Synthesis and spectroscopic characterization of azolium picrate salts

Tetrazoles are valuable intermediates for the synthesis of energetic materials and combined with energetic anions such as azide, dinitramide, nitrate or picrate give compounds with interesting energetic properties. Azolium picrate salts with the following cations were prepared in high yields and purities: 1-methyl-5-amino-1H-tetrazolium (1a), 1,4-dimethyl-5-amino-1H-tetrazolium (2a), 1-methylguanazinium (3a) and 1,3-dimethyl-5-amino-1H-tetrazolium (4a). The compounds were fully characterized by elemental analysis, mass spectrometry and vibrational and multinuclear NMR (H-1, C-13 and N-15) spectroscopies. The thermal behavior of the picrate salts was assessed by DSC (Differential Scanning Calorimetry) measurements revealing high thermal stabilities. In addition, the long-term stabilities of compounds la and 4a was assessed by TSC (Thermal Safety Calorimetry). Lastly, all compounds described here are stable to water and can easily be prepared on a large scale from cheap starting materials, making them of interest as new energetic compounds.