Chemistry:Guanidine nitrate

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Guanidine nitrate
Guanidinium nitrate.png
Ball-and-stick models of the constituent ions
Names
IUPAC name
Guanidinium nitrate
Identifiers
3D model (JSmol)
ChemSpider
EC Number
  • 208-060-1
RTECS number
  • MF4350000
UNII
UN number 1467
Properties
CH6N4O3
Molar mass 122.1
Appearance White solid
Density 1.436 g/cm3
Melting point 216 °C (421 °F; 489 K)
Boiling point Decomposes commencing at 240 °C
160 g/L at 20 °C
Hazards
Safety data sheet MSDS
GHS pictograms GHS03: OxidizingGHS05: CorrosiveGHS07: Harmful
GHS Signal word Danger
H272, H302, H315, H318, H319, H332, H335
P210, P220, P221, P261, P264, P270, P271, P280, P301+312, P302+352, P304+312, P304+340, P305+351+338, P310, P312, P321, P330, P332+313, P337+313, P362, P370+378, P403+233, P405, P501
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 4: Readily capable of detonation or explosive decomposition at normal temperatures and pressures. E.g. nitroglycerinSpecial hazards (white): no codeNFPA 704 four-colored diamond
1
2
4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Guanidine nitrate is the chemical compound with the formula [C(NH2)3]NO3. It is a colorless, water-soluble salt. It is produced on a large scale and finds use as precursor for nitroguanidine,[1] fuel in pyrotechnics and gas generators. Its correct name is guanidinium nitrate, but the colloquial term guanidine nitrate is widely used.

Production and properties

Although it is the salt formed by neutralizing guanidine with nitric acid, guanidine nitrate is produced industrially by the reaction of dicyandiamide (or calcium salt) and ammonium nitrate.[2]

It has been used as a monopropellant in the Jetex engine for model airplanes. It is attractive because it has a high gas output and low flame temperature. It has a relatively high monopropellant specific impulse of 177 seconds (1.7 kN·s/kg).[note 1]

Guanidine nitrate's explosive decomposition is given by the following equation:

[math]\ce{ [C(NH2)3]NO3 (s) -> 3 H2O (g) + 2 N2 (g) + C (s) }[/math]

Uses

Guanidine nitrate is used as the gas generator in automobile airbags.[3] It is less toxic than the mixture used in older airbags of sodium azide, potassium nitrate and silica (NaN3, KNO3, and SiO2), and it is less explosive and sensitive to moisture compared to the very cheap ammonium nitrate (NH4NO3).[4]

Safety

The compound is a hazardous substance, being an explosive and containing an oxidant (nitrate). It is also harmful to the eyes, skin, and respiratory tract.[2]

Notes

  1. 1000 lbf/in2 (700 kPa) chamber pressure, 14.7 lbf/in2 (101 kPa) exit pressure, shifting equilibrium theoretical performance.
  1. E.-C. Koch, Insensitive High Explosives: III. Nitroguanidine - Synthesis - Structure - Spectroscopy- Sensitiveness, Propellants Explos. Pyrotech. 2019, 44, 267-292.https://onlinelibrary.wiley.com/doi/10.1002/prep.201800253
  2. 2.0 2.1 Thomas Güthner, Bernd Mertschenk and Bernd Schulz "Guanidine and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH, Weinheim. doi:10.1002/14356007.a12_545.pub2
  3. Tabuchi, Hiroko (2016-08-26). "A Cheaper Airbag, and Takata's Road to a Deadly Crisis (Published 2016)" (in en-US). The New York Times. ISSN 0362-4331. https://www.nytimes.com/2016/08/27/business/takata-airbag-recall-crisis.html. 
  4. Halford, Bethany (November 15, 2022). "What chemicals make airbags inflate, and how have they changed over time?". Chemical & Engineering News 100 (41). https://cen.acs.org/safety/chemicals-make-airbags-inflate-changed/100/i41. Retrieved 4 June 2023. "The chemical reaction used to deploy airbags has evolved, but one iteration resulted in massive recalls".  open access

External links