Ammonium dinitramide
| Names | |
|---|---|
| IUPAC name
Ammonium dinitramide
| |
| Other names
ADN
Dinitramide ammonium salt | |
| Properties | |
| H4N4O4 | |
| Molar mass | 124.06 g/mol |
| Appearance | White solid |
| Odor | Odorless |
| Density | 1.81 g/cm3 |
| Melting point | 93 °C (199 °F; 366 K) |
| Boiling point | 160 °C (320 °F; 433 K) (decomposes) |
| 140 g/100 ml (-15 °C) 168.1 g/100 ml (-10 °C) 225.7 g/100 ml (0 °C) 356.6 g/100 ml (20 °C)[1] | |
| Solubility | Very soluble in acetone, acetonitrile, DMF, DMSO, ethanol, methanol Soluble in butanol, propanol Slightly soluble in dioxane, ethyl acetate, isopropanol, nitromethane Insoluble in benzene, diethyl ether, heptane, hexane, toluene, xylene[2] |
| Vapor pressure | ~0 mmHg |
| Thermochemistry | |
| Std enthalpy of
formation (ΔfH |
-150.6 kJ/mol[3] |
| Hazards | |
| Safety data sheet | None |
| Related compounds | |
| Related compounds
|
Ammonium nitrate |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Ammonium dinitramide (ADN) is the ammonium salt of dinitraminic acid, having the chemical formula NH4N(NO2)2. It is a much more powerful oxidizer than ammonium nitrate.
Contents
Properties
Chemical
Ammonium dinitramide decomposes when heated to give off water vapors, nitrogen and oxygen:
- NH4N(NO2)2 → 2 N2 + 2 H2O + O2
Small amounts of nitrous oxide and nitric oxide are also produced.
Physical
Ammonium dinitramide is a colorless crystalline solid, hygroscopic. It is very soluble in water, to the point it may prevent recrystallization of supersaturated solutions when cooled.[4]
Explosive
Ammonium dinitramide may explode when exposed to strong shock or very high temperatures, but overall it is stable. Detonation velocity is around 7,000 m/s, while friction sensitivity is determined to be 64 N.[5] Heat of Explosion is given as 2668 kJ/kg.
Availability
As this compound is still researched, ADN is not currently in any supplier's stock, not even Sigma-Aldrich/Merck don't have it.
One company claims to sell this compound.
Preparation
A route to obtain ammonium dinitramide involves nitration of potassium sulfamate, a salt of sulfamic acid. A 1:3.5 sulfuric-to-nitric acid ratio maximizes nitronium ion formation, achieving 45% yield in 25 minutes. The potassium sulfamate salt is obtained by neutralizing sulfamic acid with potassium hydroxide or carbonate, then the solution is dried and solid potassium sulfamate is collected.
- H2NSO3H + KOH → H2NSO3K + H2O
- H2NSO3H + K2CO3 → H2NSO3K + H2O + CO2
In a reaction flask, a nitrating mixture consisting of 106 ml fuming nitric acid and 26.4 ml conc. sulfuric acid are added, and the flask is cooled to -40 °C. The stirring is turned on, and the dry potassium sulfamate (40 g) is slowly added in 4 g portions for 10 min. As the reaction progresses, the viscosity of the mixture increases, as the potassium (bi)sulfate precipitates, yielding the unstable dinitramidic acid. Stirring continues for 30 more minutes. The resulting mixture is poured in crushed ice, and neutralized with a cold solution of potassium hydroxide, under cooling. The product is filtrated and extracted using acetone. The yield of this process is almost 50%. The ammonium dinitramide is obtained from the potassium salt via metathesis with ammonium sulfate in isopropanol.[6][7] An approximate equation for the nitration can be written as:
- H2NSO3K + 2 HNO3 → HN(NO2)2 + KHSO4 + H2O
Urethane nitration is another synthesis route. Conc. fumic nitric acid reacts with dry ethyl carbamate to yield N-nitrourethane. Ammonia is added, yielding N-nitrourethane ammonium salt (ammonium ethyl N-nitrocarbamate). This product is nitrated a second time using dinitrogen pentoxide to give ethyl dinitrocarbamate. Ethyl dinitrocarbamate is treated with ammonia, which yields ammonium dinitramide, and regenerate ethyl carbamate.[8]
- CH3CH2−O−C(=O)−NH2 + HNO3 → CH3CH2−O−C(=O)−NH−NO2 + H2O
- CH3CH2−O−C(=O)−NH−NO2 + NH3 → [CH3CH2−O−C(=O)−N−NO2][NH4]
- [CH3CH2−O−C(=O)−N−NO2][NH4] + O(NO2)2 → CH3CH2−O−C(=O)−N(NO2)2 + NH4NO3
- CH3CH2−O−C(=O)−N(NO2)2 + 2 NH3 → CH3CH2−O−C(=O)−NH2 + NH4N(NO2)2
Another route to this compounds given in literature involves dissolving nitramide in dry and cold (-10 °C) acetonitrile, followed by the addition of nitronium tetrafluoroborate. The mixture is stirred for 10 min, after which an etheric solution of ammonia in isopropanol is added to the acetonitrile solution. The solvent is removed from the product and the ADN is recrystallized from n-butanol.[9]
- H2N-NO2 + NO2BF4 → HN(NO2)2 + HBF4
- HN(NO2)2 + NH3 → NH4N(NO2)2
The reaction of dinitrogen pentoxide with ammonia in dichloromethane at -78 °C, is claimed to give ammonium dinitramide. To obtain the compound, the reaction product is warmed to room temperature, the CH2Cl2 is removed then the compound is extracted with acetone. Further purification can be achieved by recrystallizing the compound from n-butanol. Total yield is 15%. If the reaction takes place at higher temperatures, the yield will be lower.[10]
A synthesis without a source is given on Wikipedia, but due to the lack of references it's unclear if it actually works: Ammonium dinitramide can be synthesized from ammonium nitrate, anhydrous nitric acid, and fuming sulfuric acid containing 20% free sulfur trioxide. A base other than ammonia must be added before the acid dinitramide decomposes. The final product is obtained by fractional crystallization.
Projects
- Rocket fuel and propellant
- Oxidizer
- Source of dinitramide for reactions
Handling
Safety
Ammonium dinitramide is a powerful oxidizer and may explode under strong heating or shock. Handle it with care.
Storage
Ammonium dinitramide should be kept in closed plastic bottles, away from acids and anything combustible.
Disposal
Carefully heating the compound will cause it to decompose. For safety, you can mix it with a non-flammable material, like gypsum before heating.
References
- ↑ https://pubs.acs.org/doi/abs/10.1021/je0600698
- ↑ Energy Condensed Systems. - Ed. by B.P. Zhukov, 2nd ed. - Moscow: Janus-K, 2000 (Энергетические конденсированные системы. - Под ред. Жукова Б.П., 2-е изд. - М.: Янус-К, 2000)
- ↑ Propellants, Explosives, Pyrotechnics. - 2004. - Vol. 29, No. 3 pp. 183
- ↑ https://publica-rest.fraunhofer.de/server/api/core/bitstreams/0c792c3c-a500-438d-89d6-cf0d555ef623/content
- ↑ https://eurenco.com/wp-content/uploads/Product-Catalogue-EURENCO-2.pdf
- ↑ https://patents.google.com/patent/US5976483
- ↑ https://www.researchgate.net/publication/288230194_Safety_of_Ammonium_Dinitramide_Synthesis_vs_Size_of_a_Commercial_Production_Scale
- ↑ https://patentimages.storage.googleapis.com/9c/54/a3/93c7859bbd0bf9/US5714714.pdf
- ↑ Bottaro, Jeffrey C.; Penwell, Paul E.; Schmitt, Robert J.; Journal of the American Chemical Society; vol. 119; nb. 40; (1997); p. 9405 - 9410
- ↑ Bottaro, Jeffrey C.; Penwell, Paul E.; Schmitt, Robert J.; Journal of the American Chemical Society; vol. 119; nb. 40; (1997); p. 9405 - 9410
