1-Nitratoethyl-5-nitriminotetrazole derivatives – Shaping future high explosives

1-(2-Nitratoethyl)-5-nitriminotetrazole (2) was formed by the reaction of 1-(2-hydroxyethyl-5-aminotetrazole (1) and 100% HNO3. Compound 1 was obtained by alkylation of 5-amino-1H-tetrazole. Next to the known byproduct 1-(2-hydroxyethyl)-5-nitriminotetrazole (3), a second one, 1-(2-nitratoethyl)-5-aminotetrazolium nitrate (4) was obtained and fully characterized. Nitrogen-rich salts such as the ammonium (5), hydroxylammonium (6), guanidinium (7), aminoguanidinium (8), diaminoguanidinium (9) and triaminoguanidinium (10) 1-(2-nitratoethyl)-5-nitriminotetrazolate were prepared by deprotonation or metathesis reactions. The reaction of 2 and diaminourea yielded 1-(2-nitratoethyl)-5-aminotetrazole (11). Compounds 4–11 were fully characterized by single crystal X-ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis and DSC measurements. The heats of formation of 5–10 were calculated by the atomization method based on CBS-4M enthalpies. Regarding the possible application of these compounds as energetic materials or high explosives, several detonation parameters such as the detonation pressure, velocity, energy and temperature were computed using the EXPLO5 code and the X-ray densities as well as the computed heats of formation. In addition the sensitivities towards impact, friction and electrical discharge were tested using the BAM drophammer, a friction tester as well as a small scale electrical discharge device.

1-(2-Nitratoethyl)-5-nitriminotetrazole (2) was formed by the reaction of 1-(2-hydroxyethyl-5-aminotetrazole (1) and 100% HNO3. Next to the known byproduct 1-(2-hydroxyethyl)-5-nitriminotetrazole (3), a second one, 1-(2-nitratoethyl)-5 aminotetrazolium nitrate (4) was obtained and fully characterized. The nitrogen-rich salts ammonium (5), hydroxylammonium (6), guanidinium (7), aminoguanidinium (8), diaminoguanidinium (9) and triaminoguanidinium (10) 1-(2-nitratoethyl)-5-nitriminotetrazolate were prepared by deprotonation or metathesis reactions. The reaction of 2 and diaminourea yielded 1-(2-nitratoethyl)-5-aminotetrazole (11). The structures of compounds 4–11 were determined by single crystal X-ray diffraction yielding densities between 1.60 and 1.80 g cm-3. In comparison to 3 lower decomposition temperatures for the nitrate esters were measured by differential scanning calorimetry. The heats of formation of 4–11 which are all positive were calculated by the atomization method based on CBS-4M enthalpies. Several detonation parameters such as the detonation pressure, velocity, energy and temperature were computed using the EXPLO5 code, mostly resulting in values between those of PETN and RDX. The measured sensitivities towards impact, friction and electrical discharge are also in the range of PETN and RDX.Figure optionsDownload as PowerPoint slideHighlights
► Nitrogen-rich salts of 1-nitratoethyl-5-nitriminotetrazole as new secondary explosives.
► Facile synthesis with good purities and yields.
► Full characterization of the chemical and physico-chemical properties.
► Moderate sensitivities were measured towards impact and friction.
► Calculated detonation parameters in the range of PETN and RDX.