Rates of reaction of propyl radicals with molecular oxygen

Ruiz, Rennie P.; Bayes, Kyle D.

doi:10.1021/j150656a033

Cited by 69 publications

(59 citation statements)

References 3 publications

(3 reference statements)

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“…It is not surprising, but the k(r) curves in Fig. 2 are quite similar for the same [56]; reported to be independent of pressure over the range 1-4 Torr (He). c Lenhardt et al [57]; reported to be independent of pressure over the range 1-4 Torr (He).…”

Section: And T-butyl [supporting

confidence: 54%

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O₂ and implications for simplified kinetics of alkylperoxy radicals

Miyoshi

2011

Int J of Chemical Kinetics

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The recombination reactions of prototypical alkyl radicals (R) with O 2 , R + O 2 → RO 2 , have been investigated theoretically by using the variational transition state theory and Rice-Ramsperger-Kassel-Marcus theory/master equation calculations based on the CASPT2(7,5)/aug-cc-pVDZ//B3LYP/6-311G(d,p) potential energy curves and B3LYP/6-311G(d,p) geometries and vibrational frequencies. The calculated high-pressure limiting rate constants well reproduced the experimental room temperature rate constants for ethyl, i -propyl, n-butyl, s -butyl, and t-butyl radicals and were nearly the same for the same class of alkyl radicals, namely for primary (ethyl and n-butyl) and for secondary (i -propyl and s -butyl) radicals. Hypothetical falloff calculations ignoring the subsequent dissociation/isomerization reactions of RO 2 indicated that the low-pressure limiting (LPL) rate constants increase monotonically and systematically with the size of the molecule and are almost identical for the same-sized C 4 alkyl radicals, n-butyl, s -butyl, and t-butyl. With the extended calculations for 1-hexyl (C 6 H 13 ) and 2,4,4-trimethylpentyl (C 8 H 17 )+ O 2 based on the B3LYP/6-311G(d,p) calculations and estimated potential energy curves, class-specific molecular size dependent falloff rate expression was proposed. The analysis of the unexpected behavior of the LPL rate constants for large alkyl

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Section: And T-butyl [supporting

confidence: 54%

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O₂ and implications for simplified kinetics of alkylperoxy radicals

Miyoshi

2011

Int J of Chemical Kinetics

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“…The Journal of Physical Chemistry A Article Figures 10 and 11 shows comparisons of the measured logarithmic decay times for n-R and i-R in precursor/O 2 /He mixtures following pulsed photolysis to produce n-R and i-R 44,45 and predictions using the a priori and multiscale informed models at various temperatures and pressures. The a priori and multiscale informed models yield comparable agreement with experimental data, though the multiscale informed model generally reproduces the experimental data more closelywell within a factor of 2 (the uncertainty assigned here).…”

Section: Results With Multiscale Informedmentioning

confidence: 99%

Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

et al. 2015

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The present paper describes further development of the multiscale informatics approach to kinetic model formulation of Burke et al. (Burke, M. P.; Klippenstein, S. J.; Harding, L. B. Proc. Combust. Inst. 2013, 34, 547-555) that directly incorporates elementary kinetic theories as a means to provide reliable, physics-based extrapolation of kinetic models to unexplored conditions. Here, we extend and generalize the multiscale informatics strategy to treat systems of considerable complexity-involving multiwell reactions, potentially missing reactions, nonstatistical product branching ratios, and non-Boltzmann (i.e., nonthermal) reactant distributions. The methodology is demonstrated here for a subsystem of low-temperature propane oxidation, as a representative system for low-temperature fuel oxidation. A multiscale model is assembled and informed by a wide variety of targets that include ab initio calculations of molecular properties, rate constant measurements of isolated reactions, and complex systems measurements. Active model parameters are chosen to accommodate both "parametric" and "structural" uncertainties. Theoretical parameters (e.g., barrier heights) are included as active model parameters to account for parametric uncertainties in the theoretical treatment; experimental parameters (e.g., initial temperatures) are included to account for parametric uncertainties in the physical models of the experiments. RMG software is used to assess potential structural uncertainties due to missing reactions. Additionally, branching ratios among product channels are included as active model parameters to account for structural uncertainties related to difficulties in modeling sequences of multiple chemically activated steps. The approach is demonstrated here for interpreting time-resolved measurements of OH, HO2, n-propyl, i-propyl, propene, oxetane, and methyloxirane from photolysis-initiated low-temperature oxidation of propane at pressures from 4 to 60 Torr and temperatures from 300 to 700 K. In particular, the multiscale informed model provides a consistent quantitative explanation of both ab initio calculations and time-resolved species measurements. The present results show that interpretations of OH measurements are significantly more complicated than previously thought-in addition to barrier heights for key transition states considered previously, OH profiles also depend on additional theoretical parameters for R + O2 reactions, secondary reactions, QOOH + O2 reactions, and treatment of non-Boltzmann reaction sequences. Extraction of physically rigorous information from those measurements may require more sophisticated treatment of all of those model aspects, as well as additional experimental data under more conditions, to discriminate among possible interpretations and ensure model reliability.

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“…In the case of the C 2 H 5 + O 2 reaction, the rate constant is near the high-pressure limit at 10 Torr of He, 29 and in the case of n-and i-C 3 H 7 + O 2 and CH 3 -CO + O 2 , the rate constants are in the high-pressure limit at 1-4 Torr of He. 30,31 This could be explained by the resonance stabilization of the vinoxy radicals. As shown in Table 2, C-O bond dissociation energies (BDEs) of the peroxy radicals (112-121 kJ mol -1 ) are smaller than those of alkylperoxy radicals (136-158 kJ mol -1 ).…”

Section: Resultsmentioning

confidence: 99%

Kinetic Study on Reactions of 1- and 2-Methylvinoxy Radicals with O₂

et al. 2000

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The reactions of 1-and 2-methylvinoxy radicals with O 2 have been studied by laser-induced fluorescence coupled with pulsed laser photolysis of precursor molecules at room temperature (298 ( 5 K). The rate constants for both reactions showed typical falloff pressure dependence in the investigated pressure range (8-330 Torr, He buffer), which suggests the dominance of recombination processes to form peroxy radicals. From the Rice-Ramsperger-Kassel-Morcus fit to the experimental data, the limiting high-pressure rate constants were derived to be k ∞ (1-methylvinoxy + O 2 ) ) 9.8 × 10 -13 and k ∞ (2-methylvinoxy + O 2 ) ) 1.3 × 10 -12 cm 3 molecule -1 s -1 , which are 5-7 times larger than that for the reaction of a nonsubstituted vinoxy radical. The influence of the methyl substituent effect and the resonance stabilization on the rate constants is discussed.

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Rates of reaction of propyl radicals with molecular oxygen

Cited by 69 publications

References 3 publications

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O₂ and implications for simplified kinetics of alkylperoxy radicals

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O₂ and implications for simplified kinetics of alkylperoxy radicals

Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

Kinetic Study on Reactions of 1- and 2-Methylvinoxy Radicals with O₂

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Rates of reaction of propyl radicals with molecular oxygen

Cited by 69 publications

References 3 publications

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O2 and implications for simplified kinetics of alkylperoxy radicals

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O2 and implications for simplified kinetics of alkylperoxy radicals

Multiscale Informatics for Low-Temperature Propane Oxidation: Further Complexities in Studies of Complex Reactions

Kinetic Study on Reactions of 1- and 2-Methylvinoxy Radicals with O2

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Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O₂ and implications for simplified kinetics of alkylperoxy radicals

Molecular size dependent falloff rate constants for the recombination reactions of alkyl radicals with O₂ and implications for simplified kinetics of alkylperoxy radicals

Kinetic Study on Reactions of 1- and 2-Methylvinoxy Radicals with O₂