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.

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Preparation and structure

The compound is prepared by treatment of ammonium salts, such as ammonium nitrate with chlorine:

4 NH₃ + 3 Cl₂ → 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°.^[1] 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.^[2]

References

1. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
2. ^ Bernard A, Carbonnelle S, de Burbure C, Michel O, Nickmilder M (2006). "Chlorinated pool attendance, atopy, and the risk of asthma during childhood". Environmental Health Perspectives 114 (10).

Further reading

• Jander, J. (1976). Adv. Inorg. Chem. Radiochem. 19: 2.
• P. Kovacic, M. K. Lowery, K. W. Field (1970). "Chemistry of N-bromamines and N-chloramines". Chemical Reviews 70 (6). doi:10.1021/cr60268a002.
• Hartl, H.;, Schoner, J.; Jander, J.; Schulz, H. (1975). "Structure of Solide Nitrogen-Trichloride (-125°C)". Zeitschrift für Anorganische und Allgemeine Chemie 413 (1).
• Cazzoli, G.; Favero, P. G.; Dalborgo, A. (1974). "Molecula-Structure, Nuclear-Quadruple Coupling-Constant and Dipole-Moment of Nitrogen Trichloride from Microwave Spectroscopy". Journal of Molecular Spectroscopy 50 (1-3).
• Bayersdo, L.; Engelhar, U., Fischer, J.; Hohne, K.; Jander, J. (1969). "Nitrogen-chlorine compounds: Infrared spectra and Raman spectra of nitrogen trichloride". Zeitschrift für anorganische und allgemeine Chemie 366 (3-4).