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.

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

Activation energy for the decomposition of explosives is a crucial parameter of performance. The dramatic suppression of activation energy in condensed phase decomposition of nitroaromatic explosives has been an unresolved issue for over a decade. We rationalize the reduction in activation energy as a result of a mechanistic change from unimolecular decomposition in the gas phase to a series of radical bimolecular reactions in the condensed phase. This is in contrast to other classes of explosives, such as nitramines and nitrate esters, whose decomposition proceeds via unimolecular reactions both in the gas and in the condensed phase. The thermal decomposition of a model nitroaromatic explosive, 2,4,6-trinitrotoluene (TNT), is presented as a prime example. Electronic structure and reactive molecular dynamics (ReaxFF-lg) calculations enable to directly probe the condensed phase chemistry under extreme conditions of temperature and pressure, identifying the key bimolecular radical reactions responsible for ...

Decomposition of condensed phase energetic materials: interplay between uni- and bimolecular mechanisms.

The widespread and long-term use of TNT has led to extensive study of its thermal and explosive properties. Although much research on the thermolysis of TNT and polynitro organic compounds has been undertaken, the kinetics and mechanism of the initiation and propagation reactions and their dependence on the temperature and pressure are unclear. Here, we report a comprehensive computational DFT investigation of the unimolecular adiabatic (thermal) decomposition of TNT. On the basis of previous experimental observations, we have postulated three possible pathways for TNT decomposition, keeping the aromatic ring intact, and calculated them at room temperature (298 K), 800, 900, 1500, 1700, and 2000 K and at the detonation temperature of 3500 K. Our calculations suggest that at relatively low temperatures, reaction of the methyl substituent on the ring (C-H alpha attack), leading to the formation of 2,4-dinitro-anthranil, is both kinetically and thermodynamically the most favorable pathway, while homolysis of the C-NO(2) bond is endergonic and kinetically less favorable. At approximately 1250-1500 K, the situation changes, and the C-NO(2) homolysis pathway dominates TNT decomposition. Rearrangement of the NO(2) moiety to ONO followed by O-NO homolysis is a thermodynamically more favorable pathway than the C-NO(2) homolysis pathway at room temperature and is the most exergonic pathway at high temperatures; however, at all temperatures, the C-NO(2) --> C-ONO rearrangement-homolysis pathway is kinetically unfavorable as compared to the other two pathways. The computational temperature analysis we have performed sheds light on the pathway that might lead to a TNT explosion and on the temperature in which it becomes exergonic. The results appear to correlate closely with the experimentally derived shock wave detonation time (100-200 fs) for which only the C-NO(2) homolysis pathway is kinetically accessible.

Mechanism of thermal unimolecular decomposition of TNT (2,4,6-trinitrotoluene): a DFT study.

2,4,5-Trinitroimidazolate (TNI) salts with "high-nitrogen" cations tend to be highly hydrogen bonded and have heats of formation ranging up to 616 kJ mol(-1). Density, oxygen balance, and thermostability are enhanced by the presence of TNI. Based on theoretical calculations, all of the new salts are potential propellants.

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2,4,5-Trinitroimidazole-Based Energetic Salts

Studies on energetic compounds. Part 8 : Thermolysis of salts of HNO3 and HClO4

Studies on energetic compounds. Part XI: preparation and thermolysis of polynitro organic compounds.

Studies on energetic compounds Part 3. Kinetics of thermolysis of dimethylanilinium nitrates

Thermolysis of nitrophenates (C-NO2 explosives) of transition metals of 3d-series have been studied by DTA, impact, friction, and explosion delay measurements. Explosion delay (DE), explosion temperature (ET), activation energy for explosion (E∗), and height for 50% explosion (h50%) have been found to be in the order: trinitro<dinitro<p mononitrophenates of transition metals. Only trinitrophenates have been found to be friction sensitive. It has been observed that these salts dehydrate below 140°C and at higher temperatures corresponding metal oxide and nitrosubstituted diphenylethers (as intermediates) are formed. The oxidative decomposition reactions seem to occur in adsorbed phase between NO2, MO, and radical species leading to explosion.

Nitrophenates of transition metals1 part II. DTA, explosion delay, impact and friction sensitivity studies

A large number of nitrophenates of transition metals have been synthesised and characterised during the programme of formulation of new energetic materials. These compounds have been found to be ionic salts and number of water of crystallisation was found to depend upon the number of nitro groups.

S. Mudi Mannan

Papers

Studies on energetic compounds. Part 8 : Thermolysis of salts of HNO3 and HClO4

Studies on energetic compounds. Part XI: preparation and thermolysis of polynitro organic compounds.

Studies on energetic compounds Part 3. Kinetics of thermolysis of dimethylanilinium nitrates

Nitrophenates of transition metals1 part II. DTA, explosion delay, impact and friction sensitivity studies

Nitrophenates of transition metals part I. synthesis and characterisation