Synthesis and Properties of Polynitro 3, 3, 7, 7-Tetra(trifluoromethyl)-2, 4, 6, 8-tetraazabicyclo [3.3.0]octane

In order to explore the effect of trifluoromethyl group on the performance of energetic materials, 2, 6-dinitrate- 3, 3, 7, 7-tetra-trifluoromethyl-2, 4, 6, 8-tetraazabicyclo [3.3.0] octane (4), 2, 4, 6-trinitro-3, 3, 7, 7-tetra-trifluoromethyl-2, 4, 6, 8-tetraazabicyclo [3.3.0] octane (5) and 2, 4, 6, 8-tetranitrate-3, 3, 7, 7-tetra-trifluoromethyl-2, 4, 6, 8-tetraazabicyclo [3.3.0] octane (6) were synthesized from the aza-fused ring precursor (3, 3, 7, 7-tetra-trifluoromethyl-2, 4, 6, 8-tetraazabicyclo [3.3.0] octane) through improved multi-step nitration in fuming nitric acid. The precursor was obtained from condensation of diaminohexafluoropropane and glyoxal. The structure of all nitration products were characterized by 1H, 13C and 15N NMR. The density of compound 6 is the highest (up to 2.08 g•cm-3) by testing with exhaust gas method. For all three compounds, the impact sensitivity measured by the dropping hammer lift is greater than 30 J, and the friction sensitivity based on BAM method is greater than 360 N. The TG-DTG analysis shows that the mass loss of all three products is more than 90% and their thermal stability decrease with the increase of nitro group. The detonation properties were estimated by Monte-Carlo statistical methods and theoretical models using Gaussian 09 calculation package. The detonation velocity and detonation pressure of compound 6 are 11937 m•s-1 and 74.3 GPa, respectively. Due to the high density and greater electronegativity, the introduction of CF3 group reduces the sensitivity while maintaining higher density and good detonation performance compared with that of tetranitroglycoluril (TNGU). It also opens up new ideas for the research of energetic materials. © 2020, Editorial Board of Chinese Journal of Energetic Materials. All right reserved.