2-Tetrazene Derivatives as New Energetic Materials; Synthesis, Characterization and Energetic Properties

The oxidation of 1,1-dimethylhydrazine with aqueous monochloramine yielded (E)-1,1,4,4-tetramethyl-2-tetrazene (1) as a pale yellow liquid with hypergolic properties. 1 can be oxidized with potassium permanganate to form (E)-1-formyl-1,4,4-trimethyl-2-tetrazene (2) and (E)-1,4-diformyl-1,4dimethyl-2-tetrazene (3). Additionally, 1 reacts with a diethyl ether solution of monochloramine to form a stable 1,1,4,4-tetramethyl-2-tetrazenium chloride salt (4). The chloride in salt 4 was exchanged with various energetic anions, such as nitrate (5), perchlorate (6), 5,5 ́-azobistetrazolate (7*6H2O), picrate (8) and azide (9). All materials were characterized by analytical and spectroscopic methods and the solid state structures of compounds 2-8 were elucidated. Due to the energetic nature of these materials, they were submitted to friction and impact sensitivity tests and DSC analysis was used to assess their thermal stabilities. Furthermore, the heats of formation of compounds 2-8 were computed using quantum mechanical methods (CBS-4M) and their detonation parameters (pressure and velocity) and specific impulses were also calculated. Lastly, the 2-tetrazene derivatives presented here are of potential interest either as building blocks or as a new class of low toxicity, low sensitivity energetic materials.