Hydrogen Abstraction from the Hydrazine Molecule by an Oxygen Atom

Spada, Rene F. K.; Ferrão, Luiz F. A.; Rocha, Roberta Jachura; Iha, Koshun; Rocco, José Atílio Fritz Fidel; Roberto‐Neto, Orlando; Lischka, Hans; Machado, Francisco B. C.

doi:10.1021/jp507784n

Cited by 11 publications

(12 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using these data, the rate constants were calculated with the improved canonical variational theory (ICVT), with small curvature tunneling (SCT) corrections. The rate constants reported in this work using the hydrazine dimer reproduce the experimental trend reported by Vaghjiani 10 and are significantly closer to his measured values than the results reported in our previous work 13 considering a single hydrazine molecule.…”

Section: ■ Introductionsupporting

confidence: 91%

“…The calculated values of the rate constants were also compared to the measured ones and also with the results of our previous work, which considered a single hydrazine molecule only. The results reported in this work using a hydrazine dimer model lead to a significantly better quantitative and also qualitative agreement with the experimental results by Vaghjiani. , On the basis of the fact that the oxygen depletion has been measured in a hydrazine-rich atmosphere, our results strongly indicate that the hydrazine dimer plays an important role and should be included in modeling the mechanism of the global N 2 H 4 + O reaction.…”

Section: Discussionmentioning

confidence: 97%

“…The hydrazine molecule (N 2 H 4 ) is an energy-rich compound, which is used as propellant for the attitude-control jets in spacecraft vehicles and satellites. , Radical reactions play an important role in associated combustion and decomposition processes. An important case in this context is the reaction involving hydrazine and atomic oxygen (O( 3 P)), which has received special attention in several experimental and theoretical investigations. − …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermochemical and Kinetics of Hydrazine Dehydrogenation by an Oxygen Atom in Hydrazine-Rich Systems: A Dimer Model

et al. 2015

Self Cite

View full text Add to dashboard Cite

The kinetics of the reaction of N2H4 with oxygen depends sensitively on the initial conditions used. In oxygen-rich systems, the rate constant shows a conventional positive temperature dependence, while in hydrazine-rich setups the dependence is negative in certain temperature ranges. In this study, a theoretical model is presented that adequately reproduces the experimental results trend and values for hydrazine-rich environment, consisting of the hydrogen abstraction from the hydrazine (N2H4) dimer by an oxygen atom. The thermochemical properties of the reaction were computed using two quantum chemical approaches, the coupled cluster theory with single, double, and noniterative triple excitations (CCSD(T)) and the M06-2X DFT approach with the aug-cc-pVTZ and the maug-cc-pVTZ basis sets, respectively. The kinetic data were calculated with the improved canonical variational theory (ICVT) using a dual-level methodology to build the reaction path. The tunneling effects were considered by means of the small curvature tunneling (SCT) approximation. Potential wells on both sides of the reaction ((N2H4)2 + O → N2H4···N2H3 + OH) were determined. A reaction path with a negative activation energy was found leading, in the temperature range of 250-423 K, to a negative dependence of the rate constant on the temperature, which is in good agreement with the experimental measurements. Therefore, the consideration of the hydrazine dimer model provides significantly improved agreement with the experimental data and should be included in the mechanism of the global N2H4 combustion process, as it can be particularly important in hydrazine-rich systems.

show abstract

Section: ■ Introductionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermochemical and Kinetics of Hydrazine Dehydrogenation by an Oxygen Atom in Hydrazine-Rich Systems: A Dimer Model

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…In previous works, we have employed the dual-level methodology to calculate accurately the properties of several chemical reactions. ,,− In this work, with the experience gained from previous research, a rigorous analysis was carried out regarding the coupling of the low and high-level methods, in particular when calculating the thermochemical properties, and subsequent rate constant calculations. We have analyzed in which conditions this coupling can generate artificial tunneling and variational effects in the calculated rate constants.…”

Section: Introductionmentioning

confidence: 99%

Thermochemical and Kinetics of CH₃SH + H Reactions: The Sensitivity of Coupling the Low and High-Level Methodologies

et al. 2017

Self Cite

View full text Add to dashboard Cite

The reaction system formed by the methanethiol molecule (CHSH) and a hydrogen atom was studied via three elementary reactions, two hydrogen abstractions and the C-S bond cleavage (CHSH + H → CHS + H (R1); → CHSH + H (R2); → CH + HS (R3)). The stable structures were optimized with various methodologies of the density functional theory and the MP2 method. Two minimum energy paths for each elementary reaction were built using the BB1K and MP2 methodologies, and the electronic properties on the reactants, products, and saddle points were improved with coupled cluster theory with single, double, and connected triple excitations (CCSD(T)) calculations. The sensitivity of coupling the low and high-level methods to calculate the thermochemical and rate constants were analyzed. The thermal rate constants were obtained by means of the improved canonical variational theory (ICVT) and the tunneling corrections were included with the small curvature tunneling (SCT) approach. Our results are in agreement with the previous experimental measurements and the calculated branching ratio for R1:R2:R3 is equal to 0.96:0:0.04, with k = 9.64 × 10 cm molecule s at 298 K.

show abstract

“…To estimate the barrier heights of the title reaction more precisely, a dual-level methodology was used similar to previous reactions of hydrazine with atomic oxygen simulated in the atmospheric conditions [40][41][42] . Thus, the CCS(T)/CBS//MP2/aTZ level was chosen.…”

Section: Methodsmentioning

confidence: 99%

Atmospheric Reaction of Hydrazine Plus Hydroxyl Radical. I. Reliable Pathways

Douroudgari

Vahedpour

Khouini

2021

Preprint

View full text Add to dashboard Cite

Understanding the mechanism of hydrazine oxidation reaction by OH radical accompanied by the rate constants of all possible pathways is important. They are key parameters to explain the fate of hydrazine in the atmosphere. To reach the mentioned parameters, higher-level calculations by using quantum chemical methods have been implemented comprehensively for reliable channels such as H-abstraction, SN2, and addition/elimination reactions. To estimate the barrier energies of H-abstraction channels accurately, large numbers of the CCSD(T)/X calculations (where X denotes the augmented Dunning and Pople double zeta or triple zeta basis sets) have been applied to the optimized geometries of the MP2/aug-cc-pVTZ, MP2/maug-cc-pVTZ, and M062X/maug-cc-pVTZ levels. Contributions of excited states on the computed potential energy surface have been considered by the MR-MP2 (multi-reference) method in conjunction with the large augmented quadruple zeta, aug-cc-pVQZ, basis sets. The direct dynamic calculations have been carried out using the accurate energies of the CCSD(T) method and the partition functions of the second-order MØller-Plesset perturbation theory, and also by the validated M06-2X method with the aug-cc-pVTZ, and maug-cc-pVTZ basis sets. Finally, The VTST and TST theories have been used to calculate the temperature dependence of rate constants of the considered pathways. Also, the pressure-dependent rate constants of the barrierless pathways have been investigated by the strong collision master equation/RRKM theory.

show abstract

Hydrogen Abstraction from the Hydrazine Molecule by an Oxygen Atom

Cited by 11 publications

References 38 publications

Thermochemical and Kinetics of Hydrazine Dehydrogenation by an Oxygen Atom in Hydrazine-Rich Systems: A Dimer Model

Thermochemical and Kinetics of Hydrazine Dehydrogenation by an Oxygen Atom in Hydrazine-Rich Systems: A Dimer Model

Thermochemical and Kinetics of CH₃SH + H Reactions: The Sensitivity of Coupling the Low and High-Level Methodologies

Atmospheric Reaction of Hydrazine Plus Hydroxyl Radical. I. Reliable Pathways

Contact Info

Product

Resources

About

Hydrogen Abstraction from the Hydrazine Molecule by an Oxygen Atom

Cited by 11 publications

References 38 publications

Thermochemical and Kinetics of Hydrazine Dehydrogenation by an Oxygen Atom in Hydrazine-Rich Systems: A Dimer Model

Thermochemical and Kinetics of Hydrazine Dehydrogenation by an Oxygen Atom in Hydrazine-Rich Systems: A Dimer Model

Thermochemical and Kinetics of CH3SH + H Reactions: The Sensitivity of Coupling the Low and High-Level Methodologies

Atmospheric Reaction of Hydrazine Plus Hydroxyl Radical. I. Reliable Pathways

Contact Info

Product

Resources

About

Thermochemical and Kinetics of CH₃SH + H Reactions: The Sensitivity of Coupling the Low and High-Level Methodologies