Synthesis of Trinitromethyl-Functionalized [5,6]-Furazan–Piperazine–Triazole Fused-Ring Energetic Compounds with High Energy and Low Sensitivity

Abstract A novel [5,6,5]-fused nitrogen-rich heterocyclic framework was designed and synthesized, into which trinitro-methyl groups were introduced. The rigid planar conjugated framework of the fused ring effectively balances the instability imparted by the trinitro-methyl moieties. Due to the synthetic difficulty of the [5,6,5]-fused nitrogen-rich heterocyclic framework, compounds bearing trinitro-methyl groups on such a scaffold are extremely rare. 8-(Trinitromethyl)-[1,2,5]oxadiazolo[3,4-e][1,2,4]triazolo[4,3-a]pyrazin-5-amine (8) exhibits excellent density and detonation performance (ρ = 1.90 g/cm3; Dv = 9109 m/s), surpassing the conventional energetic materials RDX (ρ = 1.80 g/cm3; Dv = 8795 m/s) and comparable to HMX (ρ = 1.91 g/cm3; Dv = 9221 m/s). In addition, compound 8 (IS = 15 J, FS = 160 N) exhibits lower mechanical sensitivity than HMX (IS = 7.4 J, FS = 120 N). The outstanding properties of compound 8 make it a promising candidate as a new high-energy insensitive energetic material.