Salts dinitramide

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. ... 

Bottaro, J.C., Schmitt, R.J., Penwell, P.E., and Ross, D.S. (1991) Manufacture of dinitramide salts for rocket propellants, US Patent Appl. PCT/US91/04277 Inti. Publ., No. WO91/19670 Chem. Abstr., (1992), 116, 217512s. 

Synthesis of dinitramide salts. Proc. 25th Inti. Annual Conference of ICT, Karlsruhe, Germany, June 28-July 1,1994, pp. 13/1-13/9. 

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. 

Dinitramide Salts of Alkali Metals and Their Formulations... 

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. 

Alkali metal dinitramide salts are synthesized from aqueous solution of commercially available ADN by adding corresponding alkali metal hydroxide ... 

Alkali dinitramide salts oxidizers for special pyrotechnic applications. Proc.34th Intl.Ann.Conf. of ICT, Karlsruhe, Germany, June 24-27, 2003, pp. 38/1-38/5. 

The existence and preparation of stable dinitramides was disclosed publicly in two patent applications filed by the US military contractor SRI [1,2]. They cover a series of dinitramide salts, including ADN. The anion, N(N02)2", was named here for the first time as dinitramide, in contrast to the covalent alkyl compounds called dinitramines. The protonated form of the dinitramide anion was named dinitraminic acid, HN(N02)2. 

A large number of dinitramide salts have been reported in the literature. They are formed with metallic cations or with protonated organic nitrogen bases. 

Most of the metal salts will probably have a limited practical value due to poor thermal stability, low melting points and high hygroscopicity. For example, the dinitramide salts of Li, Na, K, Rb, and Cs all suffer from significant gas losses already at 80°C. 

So far, most interest has been focused on the dinitramide salts of nitrogen bases, particularly ADN. ADN starts to decompose slowly at 85°C. A vacuum stability test showed that 0.88 ml of gas per gram were evolved from a sample over a period of 40 hours. Despite this instability, it has been demonstrated that ADN-based formulations fulfill the military stability requirements at 80°C. However it is unlikely that ADN could be used in any military or commercial applications above its melting point. The rate of decomposition and its autocatalytic behavior conflict with safety considerations. 

Sensitivities have been studied for a number of dinitramide salts. The impact sensitivity has been published for ADN by several different laboratories. Below are values reported from the Naval Air Warfare Center, China Lake (CL), and FOI. As can be seen, the impact sensitivity is somewhat greater than RDX. Neat ADN is classified as LID according to the UN regulations for Transport of Dangerous Goods, which is the same classification that applies for RDX. 

Solutions of dmitramic acid can be used to synthesize dinitramide salts with metal hydroxides, carbonates or oxides, and the salts of amine bases ... 

The metal dinitramides are crystalline substances that are generally stable at 298 K and have low-melting points. They are usually nicely soluble in water, alcohols, acetonitrile, and other polar solvents. Heavy metal dinitramides like silver dinitramide are sensitive to friction. Silver dinitramide is used in metathesis reactions with halides to produce dinitramide salts. 

The optimized configuration of the dinitramide ion was determined to have C2 symmetry,[70] with the nitro groups twisted such that the oxygen atoms are positioned below and above the plane of the nitrogen atoms. There are small barriers of less than 3 kcal/mol for rotation in either direction about the N-NO2 bond. This characteristic has been used to explain the large variety of twist angles observed for the series of dinitramide salts.[30-36]... 

This section is introduced with the interesting report in a patent that the thermal stability of N,AT-dinitramide salts [M+[N(N02)]" in which M+ is a nitrogen-containing cation, is improved by mixing the salt with small amounts of a base of type 1 [107]. N,AT-Dinitramide salts are used as explosives and as rocket propellant oxidizers. 

M. D. Cliff, M. W. Smith, J. Energetic Mater. 1999, 17, 69-86. Thermal characteristics of alkali metal dinitramide salts. 

Dinitramide salts, and those of related pseudohalides, are also discussed in Section 11.9.3. A further five [N(N02)2] salts with various tetrazolium cations provide an opportunity to assess the inpact of variations in the latter on interionic interactions. These are (i) [5-amino-l-methyl-lEl-tetrazol-4-ium][N(N02)2] [269], which has a layer structure with all dinitramide... 

A series of dinitramide salts, [ER3][N(N02)2l (E = S, Se or Te R = Me or Ph), has been described, though only the structures of [SePh3] and [TePh3] salts are reported [659]. Other than a description of the methyl compounds as oily , no information regarding any of their melting temperatures is provided. The [EMe3] salts reportedly decompose more quickly than their phenyl analogues. 

Azaheterocyclic anions incorporated into so-called energetic salts are shown in Figure 11.8. Most are associated with protic cations. Dinitramide salts and those of related pseudohalides are also discussed in Section 11.9.3. 

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). 

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