Chemistry:Urea nitrate

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Not to be confused with nitrourea.
Urea nitrate
Structural formulae of the ions in urea nitrate
Ball-and-stick models of the ions in urea nitrate
Identifiers
3D model (JSmol)
ChemSpider
UNII
Properties
CH5N3O4
Molar mass 123.068 g·mol−1
Density 1.67±0.011 g/cm3[1]
Melting point 157–159 °C (315–318 °F; 430–432 K)
167.2±0.5 mg/mL[1]
Solubility in Ethanol 14.2±0.1 mg/mL[1]
Solubility in Acetone 10.4±0.2 mg/mL[1]
Solubility in Methanol 54.8±0.9 mg/mL[1]
Explosive data
Shock sensitivity Low
Friction sensitivity Low
Detonation velocity 4700 m/s
Hazards
GHS pictograms GHS01: Explosive GHS03: Oxidizing GHS05: Corrosive
GHS Signal word DANGER
H201, H271, H301, H304, H314, H332
P220, P233, P260, P250, P305+351+338
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondFlammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazards (white): no code
1
2
3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Tracking categories (test):
Crystals of urea nitrate

Urea nitrate is a fertilizer-based high explosive that has been used in improvised explosive devices in Afghanistan, Pakistan, Iraq, and various terrorist acts elsewhere in the world such as in the 1993 World Trade Center bombings.[2] It has a destructive power similar to better-known ammonium nitrate explosives, with a velocity of detonation between 3,400 m/s (11,155 ft/s) and 4,700 m/s (15,420 ft/s).[3] It has chemical formula of CH
5N
3O
4 or (NH
2)
2COHNO
3.

Urea nitrate is produced in one step by reaction of urea with nitric acid. This is an exothermic reaction, so steps must be taken to control the temperature.

It was discovered in 1797 by William Cruickshank,[4] inventor of the Chloralkali process.

Urea nitrate explosions may be initiated using a blasting cap.[3]

Chemistry

Urea contains a carbonyl group. The more electronegative oxygen atom pulls electrons away from the carbon atom, forming a polar bond with greater electron density around the oxygen atom, giving it a partial negative charge. In a simplistic sense, nitric acid dissociates in aqueous solution into protons (hydrogen cations) and nitrate anions. The electrophilic proton contributed by the acid is attracted to the negatively charged oxygen atom on the urea molecule and the two form a covalent bond. The formed O-H bond is stabilized into a hydroxyl group when the oxygen abstracts an electron pair away from the central carbon atom, which leads to bond resonance between it and the two amino groups. As such, the urea cation can be thought of as a amidinium species. Paired with the spectator nitrate counteranion, it forms urea nitrate.

(NH
2)
2CO (aq) + HNO
3 (aq) → [(NH
2)
2COH]+
[NO
3]−
 (s)

The compound is favored by many amateur explosive enthusiasts as a principal explosive for use in larger charges. In this role it acts as a substitute for ammonium nitrate based explosives. This is due to the ease of acquiring the materials necessary to synthesize it, and its greater sensitivity to initiation compared to ammonium nitrate based explosives.[5]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Oxley, Jimmie C.; Smith, James L.; Vadlamannati, Sravanthi; Brown, Austin C.; Zhang, Guang; Swanson, Devon S.; Canino, Jonathan (2013). "Synthesis and Characterization of Urea Nitrate and Nitrourea". Propellants, Explosives, Pyrotechnics 38 (3): 335–344. doi:10.1002/prep.201200178. https://digitalcommons.uri.edu/chm_facpubs/824. 
  2. ↑ Aaron Rowe (18 September 2007). "Chem Lab: Spray-On Test for Improvised Explosives". Wired. http://blog.wired.com/wiredscience/2007/09/spray-on-test-f.html. 
  3. ↑ 3.0 3.1 "Explosives - ANFO (Ammonium Nitrate - Fuel Oil)". GlobalSecurity.org. https://www.globalsecurity.org/military/systems/munitions/explosives-anfo.htm. 
  4. ↑ Rosenfeld, Louis (1999) (in en). Four Centuries of Clinical Chemistry. CRC Press. ISBN 978-90-5699-645-1. https://books.google.com/books?id=KPX6Yvax9jkC&pg=PA40. 
  5. ↑ D'Uva, Joshua A.; DeTata, David; Fillingham, Ryan; Dunsmore, Robert; Lewis, Simon W. (December 2021). "Synthesis and characterisation of homemade urea nitrate explosive from commercial sources of urea" (in en). Forensic Chemistry 26. doi:10.1016/j.forc.2021.100369. https://linkinghub.elsevier.com/retrieve/pii/S2468170921000655. 

Further reading



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