Decomposition ammonium dinitramide

Politzer, R, Seminario, J. M., Concha, M. (1998). Energetics of ammonium dinitramide decompositions Steps. J. Molec. Struct. (Theochem) 427,123-129. 

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. 

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 perchlorate and ammonium dinitramide can decompose by similar routes, but perchlorate, in particular, has several other decomposition pathways available. One decomposition route of ADN produces ammonium nitrate andN20 [138],... 

M. D. Pace, Nitrogen Radical from Thermal and Photochemical Decomposition of Ammonium Perchlorate, Ammonium Dinitramide, and Cyclic Nitramines, M. R. S. Proceed, 296 (1993) 53-60. 

S. Vyazovkin, C.A. Wight Thermal Decomposition of Ammonium Dinitramide at Moderate and High Temperatures, J. Phys. Chem., 101 (1996) 7217-7221. 

Organic dinitramines of the type RCH2CH2N(N02)2 with an electron accepting group (R = CN, CHO, COR, COOR, or NO2) eliminate ammonium dinitramide and acrylic compounds H2C=CHR during decomposition in aqueous solutions of ammonia. 

All nitration reactions are highly exothermic and require temperatures below 273 K to achieve good yields and to avoid decomposition of ammonium dinitramide to gaseous products and ammonium nitrate. 

At ambient conditions ammonium dinitramide has not been found to be polymorphic the crystal structure of the orthorhombic a form under those conditions has been reported by Gilardi et al. (1997). The pressure/temperature studies led to the discovery of a second monoclinic phase (/3) formed from the a phase at 2.0 0.2 GPa. As the pressure is further raised, a solid state rearrangement, melting, and thermal decomposition take place. 

Ammonium Dinitramide. The thermal decomposition of ADN has been investigated in a large number of experimental studies.[55-60] The mechanism appears to be quite complex and highly dependent on experimental temperature and pressure conditions. Here we summarize only the main models that have been proposed. Brill and coworkers [56] have proposed a mechanism for the gas-phase decomposition that involves sublimation to NH3 and HN(N02)2 via the reactions ... 

Figure 5. Possible steps involved in decomposition of ammonium dinitramide (after Politzer etal.

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). 

DSC and DTA measurements show melting of ADN, NH4N(N02)2, at 328 K, the onset of decomposition at 421 K, and an exothermic peak at 457 K.l l Gasification of 30% of the mass of ADN occurs helow the exothermic peak temperature, and the remaining 70% decomposes after the peak temperature. The decomposition is initiated by dissociation into ammonia and hydrogen dinitramide. The hydrogen dinitramide further decomposes to ammonium nitrate and NjO. The final decomposition products in the temperature range 400-500 K are NH3, HjO, NO,... 

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 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 ... 

---