Simple and energetic: Novel combination of furoxan and 1,2,4-triazole rings in the synthesis of energetic materials

Novel family of nitrogen-rich energetic (1,2,4-triazolyl) furoxan salts with balanced performance

“…Parent biheterocyclic cores, namely 4-azido-3-(1H-1,2,4triazol-3-yl)furoxan 1a and 3-cyano-4-(1H-1,2,4-triazol-3-yl) furoxan 1b were synthesized according to our recently reported procedure (Larin et al, 2022) via PTSA-catalyzed cyclocondensation of the available amidrazones 2a,b with trimethyl orthoformate. Thus formed biheterocyclic compounds 1a,b were treated with AgNO 3 to obtain corresponding silver salts 3a,b which were further subjected to a metathesis reaction with various nitrogen-rich bases (in a form of hydrochlorides) affording two arrays of high-nitrogen energetic salts 4a-c and 5a-d. Cyano group in compound 1a was also converted to the tetrazolate anion through cycloaddition with in situ generated TMSN 3 (Scheme 1).…”

“…All standard reagents were purchased from Aldrich or Acros Organics and used without further purification. Amidrazones 2a ( Fershtat et al, 2015b ) and 2b ( Larin et al, 2021 ), 3-cyano-4-(1 H -1,2,4-triazol-3-yl)furoxan 3a and 4-azido-3-(1 H -1,2,4-triazol-3-yl)furoxan 3b ( Larin et al, 2022 ) were synthesized according to the literature.…”

“…A combination of structurally diversed nitrogen-rich heterocycles linked via N , N ′-ethylene bridges was also reported as one of the promising approaches to balance energetic properties of the resulted energy-rich materials ( Kumar et al, 2016a ; Kumar et al, 2016b ). Recently, our team reported a preparation of energetic (1,2,4-triazolyl) furoxans with good detonation performance and decreased sensitivity ( Larin et al, 2022 ). However, it is known that NH-fragment of the 1,2,4-triazole ring is weakly acidic ( Garratt, 1996 ) and may stimulate corrosivity which is undesired for any potential application.…”

(2‐Vinyltetrazolyl)furoxans as New Potential Energetic Monomers

“…Thus, impact insensitivity of compound 2 d (>100 J) may be attributed to the weak delocalization of the negative charge in the molecule which is connected to the far disposition of the vinyl‐ and amino groups. On the other hand, the higher impact sensitivity of (2‐vinyltetrazolyl)furoxans 2 a – c (0.8‐3.5 J) could be explained by the depletion of electronic charge caused by the furoxan ring resulting in an increase of electropositive area, which is especially noticeable in the case of azido derivative 2 b [29c] . The presence of the amino functionality is a determining factor to achieve lower impact sensitivity in the synthesized series of energetic monomers (3.5 J for 2 a , 100 J for 2 d ).…”

First Example of 1,2,5‐Oxadiazole‐Based Hypergolic Ionic Liquids: A New Class of Potential Energetic Fuels

“…Meanwhile, 1,2,5‐oxadiazole (furazan) and 1,2,5‐oxadiazole 2‐oxide (furoxan) scaffolds are valuable building blocks due to their high positive enthalpies of formation and huge nitrogen‐oxygen contents presented within the core. Moreover, the functionalization of the 1,2,5‐oxadiazole backbone enables the preparation of energetic materials with high densities and improved properties [23–34] . Considering these advantages and versatility of the 1,2,5‐oxadiazole ring in the preparation of explosives, we proposed that its incorporation into the structure of ILs would be a promising combination enroute to novel potential high‐performance energetic fuels.…”