Nitrogen trichloride

Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling liquid, is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine (for example, in swimming pools between disinfecting chlorine and urea in urine from bathers). In pure form, NCl3 is highly reactive. Nitrogen trichloride can form in small amounts when public water supplies are disinfected with monochloramine. Nitrogen trichloride was trademarked as Agene and used to artificially bleach and age flour. It has been used as a teargas.

Preparation and structure
The compound is prepared by treatment of ammonium salts, such as ammonium nitrate with chlorine:
 * 4 NH3 +  3 Cl2  &rarr;  NCl3  +  3 NH4Cl

Intermediates in this coversion include chloramine and dichloramine, NH2Cl and NHCl2, respectively.

Like ammonia, NCl3 is a pyramidal molecule. The N-Cl distances are 1.76 Â, and the Cl-N-Cl angles are 107°. The electronegativities are very similar for nitrogen (3.04) and chlorine (3.16).

Safety
Nitrogen trichloride is a dangerous explosive, being sensitive to light, heat, and organic compounds. Pierre Louis Dulong first prepared it in 1812, and lost two fingers and an eye in two separate explosions. An explosion from NCl3 blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a coworker. Belgian researchers reported a possible link between NCl3 and rising numbers of childhood asthma cases.