Derivatives of 2-(3,4-dinitro-1H-pyrazol-1-yl) acetonitrile: design strategy, syntheses, and properties of a series of new melt-cast explosives

Abstract

Melt-cast explosives, the most widely used energetic materials in military composite explosives, play an important role in improving the energy and safety performance of military composite explosives. In this work, a new structural type of melt cast material was designed by linking 3,4-dinitro-1H-pyrazole with tetrazole or 1,2,4-oxadiazole through a N–CH₂–C bridge. All the compounds were thoroughly characterized using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and elemental analysis. The structures of compounds 4, 6 and 7 were unambiguously confirmed using X-ray single crystal diffraction analysis. The crystal densities of the three compounds were between 1.66 g cm⁻³ and 1.81 g cm⁻³. The impact and friction sensitivities were measured using standard BAM fall-hammer techniques, and their detonation performances were computed using the EXPLO5 v6.05.04 program. The melting points of 4 and 6 are 91.5 °C and 93 °C, respectively, and they exhibited high thermal stabilities and were found to be insensitive towards impact and friction. The overall properties of 4 and 6 are superior to the traditional melt-cast explosives 2,4,6-trinitrotoluene (TNT), dinitroanisole (DNAN) and 3,3′-bi(1,2,4-oxadiazole)-5,5′-diylbis(methylene) dinitrate (BODN), and may have excellent potential applications as insensitive melt-cast explosives.