Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling and explosive liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine (for example, in swimming pools). Alongside monochloramine and dichloramine, trichloramine is responsible for the distinctive 'chlorine smell' associated with swimming pools, where the compound is readily formed as a product from hypochlorous acid reacting with ammonia and other nitrogenous substances in the water, such as urea from urine.
3D model (JSmol)
CompTox Dashboard (EPA)
|Appearance||yellow oily liquid|
|Melting point||−40 °C (−40 °F; 233 K)|
|Boiling point||71 °C (160 °F; 344 K)|
|Solubility||soluble in benzene, chloroform, CCl4, CS2, PCl3|
|orthorhombic (below −40 °C)|
Std enthalpy of
|NFPA 704 (fire diamond)|
|93 °C (199 °F; 366 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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The compound is prepared by treatment of ammonium salts, such as ammonium nitrate with chlorine.
The chemistry of NCl3 has been well explored. It is moderately polar with a dipole moment of 0.6 D. The nitrogen center is basic but much less so than ammonia. It is hydrolyzed by hot water to release ammonia and hypochlorous acid.
NCl3 explodes to give N2 and chlorine gas. This reaction is inhibited for dilute gases.
Nitrogen trichloride can form in small amounts when public water supplies are disinfected with monochloramine, and in swimming pools by disinfecting chlorine reacting with urea in urine and sweat from bathers.
Nitrogen trichloride can irritate mucous membranes—it is a lachrymatory agent, but has never been used as such. The pure substance (rarely encountered) is a dangerous explosive, being sensitive to light, heat, even moderate shock, and organic compounds. Pierre Louis Dulong first prepared it in 1812, and lost two fingers and an eye in two explosions. In 1813, an NCl3 explosion blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a co-worker. They were both injured in another NCl3 explosion shortly thereafter.
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