Nitrogen trichloride

Preparation and occurrence

The compound is generated by treatment of ammonium chloride with calcium hypochlorite. When prepared in an aqueous-dichloromethane mixture, the trichloramine is extracted into the nonaqueous phase. Intermediates in this conversion include monochloramine and dichloramine, and , respectively.

Nitrogen trichloride, trademarked as Agene, was at one time used to bleach flour, but this practice was banned in the United States in 1949 due to safety concerns.

Structure and properties

Like ammonia, is a pyramidal molecule. The N-Cl distances are 1.76 Å, and the Cl-N-Cl angles are 107°.

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.

Reactions and uses

The chemistry of 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 + 3H2O - NH3 + 3HClO

Concentrated samples of NCl3 can explode to give N2 and chlorine gas.

2NCl3 - N2 + 3Cl2

In the presence of aluminium trichloride, NCl3 reacts with some branched hydrocarbons to produce, after a hydrolysis step, amines.

Safety

Nitrogen trichloride can irritate mucous membranesit is a lachrymatory agent, but has never been used as such. The compound (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 several fingers and an eye in two explosions. In 1813, an explosion blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a co-worker. They were both injured in another explosion shortly thereafter.

References

References

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