Obtaining advanced insensitive energetic materials by regioselectively introducing N-oxide groups onto 6-trifluoromethyl-1,2,4,5-tetrazine-3-amine

Abstract

Three N-oxide energetic compounds were selectively obtained from 6-trifluoromethyl-1,2,4,5-tetrazin-3-amine using four kinds of oxidation systems. Their structures were verified through ¹H NMR, ¹³C NMR, IR, single-crystal X-ray diffraction, and elemental analysis, and their thermal properties were studied through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Moreover, their heats of formation and detonation properties were obtained using the Gaussian 09 and EXPLO5 v6.01 programs, respectively. Among them, compound 5 had excellent mechanical sensitivities (IS ​> ​60 ​J, FS ​> ​360 ​N) and high detonation performance (v_D ​= ​7351 ​m ​s⁻¹, p ​= ​23.9 ​GPa), which were comparable to those of TNT. Compound 7 was more sensitive (IS ​= ​27 ​J, FS ​> ​360 ​N) than compound 5, which was the isomer of compound 7. The mechanism for regioselectively introducing N-oxide was deeply investigated through the natural bond orbital (NBO) charge analysis. Furthermore, the relationships between the sites of N-oxides and the sensitivities were investigated using Hirschfeld surfaces, electrostatic potential, and 2D fingerprint plots, This study can be used as a reference for the development of the next generation of N-oxide-containing explosives.