Energetic salts offer many advantages over conventional energetic molecular compounds. The use of nitrogen containing anions and cations contributes to high heats of formations and high densities. Their low carbon and hydrogen content gives rise to a good oxygen balance. The decomposition of these compounds is predominantly through the generation of dinitrogen which makes them very promising candidates for highly energetic materials for industrial or military applications.

Energetic nitrogen-rich salts and ionic liquids.

New energetic salts (4−9, 11, 13, 16, 21, 22, 29−34, 36, 37, 42, 43, 46, 47) were synthesized via the quaternization of azido or nitro derivatives of imidazole, 1,2,4-triazole, and substituted derivatives of tetrazole with nitric or perchloric acid or with iodomethane followed by metathesis reaction with silver nitrate or silver perchlorate. The structures of 1,4-dimethyl-3-azido-1,2,4-triazolium nitrate (5), 3-azido-1,2,4-triazolium nitrate (6), 1-methyl-4-amino-1,2,4-triazolium perchlorate (16), and 1,4-dimethyl-2-H-1,2,4-triazolium triiodide (20) were confirmed by single-crystal X-ray analysis. Most of the salts exhibit good thermal stabilities and low melting points. By using constant volume combustion energies that were determined experimentally using an oxygen bomb calorimeter, the standard molar enthalpies of formation were derived based on designed Hess thermochemical cycles.

New Energetic Salts Based on Nitrogen-Containing Heterocycles

Energetische Salze bieten zahlreiche Vorteile gegenuber herkommlichen energetischen Molekulverbindungen. Die Verwendung von stickstoffhaltigen Kationen und Anionen tragt zu hoheren Bildungswarmen und Dichten bei, wobei durch den niedrigen Gehalt an Kohlenstoff und Wasserstoff auch eine gute Sauerstoffbilanz erzielt wird. Da bei der Zersetzung dieser stickstoffreichen Verbindungen ein groserer Anteil von Distickstoff entsteht, sind sie vielversprechende hochenergetische Materialien fur technische und militarische Anwendungen.

Stickstoffreiche energetische Salze und ionische Flüssigkeiten

Energetic salts comprising substituted imidazolium and 1,2,4-triazolium cations and 4,5-dinitro-imidazolate and 5-nitrotetrazolate anions were synthesized and characterized. On the basis of experimentally obtained heats of combustion, the calculated heats of formation range from ΔHf° = 80 (3) to 1071 kJ/mol (13). Imidazolate salts are more dense but have lower heats of formation than their tetrazolate analogues. Salts 4, 5, 8, and 11−14 fall into the ionic liquid class (mp < 100 °C). The structure of 1,2,4-triazolium 5-nitrotetrazolate (10) was confirmed by X-ray analysis.

Energetic azolium azolate salts.

Many advantages accrue from nitrogen-rich heterocyclic compounds compared to traditional molecular energetic compounds. Utilization of heterocyclic nitrogen-containing cations and anions in energetic salts gives rise to lower vapor pressures, higher heats of formation and higher densities. Additionally, smaller amounts of hydrogen and carbon contribute to a better oxygen balance than normally is found with their carbocyclic analogues. Nitrogen-rich compounds are promising high energetic materials that may be more acceptable than their alternatives for both industrial and military uses since a higher percentage of their decomposition products will be dinitrogen.

Nitrogen-Rich Heterocycles

: The heats of formation of two series of triazoles, 3-azido-s-triazoles, and 4-amino-3-azido-s-triazoles, were determined from the heat of combustion in an oxygen bomb calorimeter. Differential thermograms were obtained to determine the thermal stability of each compound. Of the series of azides studied, the 3-azido-s-triazoles offer greater promise in propellant applications due to their thermal stability and shock insensitivity. (Author)

Paul C. Marx

Papers

Energy of combustion and differential thermograms of organic azides