Nitrogen trichloride
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.[1]
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| Names | |||
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| Other names
Trichloramine Agene Nitrogen(III) chloride Trichloroazane Trichlorine nitride | |||
| Identifiers | |||
3D model (JSmol) |
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| ECHA InfoCard | 100.030.029 | ||
| EC Number |
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| 1840 | |||
PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |||
| NCl3 | |||
| Appearance | yellow oily liquid | ||
| Odor | chlorine-like | ||
| Density | 1.653 g/mL | ||
| Melting point | −40 °C (−40 °F; 233 K) | ||
| Boiling point | 71 °C (160 °F; 344 K) | ||
| immiscible slowly decomposes | |||
| Solubility | soluble in benzene, chloroform, CCl4, CS2, PCl3 | ||
| Structure | |||
| orthorhombic (below −40 °C) | |||
| trigonal pyramidal | |||
| 0.6 D | |||
| Thermochemistry | |||
Std enthalpy of formation (ΔfH⦵298) |
232 kJ/mol | ||
| Hazards | |||
| NFPA 704 (fire diamond) | |||
| 93 °C (199 °F; 366 K) | |||
| Related compounds | |||
Other anions |
Nitrogen trifluoride Nitrogen tribromide Nitrogen triiodide | ||
Other cations |
Phosphorus trichloride Arsenic trichloride | ||
Related chloramines |
Monochloramine Dichloramine | ||
Related compounds |
Nitrosyl chloride | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation and structure
The compound is prepared by treatment of ammonium salts, such as sal ammoniac with a chlorine source.
Intermediates in this conversion include monochloramine and dichloramine, NH2Cl and NHCl2, respectively.
Like ammonia, NCl3 is a pyramidal molecule. The N-Cl distances are 1.76 Å, and the Cl-N-Cl angles are 107°.[2]
Reactions and uses
The chemistry of NCl3 has been well explored.[3] 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 + 3 H2O → NH3 + 3 HOCl
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, trademarked as Agene, was at one time used to bleach flour,[4] but this practice was banned in the United States in 1949 due to safety concerns.
Safety
Nitrogen trichloride can irritate mucous membranes—it is a lachrymatory agent, but has never been used as such.[5][6] 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 several fingers and an eye in two explosions.[7] 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.[8]
See also
References
- "Chlorine Chemistry - Chlorine Compound of the Month: Chloramines: Understanding "Pool Smell"". American Chemistry Council. Retrieved 17 December 2019.
- Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 978-0-12-352651-9.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- Hawthorn, J.; Todd, J. P. (1955). "Some effects of oxygen on the mixing of bread doughs". Journal of the Science of Food and Agriculture. 6 (9): 501–511. Bibcode:1955JSFA....6..501H. doi:10.1002/jsfa.2740060906.
- White, G. C. (1999). The Handbook of Chlorination and Alternative Disinfectants (4th ed.). Wiley. p. 322. ISBN 978-0-471-29207-4.
- "Health Hazard Evaluation Report: Investigation of Employee Symptoms at an Indoor Water Park" (PDF). NIOSH ENews. 6 (4). August 2008. HETA 2007-0163-3062.
- Thénard J. L.; Berthollet C. L. (1813). "Report on the work of Pierre Louis Dulong". Annales de Chimie et de Physique. 86 (6): 37–43.
- Thomas, J.M. (1991). Michael Faraday and The Royal Institution: The Genius of Man and Place (PBK). CRC Press. p. 17. ISBN 978-0-7503-0145-9.
Further reading
- Jander, J. (1976). Recent Chemistry and Structure Investigation of Nitrogen Triiodide, Tribromide, Trichloride, and Related Compounds. pp. 1–63. doi:10.1016/S0065-2792(08)60070-9. ISBN 9780120236190.
{{cite book}}:|journal=ignored (help) - Kovacic, P.; Lowery, M. K.; Field, K. W. (1970). "Chemistry of N-Bromamines and N-Chloramines". Chemical Reviews. 70 (6): 639–665. doi:10.1021/cr60268a002.
- Hartl, H.; Schöner, J.; Jander, J.; Schulz, H. (1975). "Die Struktur des Festen Stickstofftrichlorids (−125 °C)". Zeitschrift für Anorganische und Allgemeine Chemie. 413 (1): 61–71. doi:10.1002/zaac.19754130108.
- Cazzoli, G.; Favero, P. G.; Dal Borgo, A. (1974). "Molecular Structure, Nuclear Quadrupole Coupling Constant and Dipole Moment of Nitrogen Trichloride from Microwave Spectroscopy". Journal of Molecular Spectroscopy. 50 (1–3): 82–89. Bibcode:1974JMoSp..50...82C. doi:10.1016/0022-2852(74)90219-7.
- Bayersdorfer, L.; Engelhardt, U.; Fischer, J.; Höhne, K.; Jander, J. (1969). "Untersuchungen an Stickstoff–Chlor-Verbindungen. V. Infrarot- und RAMAN-Spektren von Stickstofftrichlorid". Zeitschrift für Anorganische und Allgemeine Chemie. 366 (3–4): 169–179. doi:10.1002/zaac.19693660308.
