Urea nitrate

Urea nitrate is a fertilizer-based high explosive that has been used in improvised explosive devices in Afghanistan, Pakistan, Iraq, and various other terrorist acts elsewhere in the world, like 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 11,155 ft/s (3,400 m/s) and 15,420 ft/s (4,700 m/s).[3]

Urea nitrate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.004.276
UNII
Properties
CH5N3O4
Molar mass 123.068 g/mol
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 Ethanol 14.2±0.1 mg/mL

Methanol 54.8±0.9 mg/mL Acetone 10.4±0.2 mg/mL [1]

Explosive data
Shock sensitivity Very low
Friction sensitivity Very low
Detonation velocity 4700 m/s
Hazards
GHS pictograms
GHS Signal word Danger
GHS hazard statements
 H201, H271, H301, H304, H314, H332
P220, P233, P260, P250, P305+351+338
NFPA 704 (fire diamond)
Flammability 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).
N verify (what is YN ?)
Infobox references
Not to be confused with nitrourea.

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.

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 forming a greater electron density around the oxygen, giving the oxygen a partial negative charge and forming a polar bond. When nitric acid is presented, it ionizes. A hydrogen cation contributed by the acid is attracted to the oxygen and forms a covalent bond [electrophile H+]. The electronegative NO3− ion then is attracted to the positive hydrogen ion. This forms an ionic bond and hence the compound urea nitrate.

(NH2)2CO (aq) + HNO3 (aq) → (NH2)2COHNO3 (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.

References
  1. Oxley, Jimmie & Smith, James & Vadlamannati, Sravanthi & Brown, Austin & Zhang, Guang & Swanson, Devon & Canino, Jonathan. (2013). Synthesis and Characterization of Urea Nitrate and Nitrourea. Propellants, Explosives, Pyrotechnics. 38. 10.1002/prep.201200178.
  2. Aaron Rowe (18 September 2007). "Chem Lab: Spray-On Test for Improvised Explosives". Wired.
  3. "Explosives - ANFO (Ammonium Nitrate - Fuel Oil)". GlobalSecurity.org.

Further reading
Urea nitrate


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