Nitrogen‐Rich Salts of 1H,1′H‐5,5′‐Bitetrazole‐1,1′‐diol: Energetic Materials with High Thermal Stability

Abstract

Abstract1H,1′H‐5,5′‐Bitetrazole‐1,1′‐diol was synthesized starting from glyoxal, which is converted to glyoxime after treatment with hydroxylamine. Chlorination of glyoxime with Cl2 gas in ethanol and following chloro/azido exchange yields diazidoglyoxime, which is cyclized under acidic conditions (HCl gas in diethyl ether) to give 1H,1′H‐5,5′‐bitetrazole‐1,1′‐diol dihydrate (1). A large variety of nitrogen‐rich salts of 1 such as the diammonium (2), the dihydrazinium (3), the bis‐guanidinium (4), the bis(aminoguanidinium) (5), the diaminoguanidinium salt monohydrate (6), the triaminoguanidinium salt monohydrate (7), the 1‐amino‐3‐nitroguanidinium salt dihydrate (8), the diaminouronium salt monohydrate (9), the bis(oxalyldihydrazidinium) (10), the oxalyldihydrazidinium salt dihydrate (11), the 3,6‐dihydrazino‐1,2,4,5‐tetrazinium (12), the 5‐aminotetrazolium (13), the bis(5‐amino‐1‐methyl‐1H‐tetrazolium) salt (14), the bis(5‐amino‐2‐methyl‐2H‐tetrazole) adduct (15), and the 1,5‐diaminotetrazolium salt (16) were synthesized by means of Brønsted acid–base or metathesis reactions. All compounds were fully characterized by vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC) measurements. The crystal structures of 1–16 could be determined by using single‐crystal X‐ray diffraction. The heats of formation of 1–16 were calculated by using the atomization method on the basis of CBS‐4M enthalpies. With regard to their potential use as cyclotrimethylene trinitramine (RDX) or hexanitrostilbene (HNS) replacements, several detonation parameters such as the detonation pressure, detonation velocity, explosion energy, and explosion temperature were computed using the EXPLO5 code on the basis of the experimental (X‐ray) densities and calculated heats of formation. In addition, the sensitivities towards impact, friction, and electrical discharge were tested using the BAM drop hammer, a friction tester, as well as a small‐scale electrical discharge device.