Nitrogen-rich salts based on N-(5-(1,2,4-oxadiazol-3-yl)-1,3,4-oxadiazol-2-yl)nitramide: synthesis, characterization and performance

摘要

Nitrogen-rich energetic materials have been studied widely for military and civilian applications. Development of energetic compounds with excellent detonation performance and low mechanical sensitivities is a long-term goal in the area of energetic materials. In order to investigate the detonation performance of combination of 1,2,4-oxadiazole and 1,3,4-oxadiazole and further explore new energetic materials, nitrogen-rich salts containing N-(5-(l ,2,4-oxadiazol-3-yl)-l 3,4-oxadiazol-2-yl)nitramide anions with energetic cations (carbonic hydrazylhydrazidinium, guanidinium, aminoguanidinium, 1,2,4-triazolium and 4-amino-1,2,4-triazolium) were successfully prepared in high yield and purity. N-(5-(l ,2,4-oxadiazol-3-yl)-l 3,4-oxadiazol-2-yl)nitramide was formed by the reaction of 5-(1,2,4-oxadiazol-3-yl)-1,3,4-oxadiazol-2-amine and fuming HNO_3 at room temperature. 5-(1,2,4-oxadiazol-3-yl)-1,3,4-oxadiazol-2-amine was prepared in 4 steps by using readily available ethyl cyanoformate as the starting material. All the new compounds were fully characterized by FT-IR , H NMR, ,3C NMR spectrometry, elemental analysis and differential scanning calorimetry (DSC), and their physical and energetic properties were investigated. Their heats of formation (HOF) and detonation properties (detonation velocity and detonation pressure) were computed by Gaussian 09 and EXPLO 5 program, respectively. Moreover, impact sensitivity (IS) and friction sensitivity (FS) were determined by standard BAM methods. These compounds exhibited high density, positive HOF, good detonation properties, low mechanical sensitivities and acceptable thermal stability. These results indicated that the combination of 1,2,4-oxadiazole and 1,3,4-oxadiazole provides a promising route to improve the properties of energetic materials. energetic materials; oxadiazole; sensitivity; thermal stability; detonation performance