Energetic Di-and trinitromethylpyridines: Synthesis and characterization

Pyridine derivatives based on the addition of trinitromethyl functional groups were synthesized by the reaction of N₂O₄ with the corresponding pyridinecarboxaldoximes, then they were converted into dinitromethylide hydrazinium salts. These energetic compounds were fully characterized by IR and NMR spectroscopy, elemental analysis, differential scanning calorimetry (DSC), and X-ray crystallography. These pyridine derivatives have good densities, positive enthalpies of formation, and acceptable sensitivity values. Theoretical calculations carried out using Gaussian 03 and EXPLO5 programs demonstrated good to excellent detonation velocities and pressures. Each of these compounds is superior in performance to TNT, while 2,6-bis(trinitromethyl)pyridine (D = 8700 m·s⁻¹, P = 33.2 GPa) shows comparable detonation performance to that of RDX, but its thermal stability is too low, making it inferior to RDX.