Preparation of novel heat-resistant and insensitive fused ring energetic materials

Compared with traditional polycyclic-based heterocyclic energetic compounds, the synthesis of fused ring compounds is more challenging since only a few substrates meet the structural requirements for a fused cyclization reaction. In the case of a limited number of substrates, it is necessary to explore other methods to synthesize new fused ring compounds. Here, through the cyclization reaction of 1H-pyrazole-4-carbimidate (4) and hydrazinyl compounds, a series of nitrogen-rich heterocyclic fused compounds were synthesized in this work. The method of synthesizing fused compounds in this work is rarely reported in the energetic field. In addition, the newly synthesized compounds 5-7 and 10-11 demonstrate excellent thermal stability. Compounds 5 (Td = 360 degrees C) and 6 (Td = 372 degrees C) have higher initial decomposition temperatures than 1,3,5-triamino-2,4,6-trinitrobenzene (TATB: Td = 350 degrees C). Moreover, the newly synthesized compounds 5-7 and 10-11 show low sensitivity (IS: 26 to 40 J, FS: 288 to 360 N). The detonation velocities of compounds 7 and 11 are 8047 and 8004 m s-1, respectively, which are obviously higher than that of the famous heat resistant explosive 2-bis(2,4,6-trinitrophenyl) ethene (HNS: Dv = 7612 m s-1) and slightly lower than that of TATB (Dv = 8179 m s-1). This work is anticipated to motivate researchers to comprehensively consider multiple heat-resistance-imparting strategies for designing heat-resistant explosives, and expand the train of thought for the scientific development of advanced heat-resistant explosives. Compared with traditional polycyclic-based heterocyclic energetic compounds, the synthesis of fused ring compounds is more challenging since only a few substrates meet the structural requirements for a fused cyclization reaction.