Combining performance with thermal stability: Synthesis and characterization of 5-(3,5-dinitro-1H-pyrazol-4-yl)-1H-tetrazole and its energetic derivatives

摘要

The demand for better, more efficient and environmentally friendly high-energy dense materials (HEDMs) in the military but also in the civilian sector is constantly increasing. Nitrogen-rich heterocycles play an important role as building blocks in the development of new energetic materials. During the past decades, various different five- and six-membered heterocycles (e.g. pyrazoles, triazoles, tetrazoles, tetrazines) were investigated extensively with regard to their suitability as potential new high explosives. 3,3'5,5'-Tetranitro-4,4 '-bipyrazole, bis(3,4,5-trinitro-pyrazol-l-yl)-methane and dihydroxylammonium 5,5 '-bitetrazole-1,1 '-dioxide are substantial examples for azole based explosives which exhibit not only good stability toward external stimuli but also show high performance. In this study we present the synthesis of 5-(3,5-dinitro-lH-pyrazol-4-yl)-1H-tetrazole and its energetic derivatives starting from 4-amino-3,5-dinitropyrazole, which was diazotized and cyanide substituted. A subsequent cycloaddition reaction with sodium azide led to 5-(3,5-dinitro-IH-pyrazol-4-yl)-lH-tetrazole (3). Several alkali metal and nitrogen-rich salts were prepared and characterized by low-temperature X-ray diffraction. Additionally, all compounds were analyzed by vibrational spectroscopy (IR) 'H and 13 C NMR spectroscopy, elemental analysis and differential thermal analysis (DTA). Additionally the heats of formation for anhydrous compounds were calculated using the atomization method based on CBS-4M enthalpies as well as some detonation parameters by using the EXPLO5 code (V6.05). Furthermore, the sensitivities of I and selected salts toward friction, impact and electrostatic discharge were determined.