Guanidine nitrate explained

Guanidine nitrate is the chemical compound with the formula [C(NH<sub>2</sub>)<sub>3</sub>]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).[3]

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

[C(NH2)3]NO3 (s) -> 3 H2O (g) + 2 N2 (g) + C (s)

Uses

Guanidine nitrate is used as the gas generator in automobile airbags.[4] 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).[5]

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]

External links

Notes and References

  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. Thomas Güthner, Bernd Mertschenk and Bernd Schulz "Guanidine and Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2006, Wiley-VCH, Weinheim.
  3. 1000 lbf/in2 (700 kPa) chamber pressure, 14.7 lbf/in2 (101 kPa) exit pressure, shifting equilibrium theoretical performance, calculated in ProPEP.
  4. News: Tabuchi. Hiroko. Hiroko Tabuchi. 2016-08-26. A Cheaper Airbag, and Takata's Road to a Deadly Crisis (Published 2016). en-US. The New York Times . 2021-03-10. 0362-4331.
  5. Halford . Bethany . What chemicals make airbags inflate, and how have they changed over time? . . November 15, 2022 . 100 . 41 . 4 June 2023 . The chemical reaction used to deploy airbags has evolved, but one iteration resulted in massive recalls.