Dissociative ring-closure in aliphatic hydroperoxyl radicals

Chan, Wai‐To; Pritchard, H. O.; Hamilton, Ian

doi:10.1039/a901134j

Cited by 21 publications

(46 citation statements)

References 15 publications

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“…On the other hand, BH&HLYP has been shown to provide a reliable estimate of the activation energy for the concerted dissociation of s-trioxane ((CH 2 O) 3 ) to CH 2 O ͑Ref. 25͒ and for the dissociative cyclization of alkyl hydroperoxyl radical to epoxide and hydroxyl radical, 26 two reactions bearing some degree of similarity to the concerted and partial ozonolysis pathways in this study. Calibration data of the performance of DFT methods for characterization of diradical transition states is lacking.…”

Section: Methodsmentioning

confidence: 71%

Mechanisms for the ozonolysis of ethene and propene: Reliability of quantum chemical predictions

Chan

Hamilton

2003

The Journal of Chemical Physics

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Reactions of ozone with ethene and propene leading to primary ozonide ͑concerted and stepwise ozonolysis͒ or epoxide and singlet molecular oxygen ͑partial ozonolysis͒ are studied theoretically. The mechanism of concerted ozonolysis proceeds via a single transition structure which is a partial diradical. The transition structures and intermediates in the stepwise ozonolysis and partial ozonolysis mechanisms are singlet diradicals. Spin-restricted and unrestricted density functional methods are employed to calculate the structures of the closed-shell and diradical species. Although the partial diradicals exhibit moderate to pronounced instability in their RDFT and RHF solutions, RDFT is required to locate the transition structure for concerted ozonolysis. Spin projected fourth-order Møller-Plesset theory ͑PMP4͒ was used to correct the DFT energies. The calculated pre-exponential factors and activation energies for the concerted ozonolysis of ethene and propene are in good agreement with experimental values. However, the PMP4//DFT procedure incorrectly predicts the stepwise mechanism as the favored channel. UCCSD͑T͒ predicts the concerted mechanism as the favored channel but significantly overestimates the activation energies. RCCSD͑T͒ is found to be more accurate than UCCSD͑T͒ for the calculation of the concerted mechanism but is not applicable to the diradical intermediates. The major difficulty in accurate prediction of the rate constant data for these reactions is the wide range of spin contamination for the reference UHF wave functions and UDFT solutions across the potential energy surface. The possibility of the partial ozonolysis mechanism being the source of epoxide observed in some experiments is discussed.

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Section: Methodsmentioning

confidence: 71%

Mechanisms for the ozonolysis of ethene and propene: Reliability of quantum chemical predictions

Chan

Hamilton

2003

The Journal of Chemical Physics

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“…Nevertheless, these values were consistent with a decrease of the ring strain energy when increasing the size of the cycle. This is not the case for the values calculated by quantum mechanical methods by Chan et al [168], which lead to an activation energy of 15 kcal/mol for the formation of oxiranes, 24 kcal/mol for that of oxetanes, 16 kcal/mol for that of furans and 18 kcal/mol for that of pyrans. Figure 10 illustrates the different possibilities of decomposition.…”

Section: Figure 9 Tablementioning

confidence: 86%

Detailed chemical kinetic models for the low-temperature combustion of hydrocarbons with application to gasoline and diesel fuel surrogates

Battin‐Leclerc

2008

Progress in Energy and Combustion Science

572

379

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“…Much fewer theoretical studies of the formation of cyclic ethers have been performed than in the case of isomerizations. The first of these theoretical studies has been performed by Chan et al (51) (BH&HLYP method) who obtained activation energies not consistently decreasing when increasing the size of the cycle. In addition, the calculations of Chan et al (51) were the first showing the need to differentiate the type of carbon atom involved in the ring closure.…”

Section: Improvements Of Thermochemical and Kinetic Parametersmentioning

confidence: 99%

Improvement of the Modeling of the Low-Temperature Oxidation ofn-Butane: Study of the Primary Reactions

et al. 2012

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This paper revisits the primary reactions involved in the oxidation of n-butane from low to intermediate temperatures (550-800 K) including the negative temperature coefficient (NTC) zone. A model that was automatically generated is used as a starting point and a large number of thermochemical and kinetic data are then re-estimated. The kinetic data of the isomerization of alkylperoxy radicals giving (•)QOOH radicals and the subsequent decomposition to give cyclic ethers has been calculated at the CBS-QB3 level of theory. The newly obtained model allows a satisfactory prediction of experimental data recently obtained in a jet-stirred reactor and in rapid compression machines. A considerable improvement of the prediction of the selectivity of cyclic ethers is especially obtained compared to previous models. Linear and global sensitivity analyses have been performed to better understand which reactions are of influence in the NTC zone.

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Dissociative ring-closure in aliphatic hydroperoxyl radicals

Cited by 21 publications

References 15 publications

Mechanisms for the ozonolysis of ethene and propene: Reliability of quantum chemical predictions

Mechanisms for the ozonolysis of ethene and propene: Reliability of quantum chemical predictions

Detailed chemical kinetic models for the low-temperature combustion of hydrocarbons with application to gasoline and diesel fuel surrogates

Improvement of the Modeling of the Low-Temperature Oxidation ofn-Butane: Study of the Primary Reactions

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