica Lactone (AAL) Initiated by O(3P) at 298, 550, and 700 K

Study of the Synchrotron Photoionization Oxidation of Alpha-Angelica Lactone (AAL) Initiated by O(3P) at 298, 550, and 700 K

Product Branching Fractions of the CH + Propene Reaction from Synchrotron Photoionization Mass Spectrometry

Product Detection of the CH Radical Reactions with Ammonia and Methyl-Substituted Amines

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