4,4′-Bis(trinitromethyl)-3,3′-azo/azoxy-furazan: High-energy dense oxidizers

• 4,4’-Bis(trinitromethyl)-3,3’-azo/azoxy-furazan was synthesized as high-energy dense oxidizers. • Two oxidizers exhibit high densities of 1.865 and 1.887 g cm -3 , respectively. • Two oxidizers have positive oxygen balances (OB CO2 ) of +6.9 % and +10.0 %. • The thermal decomposition temperature of oxidizer 8 is higher than 150 °C. Finding a chlorine-free, environmentally friendly, high-energy dense oxidizer with a high heat of formation as an alternative to ammonium perchlorate (AP) has remained an extremely challenging task in the field of energetic materials. In the present work, two organic oxidizers, 4,4’-bis(trinitromethyl)-3,3’-azofurazan ( 8 ) and 4,4’-bis(trinitromethyl)-3,3’-azoxyfurazan ( 10 ), were designed and synthesized via a two-step reaction from 3-amino-4-(carboxymethyl)furazan. Their structural features were investigated by single-crystal X-ray diffraction, scanning electron microscopy, nuclear magnetic resonance, infrared spectroscopy, elemental analysis, and several theoretical techniques. Both of the newly synthesized organic oxidizers ( 8 and 10 ) exhibit positive oxygen balances, high densities, poor solubility in water, decent thermal stabilities, acceptable mechanical sensitivities, extremely high heats of formation, and excellent detonation performances. The best specific impulses are obtained for the environmentally friendly oxidizers 8 and 10 with calculated values of 273.9 s and 275.9 s, respectively, in a composite propellant consisting of 77 % oxidizer, 9 % aluminium, and 14% binder. Both of these exceed the specific impulse (263 s) of the currently widely used oxidizer AP in the similar composition. Oxidizers 8 and 10 are expected to have promising applications as high-energy dense oxidizers for various scientific, space, and military projects.