Bis-oxadiazole, or more formally known as bis(1,2,4-oxadiazole)bis(methylene) dinitrate, is a nitrated heterocyclic compound of the oxadiazole family.[1]
Bis-oxadiazole is related to bis-isoxazole tetranitrate (BITN), which was developed at the United States Army Research Laboratory (ARL). With a high nitrogen content, these compounds are poised to release a large volume of very stable N2.[2] It is a “melt-cast” explosive material that is potentially both more powerful and environmentally friendly alternative to TNT.[3]
Synthesis
Glyoxalcondenses with hydroxylamine to yield diaminoglyoxime (DAG). Treating DAG with methyl glycolate [pt] in the presence of base at high temperature, followed by nitration, yields bis(1,2,4-oxadiazole).[4]
Replacement for TNT
TNT is attractive explosive because it is a melt-castable. A low melting point of about 80 °C and high decomposition temperature of 295 °C allows manufacturers to safely pour TNT into molds. The production of TNT generates hazardous waste, e.g. red water and pink water.[1]
Bis-oxadiazole, which is also melt-castable, is about 1.5 times more powerful than TNT and yet produces less hazardous wastes.[1]
Physical Properties of Bis-oxadiazole Compared to TNT[4]
Physical Property
bis-oxadiazole
TNT
Onset temperature of melting
84.5 °C
80.4 °C
Onset temperature of decomposition
183.4 °C
295.0 °C
Derived density from X-ray data
1.832 g cm−3
1.65 g cm−3
Detonation pressure
29.4 GPa
20.5 GPa
Detonation velocity
8180 m s−1
6950 m s−1
Molar enthalpy of formation
-79.4 kJ mol−1
-59.3 kJ mol−1
A major challenge in the production of bis-oxadiazole is its low yield.[5]
bis(methylene)_dinitrate.svg)
