Hydrogen dinitramide

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,... 

The research into energetic molecules which produce a large amount of gas per unit mass, led to molecular structures which have a high hydrogen to carbon ratio. Examples of these structures are hydrazinium nitroformate (HNF) and ammonium dinitramide (ADN). The majority of the development of HNF has been carried out in The Netherlands whereas the development of ADN has taken place in Russia, USA and Sweden. ADN is a dense non chlorine containing powerful oxidiser and is an interesting candidate for replacing ammonium perchlorate as an oxidiser for composite propellants. ADN is less sensitive to impact than RDX and HMX, but more sensitive to friction and electrostatic spark. 

Ammonium dinitramide, 4523a Ammonium 3,5-dinitro-l,2,4-triazolide, 0819 Ammonium l,2-ethylenebis(nitramide), 0968 Ammonium fluoride, 4293 Ammonium fluorochromate, 4218 Ammonium hexachloroplatinate, 4180 Ammonium hexacyanoferrate(II), 2572 Ammonium hexanitrocobaltate(3—), 4200 Ammonium hydrogen sulfite, 4540 Ammonium hydroxide, 4539... 

In many energetic materials, significant hydrogen bonding is observed. This is particularly true of a number of salts of the dinitramide anion. In... 

In the gas phase, the dinitramide ion N(N02)2 has symmetry. In the solid state, the symmetry is often distorted by interactions with the counterion, for example, hydrogen bonding with the ammonium ion in ammonium dinitramide (see Table 33). The N-NO2 rotation barrier is very low. In fact, though the bond lengths of the nitramide ion remain fairly constant, no two-dinitramide crystal structures show the same geometry of the dinitramide anion. The crystal stmcture of lithium dinitramide shows the symmetric anion. 

An alternative mechanism was suggested by Oxley and coworkers. [59] They concluded that above 160°C the decomposition occurs by a free-radical mechanisms while an ionic mechanism is important below this temperature. The decomposition of ADN leads to nitrous oxide, nitric acid or nitrate and nitrogen gas. It was assumed that the first step in ADN decomposition is hydrogen transfer to form ammonia and dinitramic acid. Several proposed decomposition pathways for ADN decomposition that involve conversion of the dinitramide ion to N2O have been proposed but they await confirmation.[59]... 

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