Synthesis of 5-(1H-Tetrazolyl)-1-hydroxy-tetrazole and energetically relevant nitrogen-rich ionic derivatives

Abstract

Sodium 5-cyanotetrazolate sesquihydrate (1) was prepared from sodium azide and two equivalents of sodium cyanide under acidic conditions. Sodium 5-cyanotetrazolate sesquihydrate (1) reacts with hydroxylammonium chloride to form 5-aminohydroximoyl tetrazole (2). 5-Aminohydroximoyl tetrazole (2) is treated with sodium nitrite and hydrochloric acid to form 5-chlorohydroximoyl- tetrazole (3). The chloride azide exchange yields 5-azidohydroximoyl-tetrazole monohydrate (4). When compound 4 is treated with hydrochloric acid, 5-(1H-tetrazolyl)-1-hydroxytetrazole (5) is obtained in good yield. Compound 5 can be deprotonated twice by various bases. Different ionic derivatives such as bis(hydroxylammonium) (6), bis(hydrazinium) (7), bis(guanidinium) (8), bis(aminoguanidinium) (9), bis(ammonium) (10), and diaminouronium (11) 5-(1-oxidotetrazolyl)-tetrazolate were synthesized and characterized. With respect to energetic use salts 6 and 7 are most relevant. Compounds 3-9 and 11 were characterized using low temperature single-crystal X-ray diffraction. All compounds were investigated by NMR and vibrational (IR, Raman) spectroscopy, mass spectrometry and elemental analysis. The thermal properties were determined by differential scanning calorimetry (DSC). The sensitivities towards impact (4: 4 J, 5: 40 J, 6: 12 J, 7: 40 J), friction: (4: 60 N, 5: 240 N, 6: 216 N, 7: 240 N), and electrical discharge (5: 0.40 J, 6: 0.75 J, 7: 0.75 J), were investigated using BAM standards and a small scale electrostatic discharge tester. The detonation parameters of 5-7 were calculated using the EXPLO5.06 code and calculated (CBS-4 M) enthalpy of formation values. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.