Design and Synthesis of Energetic Materials towards Versatile Applications by N‐trinitromethyl and N‐nitromethyl Functionalization of Nitroimidazoles

Modifying the properties of energetic materials is important not only for gaining insight into the relationship between structures and properties but also for multiple applications. A new family of energetic compounds, polynitroimidazoles featuring trinitromethyl, nitromethyl and methyl acetate moieties at the nitrogen position of heterocyclic rings were synthesized. The high-energy oxidizers 2-nitro and 4-nitro-1-(trinitromethyl)-1H-imidazoles were obtained by nitration of 1-acetonylpolynitroimidazoles in fuming HNO3 and concentrated H2 SO4 . 4,5-Dinitro-1-(nitromethyl)-1H-imidazole and 4,5-dinitro-1-(acetate methyl)-1H-imidazole were afforded by using 68 % HNO3 and concentrated H2 SO4 through controllable synthesis. All the intermediates and the target compounds were confirmed by X-ray diffraction. It is noteworthy that one of the N-trinitromethyl nitroimidazole derivatives showed high density (ρ: 1.88 g cm-3 ), attractive positive oxygen balance (Ω: +18.3 %) and good detonation performance (D: 9003 m s-1 ) exceeding those of ADN, while N-nitromethyl derivative behaved higher thermal stability and lower sensitivity in contrast to those of NG. N-acetate methyl derivative gave an interesting melt-castable property (Tm.p .: 86 o C, Td : 224 o C), acceptable detonation performance as well as low sensitivity towards impact and friction (IS>40 J, FS>360 N), making it a competitive replacement for DNAN. These chemical and physical properties indicate that these novel materials show promising energetic performance towards future applications.