No abstract

A smooth synthesis of 4H-[1,2,3]triazolo[4,5-c]-[1,2,5]oxadiazole 5-oxide 1 and its energetic salts (ammonium, hydroxylammonium, guanidinium, triaminoguanidinium) is reported. The compounds synthesized were characterized by multinuclear nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy, mass spectrometry, elemental analysis, differential scanning calorimetry, single-crystal, and powder X-ray diffraction. All the compounds possess a beneficially high enthalpy of formation (88.9−168.0 kcal•mol −1 ). These data, in combination with the experimentally determined densities (1.702−1.934 g• cm −1 ), were used to calculate the detonation pressures (33.9−43.1 GPa) and velocities (8.86−9.31 km•s −1 ). The majority of the synthesized energetic salts had moderate impact and friction sensitivity, which made them promising candidates for various energy applications, including their use as components of solid composite propellants. It was shown that compounds 1 and 2c−f had higher energetic characteristics as components of solid composite propellants (the specific impulse was higher by 5−10 s) than HMX or CL-20 in propellant formulations.

Energetic compounds 1-6, consisting of one or two furazan rings linked by azo or azoxy bridges and one or two nitro-NNOazoxy substituents, were synthesized by nitration of the corresponding tert-butyl-NNO-azoxy precursors with NO 2 BF 4. Novel methods for the synthesis of 3,4-bis(tert-butyl-NNOazoxy)furazan (7) and bis-4,4'-(tert-butyl-NNO-azoxy)-3,3'-azoxyfurazan (21) were elaborated. The nitro-NNO-azoxy compounds obtained display high calculated detonation performance (v D = 8.07-9.40 km s À 1 and P C-J = 27.4-43.4 GPa) that is superior to the corresponding nitrofurazans (DNF, DNAzF, DNAF). The replacement of nitrofurazans with the corresponding (nitro-NNO-azoxy)furazans increases the specific impulse of the model solid composite propellant formulations by 2-10 s, which is due to high calculated heats of formation (600-892 kcal kg À 1) and positive oxygen balance (0-20 %) of the latter compounds.

7‐Nitro‐3‐(nitro‐NNO‐azoxy)[1,2,4]triazolo[5,1‐c][1,2,4]‐triazin‐4‐amine (4) is the first high‐melting compound bearing adjacent nitro‐NNO‐azoxy and amino groups. It was synthesized by nitration of 7‐nitro‐3‐(tert‐butyl‐NNO‐azoxy)[1,2,4]triazolo[5,1‐c][1,2,4]triazin‐4‐amine (3) with NO2BF4. Compound 4 is a rather thermally stable (decomposition onset temperature 154 °C), highly energetic (calculated heat of formation 580 kcal·kg–1), and highly dense (1.875 g cm–3) material with a CO‐level oxygen balance.

A two‐step synthetic approach to previously unknown 1,2,3,4‐tetrazine 1,3‐dioxides annulated with 1(2)‐aryl‐1,2,3‐triazoles was developed. The first step involved the formation of 5‐amine‐4‐(tert‐butyl‐NNO‐azoxy)‐1(2)‐aryl‐1(2)H‐1,2,3‐triazoles starting from (tert‐butyl‐NNO‐azoxy)acetonitrile. The second step included their cyclization to give the titled triazolotetrazines. Their structures were confirmed by 1H NMR, 13C NMR, and 14N NMR spectroscopy; HRMS; and X‐ray diffraction studies. Common features and distinctions in the molecular structures of these compounds, including aromaticity, were explored.