Nitroguanidine

Not to be confused with Guanidine nitrate.

Nitroguanidine - sometimes abbreviated NGu - is a colorless, crystalline solid that melts at 257 °C and decomposes at 254 °C. Nitroguanidine is an extremely insensitive but powerful high explosive. Wetting it with > 20 wt.-% water effects desensitization from HD 1.1 down to HD 4.1 (flammable solid).^[2] Nitroguanidine is used as an energetic material, i.e., propellant or high explosive, precursor for insecticides, and for other purposes.

Nitroguanidine

Names
IUPAC name 1-Nitroguanidine
Other names Picrite NGu NQ[1]
Identifiers
CAS Number	556-88-7 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:39180 Y
ChemSpider	10701 Y
ECHA InfoCard	100.008.313
PubChem CID	11174
UNII	NAY6KWL67F Y
CompTox Dashboard (EPA)	DTXSID4024222
InChI InChI=1S/CH4N4O2/c2-1(3)4-5(6)7/h(H4,2,3,4) Y Key: IDCPFAYURAQKDZ-UHFFFAOYSA-N Y InChI=1/CH4N4O2/c2-1(3)4-5(6)7/h(H4,2,3,4) Key: IDCPFAYURAQKDZ-UHFFFAOYAN
SMILES NC(N)=N[N+]([O-])=O
Properties
Chemical formula	CH4N4O2
Molar mass	104.07 g/mol
Appearance	Colorless crystalline solid
Density	1.77 g/cm3
Melting point	257 °C (495 °F; 530 K)
Solubility in water	3.45 g/kg (in water at 25 °C)
Explosive data
Shock sensitivity	> 50 J
Friction sensitivity	> 350 N
RE factor	1.5
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Explosive
Related compounds
Related compounds	Guanidine Guanidine nitrate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Manufacture

Nitroguanidine is produced worldwide on a large scale starting with the reaction of dicyandiamide (DCD) with ammonium nitrate to afford the salt guanidinium nitrate, which is then nitrated by treatment with concentrated sulfuric acid at low temperature.^[3]

[C(NH₂)₃]NO₃ → (NH₂)₂CNNO₂ + H₂O

The guanidinium nitrate intermediate may also be produced via the Boatright–Mackay–Roberts (BMR) process, in which molten urea is reacted with molten ammonium nitrate in the presence of silica gel.^[3][4] This process had been commercialized because of its attractive economic features.

2 NH₂CONH₂ + NH₄NO₃ → [C(NH₂)₃]NO₃ + 2 NH₃ + CO₂

Uses

Explosives

Nitroguanidine has been in use since the 1930s as an ingredient in triple-base gun propellants in which it reduces flame temperature, muzzle flash, and erosion of the gun barrel but preserves chamber pressure due to high nitrogen content. Its extreme insensitivity combined with low cost has made it a popular ingredient in insensitive high explosive formulations (e.g AFX-453, AFX-760, IMX-101, AL-IMX-101, IMX-103, etc.).^[5]

The first triple-base propellant, featuring 20-25% of nitroguanidine and 30-45% nitroglycerine, was developed at the Dynami Nobel factory at Avigliana and patented by its director Dr. Modesto Abelli (1859-1911) in 1905.^[6][7]

Nitroguanidine's explosive decomposition may be given by the following idealized equation:

3 O₂N−N=C(NH₂)₂ → 3 CO₂ + 4 N₂ + 4 NH₃

Pesticides

Nitroguanidine derivatives are used as insecticides, having a comparable effect to nicotine. Derivatives include clothianidin, dinotefuran, imidacloprid, and thiamethoxam.

Structure

Following several decades of debate, it could be confirmed by NMR spectroscopy, and both x-ray and neutron diffraction that nitroguanidine exclusively exists as the nitroimine tautomer both in solid state and solution.^[8][9][10]

Related compounds

The nitrosoylated derivative, nitrosoguanidine, is used to mutagenize bacterial cells for biochemical studies.