Construction of new framework of 1,3,4-oxadiazole energetic compounds using 1,1-dichloro-2-nitroethylene: design of high-performance molten-cast explosives

Abstract

The design of low melting point energetic compounds has always been a difficult point. Two strategies are usually adopted one of them: (1) the construction of a suitable energetic skeleton; (2) the introduction of substituents that regulates the melting point. In this study, a spontaneous cyclization strategy for 1,1-dichloro-2-nitroethylene was adopted to introduce substituents for regulating the melting point while constructing a suitable energetic framework. All the compounds were characterized, and the structures of some compounds were characterized by X-ray diffraction. The thermal and detonation properties of all the compounds were studied; 2-nitromethyl-5-(2,4,6-trinitrophenyl)-1,3,4-oxadiazole, 2-nitromethyl-5-(5-nitroamino-1,2,4-triazol-3-yl)-1,3,4-oxadiazole hydroxylamine salt, 2-nitromethyl-5-(5-nitroamino-1,2,4-triazol-3-yl)-1,3,4-oxadiazole-3-amino-1,2,4-triazole salt, and 2-nitromethyl-5-(5-nitroamino-1,2,4-triazol-3-yl)-1,3,4-oxadiazole-4-amino-1,2,4-triazole salt had melting points equivalent to that of TNT (100.4, 94.2, 93.9 and 82.9 °C, respectively). They corresponding detonation velocities were 7587, 9033, 8290, and 8442 m/s, indicating the potential use of these compounds as molten-cast explosive carriers. Therefore, 2-nitromethyl-1,3,4-oxadiazole energetic compounds provide a new choice for the development of high-energy explosives and molten-cast explosives. Moreover, this synthetic method prevents the use of highly toxic cyclization reagents and simultaneously incorporates two strategies for lowering the melting point. Thus, this study lays a foundation for the expansion of engineering applications.