A New General Correlation for Predicting Impact Sensitivity of Energetic Compounds

This paper describes an improved simple model for prediction of impact sensitivity of different classes of energetic compounds containing nitropyridines, nitroimidazoles, nitropyrazoles, nitrofurazanes, nitrotriazoles, nitropyrimidines, polynitroarenes, benzofuroxans, polynitroarenes with α‐CH, nitramines, nitroaliphatics, nitroaliphatic containing other functional groups, and nitrate energetic compounds. The model is based on some molecular structural parameters. It is applied for 90 explosives, which have different molecular structures. The predicted results are compared with outputs of complex neural network approach as one of the best available methods. Root mean squares (rms) of deviations of different energetic compounds are 24 and 49 cm, corresponding to 5.88 and 12.01 J with 2.5 kg dropping mass, for new and neural network methods, respectively. The novel model also predicts good results for eight new synthesized and miscellaneous explosives with respect to experimental data.     

Prediction of Sensitivity of Energetic Compounds with a New Computer Code

Impact, electrostatic, and shock sensitivities of energetic compounds are three important parameters for the assessment of hazardous energetic materials. A novel easy to handle and user‐friendly computer code, written in Visual Basic, is introduced to predict these parameters, by solely using the molecular structure of an energetic molecule. It is able to predict impact sensitivity for different types of energetic compounds including nitropyridines, nitroimidazoles, nitropyrazoles, nitrofurazanes, nitrotriazoles, nitropyrimidines, polynitro arenes, benzofuroxans, polynitro arenes with α‐CH, nitramines, nitroaliphatics, nitroaliphatic containing other functional groups, and nitrate energetic compounds. It can also provide reliable results for electrostatic and shock sensitivities of some classes of high explosives including nitroaromatic and nitramine compounds. The prediction of this code give good values for some newly reported energetic compounds, where experimental data are available.     

Charge Density Distribution,Electrostatic Properties,and Impact Sensitivity of the High Energetic Molecule TNB: A Theoretical Charge Density Study

A quantum chemical calculation and a charge density analysis have been performed on the energetic molecule trinitrobenzene (TNB) to characterize its bond strength and to relate the bond topological parameters with the impact sensitivity. The optimized geometry of the molecule was calculated by the density functional method B3P86 with the basis set 6‐311G**. The bond topological analysis predicts a significantly low bond electron density (∼1770 e nm⁻³) as well as Laplacian of electron density (−1.67×10⁶ e nm⁻⁵) for C N bonds. This low value of the Laplacian indicates, the charges of these bonds are highly depleted, which confirms that these are the weakest bonds in the molecule. The N=O bonds bear a high negative value of Laplacian, reflecting that the bond charges are highly concentrated. The isosurface of the molecular, electrostatic potential (ESP) shows large electronegative regions at the vicinity of  NO₂ groups. Further analysis of ESP in the bonding region allows predicting the impact sensitivity. A sound relationship has been found between the ESP at the mid point of the bonds and its bond charge depletion. The positive ESP at the mid points of highly charge depleted C NO₂ bonds reveals that these bonds are the sensitive bonds in the molecule.     

The Correlation between Electric Spark Sensitivity of Polynitroaromatic Compounds and Their Molecular Electronic Properties

In this paper, a relationship between electric spark sensitivity and molecular electronic properties is studied for polynitroaromatic compounds. The lowest unoccupied molecular orbital energy and the Mulliken charges of the nitro group, and the number of the aromatic rings as well as certain substituted groups attached to the aromatic ring can be used for the prediction of the electric spark sensitivity. Electric spark sensitivities calculated by such a correlation are reasonably close to the experimental data for both 17 polynitroaromatic explosives as training set and 11 polynitroaromatic explosives as test set.     

Statistical Assessment Methods for the Sensitivity of Energetic Materials

The joint research project Particle Processing and Characterization was started in March 2003 under the EUROPA ERG1 Arrangement, with the objective to study the influence of crystallization and processing techniques on particle quality and its implication for the formulation of PBX with IM behavior. As sensitivity assessment is a crucial task of the project, impact sensitivity tests of HMX and RDX samples have been performed at two different laboratories, and several statistical techniques have been tested in addition to the standard BAM “1/6” and Bruceton “up and down” methods.     

Simple Relationship for Predicting Impact Sensitivity of Nitroaromatics,Nitramines, and Nitroaliphatics

This paper describes the development of a simple model for predicting the impact sensitivity of nitroaromatics, benzofuroxans, nitroaromatics with α‐CH, nitramines, nitroaliphatics, nitroaliphatics containing other functional groups, and nitrate energetic compounds using their molecular structures. The model is optimized using a set of 86 explosives for which different structural parameters exist. The model is applied to a test set of 120 explosives from a variety of the mentioned chemical families in order to confirm the reliability of a new method. Elemental composition and two specific structural parameters, that can increase or decrease impact sensitivity, would be needed in this new scheme. The predicted impact sensitivities for both sets have a root mean square (rms) of deviation from experiment of 23 cm, which shows good agreement with respect to the measured values as compared to the best available empirical correlations.     

Simple Method for Prediction of the Standard Gibbs Free Energy of Formation of Energetic Compounds

A reliable simple method for prediction of the standard Gibbs energy of formation (Δ_fG^θ) of energetic compounds containing nitroaromatic, acyclic, and cyclic nitramine, nitrate ester, and nitroaliphatic compounds is introduced herein. The method is based on the contribution of elemental composition (Δ_fG_elem^θ) and the correcting function for the presence of additive and non‐additive molecular fragments (Δ_fG_corr^θ). In presence of some molecular moieties, Δ_fG_corr^θ may increase or decrease the value of Δ_fG_elem^θ, depending on the intermolecular interactions. The experimental root‐mean‐square error (RMSE) of the novel correlation (22.7 kJ mol⁻¹) is quite good. For some energetic compounds, where the computed values of two complex models of the quantitative structure‐property relationship (QSPR) theory were available, the experimental RMSE developed by the new method is smaller than the values obtained by QSPR method.