Nitroguanidine
{{Distinguish|Guanidine nitrate}}
{{chembox
| Watchedfields = changed
| verifiedrevid = 444027788
| ImageFileL1 = Nitroguanidine.svg
| ImageFileR1 = Nitroguanidine structure.png
| IUPACName = 1-Nitroguanidine
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10701
| InChI = 1/CH4N4O2/c2-1(3)4-5(6)7/h(H4,2,3,4)
| InChIKey = IDCPFAYURAQKDZ-UHFFFAOYAN
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/CH4N4O2/c2-1(3)4-5(6)7/h(H4,2,3,4)
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = IDCPFAYURAQKDZ-UHFFFAOYSA-N
| CASNo = 556-88-7
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = NAY6KWL67F
| PubChem = 11174
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 39180
| SMILES = NC(N)=N[N+]([O-])=O
}}
|Section2={{Chembox Properties
| Formula = CH4N4O2
| MolarMass = 104.07 g/mol
| Appearance = Colorless crystalline solid
| Density = 1.77 g/cm3
| MeltingPtC = 257
| BoilingPtC =
| BoilingPt_notes =
| Solubility = 3.45 g/kg (in water at 25 °C)
}}
|Section4={{Chembox Explosive
| ShockSens = > 50 J
| FrictionSens => 350 N
| DetonationV =
| REFactor = 1.00
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards = Explosive
| FlashPt =
| AutoignitionPt =
}}
|Section8={{Chembox Related
| OtherFunction =
| OtherFunction_label =
| OtherCompounds = Guanidine
Guanidine nitrate
}}
}}
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).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
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.{{cite journal | last=Koch | first=Ernst‐Christian | title=Insensitive High Explosives: III. Nitroguanidine – Synthesis – Structure – Spectroscopy – Sensitiveness | journal=Propellants, Explosives, Pyrotechnics | volume=44 | issue=3 | date=2019 | issn=0721-3115 | doi=10.1002/prep.201800253 | pages=267–292}}
:{{chem2|[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.{{cite tech report |last1=Steele |first1=N. W. |last2=Doyle |first2=J. A. |last3=Whippen |first3=M. G. |last4=Gorton |first4=J. A. |author5=Hercules Inc. |author-link5=Hercules Inc. |date=December 1973 |title=Process Engineering Design for Manufacture of Guanidine Nitrate |publisher=Picatinny Arsenal |number=AD-772074}} This process had been commercialized because of its attractive economic features.
:{{chem2|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.).E.-C. Koch, Insensitive High Explosives: IV. Nitroguanidine - Initiation & detonation, Def. Tech. 2019, 15, 467-487.[https://www.sciencedirect.com/science/article/pii/S2214914719302168]
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.{{Cite book |last=Fedoroff |first=Basil Timothy |url=https://books.google.com/books?id=-sNTAAAAMAAJ&pg=PA78 |title=Encyclopedia of Explosives and Related Items |date=1960 |publisher=Picatinny Arsenal |language=en}}{{US patent|899855A}}
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.{{cite journal | title = Structure of nitroguanidine: nitroamine or nitroimine? New NMR evidence from nitrogen-15 labeled sample and nitrogen-15 spin coupling constants |author1=Bulusu, S. |author2=Dudley, R. L. |author3=Autera, J. R. | journal = Magnetic Resonance in Chemistry | year = 1987 | volume = 25 | issue = 3 | pages = 234–238 | doi = 10.1002/mrc.1260250311|s2cid=97416890 |url=https://zenodo.org/record/1229291 }}{{cite journal | title = Structures of nitroso- and nitroguanidine x - ray crystallography and computational analysis |author1=Murmann, R. K. |author2=Glaser, Rainer |author3=Barnes, Charles L. | journal = Journal of Chemical Crystallography | year = 2005 | volume = 35 | issue = 4 | pages = 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.[http://scripts.iucr.org/cgi-bin/paper?S0567740881007735]