Is the CH2OH + O2 → CH2 = O + HO2 Reaction Barrierless? An Ab Initio Study on the Reaction Mechanism

Ramírez‐Ramírez, Víctor M.; Serrano‐Andrés, Luis; Nebot–Gil, Ignacio

doi:10.1007/s00214-006-0109-1

Cited by 11 publications

(9 citation statements)

References 13 publications

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“…In fact, even the T1 values of 0.04−0.05 are frequently accepted as reliable for reaction paths. 74,75 To determine the values of activation energy E a for reactions R1 and R2 more precisely, the series of pointwise CCSD(T) and QCISD(T) calculations along the initial parts of triplet MEPs for these processes, obtained at the UBH&HLYP/augcc-pvDZ level of theory, were performed. The results of these calculations are shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

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Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N₂(A³Σ_u⁺)

2016

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Comprehensive quantum chemical analysis with the usage of density functional theory and post-Hartree-Fock approaches were carried out to study the processes in the N2(A(3)Σu(+)) + CH4 and N2(A(3)Σu(+)) + C2H6 systems. The energetically favorable reaction pathways have been revealed on the basis of the examination of potential energy surfaces. It has been shown that the reactions N2(A(3)Σu(+)) + CH4 and N2(A(3)Σu(+)) + C2H6 occur with very small or even zero activation barriers and, primarily, lead to the formation of N2H + CH3 and N2H + C2H5 products, respectively. Further, the interaction of these species can give rise the ground state N2(X(1)Σg(+)) and CH4 (or C2H6) products, i.e., quenching of N2(A(3)Σu(+)) by CH4 and C2H6 molecules is the complex two-step process. The possibility of dissociative quenching in the course of the interaction of N2(A(3)Σu(+)) with CH4 and C2H6 molecules has been analyzed on the basis of RRKM theory. It has been revealed that, for the reaction of N2(A(3)Σu(+)) with CH4, the dissociative quenching channel could occur with rather high probability, whereas in the N2(A(3)Σu(+)) + C2H6 reacting system, an analogous process was little probable. Appropriate rate constants for revealed reaction channels have been estimated by using a canonical variational theory and capture approximation. The estimations showed that the rate constant of the N2(A(3)Σu(+)) + C2H6 reaction path is considerably greater than that for the N2(A(3)Σu(+)) + CH4 one.

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Section: Resultsmentioning

confidence: 99%

“…However, for the open-shell systems, the reliability limit can be greater than T1 = 0.02. In fact, even the T1 values of 0.04–0.05 are frequently accepted as reliable for reaction paths. , …”

Section: Results and Discussionmentioning

confidence: 99%

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N₂(A³Σ_u⁺)

2016

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“…In one pathway depicted in Scheme (referred to as pathway I to CH 3 CHO + HO 2 ), the α-hydroxy−ethylperoxy radical undergoes a concerted elimination reaction, providing acetaldehyde + HO 2 with a barrier of only 11.4 kcal mol −1 (26 kcal mol −1 below the entrance channel). This reaction pathway is analogous to the dominant addition−elimination pathway in the hydroxymethyl + O 2 reaction, which produces formaldehyde + HO 2 . , Following HO 2 elimination, a weakly bound complex between HO 2 and acetaldehyde forms (termed CH 3 CHO···HOO). This complex dissociates to its products with a barrier of around 10 kcal mol −1 .…”

Section: Resultsmentioning

confidence: 99%

“…Experimentally this reaction is found to produce formaldehyde (CH 2 O) + HO 2 , with rate constants on the order of 4 × 10 12 cm 3 mol −1 s −1 at room temperature, and a small negative temperature dependence. Theoretical studies of this reaction support an O 2 addition,−H 2 O elimination mechanism. , The α-hydroxyalkylperoxy radicals are important intermediates in the atmospheric oxidation of aldehydes and ketones, where they are thought to act as sinks for these ketonyl compounds. In the context of atmospheric chemistry, modeling of the hydroxyethyl + O 2 reaction system is important in extrapolating from the reactions of hydroxymethyl to hydroxyalkyl radicals, where differences in the total reaction rate are expected, while additional and potentially important reaction pathways will become available.…”

Section: Introductionmentioning

confidence: 92%

Ethanol Oxidation: Kinetics of the α-Hydroxyethyl Radical + O₂ Reaction

et al. 2009

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Bioethanol is currently a significant gasoline additive and the major blend component of flex-fuel formulations. Ethanol is a high-octane fuel component, and vehicles designed to take advantage of higher octane fuel blends could operate at higher compression ratios than traditional gasoline engines, leading to improved performance and tank-to-wheel efficiency. There are significant uncertainties, however, regarding the mechanism for ethanol autoignition, especially at lower temperatures such as in the negative temperature coefficient (NTC) regime. We have studied an important chemical process in the autoignition and oxidation of ethanol, reaction of the alpha-hydroxyethyl radical with O2(3P), using first principles computational chemistry, variational transition state theory, and Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation simulations. The alpha-hydroxyethyl + O2 association reaction is found to produce an activated alpha-hydroxy-ethylperoxy adduct with ca. 37 kcal mol(-1) of excess vibrational energy. This activated adduct predominantly proceeds to acetaldehyde + HO(2), with smaller quantities of the enol vinyl alcohol (ethenol), particularly at higher temperatures. The reaction to acetaldehyde + HO2 proceeds with such a low barrier that collision stabilization of C2O3H5 isomers is unimportant, even for high-pressure/low-temperature conditions. The short lifetimes of these radicals precludes the chain-branching addition of a second O2 molecule, responsible for NTC behavior in alkane autoignition. This result helps to explain why ignition delays for ethanol are longer than those for ethane, despite ethanol having a weaker C-C bond energy. Given its relative instability, it is also unlikely that the alpha-hydroxy-ethylperoxy radical acts as a major acetaldehyde sink in the atmosphere, as has been suggested.

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“…In particular, the hydrogen‐bond complex between HO 2 and water28–37 has also attracted much attention as it potentially affects the photochemistry of atmosphere. Furthermore, there are some theoretical and experimental investigations38–42 on the reactions of CH 2 OH, CH 3 CHOH with molecular oxygen responsible for the formation of the HO 2 radical.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet radiation curable epoxy resin encapsulant for light emitting diodes

Kumar

Keem²,

Mang

et al. 2006

J of Applied Polymer Sci

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Light-emitting diodes are currently encapsulated by thermally curable epoxy resins. Thermal curing systems require long curing cycles at high temperatures. Further, because of viscoelastic behavior of the resin, the resin tends to "creep" along the connecting wires (Weisenberg effect), which causes solderability problem. The cured resin should be removed manually, which is time consuming and labor intensive. These problems are solved by the ultraviolet radiation curable systems. UV curing is an ultrafast reaction and takes place at room temperature. No creep behavior occurs due to the rapidity of the curing. The UV curing technique can result in higher productivity and energy saving than the thermal process. This article presents results on the development of UV curable formulations based on cycloaliphatic diepoxide, diglycidyl ether of bisphenol A, and epoxidized novolac induced by cationic photoinitiators. "Mixture experimental design" was employed to arrive at the optimum composition, which meets the stringent demands of performance characteristics and durability.

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Is the CH2OH + O2 → CH2 = O + HO2 Reaction Barrierless? An Ab Initio Study on the Reaction Mechanism

Cited by 11 publications

References 13 publications

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N₂(A³Σ_u⁺)

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N₂(A³Σ_u⁺)

Ethanol Oxidation: Kinetics of the α-Hydroxyethyl Radical + O₂ Reaction

Ultraviolet radiation curable epoxy resin encapsulant for light emitting diodes

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Is the CH2OH + O2 → CH2 = O + HO2 Reaction Barrierless? An Ab Initio Study on the Reaction Mechanism

Cited by 11 publications

References 13 publications

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N2(A3Σu+)

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N2(A3Σu+)

Ethanol Oxidation: Kinetics of the α-Hydroxyethyl Radical + O2 Reaction

Ultraviolet radiation curable epoxy resin encapsulant for light emitting diodes

Contact Info

Product

Resources

About

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N₂(A³Σ_u⁺)

Theoretical Study of the Reactions of Methane and Ethane with Electronically Excited N₂(A³Σ_u⁺)

Ethanol Oxidation: Kinetics of the α-Hydroxyethyl Radical + O₂ Reaction