Nitrogen trichloride
| Nitrogen trichloride | |
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Other names
Trichloramine |
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| Identifiers | |
| CAS number | 10025-85-1  |
| PubChem | 61437 |
| ChemSpider | 55361 |
| ChEBI | CHEBI:37382 |
| RTECS number | QW974000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molar mass | 120.365 g/mol |
| Appearance | yellow oily liquid |
| Density | 1.635 g/mL |
| Melting point |
-40 °C, 233 K, -40 °F |
| Boiling point |
71 °C, 344 K, 160 °F |
| Solubility in water | Immiscible slowly decomposes |
| Solubility | soluble in benzene, chloroform, CCl4, CS2, PCl3 |
| Structure | |
| Crystal structure | rhombohedral (below -40 °C) |
| Molecular shape | trigonal pyramidal |
| Dipole moment | 0.6 D |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
+232 kJ/mol |
| Standard molar entropy S |
? J.K−1.mol−1 |
| Hazards | |
| EU classification | not listed |
| NFPA 704 |
 0
2
4
OX
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| Autoignition temperature |
93 °C |
| Related compounds | |
| Other anions | Nitrogen trifluoride Nitrogen tribromide Nitrogen triiodide |
| Other cations | Phosphorus trichloride Arsenic trichloride |
| Related chloramines | Chloramine Dichloramine |
| Related compounds | Nitrosyl chloride |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
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).
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[edit] 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 conversion include chloramine 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°.[1] The Pauling electronegativities are very similar for nitrogen (3.04) and chlorine (3.16).
Nitrogen trichloride can form in small amounts when public water supplies are disinfected with monochloramine, and between disinfecting chlorine and urea in urine from bathers). Nitrogen trichloride, trademarked as Agene, was used to artificially bleach and age flour.
[edit] Reactions
NCl3 is a highly reactive compound. The nitrogen in NCl3 is often considered to have the -3 oxidation state and the chlorine atoms are considered to be in the +1 oxidation state. Most of its reactivity is consistent with this description. It is hydrolyzed by hot water to release ammonia and hypochlorous acid.
- NCl3 + 3 H2O → NH3 + 3 HOCl
[edit] Safety
Nitrogen trichloride can irritate mucous membranes - it is tear gas, but has never been used as such.[2].[3] 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 separate explosions. An explosion from NCl3 blinded Sir Humphry Davy temporarily, inducing him to hire Michael Faraday as a co-worker.
In 2006, Belgian researchers reported a possible link between NCl3 and rising numbers of childhood asthma cases, in what they call the pool chlorine hypothesis, as an alternative to the hygiene hypothesis with a closer causal link.[4]
[edit] References
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ George Clifford White The handbook of chlorination and alternative disinfectants. 4th Edition, Wiley, 1999, ISBN 9780471292074, p. 322
- ^ National Institute for Occupational Safety and Health. (2008, August). NIOSH eNews, 6(4). Retrieved August 27, 2008, from http://www.cdc.gov/niosh/enews/enewsV6N4.html
- ^ 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): 1567–1573. doi:10.1289/ehp.8461. PMC 1626429. PMID 17035144. http://www.ehponline.org/members/2006/8461/8461.pdf.
[edit] 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): 639. doi:10.1021/cr60268a002.agene and bread
- Hartl, H.;, Schoner, J.; Jander, J.; Schulz, H. (1975). "Structure of Solide Nitrogen-Trichloride (-125°C)". Zeitschrift für Anorganische und Allgemeine Chemie 413 (1): 61–71. doi:10.1002/zaac.19754130108.
- Cazzoli, G.; Favero, P. G.; Dalborgo, A. (1974). "Molecular-Structure, Nuclear-Quadruple Coupling-Constant and Dipole-Moment of Nitrogen Trichloride from Microwave Spectroscopy". Journal of Molecular Spectroscopy 50 (1–3): 82. doi:10.1016/0022-2852(74)90219-7.
- 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): 169–. doi:10.1002/zaac.19693660308.
