Dinitramide, ammonium

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. 

ADN is more hygroscopic than AN and has lower critical relative humidity (ADN 55.2% whereas AN 61.9% at 25 °C). Hence, to prevent ADN from absorbing moisture during handling, storage and processing [70], RH in the atmosphere must be below 55%. A brief on some important properties of ADN from the point of view of end-use will be presented while comparing ADN with HNF. 

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 

Reprinted from S. Venkatachalam, G. Santhosh and K.N. Ninan, Prop., Expbs., Pyrotech., 29(2004) 178-187 2004, Wiley-VCH, Weinheim, Germany. 

N-guanylurea dinitramide (commonly known as FOX-12) has low sensitivity and is an excellent candidate for insensitive munitions [72]. It is neither hygroscopic nor soluble in water. Its thermal stability is comparable to RDX and superior to that of ADN. The substitution of ammonium in dinitramide by an organic cation results in the change of combustion temperature and reactivity of the fuel. 

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A practical application of dinitrogen pentoxide in methylene chloride reagent involves the nitration of either ammonium carbamate or nitrourethane, followed by ammonolysis to yield ammonium dinitramide, an energetic oxidizer with enormous potential for use in future high performance propellant compositions. This important reaction is discussed in more detail in Chapter 9. 

The dinitramide ion is stable in both acidic and basic solutions between pH 1-15 at room temperature but is slowly decomposed in the presence of strong concentrated acid. In contrast to alkyl V,V-dinitramines (Section 6.11.2) where the central nitrogen atom is highly electron deficient, the dinitramide anion has its negative charge delocalized over both nitrogen and oxygen atoms with the consequence that the N-N bonds are less susceptible to rupture. However, the dinitramide anion is not as stable as the nitrate anion ammonium dinitramide melts at 92 °C and decomposition starts at 130 °C. 

Ammonium dinitramide (152) is synthesized by treating a solution of ammonium ni-trourethane (150) with nitronium tetrafluoroborate or dinitrogen pentoxide in methylene chloride at -30 °C, followed by ammonolysis of the resulting ethyl A,lV-dinitrourethane (151)7 Ammonium dinitramide can be prepared from the nitration of ethyl carbamate and ammonium carbamate with the same reagents. This is currently the most efficient route to ammonium dinitramide and is used for its manufacture (Section 9.11). 

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. ... 

Miller, R. R., and Guimont, J. M Ammonium Dinitramide Based Propellants, Solid Rocket Technical Committee Lecture Series, AlAA Aerospace Sciences Meeting, Reno, Nevada, 1994. 

Ammonium dinitramide (ADN) is a crystalline oxidizer with the formula NH4N(N02)2, that is, it is composed ofionicaUy bonded ammonium cations, NH4, and dinitramide anions, N(N02)2- Though ADN is crystalline and has a high oxygen content, similar to AP and KP, it has no halogen or metal atoms within its structure. ADN is used as an oxidizer in smokeless composite propellants, similar to AN and HNF. It melts at about 364 K, accompanied by the latent heat of fusion. 

Santhosh, G., Venkatachalam, S., Krishnan, K., Catherine, B. K., and Ninan, K. N., Thermal Decomposition Studies on Advanced Oxidiser Ammonium Dinitramide, Proceedings of the 3 rd International Conference on High-Energy Materials, Thiruvanan-thapuram, India, 2000. 

Ammonium dinitramide Ammonium dinitramide Ammonium dinitramide Binary explosive... 

Binary explosive Hydrazine nitroform Hydrazinium nitroformate Hexanitrotetrachloroazobenzene Ammonium dinitramide... 

Freeman, J. M., and Sigman, R. K., Combustion of Propellants with Ammonium Dinitramide, AIAA-98-3387, AIAA, Re-ston, Virginia (1998). 

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