Dinitramide ammonium salt

Apart from the ammonium salt of dinitramidic acid, many different stable oxygen-rich salts with a variety of cations are possible which could provide a new class of energetic materials. The presence of -N(N02)2 groups in these compounds imparts high heat of formation, density and oxygen balance and hence has received a lot of attention in recent years. The alkali metal dinitramide... 

Each of the ammonium salts, and even hydroxylammonium nitrate, initiate decomposition in the same fashion—loss of amine. Indeed, ammonium nitrate, perchlorate, and dinitramidate all sublime. 

The nitration of nitramine (153) with nitronium tetrafluoroborate, followed by neutralization of the resulting dinitraminic acid with ammonia, also generates ammonium dinitramide (152). Neutralization of this reaction with alkylamines, instead of ammonia, yields the corresponding alkylammonium salts of dinitramide. The nitration of ammonia with dinitrogen pentoxide (15 %) or nitronium salts like the tetrafluoroborate (25 %) yield ammonium dinitramide (152) through the initial formation of nitramine. 

Ammonium dinitramide has been synthesized from the nitration of ammonium sulfamate with strong mixed acid at -35 to -45 °C followedby neutralization of the resulting dinitraminic acid with ammonia. The yield is 45 % when the mole ratios of sulfuric acid to nitric acid is 2 1 and ammonium sulfamate to total acid is 1 6. The nitration of other sulfonamide derivatives, followed by hydrolysis with metal hydroxides, also yields dinitramide salts. ... 

Ammonium dinitramide (ADN) [NH4N(N02)2] is a relatively newly discovered inorganic solid salt, mainly intended as an oxidizer for composite propellants and it is widely known at present Dinitramide salts were reported [64, 65] from USA in 1996 while Russians [66] used these salts in their various missile programs in 1971. 

Ammonium dinitramide (ADN) and hydrazinium nitroformate (HNF) are potential high performance and eco-friendly replacements for AP in composite propellants and efforts are being made all over the globe in this direction. Similarly, there is a need to study these high performance oxidizers and their salts for pyrotechnic applications. Some groups of researchers have already initiated research in this direction and several alkali dinitramide salts have been synthesized and characterized for their elemental content, solubility, thermal behavior and crystal structures. 

The decomposition of ADN can follow at least two different routes. One involves the formation, at 127°C, of ammonium nitrate and N20 [10], followed by a second step, with onset above 200°C, in which the AN decomposes to N02 and water. Potassium dinitramide decomposes with an analogous initial step, forming KNO3. A second route for ADN begins with dissociation of the salt into ammonia and dinitraminic acid, HN(N02)2. This can be viewed as an acid/base equilibrium ... 

Ionic liquids should also be very suitable for use as monopropellants, but the salts used must contain either the oxidizer and fuel combined, or salt mixtures which contain both oxidizing and reducing salts. Since these mixtures are homogeneous systems which contain both the oxidizer and fuel, they can be labeled as monopropellants, just as hydrazine is. Particularly interesting are salt mixtures which are less toxic and have a lower vapor pressure than hydrazine. Such mixtures are also known as green propellants . Suitable anions are the nitrate or dinitramide ions [58], A combination which has already been studied intensively as an oxidizer is the HAN, hydroxylammonium nitrate system. ADN, ammonium nitrate (AN) and hydrazinium nitrate (HN) have also been investigated. As fuels, hydroxylammonium azide (HAA), ammonium azide (AA) or hydrazinium azide (HA) may be appropriate. As a rule, these salt mixtures are not used as pure substances on safety grounds, but with 20 or 40% water added they then decompose catalytically in an exothermic reaction. Table 9.7 shows the dependence of the calculated specific impulses on the water content for such salt mixtures. 

R. Gilardi, J. FUppen-Anderson, C. Geoige, R. J. Butcher, J. Am. Chem. Soc. 1997, 119, 9411-9416. A new class of flexible energetic salts The crystal structures of the ammonium, lithium, potassium, and cesium salts of dinitramide. 

Venkatachalam, S., Santhosh, G. and Ninan, K.N., An overview on the synthetic routes and properties of ammonium dinitramide (ADN) and other dinitramide salts. Propellants, Explos., Pyrotech. 29 (3), 178-187 (2004). 

The currently most promising chlorine-free oxidizers which are being researched at present are ammonium dinitramide (ADN), which was first developed in Russia (Nikolaj Latypov) and is being commercialized today by EURENCO, as well as the nitroformate salts hydrazinium nitroformate (HNF, APP, Netherlands) and triaminoguanidinium nitroformate (Germany) (Fig. 1.19) [8]. The salt hydroxyl ammonium nitrate, HO—NH3 NO3 (HAN) is also of interest. However, all four compounds possess relatively low decomposition temperatures and TAGNF only has a positive oxygen balance with respect to CO (not to CO2). 

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