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Niu S, Wu X, Hou Q, Luo G, Qu W, Zhao F, Wang G, Zhang F. Theoretical Kinetic Studies on Thermal Decomposition of Glycerol Trinitrate and Trimethylolethane Trinitrate in the Gas and Liquid Phases. J Phys Chem A 2023; 127:1283-1292. [PMID: 36715586 DOI: 10.1021/acs.jpca.2c07282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Glycerol trinitrate (NG) and trimethylolethane trinitrate (TMETN), as typical nitrate esters, are important energetic plasticizers in solid propellants. With the aid of high-precision quantum chemical calculations, the Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation theory and the transition state theory have been employed to investigate the decomposition kinetics of NG and TMETN in the gas phase (over the temperature range of 300-1000 K and pressure range of 0.01-100 atm) and liquid phase (using water as the solvent). The continuum solvation model based on solute electron density (SMD) was used to describe the solvent effect. The thermal decomposition mechanism is closely relevant to the combustion properties of energetic materials. The results show that the RO-NO2 dissociation channel overwhelmingly favors other reaction pathways, including HONO elimination for the decomposition of NG and TMETN in both the gas phase and liquid phase. At 500 K and 1 atm, the rate coefficient of gas phase decomposition of TMETN is 5 times higher than that of NG. Nevertheless, the liquid phase decomposition of TMETN is a factor of 5835 slower than that of NG at 500 K. The solvation effect caused by vapor pressure and solubility can be used to justify such contradictions. Our calculations provide detailed mechanistic evidence for the initial kinetics of nitrate ester decomposition in both the gas phase and liquid phase, which is particularly valuable for understanding the multiphase decomposition behavior and building detailed kinetic models for nitrate ester.
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Affiliation(s)
- Shiyao Niu
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui230029, China.,Science and Technology on Combustion and Explosion Laboratory, Xi'an Modern Chemistry Research Institute, Xi'an, Shaanxi710065, China.,Heifei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230029, China
| | - Xiaoqing Wu
- Heifei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230029, China.,College of Information Engineering, China Jiliang University, Hangzhou, Zhejiang310018, China
| | - Qifeng Hou
- Heifei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230029, China
| | - Guangda Luo
- Heifei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230029, China
| | - Wengang Qu
- Science and Technology on Combustion and Explosion Laboratory, Xi'an Modern Chemistry Research Institute, Xi'an, Shaanxi710065, China
| | - Fengqi Zhao
- Science and Technology on Combustion and Explosion Laboratory, Xi'an Modern Chemistry Research Institute, Xi'an, Shaanxi710065, China
| | - Gongming Wang
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, Anhui230029, China
| | - Feng Zhang
- Heifei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui230029, China
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Mahmood A, Akram T, Kiani M, Akram T, Tian X, Sun Y. Mechanism and Regioselectivity in Methylation of Nitronates [CH2NO2]−: Resonance vs Inductive Effects. NEW J CHEM 2022. [DOI: 10.1039/d2nj02947b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Density functional theory calculations were performed to investigate the mechanism, regioselectivity, and the resonance and inductive effects in methylation of nitronate reactions in the gas-phase and in solutions (water, DMF,...
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Leitão EFV, Angelo Fonseca de Souza M, do Monte SA, Ventura E. Competition between electron transfer and base-induced elimination mechanisms in the gas-phase reactions of superoxide with alkyl hydroperoxides. Phys Chem Chem Phys 2021; 23:5583-5595. [PMID: 33655284 DOI: 10.1039/d0cp05761d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Understanding the mechanism responsible for peroxides decomposition is essential to explain several biochemical processes. The mechanisms of the intrinsic reactions between the superoxide radical anion (O2˙-) and methyl, ethyl, and tert-butyl hydroperoxides (ROOH, with R = Me, Et, and t-Bu) have been characterized to understand the mechanism responsible for peroxides decomposition. The reaction energy diagrams suggest a competition between the spin-allowed and spin-forbidden electron transfer (ET), and base-induced elimination (ECO2) mechanisms. In all cases, the spin-allowed ET mechanism describes formation of the ozonide anion radical (O3˙-), either complexed with an alcohol molecule or separated. For the O2˙-/MeOOH(EtOOH) reactions, HCO2- (MeCO2-) + H2O + HO˙ and OH- + CH2O(MeCHO) + HO2˙ products are associated with the spin-forbidden ET and ECO2 channels, respectively. On the other hand, for the reaction between O2˙- and t-BuOOH, the spin-forbidden ET route describes formation of the MeCOCH2- enolate (either separated or hydrated) along with the methyl peroxyl (MeO2˙) radical. In addition, the regeneration of O2˙-via spin-forbidden ET and ECO2 channels was also characterized from the decomposition of ROOH, yielding diols (CH2(OH)2 and MeCH(OH)2), aldehydes (CH2O and MeCHO), and oxirane (cyc-CH2CMe2O).
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Affiliation(s)
- Ezequiel Fragoso Vieira Leitão
- Unidade Acadêmica de Ciências Exatas e da Natureza, Universidade Federal de Campina Grande, Cajazeiras, PB 58900-000, Brazil.
| | | | - Silmar Andrade do Monte
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, PB 58-059-900, Brazil
| | - Elizete Ventura
- Departamento de Química, CCEN, Universidade Federal da Paraíba, João Pessoa, PB 58-059-900, Brazil
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Leitão EFV, Ventura E, de Souza MAF, Riveros JM, do Monte SA. Spin-Forbidden Branching in the Mechanism of the Intrinsic Haber-Weiss Reaction. ChemistryOpen 2017. [PMID: 28638768 PMCID: PMC5474656 DOI: 10.1002/open.201600169] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The mechanism of the O2⋅− and H2O2 reaction (Haber–Weiss) under solvent‐free conditions has been characterized at the DFT and CCSD(T) level of theory to account for the ease of this reaction in the gas phase and the formation of two different set of products (Blanksby et al., Angew. Chem. Int. Ed. 2007, 46, 4948). The reaction is shown to proceed through an electron‐transfer process from the superoxide anion to hydrogen peroxide, along two pathways. While the O3⋅− + H2O products are formed from a spin‐allowed reaction (on the doublet surface), the preferred products, O⋅−(H2O)+3O2, are formed through a spin‐forbidden reaction as a result of a favorable crossing point between the doublet and quartet surface. Plausible reasons for the preference toward the latter set are given in terms of the characteristics of the minimum energy crossing point (MECP) and the stability of an intermediate formed (after the MECP) in the quartet surface. These unique results show that these two pathways are associated with a bifurcation, yielding spin‐dependent products.
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Affiliation(s)
- Ezequiel F V Leitão
- Departamento de Química Universidade Federal da ParaíbaJoão Pessoa, PB 58.059-900 Brazil
| | - Elizete Ventura
- Departamento de Química Universidade Federal da ParaíbaJoão Pessoa, PB 58.059-900 Brazil
| | - Miguel A F de Souza
- Instituto de Química Universidade Federal do Rio Grande do Norte Natal, RN 59072-970 Brazil
| | - José M Riveros
- Departamento de Química Fundamental Universidade de São Paulo Av. Prof. Lineu Prestes, 748 05508-000 São Paulo, SP, Brazil João Pessoa, PB, 58.059-900 Brazil
| | - Silmar A do Monte
- Departamento de Química Universidade Federal da ParaíbaJoão Pessoa, PB 58.059-900 Brazil
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de Oliveira PMC, Silva JAB, Longo RL. Benchmark, DFT assessments, cooperativity, and energy decomposition analysis of the hydrogen bonds in HCN/HNC oligomeric complexes. J Mol Model 2017; 23:56. [PMID: 28161784 DOI: 10.1007/s00894-017-3235-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Accepted: 01/13/2017] [Indexed: 02/05/2023]
Abstract
Hydrogen cyanide (HCN) and its tautomer hydrogen isocyanide (HNC) are relevant for extraterrestrial chemistry and possible relation to the origin of biomolecules. Several processes and reactions involving these molecules depend on their intermolecular interactions that can lead to aggregates and liquids especially due to the hydrogen bonds. It is thus important to comprehend, to describe, and to quantify their hydrogen bonds, mainly their nature and the cooperativity effects. A systematic study of all linear complexes up to pentamers of HCN and HNC is presented. CCSD(T)/CBS energy calculations, with and without basis set superposition error (BSSE) corrections for energies and geometries, provided a suitable set of benchmarks. Approximated methods based on the density functional theory (DFT) such as BP86, PBE, TPSS, B3LYP, CAM-B3LYP with and without dispersion corrections and long-range corrections, were assessed to describe the interaction energies and cooperativity effects. These assessments are relevant to select DFT functionals for liquid simulations. Energy decomposition analysis was performed at the PBE/STO-TZ2P level and provided insights into the nature of the hydrogen bonds, which are dominated by the electrostatic component. In addition, several linear relationships between the various energy components and the interaction energy were obtained. The cooperativity energy was also found to be practically linear with respect to the interaction energy, which may be relevant for designing and/or correcting empirical force fields. Graphical Abstract Hydrogen bonds in HCN/HNC oligomeric complexesᅟ.
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Affiliation(s)
| | - Juliana A B Silva
- Centro Acadêmico do Agreste, Universidade Federal de Pernambuco, 55002-970, Caruaru, PE, Brazil
| | - Ricardo L Longo
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50740-540, Recife, PE, Brazil.
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Proenza YG, de Souza MAF, Longo RL. Dynamical Bifurcation in Gas-Phase XH - + CH 3 Y S N 2 Reactions: The Role of Energy Flow and Redistribution in Avoiding the Minimum Energy Path. Chemistry 2016; 22:16220-16229. [PMID: 27651104 DOI: 10.1002/chem.201602976] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Indexed: 11/10/2022]
Abstract
The gas-phase reactions of XH- (X=O, S) + CH3 Y (Y=F, Cl, Br) span nearly the whole range of SN 2 pathways, and show an intrinsic reaction coordinate (IRC) (minimum energy path) with a deep well owing to the CH3 XH⋅⋅⋅Y- (or CH3 S- ⋅⋅⋅HF) hydrogen-bonded postreaction complex. MP2 quasiclassical-type direct dynamics starting at the [HX⋅⋅⋅CH3 ⋅⋅⋅Y]- transition-state (TS) structure reveal distinct mechanistic behaviors. Trajectories that yield the separated CH3 XH+Y- (or CH3 S- +HF) products directly are non-IRC, whereas those that sample the CH3 XH⋅⋅⋅Y- (or CH3 S- ⋅⋅⋅HF) complex are IRC. The IRCIRC/non-IRC ratios of 90:10, 40:60, 25:75, 2:98, 0:100, and 0:100 are obtained for (X, Y)=(S, F), (O, F), (S, Cl), (S, Br), (O, Cl), and (O, Br), respectively. The properties of the energy profiles after the TS cannot provide a rationalization of these results. Analysis of the energy flow in dynamics shows that the trajectories cross a dynamical bifurcation, and that the inability to follow the minimum energy path arises from long vibration periods of the X-C⋅⋅⋅Y bending mode. The partition of the available energy to the products into vibrational, rotational, and translational energies reveals that if the vibrational contribution is more than 80 %, non-IRC behavior dominates, unless the relative fraction of the rotational and translational components is similar, in which case a richer dynamical mechanism is shown, with an IRC/non-IRC ratio that correlates to this relative fraction.
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Affiliation(s)
- Yaicel G Proenza
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, 50.740-560, Recife, PE, Brazil
| | - Miguel A F de Souza
- Instituto de Química, CCET, Universidade Federal do Rio Grande do Norte, 59.072-970, Natal, RN, Brazil
| | - Ricardo L Longo
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, 50.740-560, Recife, PE, Brazil.
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Mahmood A, Longo RL. Structural and relative energy assessments of DFT functionals and the MP2 method to describe the gas phase methylation of nitronates: [R1R2CNO2]− + CH3I. Phys Chem Chem Phys 2016; 18:17062-70. [DOI: 10.1039/c5cp07833d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structures and energetics of CH3I + [R1R2CNO2]− gas phase C- and O-methylation reactions were computed with several functionals and ECP/basis sets and compared to CCSD(T)/CBS.
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Affiliation(s)
- Ayyaz Mahmood
- Departamento de Química Fundamental
- CCEN
- Universidade Federal de Pernambuco
- Cidade Universitária
- Recife
| | - Ricardo L. Longo
- Departamento de Química Fundamental
- CCEN
- Universidade Federal de Pernambuco
- Cidade Universitária
- Recife
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Launder AM, Agarwal J, Schaefer HF. Exploring mechanisms of a tropospheric archetype: CH3O2 + NO. J Chem Phys 2015; 143:234302. [PMID: 26696057 DOI: 10.1063/1.4937381] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Methylperoxy radical (CH3O2) and nitric oxide (NO) contribute to the propagation of photochemical smog in the troposphere via the production of methoxy radical (CH3O) and nitrogen dioxide (NO2). This reaction system also furnishes trace quantities of methyl nitrate (CH3ONO2), a sink for reactive NOx species. Here, the CH3O2 + NO reaction is examined with highly reliable coupled-cluster methods. Specifically, equilibrium geometries for the reactants, products, intermediates, and transition states of the ground-state potential energy surface are characterized. Relative reaction enthalpies at 0 K (ΔH0K) are reported; these values are comprised of electronic energies extrapolated to the complete basis set limit of CCSDT(Q) and zero-point vibrational energies computed at CCSD(T)/cc-pVTZ. A two-part mechanism involving CH3O and NO2 production followed by radical recombination to CH3ONO2 is determined to be the primary channel for formation of CH3ONO2 under tropospheric conditions. Constrained optimizations of the reaction paths at CCSD(T)/cc-pVTZ suggest that the homolytic bond dissociations involved in this reaction path are barrierless.
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Affiliation(s)
- Andrew M Launder
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Jay Agarwal
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA
| | - Henry F Schaefer
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602, USA
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Mahmood A, Teixeira ES, Longo RL. Understanding the Reactivity and Regioselectivity of Methylation of Nitronates [R(1)R(2)CNO2](-) by CH3I in the Gas Phase. J Org Chem 2015; 80:8198-205. [PMID: 26181145 DOI: 10.1021/acs.joc.5b01273] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Methylation of [R(1)R(2)CNO2](-), where R(1) = R(2) = H (1), R(1) = CH3 and R(2) = H (2), R(1) = R(2) = CH3 (3), and R(1) + R(2) = c-(CH2)2 (4), by CH3I was studied by an ab initio MP2/CBS method, RRKM theory, and kinetic simulations. Contrary to a previous proposal for the reaction mechanism, C-methylation is the preferred pathway of thermodynamics and kinetics. This is corroborated by the agreement between the calculated and experimental reactivity trend 4 ≫ 3 > 2 > 1. The regioselectivity toward C-alkylation is explained by the much larger exothermicity of this reaction channel compared to that of O-alkylation. The increase in reactivity with an increase in the crowdedness of the central carbon atom is explained by differences in sp(3) character at this atom and the decrease in the vibrational frequency associated with pyramidalization around this carbon atom.
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Affiliation(s)
- Ayyaz Mahmood
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Erico Souza Teixeira
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Ricardo L Longo
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE 50740-560, Brazil
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