Ammonium dinitramide

Ammonium dinitramide was invented in 1971 at the Zelinsky Institute of Organic Chemistry in the USSR. Initially all information related to this compound was classified because of its use as a rocket propellant, particularly in Topol-M intercontinental ballistic missiles. In 1989 ammonium dinitramide was independently synthesized at SRI International. SRI obtained US and international patents for ADN in the mid-1990s, at which time scientists from the former Soviet Union revealed that they had discovered ADN earlier. == Propellant mixtures ==

ADN can be mixed with conventional propellants such as nitrocellulose to improve its oxygen balance. One of the challenges of using ADN is its hygroscopicity. Hu et al. have investigated the possibility of reducing the hygroscopicity of ADN by co-crystallization with 3,4-diaminofurazan. There is also interest in using ADN to make liquid monopropellants. When ADN is co-crystalized with a crown ether (18C6), the hygroscopicity is greatly reduced, but so is its performance as an explosive. ADN was mixed with amine nitrates in order to lower its melting point for use as a liquid monopropellant. The onset temperature for ADN was essentially unchanged, but some cross-reaction with the amine nitrates was observed. Kim et al. have also examined mixtures of ADN with hydrogen peroxide as a potential liquid monopropellant. == Preparation ==

There are at least 20 different synthesis routes that produce ammonium dinitramide. In the laboratory ammonium dinitramide can be prepared by nitration of sulfamic acid or its salts (here sodium sulfamate) at low temperatures in the presence of concentrated sulfuric acid, followed by neutralization of the intermediate dinitramidic acid () with ammonia: : : The process is performed under red light, since the compound is decomposed by higher-energy photons. An improvement of this method instead synthesizes Guanylurea dinitramide (FOX-12) as a starting point, reacts this with potassium hydroxide (KOH) to form a potassium dinitramide (KDN), and finally produces ammonium dinitramide via salt metathesis reaction of KDN with ammonium sulfate. Ethyl carbamate is nitrated with nitric acid: : and then reacted with ammonia to form the ammonium salt of N-nitrourethane: : This is nitrated again with nitrogen pentoxide to form ethyl dinitrocarbamate and ammonium nitrate: : Finally, treatment with ammonia again splits off the desired ammonium dinitramide and regenerates the urethane starting material: : ==References==