Rate constants for the reactions ofCH3O with CH2O, CH3CHO and i-C4H10

Fittschen, C.; Delcroix, B.; Gomez, Nathalie; Devolder, P.

doi:10.1051/jcp:1998359

Cited by 24 publications

(15 citation statements)

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“…RO + NO. This well known alkoxy radical source has been used in several studies 14,20,22,24,25 as it has been shown that the cleavage to give NO and alkoxy radicals is by far the dominant photolysis channel. 26 Alkyl nitrites have been prepared by adding a 50% solution of H 2 SO 4 to a mixture of NaNO 2 and the appropriate alcohol, 27 i.e.…”

Section: Methodsmentioning

confidence: 99%

Atmospheric fate of alkoxy radicals: branching ratio of evolution pathways for 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals

Meunier

Doussin

Chevallier

et al. 2003

Phys. Chem. Chem. Phys.

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As the last step of VOC oxidation in the atmosphere, the evolution of alkoxy radicals determines the nature and the concentration of the secondary compounds formed. Branching ratios between decomposition and reaction with O 2 of 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals have been measured at room temperature and atmospheric pressure in a simulation chamber using FTIR spectroscopy as an analytical device. k dec /k O 2 is equal to (3.8 AE 0.4) Â 10 16 , (2.9 AE 0.3) Â 10 16 , (2.9 AE 0.4) Â 10 18 and (4.1 AE 0.8) Â 10 18 molecules cm À3 for each, respectively. This ratio has been observed to vary, depending on the leaving alkyl group and the class of alkoxy. No additional decomposition due to excited radicals has been observed.

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Section: Methodsmentioning

confidence: 99%

Atmospheric fate of alkoxy radicals: branching ratio of evolution pathways for 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals

Meunier

Doussin

Chevallier

et al. 2003

Phys. Chem. Chem. Phys.

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“…while that from the hydroxyl group have been estimated by analogy with the reactions of phenol 41,54 (reactions 21-33). In the case of the H-abstraction by CH3O radical (reaction 33), for which no data was available, the activation energy was set equal to that of the reaction with acetaldehyde 55 . OC6H4OCH3 radical can isomerize to OHC6H4OCH2 by an internal H-atom transfer (reaction 34), which rate constant was estimated using Benson's rules 56,57 .…”

Section: Kinetic Modelingmentioning

confidence: 99%

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

et al. 2018

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Guaiacol or 2-methoxy phenol is one of the main primary tars produced during lignin pyrolysis. Tar conversion in the gas phase influences the production of gaseous and condensable products, and is also responsible for PAH and soot formation during biomass and bio-oil gasification or combustion. Guaiacol pyrolysis and oxidation under stoichiometric conditions were studied in a jet stirred reactor between 623 and 923 K for a residence time of 2 s and under a pressure of 800 Torr (106.7 kPa). Speciation was obtained thanks to online gas chromatography using flame ionization detection and mass spectrometry and allowed the quantification of 22 species in pyrolysis and 42 species in oxidation. Decomposition of guaiacol starts at 650 K, and a conversion degree of 50% is obtained at about 785 K in pyrolysis and 765 K in oxidation. The main products of reaction are pyrocatechol o-HOCHOH, o-hydroxybenzaldehyde, methylcatechols, and light products, such as methane, carbon monoxide, ethylene, and hydrogen. A detailed kinetic model based on a combustion model for light aromatics and anisole has been extended to guaiacol. Thermochemical data of guaiacol and main products were calculated theoretically at the CBS-QB3 level of theory. The model predicts well the conversion of guaiacol and the formation of the main products. Guaiacol decomposes mainly through a unimolecular O-C bond breaking to hydroxy phenoxy and methyl radicals in both pyrolysis and oxidation, but H atom abstractions are also of importance in the low temperature range of the study. The unimolecular mechanism leads mainly to pyrocatechol and methylcatechols, whereas the chain radical mechanism is responsible for the formation of hydroxybenzaldehyde. As for anisole but in a much lower extent, an early formation of benzene and soot precursors is observed.

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“…We have used k 9 = 7.0 10 À14 cm 3 molecule À1 s À1 as determined by Fittschen et al [30] in a study of laser flash photolysis of methyl nitrite and detection of CH 3 O by laser-induced fluorescence. This value supersedes earlier estimates of k 9 /k 8 % 14 by Kelly and Heicklen, [31] who worked with azomethane in the presence of oxygen as a source of CH 3 O 2 and CH 3 O, and of k 9 = 1.5 10 À13 cm 3 molecule À1 s À1 by Moortgat et al, [29] who studied acetaldehyde photooxidation and applied a detailed reaction mechanism to account for the product distribution, especially CH 3 OH.…”

Section: Computer Simulationsmentioning

confidence: 99%

Photolysis of Acetaldehyde in Air: CH₄, CO and CO₂Quantum Yields

2010

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The quantum yields for CO and CH(4), formed in the photolysis of about 200 μmol mol(-1) of acetaldehyde in air at atmospheric pressure, were determined at 15 wavelengths in the range: 250-330 nm. The quantum yields for CO(2) were determined at nine wavelengths in the range: 250-315 nm. The products are mainly assigned to three primary processes: I) CH(3)CHO*→CH(3)+HCO, II) CH(3)CHO*→CH(4)+CO, III) CH(3)CHO*→CH(3)CO+H, with dissociation occurring from the initially populated S(1) singlet state of acetaldehyde. The pressure dependence of the quantum yields at wavelengths of 270, 304.4, and 313 nm exhibits a Stern-Volmer behavior in all cases. Collisional quenching is shown to deactivate the singlet state S(1) by pressure-induced intersystem crossing to the neighboring triplet state, which is subsequently rapidly quenched by oxygen. Quenching coefficients as a function of excitation energy are obtained by comparison with literature data; the wavelength dependence of individual primary quantum yields is also derived. CO(2) quantum yields at 304.4 and 313 nm were found to increase with rising CH(3)CHO concentrations due to secondary reactions. The reaction mechanism responsible for this effect was explored by means of computer simulations.

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Rate constants for the reactions ofCH₃O with CH₂O, CH₃CHO and i-C₄H10

Cited by 24 publications

References 0 publications

Atmospheric fate of alkoxy radicals: branching ratio of evolution pathways for 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals

Atmospheric fate of alkoxy radicals: branching ratio of evolution pathways for 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

Photolysis of Acetaldehyde in Air: CH₄, CO and CO₂Quantum Yields

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Rate constants for the reactions ofCH3O with CH2O, CH3CHO and i-C4H10

Cited by 24 publications

References 0 publications

Atmospheric fate of alkoxy radicals: branching ratio of evolution pathways for 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals

Atmospheric fate of alkoxy radicals: branching ratio of evolution pathways for 1-propoxy, 2-propoxy, 2-butoxy and 3-pentoxy radicals

Kinetic Study of the Pyrolysis and Oxidation of Guaiacol

Photolysis of Acetaldehyde in Air: CH4, CO and CO2Quantum Yields

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Product

Resources

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Rate constants for the reactions ofCH₃O with CH₂O, CH₃CHO and i-C₄H10

Photolysis of Acetaldehyde in Air: CH₄, CO and CO₂Quantum Yields