The effect of nitro groups on N<sub>2</sub> extrusion from aromatic azide-based energetic materials

Shoaf, Ashley L.; Bayse, Craig A.

doi:10.1039/c9nj03220g

Cited by 14 publications

(14 citation statements)

References 80 publications

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“…Therefore, when compared to Model 1, the inclusion of a new property ( Q 2 ) describing electron delocalization in the ring overall improves the agreement with experimental h 50 values. The inclusion of this effect agrees with chemical intuition and previous works that found the greater the electronic delocalization in a molecule, the greater the chemical stability of the substance and, therefore, the lower its sensitivity to impact [2, 17–18, 22, 23b, 27].…”

Section: Resultssupporting

confidence: 89%

“…They focused on trigger bonds (e. g., N−NO 2 ) and showed that %WBI (a relative scale for bond activation) correlates well with impact sensitivity, especially for intramolecular hydrogen bonded energetic materials. They also studied the effect of nitro groups on N−N 2 bonds of aromatic azides and computed the N 2 extrusion pathways of several nitrosubstituted azides (o‐NAzB, m‐NAzB, p‐NAzB, azido‐2,4,6‐trinitrobenzene (AzTNB), azidopentanitrobenzene (AzPNB) and TAzTNB) using %WBIs [22].…”

Section: Introductionmentioning

confidence: 99%

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Correlation Between Molecular Charge Properties and Impact Sensitivity of Explosives: Nitrobenzene Derivatives

Oliveira

Borges

2021

Propellants Explo Pyrotec

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Nitrobenzenic explosives can have high energy density and low impact sensitivity. In this work, the density functional theory (DFT) charge density of 50 nitrobenzenic molecules was analyzed using the Distributed Multipole Analysis (DMA) method to investigate the impact sensitivity of their explosives. The DMA monopole, dipole and quadrupole electric multipoles localized on the atoms of a molecule provide a very detailed picture of the molecular charge density and have a clear chemical interpretation. The DMA multipoles of each molecule were used to develop models correlating molecular charge properties and impact sensitivity of nitrobenzenic explosives, which is quantified by the quantity h50. Three models previously applied to 17 nitroaromatic molecules (J. Phys. Chem. A 115, 9055, 2011) are now examined for a larger dataset of 50 molecules. Model 1 used the nitro group charge as a single parameter for h50 prediction, Model 2 additionally included the quadrupole values of the benzene ring atoms (a measure of charge delocalization) and Model 3 included the dipole moment (indicator of site polarization) of the nitro groups of each molecule, as well as the average C−NO2 bond distance, which quantifies bond strength. Two additional new models that include the quadrupole values of the nitro group were also proposed. The original three models (Models 1–3), as well as the new models (4‐5), applied to the set of 50 nitrobenzenic molecules, displayed good results even when compared with the previous work. Among the computed DMA electrical multipole values, two proved to be essential for developing a good model, as found before for the smaller set: the DMA quadrupole values of the ring atoms that quantify the degree of electronic delocalization in the ring and the total DMA charge (monopole) values of the explosophore nitro group.

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Section: Resultssupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Correlation Between Molecular Charge Properties and Impact Sensitivity of Explosives: Nitrobenzene Derivatives

Oliveira

Borges

2021

Propellants Explo Pyrotec

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“…We again used molecular mechanics to obtain a series of conformers for each compound and then applied our statistical modeling methods towards the prediction of Tdec (using a Boltzmann averaged dataset) and log(IS) (using a minimum energy conformer dataset). The 54 tetrazoles in this dataset with reported Tdec values were split into a 60:40 train:test set (33 tetrazoles in training set and 21 tetrazoles in test set) using the Kennard-Stone algorithm 44 to provide a reproducible uniform distribution of sensitivity property values for model development.…”

Section: Performancementioning

confidence: 99%

“…50 This concerted reaction mechanism is not accessible to other classes of azides, which most likely decompose via transient nitrene species and the liberation of molecular nitrogen. 44 As such, models generated including these azides are a useful tool in mechanistic classification but fail to provide the detailed chemical interpretability we desired. This mechanistic divergence prompted us to exclude the nine acyl, peroxo, and iminyl azides in our dataset from further Tdec modeling efforts.…”

Section: Qspr For Azide Hemsmentioning

confidence: 99%

An Explosophore-Based Approach Towards the Prediction of Energetic Material Sensitivity Properties

Rein

Meinhardt

Wahlman

et al. 2021

Preprint

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Accurate prediction of the sensitivity properties of high-energy materials (HEMs) and the study of their decomposition mechanisms are two major focuses within energetics research. Due to the hazards associated with the synthesis and handling of energetic materials, predictive models for HEM sensitivity are of great importance in enabling the safe and efficient development of future HEMs. Traditional predictive modeling of HEM decomposition via machine learning algorithms generally displays limited interpretability, while mechanistic studies of HEMs typically focus on small subsets of structurally analogous compounds lacking generalizability. This study aims to bridge the gap between predictive modeling and computational mechanistic analysis of HEMs, with the goal of providing chemically interpretable models for HEM sensitivity property prediction. Herein, we disclose the use of multivariate linear regression (MLR) modeling for the prediction of the decomposition temperature and impact sensitivity of HEMs. We report an explosophore-based approach to sensitivity property prediction featuring an ensemble of quantum mechanical parameters and computational workflows that enable rapid parameterization and modeling of energetic functional groups. We then employ these methods to accurately predict sensitivity properties of nitrogen-rich tetrazole and azide HEMs. These statistical MLR models are readily interpreted based on the principles of physical organic chemistry, producing structure-property relationships to guide the rational design of new HEMs. Furthermore, we extend our explosophore-based approach to predict the sensitivity properties of HEMs containing multiple, non-equivalent energetic functional groups through the identification of molecular triggers for the bulk decomposition of HEMs. Finally, we showcase the viability of our methods towards ab initio virtual screening of HEMs through predictive modeling of external test sets of tetrazole HEMs using structures and parameters generated exclusively in silico.

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“…In spite of being widely accepted that N 2 elimination is the first step in the decomposition of azides, there is some contention with the chemistry of aliphatic azides when 1,2‐H shift is a plausible reaction pathway that would lead to formation of imine derivatives, that is, two reaction mechanisms are proposed for such a dissociation: (i) a synchronous mechanism that leads to N 2 and imine formation in a single step; (ii) a mechanism in two steps in which N 2 is produced in conjunction with the nitrene inter‐mediate and in a second step the 1,2‐H shift on the nitrene intermediate occurs. Due to the fact that both the nitrene and the imine intermediates are important reactants that can be applied in various chemical fields, it is always of general interest to establish the route that leads to formation of such com‐pounds.…”

Section: Introductionmentioning

confidence: 99%

Insights into the Thermal and Photochemical Reaction Mechanisms of Azidoacetonitrile. Spectroscopic and MS‐CASPT2 Calculations

Algarra

Soto

2020

ChemPhysChem

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This work studies the photochemical and thermal decompositions of azidoacetonitrile (N3CH2CN) from both the experimental and theoretical points of view. The data of the photochemical experiments are taken from the literature, while the thermal decomposition have been carried out by us. In addition, we have performed ab initio calculations of the multiconfigurational type [complete active space self‐consistent field (CASSCF) and the multistate multireference perturbation theory (MS‐CASPT2)]. It is found that the first step of both type of decompositions is N2 elimination and formation of closed shell singlet nitrene. Afterwards, the nitrene tends to rapidly rearrange into formimidoyl cyanide (HNCHCN). As both reactions progress, the imine isomerizes into formimidoyl isocyanide (HNCHNC). The photoisomerization of the imine takes places thorough a conical intersection, while the same reaction on the ground electronic state occurs via a conventional transition state. The last step of the global reaction is decomposition of the imines into HCN and CNH. In photochemical conditions, the conjunction of the imines and its dissociation products (HCN and CNH) yields adenine

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The effect of nitro groups on N₂ extrusion from aromatic azide-based energetic materials

Abstract: ortho nitroaromatic azides extrude N2 through cyclization to a benzofuroxan derivative. DFT calculations show that steric and electronic factors influence the activation barriers for extrusion in energetic materials.

Cited by 14 publications

References 80 publications

Correlation Between Molecular Charge Properties and Impact Sensitivity of Explosives: Nitrobenzene Derivatives

Correlation Between Molecular Charge Properties and Impact Sensitivity of Explosives: Nitrobenzene Derivatives

An Explosophore-Based Approach Towards the Prediction of Energetic Material Sensitivity Properties

Insights into the Thermal and Photochemical Reaction Mechanisms of Azidoacetonitrile. Spectroscopic and MS‐CASPT2 Calculations

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The effect of nitro groups on N2 extrusion from aromatic azide-based energetic materials

Abstract: ortho nitroaromatic azides extrude N2 through cyclization to a benzofuroxan derivative. DFT calculations show that steric and electronic factors influence the activation barriers for extrusion in energetic materials.

Cited by 14 publications

References 80 publications

Correlation Between Molecular Charge Properties and Impact Sensitivity of Explosives: Nitrobenzene Derivatives

Correlation Between Molecular Charge Properties and Impact Sensitivity of Explosives: Nitrobenzene Derivatives

An Explosophore-Based Approach Towards the Prediction of Energetic Material Sensitivity Properties

Insights into the Thermal and Photochemical Reaction Mechanisms of Azidoacetonitrile. Spectroscopic and MS‐CASPT2 Calculations

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The effect of nitro groups on N₂ extrusion from aromatic azide-based energetic materials