Not to be confused with Guanidine nitrate.
Nitroguanidine
Watchedfieldschanged
Verifiedrevid444027788
Iupacname1-Nitroguanidine
OthernamesPicrite

Nitroguanidine - sometimes abbreviated NQ or NGu - is a colorless, crystalline solid that decomposes at 239 °C (462 °F), without melting. Nitroguanidine is an extremely insensitive but powerful high explosive. Nitroguanidine is used as an energetic material (propellant or high explosive), a precursor for insecticides,[citation needed] 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.[1]

[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.[1][2] 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.).[3]

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.[4][5]

One form of nitroguanidine's explosive decomposition may be given by the following idealized equation, which assumes it decomposes into carbon dioxide, nitrogen gas, and ammonia:[citation needed]

3 O2N\sN\dC(NH2)2 → 3 CO2 + 4 N2 + 4 NH3

However, practical reactions are likely to differ. For example, carbon monoxide and steam can be produced in anoxic conditions:

2 O2N\sN\dC(NH2)2 → 2 CO + 4 N2 + 2 H2O

In the presence of an additional source of oxygen, steam can also be produced:

O2N\sN\dC(NH2)2 + O2 → CO2 + 2 N2 + 2 H2O

Pesticides

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

Structure

It has been 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.[6][7][8]

The methylated and nitrosylated derivative methylnitronitrosoguanidine is used to mutagenize bacterial cells for biochemical studies.[citation needed]

References

  1. ^ 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
  2. ^ Steele, N. W.; Doyle, J. A.; Whippen, M. G.; Gorton, J. A.; Hercules Inc. (December 1973). Process Engineering Design for Manufacture of Guanidine Nitrate. No. AD-772074. Picatinny Arsenal
  3. ^ Koch, Ernst-Christian (August 2019). "Insensitive high explosives: IV. Nitroguanidine – Initiation & detonation". Defence Technology. 15 (4): 467–487. doi:10.1016/j.dt.2019.05.009
  4. ^ Fedoroff, Basil T.; Sheffield, Oliver E.; Clift, George D.; Reese, Earl F.; Aaronson, Henry A.; Dunkle, Cyrus G.; Walter, Hans; McLean, Dan C. (1960). "A - Abelli, Modesto". Encyclopedia of Explosives and Related Items. Vol. 1, A through Azoxy. Picatinny Arsenal, NJ: U.S. Army Research and Development Command TACOM - Ardec Warheads, Energetics and Combat Support Center. p. A2. LCCN 61-61759. AD0257189, PATR2700.
  5. ^
  6. ^ 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
  7. ^ 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. Bibcode:2005JCCry..35..317M. doi:10.1007/s10870-005-3252-y. S2CID 96090647
  8. ^ Choi, C. S. (15 October 1981). "Refinement of 2-nitroguanidine by neutron powder diffraction". Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 37 (10): 1955–1957. Bibcode:1981AcCrB..37.1955C. doi:10.1107/S0567740881007735