Incubation times, fall-off and branching ratios in the thermal decomposition of toluene: Experiments and theoryElectronic supplementary information (ESI) available: Molecular parameters used for SACM calculations and the master equation analysis, as well as correlation schemes for vibrations and rotations, used in the SACM calculations. See http://www.rsc.org/suppdata/cp/b2/b202999e/

Eng, Ronald A.; Gebert, Andreas; Goos, Elke; Hippler, H.; Kachiani, Chatuna

doi:10.1039/b202999e

Cited by 47 publications

(27 citation statements)

References 33 publications

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“…The master equation was solved assuming that the bath gas is pure Argon, adopting an exponential down model for the collisional energy transfer and using Lennard–Jones collision parameters, which were assumed to be the same as those of toluene for all the C 7 H 6 isomers. ,, Vibrational frequencies, rotational constants, and activation energies of the relevant intermediates and saddle points located on the investigated potential energy surface were calculated from ab initio simulations, as described in the Method and Theoretical Background. Because energy transfer parameters are not well-known for these molecules, we assumed an empirical value for the mean downward transfer energy ⟨Δ E down ⟩ equal to 2000 cm –1 , which was used by da Silva et al to study the benzyl decomposition reaction.…”

Section: Resultsmentioning

confidence: 99%

“…The gas phase kinetics of toluene has been the subject of much experimental and theoretical research in the last years. − Toluene is in fact not only the simplest alkylated aromatic species, but it is also found in considerable concentration in crude oils as well as in jet fuels and in gasoline, and it is formed easily in the gas phase during the pyrolysis or combustion of hydrocarbons. A detailed understanding of its decomposition kinetics and of its secondary chemistry would thus be extremely useful to model the initial stages of combustion or pyrolysis of the mentioned fuels as well as to understand if and how it can contribute to the nucleation and growth of soot.…”

Section: Introductionmentioning

confidence: 99%

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Fulvenallene Decomposition Kinetics

Polino

Cavallotti

2011

J. Phys. Chem. A

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While the decomposition kinetics of the benzyl radical has been studied in depth both from the experimental and the theoretical standpoint, much less is known about the reactivity of what is likely to be its main decomposition product, fulvenallene. In this work the high temperature reactivity of fulvenallene was investigated on a Potential Energy Surface (PES) consisting of 10 wells interconnected through 11 transition states using a 1 D Master Equation (ME). Rate constants were calculated using RRKM theory and the ME was integrated using a stochastic kinetic Monte Carlo code. It was found that two main decomposition channels are possible, the first is active on the singlet PES and leads to the formation of the fulvenallenyl radical and atomic hydrogen. The second requires intersystem crossing to the triplet PES and leads to acetylene and cyclopentadienylidene. ME simulations were performed calculating the microcanonical intersystem crossing frequency using Landau-Zener theory convoluting the crossing probability with RRKM rates evaluated at the conical intersection. It was found that the reaction channel leading to the cyclopentadienylidene diradical is only slightly faster than that leading to the fulvenallenyl radical, so that it can be concluded that both reactions are likely to be active in the investigated temperature (1500-2000 K) and pressure (0.05-50 bar) ranges. However, the simulations show that intersystem crossing is rate limiting for the first reaction channel, as the removal of this barrier leads to an increase of the rate constant by a factor of 2-3. Channel specific rate constants are reported as a function of temperature and pressure.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fulvenallene Decomposition Kinetics

Polino

Cavallotti

2011

J. Phys. Chem. A

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“…In the present study—when not specified otherwise—we set 〈Δ E 〉 equal to the experimental values [51]: 130 cm −1 for Ar and 75 cm −1 for He. In the calculations of k LJ , we based the Lennard-Jones parameters on those used in reference [51] to derive the values of 〈Δ E 〉; in particular, we used ε/k B = 410 K and σ = 6.0 Å for the adducts of OH and toluene [52], 120 K and 3.4 Å for Ar [53], and 10 K and 2.55 Å for He [51].…”

Section: Dynamics Calculationsmentioning

confidence: 99%

Kinetics of the Toluene Reaction with OH Radical

Zhang

Truhlar

2019

Research

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We calculated the kinetics of chemical activation reactions of toluene with hydroxyl radical in the temperature range from 213 K to 2500 K and the pressure range from 10 Torr to the high-pressure limit by using multistructural variational transition state theory with the small-curvature tunneling approximation (MS-CVT/SCT) and using the system-specific quantum Rice-Ramsperger-Kassel method. The reactions of OH with toluene are important elementary steps in both combustion and atmospheric chemistry, and thus it is valuable to understand the rate constants both in the high-pressure, high-temperature regime and in the low-pressure, low-temperature regime. Under the experimental pressure conditions, the theoretically calculated total reaction rate constants agree well with the limited experimental data, including the negative temperature dependence at low temperature. We find that the effect of multistructural anharmonicity on the partition functions usually increases with temperature, and it can change the calculated reaction rates by factors as small as 0.2 and as large as 4.2. We also find a large effect of anharmonicity on the zero-point energies of the transition states for the abstraction reactions. We report that abstraction of H from methyl should not be neglected in atmospheric chemistry, even though the low-temperature results are dominated by addition. We calculated the product distribution, which is usually not accessible to experiments, as a function of temperature and pressure.

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“…The Lennard-Jones parameters, ε/ k B and σ, that we used are 410 K and 6.0 Å for HT (taken to be the same as that for toluene), 38 K and 2.93 Å for H 2 , and 120 K and 3.4 Å for Ar …”

Section: Computational Detailsmentioning

confidence: 99%

Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory

2016

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Pressure-dependent reactions are ubiquitous in combustion and atmospheric chemistry. We employ a new calibration procedure for quantum Rice-Ramsperger-Kassel (QRRK) unimolecular rate theory within a chemical activation mechanism to calculate the pressure-falloff effect of a radical association with an aromatic ring. The new theoretical framework is applied to the reaction of H with toluene, which is a prototypical reaction in the combustion chemistry of aromatic hydrocarbons present in most fuels. Both the hydrogen abstraction reactions and the hydrogen addition reactions are calculated. Our system-specific (SS) QRRK approach is adjusted with SS parameters to agree with multistructural canonical variational transition state theory with multidimensional tunneling (MS-CVT/SCT) at the high-pressure limit. The new method avoids the need for the usual empirical estimations of the QRRK parameters, and it eliminates the need for variational transition state theory calculations as a function of energy, although in this first application we do validate the falloff curves by comparing SS-QRRK results without tunneling to multistructural microcanonical variational transition state theory (MS-μVT) rate constants without tunneling. At low temperatures, the two approaches agree well with each other, but at high temperatures, SS-QRRK tends to overestimate falloff slightly. We also show that the variational effect is important in computing the energy-resolved rate constants. Multiple-structure anharmonicity, torsional-potential anharmonicity, and high-frequency-mode vibrational anharmonicity are all included in the rate computations, and torsional anharmonicity effects on the density of states are investigated. Branching fractions, which are both temperature- and pressure-dependent (and for which only limited data is available from experiment), are predicted as a function of pressure.

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Cited by 47 publications

References 33 publications

Fulvenallene Decomposition Kinetics

Fulvenallene Decomposition Kinetics

Kinetics of the Toluene Reaction with OH Radical

Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory

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