Nitroguanidine

Not to be confused with Guanidine nitrate.
Nitroguanidine
Names
IUPAC name
1-Nitroguanidine
Other names
Picrite
NGu
NQ[1]
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.008.313 Edit this at Wikidata
UNII
  • InChI=1S/CH4N4O2/c2-1(3)4-5(6)7/h(H4,2,3,4) checkY
    Key: IDCPFAYURAQKDZ-UHFFFAOYSA-N checkY
  • InChI=1/CH4N4O2/c2-1(3)4-5(6)7/h(H4,2,3,4)
    Key: IDCPFAYURAQKDZ-UHFFFAOYAN
  • NC(N)=N[N+]([O-])=O
Properties
CH4N4O2
Molar mass 104.07 g/mol
Appearance Colorless crystalline solid
Density 1.77 g/cm3
Melting point 257 °C (495 °F; 530 K)
3.45 g/kg (in water at 25 °C)
Explosive data
Shock sensitivity > 50 J
Friction sensitivity > 350 N
RE factor 1.00
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).
checkY verify (what is checkY☒N ?)

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.

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 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, and both x-ray and neutron diffraction that nitroguanidine exclusively exists as the nitroimine tautomer both in solid state and solution.[8][9][10]

References

  1. ^ Gao, Han; Wang, Qinghua; Ke, Xiang; Liu, Jie; Hao, Gazi; Xiao, Lei; Chen, Teng; Jiang, Wei; Liu, Qiao'e (2017). "Preparation and characterization of an ultrafine HMX/NQ co-crystal by vacuum freeze drying method". RSC Adv. 7 (73): 46229–46235. doi:10.1039/C7RA06646E. ISSN 2046-2069.
  2. ^ United Nations, Transport of Nitroguanidine, wetted, (UN 1336) in flexible IBCs, ST/SC/AC.10/C.3/2006/52, Geneva, 13 April 2006. Accessed at https://www.unece.org/fileadmin/DAM/trans/doc/2006/ac10c3/ST-SG-AC10-C3-2006-52e.pdf
  3. ^ a b Koch, Ernst‐Christian (2019). "Insensitive High Explosives: III. Nitroguanidine – Synthesis – Structure – Spectroscopy – Sensitiveness". Propellants, Explosives, Pyrotechnics. 44 (3): 267–292. doi:10.1002/prep.201800253. ISSN 0721-3115.
  4. ^ Steele, N. W.; Doyle, J. A.; Whippen, M. G.; Gorton, J. A.; Hercules Inc. (December 1973). Process Engineering Design for Manufacture of Guanidine Nitrate (Technical report). Picatinny Arsenal. AD-772074.
  5. ^ E.-C. Koch, Insensitive High Explosives: IV. Nitroguanidine - Initiation & detonation, Def. Tech. 2019, 15, 467-487.[1]
  6. ^ Fedoroff, Basil Timothy (1960). Encyclopedia of Explosives and Related Items. Picatinny Arsenal.
  7. ^ U.S. patent 899855A
  8. ^ Bulusu, S.; Dudley, R. L.; Autera, J. R. (1987). "Structure of nitroguanidine: nitroamine or nitroimine? New NMR evidence from nitrogen-15 labeled sample and nitrogen-15 spin coupling constants". Magnetic Resonance in Chemistry. 25 (3): 234–238. doi:10.1002/mrc.1260250311. S2CID 97416890.
  9. ^ Murmann, R. K.; Glaser, Rainer; Barnes, Charles L. (2005). "Structures of nitroso- and nitroguanidine x - ray crystallography and computational analysis". Journal of Chemical Crystallography. 35 (4): 317–325. doi:10.1007/s10870-005-3252-y. S2CID 96090647.
  10. ^ S. Choi, Refinement of 2-Nitroguanidine by Neutron Powder Diffraction, Acta Crystallogr. B 1981, 37, 1955-1957.[2]