Nitroguanidine
- NQ
- Picrite
- Guanite
- Nigu
Fixed
1.78 g · cm -3
239 ° C ( decomposition)
Slightly soluble in cold water, soluble in hot water, very slightly soluble in alcohol
Attention
-92.88 KJ · mol -1
Template: Infobox chemical / molecular formula search available
Nitroguanidine ( also abbreviated nigu or NQ ) is a high-energy, metastable chemical compound from the group of Nitroimine which has great importance as a component of propellants and explosives safety.
Nitroguanidine itself is a very insensitive explosive, which is characterized by a particularly low detonation energy, but a detonation velocity of 8200 m · s- 1 which is almost as high as that of RDX (RDX, 8750 m · s -1).
Production and representation
Nitroguanidine formed by the action of cold concentrated sulfuric acid, guanidine nitrate. It can also be prepared by the reaction of dicyandiamide with ammonium nitrate.
Properties
Nitroguanidine forms colorless, orthorhombic, needle-shaped crystals. His experimental X-ray density is 1.78 g / cm ³, its melting point is 239 ° C ( Subl., decomp. ). Nitroguanidine is not hygroscopic. It is sparingly soluble in cold water, methanol and ethanol, soluble in hot water ( slow hydrolysis ), acids and bases ( decomposition). It forms addition compounds with ketones and alcohols.
Nitroguanidine exists in two forms: α - nitroguanidine ( stable) and β - nitroguanidine. Both forms are not changed by recrystallization from water, acetic acid or ammonia.
If β - nitroguanidine dissolved in 96% sulfuric acid and the solution added to water, then α - nitroguanidine separates.
The thermal decomposition of the relevant compound at temperatures above 150 ° C. As products of decomposition of dinitrogen monoxide, ammonia, nitrogen dioxide, carbon monoxide and carbon dioxide are observed.
Explosion characteristics
Nitroguanidine is very insensitive and detonated just after initiation with a booster (booster). Important explosion indicators are:
- Explosion heat 3062 kJ · kg -1.
- Detonation temperature 2800 K at maximum density calculated according to
- Detonation velocity: 8200 m · s-1 at the maximum density
- Detonation pressures: 27 GPa
- Detonation temperature: 2811 K
- Lead block expansion cm3/10 305 g
- Impact sensitivity to 50 N · m no reaction
- Friction sensitivity to 353 N pin load no reaction
- Steel sleeve test, no ignition occurs at a critical diameter 1 mm.
The detonation velocity Vd of the nitroguanidine increases, as with all explosives, with a density of. vD follows in the range of 0.3 to 1.78 g · cm -3 the following law: vD = 1.44 4.015 · Density [mm · microseconds -1] (also see graphic below )
Nitroguanidine belongs to the strong, but hard detonating explosives. Thus, the strong dependence of detonation velocity on the diameter explains. A charge having a density of 0.95 g/cm3 in a tube of 20 mm inner diameter, a velocity of detonation of 4340 m / s
Use
Nitroguanidine is used in gas - generating sets for airbags and in so-called "cold" propellant powders, which protect the legs and give less muzzle flash. Nigu is less sensitive compared to impact, friction and impact than TNT, with this, however, as to its explosive nature (chemistry), performance.
Nitroguanidine comes as a fine noble LBDNQ (low bulk density nitroguanidine ) as well as a granular HBDNQ (high bulk density NQ ) and very rarely as spherical SHBDNQ (spherical high bulk density NQ ) in the trade.
Nitroguanidine is a building block for insecticides from the fastest growing class of neonicotinoids, whose most important representatives Imidacloprid ( Bayer Crop Science), clothianidin (Takeda, Bayer Crop Science), thiamethoxam ( Syngenta ) and Dinotefuran (Mitsui Chemicals) are.
Structure
In many sources, for example, also a wrong structural formula is given for nitroguanidine, which NQ would be a nitramine. However, stands by Neutronenbeugungund 1H and 15N NMR experiments clearly states that nitroguanidine is a Nitroimin.