Nitroguanidine

Nitroguanidine- abbreviated NGu or NQ- is a colorless, crystalline solid that melts at 257 °C and decomposes at 254 °C. NGu is an extremely insensitive but powerful high explosive. Wetting NGu with > 20 wt.-% water effects desensitization from HD 1.1 down to HD 4.1 (flammable solid).
NGu is used as an energetic material (propellants, High explosives), precursor for insecticides, and for other purposes.
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, GN. GN is nitrated by treatment with concentrated sulfuric acid at low temperature.
Nitroguanidine can also be generated by treatment of urea with ammonium nitrate (BMR-process). However, owing to problems of reliability and safety, this process has never been commercialized despite its attractive economic features.
Uses.
Explosives.
Nitroguanidine is 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 NGu become a popular ingredient in insensitive high explosive formulations (e.g AFX-453, AFX-760, IMX-101, AL-IMX-101, IMX-103, etc.).
Nitroguanidine's explosive decomposition is given by the following equation:
H4N4CO2 "(s)" → 2 H2O "(g)" + 2 N2 "(g)" + C "(s)"
Pesticides.
Nitroguanidine derivatives are used as insecticides, having a comparable effect to nicotine. Derivatives include clothianidin, dinotefuran, imidacloprid, and thiamethoxam.
Biochemistry.
The nitrosoylated derivative nitrosoguanidine is often used to mutagenize bacterial cells for biochemical studies.
Structure.
Following several decades of debate, it could be confirmed by NMR-spectroscopy, X-ray and neutron diffraction that nitroguanidine exclusively exists as the nitroimine tautomer both in solid state and solution.