Combining the most suitable energetic tetrazole and triazole moieties: synthesis and characterization of 5-(1-hydroxy-3-nitro-1,2,4-triazol-5-yl)-1-hydroxy-tetrazole and its nitrogen-rich ionic derivatives

Abstract

With the synthesis of 5-(1-hydroxy-3-nitro-1,2,4-triazol-5-yl)-1-hydroxy-tetrazole (1) we can report the first successful production of a combined bis-heterocyclic system composed of 1-hydroxy-tetrazole and 1-hydroxy-1,2,4-triazole. The straightforward synthesis modifies the cyano group of the nitro-triazole starting material within four steps to the tetrazol-1-ol and finally oxidizes the triazole selectively to the 1-hydroxy-triazole, resulting in compound 1, which is a hybrid molecule of the two in energetic materials chemistry established bis-heterocyclic motifs 1,1′-dihydroxy-3,3′-dinitro-bis-1,2,4-triazole and 1,1′-dihydroxy-5,5′-bistetrazole. In order to tune and improve the performance parameters, several nitrogen rich bases were used to obtain the respective ionic derivatives. All compounds were characterized using multinuclear NMR and IR spectroscopy, differential thermal analysis (DTA) and elemental analysis. Several compounds could be further analyzed using X-ray diffraction measurements. The heats of formation for all investigated compounds were determined and the detonation properties (EXPLO5 V6.05.02) were calculated. These data, as well as the sensitivity values, were compared to related substances.