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). Nitroguanidine is used as an energetic material, i.e., propellant or high explosive, precursor for insecticides, and for other purposes.

Manufacture

Nitroguanidine is produced worldwide on a large scale starting with the reaction of

dicyandiamide 2-Cyanoguanidine is a nitrile derived from guanidine. It is a dimer of cyanamide, from which it can be prepared. 2-Cyanoguanidine is a colourless solid that is soluble in water, acetone, and alcohol, but not nonpolar organic solvents. Production ...

(DCD) with

ammonium nitrate Ammonium nitrate is a chemical compound with the chemical formula . It is a white crystalline salt consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is ...

to afford the salt

guanidinium nitrate Guanidine nitrate is the chemical compound with the formula (NH2)3O3. It is a colorless, water-soluble salt. It is produced on a large scale and finds use as precursor for nitroguanidine, fuel in pyrotechnics and gas generators. Its correc ...

, which is then nitrated by treatment with concentrated sulfuric acid at low temperature. : (NH₂)₃O₃ → (NH₂)₂CNNO₂ + H₂O Nitroguanidine can also be generated by treatment of

urea Urea, also known as carbamide, is an organic compound with chemical formula . This amide has two amino groups (–) joined by a carbonyl functional group (–C(=O)–). It is thus the simplest amide of carbamic acid. Urea serves an important r ...

with ammonium nitrate (via the

BMA process The BMA process or Degussa process is a chemical process developed by the German chemical company Degussa for the production of hydrogen cyanide from methane and ammonia in presence of a platinum catalyst. Hydrogen cyanide is used in the chemical i ...

). However, owing to problems of reliability and safety, this process has never been commercialized despite its attractive economic features.

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 IMX-101 is a high-performance insensitive high explosive composite mixture developed by BAE Systems and the United States Army to replace TNT in artillery shells, starting as soon as 2011. IMX stands for "Insensitive Munitions eXplosives", which ...

, AL-IMX-101, IMX-103, etc.). Nitroguanidine's explosive decomposition is given by the following equation: H₄N₄CO_{2 ''(s)''} → 2 H₂O_''(g)'' + 2 N_{2 ''(g)''} + C_''(s)''

Pesticides

Nitroguanidine derivatives are used as

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

s, having a comparable effect to

nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

. Derivatives include

clothianidin Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has be ...

dinotefuran Dinotefuran is an insecticide of the neonicotinoid class developed by Mitsui Chemicals for control of insect pests such as aphids, whiteflies, thrips, leafhoppers, leafminers, sawflies, mole cricket, white grubs, lacebugs, billbugs, beetles, m ...

imidacloprid Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. ...

, and

thiamethoxam Thiamethoxam is the ISO common name for a mixture of ''cis-trans'' isomers used as a systemic insecticide of the neonicotinoid class. It has a broad spectrum of activity against many types of insects and can be used as a seed dressing. Histor ...

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 Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy or magnetic resonance spectroscopy (MRS), is a spectroscopic technique to observe local magnetic fields around atomic nuclei. The sample is placed in a magnetic fiel ...

, and both

x-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

and

neutron diffraction Neutron diffraction or elastic neutron scattering is the application of neutron scattering to the determination of the atomic and/or magnetic structure of a material. A sample to be examined is placed in a beam of thermal or cold neutrons to o ...

that nitroguanidine exclusively exists as the nitroimine

tautomer Tautomers () are structural isomers (constitutional isomers) of chemical compounds that readily interconvert. The chemical reaction interconverting the two is called tautomerization. This conversion commonly results from the relocation of a hydr ...

both in solid state and solution.S. Choi, Refinement of 2-Nitroguanidine by Neutron Powder Diffraction, ''Acta Crystallogr. B'' 1981, ''37'', 1955-195

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References

{{reflist Explosive chemicals Propellants