Temperature dependence of rate constants for the H(D) + CH4 reaction in gas and aqueous phase: deformed Transition-State Theory study including quantum tunneling and diffusion effects

Sanches-Neto, Flávio O.; Coutinho, Nayara D.; Palazzetti, Federico; Carvalho-Silva, Valter H.

doi:10.1007/s11224-019-01437-3

Cited by 7 publications

(4 citation statements)

References 76 publications

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“…The d parameter differs from zero as a scale to measure the "thermal limit of propensity" with reference to the lower and higher kinetic energy values respectively to ε † and ε ‡ , see Scheme 1: (i) when β → 0 , and also remaining finite = ε † ε ‡ (Cauchy's limit [73]) Equation ( 9) also tends to the exponential law; and ii) when β → ∞ , ε ‡ β → 1 and = ε † ε ‡ remaining finite, a minimum limit can be identified for which the kinetic process may occur. Case ii) applies for d > 0, the super-Arrhenius cases: the sub limit is consistent with Wigner's threshold law for thermoneutral reactions [74][75][76]. Furthermore, taking advantage of an alternative expansion [77,78] for the Aquilanti-Mundim law…”

Section: Avoiding the Thermodynamic Limit Describes Nonlinearities Of Arrhenius Plotssupporting

confidence: 61%

From the Kinetic Theory of Gases to the Kinetics of Rate Processes: On the Verge of the Thermodynamic and Kinetic Limits

2020

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A variety of current experiments and molecular dynamics computations are expanding our understanding of rate processes occurring in extreme environments, especially at low temperatures, where deviations from linearity of Arrhenius plots are revealed. The thermodynamic behavior of molecular systems is determined at a specific temperature within conditions on large volume and number of particles at a given density (the thermodynamic limit): on the other side, kinetic features are intuitively perceived as defined in a range between the extreme temperatures, which limit the existence of each specific phase. In this paper, extending the statistical mechanics approach due to Fowler and collaborators, ensembles and partition functions are defined to evaluate initial state averages and activation energies involved in the kinetics of rate processes. A key step is delayed access to the thermodynamic limit when conditions on a large volume and number of particles are not fulfilled: the involved mathematical analysis requires consideration of the role of the succession for the exponential function due to Euler, precursor to the Poisson and Boltzmann classical distributions, recently discussed. Arguments are presented to demonstrate that a universal feature emerges: Convex Arrhenius plots (super-Arrhenius behavior) as temperature decreases are amply documented in progressively wider contexts, such as viscosity and glass transitions, biological processes, enzymatic catalysis, plasma catalysis, geochemical fluidity, and chemical reactions involving collective phenomena. The treatment expands the classical Tolman’s theorem formulated quantally by Fowler and Guggenheim: the activation energy of processes is related to the averages of microscopic energies. We previously introduced the concept of “transitivity”, a function that compactly accounts for the development of heuristic formulas and suggests the search for universal behavior. The velocity distribution function far from the thermodynamic limit is illustrated; the fraction of molecules with energy in excess of a certain threshold for the description of the kinetics of low-temperature transitions and of non-equilibrium reaction rates is derived. Uniform extension beyond the classical case to include quantum tunneling (leading to the concavity of plots, sub-Arrhenius behavior) and to Fermi and Bose statistics has been considered elsewhere. A companion paper presents a computational code permitting applications to a variety of phenomena and provides further examples.

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Section: Avoiding the Thermodynamic Limit Describes Nonlinearities Of Arrhenius Plotssupporting

confidence: 61%

From the Kinetic Theory of Gases to the Kinetics of Rate Processes: On the Verge of the Thermodynamic and Kinetic Limits

2020

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“…17–20,22,23 The degradation rate is considered one of the most important parameters to evaluate the shelf-life of the blend during its storage, where a low value of rate constant indicates greater oxidative stability. 24,25…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19][20]22,23 The degradation rate is considered one of the most important parameters to evaluate the shelf-life of the blend during its storage, where a low value of rate constant indicates greater oxidative stability. 24,25 Generally, biodiesel lled with natural or synthetic antioxidant additives can decrease the rate of degradation reactions in biodiesel. 17,21,26 The additives when associated with biodiesel fractions are a gimmick to mitigate nitrogen oxide (NO x ) emissions from the fuel combustion in diesel engines.…”

Section: Introductionmentioning

confidence: 99%

Insights into chalcone analogues with potential as antioxidant additives in diesel–biodiesel blends

et al. 2022

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“…Due to the experimental difficulties to describe the reactivity of the OC reaction processes through oxidative processes, the application of theoretical and computational protocols have become imperative for a better understanding of these phenomena. A series of papers used electronic structure calculations combined with modern reaction rate theories for treating the degradation kinetics of OCs with • OH/SO 4 •– radicals, providing measurable parameters, for example, reaction rate constant and half-life time. ,− However, the theoretical description of the reaction rate constant requires accurate quantum chemical information about the potential energy surface, which makes it a herculean protocol, considering the high computational effort demanded. − …”

Section: Introductionmentioning

confidence: 99%

“pySiRC”: Machine Learning Combined with Molecular Fingerprints to Predict the Reaction Rate Constant of the Radical-Based Oxidation Processes of Aqueous Organic Contaminants

Sanches-Neto

Dias-Silva

Queiroz

et al. 2021

Environ. Sci. Technol.

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We developed a web application structured in a machine learning and molecular fingerprint algorithm for the automatic calculation of the reaction rate constant of the oxidative processes of organic pollutants by • OH and SO 4•− radicals in the aqueous phasethe pySiRC platform. The model development followed the OECD principles: internal and external validation, applicability domain, and mechanistic interpretation. Three machine learning algorithms combined with molecular fingerprints were evaluated, and all the models resulted in high goodness-of-fit for the training set with R 2 > 0.931 for the • OH radical and R 2 > 0.916 for the SO 4•− radical and good predictive capacity for the test set with R ext 2 = Q ext 2 values in the range of 0.639−0.823 and 0.767−0.824 for the • OH and SO 4•− radicals. The model was interpreted using the SHAP (SHapley Additive exPlanations) method: the results showed that the model developed made the prediction based on a reasonable understanding of how electron-withdrawing and -donating groups interfere with the reactivity of the • OH and SO 4•− radicals. We hope that our models and web interface can stimulate and expand the application and interpretation of kinetic research on contaminants in water treatment units based on advanced oxidative technologies.

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Temperature dependence of rate constants for the H(D) + CH4 reaction in gas and aqueous phase: deformed Transition-State Theory study including quantum tunneling and diffusion effects

Cited by 7 publications

References 76 publications

From the Kinetic Theory of Gases to the Kinetics of Rate Processes: On the Verge of the Thermodynamic and Kinetic Limits

From the Kinetic Theory of Gases to the Kinetics of Rate Processes: On the Verge of the Thermodynamic and Kinetic Limits

Insights into chalcone analogues with potential as antioxidant additives in diesel–biodiesel blends

“pySiRC”: Machine Learning Combined with Molecular Fingerprints to Predict the Reaction Rate Constant of the Radical-Based Oxidation Processes of Aqueous Organic Contaminants

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