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.
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| Names | |||
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| IUPAC name
1-Nitroguanidine
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| Other names | |||
| Identifiers | |||
3D model (JSmol)
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| ChemSpider | |||
| ECHA InfoCard | 100.008.313 | ||
PubChem CID
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| UNII | |||
CompTox Dashboard (EPA)
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| 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
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Explosive | ||
| Related compounds | |||
Related compounds
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Guanidine Guanidine nitrate | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Manufacture
editNitroguanidine 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] However, owing to problems of reliability and safety, this process has never been commercialized despite its attractive economic features.
- 2 NH2CONH2 + NH4NO3 → [C(NH2)3]NO3 + 2 NH3 + CO2
Uses
editExplosives
editNitroguanidine 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
editNitroguanidine derivatives are used as insecticides, having a comparable effect to nicotine. Derivatives include clothianidin, dinotefuran, imidacloprid, and thiamethoxam.
Biochemistry
editThe nitrosoylated derivative, nitrosoguanidine, is often used to mutagenize bacterial cells for biochemical studies.
Structure
editFollowing 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
edit- ^ 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.
- ^ 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
- ^ 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.
- ^ 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.
- ^ E.-C. Koch, Insensitive High Explosives: IV. Nitroguanidine - Initiation & detonation, Def. Tech. 2019, 15, 467-487.[1]
- ^ Fedoroff, Basil Timothy (1960). Encyclopedia of Explosives and Related Items. Picatinny Arsenal.
- ^ U.S. patent 899855A
- ^ 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.
- ^ 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.
- ^ S. Choi, Refinement of 2-Nitroguanidine by Neutron Powder Diffraction, Acta Crystallogr. B 1981, 37, 1955-1957.[2]