Ammonium dinitramide

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Ammonium dinitramide
Names
IUPAC name
Azanium dinitroazanide[1]
Other names
  • Ammonium dinitroazanide[1]
  • Ammonium dinitramide[1]
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.126.585 Edit this at Wikidata
EC Number
  • 604-184-9
UNII
  • InChI=1S/N3O4.H3N/c4-2(5)1-3(6)7;/h;1H3/q-1;/p+1 checkY
    Key: BRUFJXUJQKYQHA-UHFFFAOYSA-O checkY
  • InChI=1/N3O4.H3N/c4-2(5)1-3(6)7;/h;1H3/q-1;/p+1
    Key: BRUFJXUJQKYQHA-IKLDFBCSAM
SMILES
  • [NH4+].[N-]([N+](=O)[O-])[N+](=O)[O-]
Properties
[NH4][N(NO2)2]
Molar mass 124.06 g/mol
Density 1.81 g/cm3
Melting point 93 °C (199 °F; 366 K)
Boiling point decomposes at 127 °C (261 °F; 400 K)
Structure[1]
a = 6.914 Å, b = 11.787 Å, c = 5.614 Å
α = 90.00°, β = 100.40°, γ = 90.00°
4
Thermochemistry
Std enthalpy of
formation
(ΔfH⦵298)
 −148 kJ/mol[2]
−150.6 kJ/mol
Explosive data
Shock sensitivity Low[2]
Friction sensitivity Low
Hazards
GHS labelling:
GHS01: ExplosiveGHS02: FlammableGHS07: Exclamation markGHS08: Health hazard
Danger
H201, H228, H302, H371
P210, P230, P240, P241, P250, P260, P264, P270, P280, P301+P312, P309+P311, P330, P370+P378, P370+P380, P372, P373, P401, P405, P501
Related compounds
Other cations
 Guanylurea dinitramide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Ammonium dinitramide (ADN) is an

anions −N(NO2)2. ADN decomposes under heat to leave only nitrogen, oxygen, and water
.

It makes an excellent

solid rocket oxidizer with a slightly higher specific impulse than ammonium perchlorate and, more importantly, does not leave corrosive hydrogen chloride fumes. This property is also of military interest because halogen-free smoke is harder to detect. It decomposes into low-molecular-mass gases, which contributes to higher performance without creating excessive temperatures if used in gun or rocket propellants. However, the dinitramide salt is more prone to detonation under high temperatures and shock compared with the perchlorate
.

The

carcinogenic, while LMP-103S is only moderately toxic. LMP-103S is UN Class 1.4S, allowing for transport on commercial aircraft, and was demonstrated on the Prisma satellite in 2010. Special handling is not required. LMP-103S could replace hydrazine as the most commonly used monopropellant.[3][4]

The ADN-based monopropellant FLP-106 is reported to have improved properties relative to LMP-103S, including higher performance (ISP of 259 s vs. 252 s) and density (1.362 g/cm3 vs. 1.240 g/cm3).[5]

History

Ammonium dinitramide was invented in 1971 at the

intercontinental ballistic missiles. In 1989 ammonium dinitramide was independently synthesized at SRI International.[6] 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 18 years earlier.[6]

Propellant mixtures

ADN can be mixed with conventional

hygroscopicity. Hu et al. have investigated the possibility of reducing the hygroscopicity of ADN by co-crystallization with 3,4-diaminofurazan.[8]

There is also interest in using ADN to make liquid

18C6), the hygroscopicity is greatly reduced, but so is its performance as an explosive.[9] 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.[10] Kim et al. have also examined mixtures of ADN with hydrogen peroxide as a potential liquid monopropellant.[11]

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 potassium sulfamate) at low temperatures:

KSO3NH2 + 2 HNO3 → KHSO4 + [NH4]N(NO2)2 + H2O

The process is performed under red light, since the compound is decomposed by higher-energy

photons
. The details of the synthesis remain classified.

Other sources[

fuming sulfuric acid (oleum) 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
.

Another synthesis known as the urethane synthesis method requires four synthesis steps and results in a yield of up to 60%.[12] Ethyl carbamate is nitrated with nitric acid:

CH3CH2−O−C(=O)−NH2 + HNO3 → CH3CH2−O−C(=O)−NH−NO2 + H2O

and then reacted with ammonia to form the ammonium salt of N-nitrourethane:

CH3CH2−O−C(=O)−NH−NO2 + NH3 → [CH3CH2−O−C(=O)−N−−NO2][NH+4]

This is nitrated again with

nitrogen pentoxide to form ethyl dinitrocarbamate and ammonium nitrate
:

[CH3CH2−O−C(=O)−N−−NO2][NH+4] + O(NO2)2 → CH3CH2−O−C(=O)−N(NO2)2 + [NH4]+NO−3

Finally, treatment with ammonia again splits off the desired ammonium dinitramide and regenerates the urethane starting material:

CH3CH2−O−C(=O)−N(NO2)2 + 2 NH3 → CH3CH2−O−C(=O)−NH2 + [NH+4][−N(NO2)2]

References

  1. ^ a b c d "Ammonium dinitramide". pubchem.ncbi.nlm.nih.gov. Retrieved 2024-07-18.
  2. ^
    S2CID 94304770
    .
  3. ^ "Green propellant LMP 103S". ecaps.se. Retrieved 2024-04-25.
  4. ISSN 0721-3115
    .
  5. ISBN 978-953-307-551-8
    .
  6. ^ a b "Dinitramide Salts: ADN Plus Other Salts". SRI International. Archived from the original on 2012-05-26. Retrieved 2012-04-15.
  7. PMID 36903591
    .
  8. doi:10.1016/j.cjche.2023.01.006
    .
  9. doi:10.1016/j.enmf.2022.03.001
    .
  10. doi:10.1007/s10973-018-7875-6
    .
  11. doi:10.1016/j.asr.2021.11.022
    .
  12. ^ US 5714714, Stern, Alfred G.; Koppes, William M. & Sitzmann, Michael E. et al., "Process for preparing ammonium dinitramide", published 1998-02-03, assigned to USA, Secretary of the Navy 

Further reading

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