Synthesis and Characterization of the Potential Energetic Propellant Plasticizer 3-Nitratoethyl-N-nitramino-5-nitratomethyl Isoxazole.

The synthesis of 3-(nitratoethyl-N-nitramino)-5-(nitratomethyl) isoxazole (C6 H7 N5 O9 , 1) is presented, and its energetic properties were ascertained and analyzed for energetic applications potential. 1 was found to be a solid without melting behavior, begins to decompose at 140 °C, and has a thermal onset decomposition temperature of 171.5 °C. 1 was synthesized in 5 steps from glyoxylic acid, and was found to exhibit acceptable sensitivities to impact, friction, and electrostatic discharge. The presence of the nitratoethyl nitramino (NENA) moiety, coupled with the high density (1.71 g cm-3 ) and superior calculated specific impulse (247.6 s) over the commonly employed gun propellant n-butyl NENA (density=1.22 g cm-3 , specific impulse=221 s), makes 1 a potential energetic plasticizer for next generation gun and rocket propellants. In addition, a modified procedure for the synthesis of dibromoformaldoxime (DBFO) was developed to provide this material in respectable yields on one mole scale. The safety considerations of DBFO are also highlighted, in which this compound sublimes, and must be handled with care, as it will cause burns upon contact with the skin.

Synthesis and Characterization of the Potential Melt-Castable Explosive 3-(1,2,4-Oxadiazolyl)-5-Nitratomethyl Isoxazole.

The synthesis of 3-(1,2,4-oxadiazolyl)-5-nitratomethyl isoxazole (C6 H4 N4 O5 ), its physical properties, and its theoretical performances are described. This energetic material was found to have a melting point range of 76.6-79.2 °C, and a thermal onset decomposition temperature of 184.5 °C. These thermal features put this material into the standalone melt-castable explosive class. The material was found to have TNT performance, and was found to be insensitive to impact, friction, and electrostatic discharge, despite having a nitric ester functionality. A critical reaction in making this molecule was the desymmetrization of diaminoglyoxime. The optimization of this transformation is described. Previous reports of this desymmetrization were found to be inaccurate, as the desymmetrization reaction produces a co-crystal of mono- and bi-1,2,4-oxadiazole products.