Nitrogen trichloride

Nitrogen trichloride
Other names Trichloramine Agene Nitrogen(III) chloride Trichloroazane Trichlorine nitride
Identifiers
CAS number	10025-85-1
PubChem	61437
ChemSpider	55361 Y
ChEBI	CHEBI:37382 Y
RTECS number	QW974000
Jmol-3D images	Image 1
SMILES ClN(Cl)Cl
InChI InChI=1S/Cl3N/c1-4(2)3 Y Key: QEHKBHWEUPXBCW-UHFFFAOYSA-N Y InChI=1/Cl3N/c1-4(2)3 Key: QEHKBHWEUPXBCW-UHFFFAOYAZ
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 ΔfHo298	+232 kJ/mol
Standard molar entropy So298	? J.K−1.mol−1
Hazards
EU classification	not listed
NFPA 704	0 2 4 OX
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
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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 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, and at given levels it can irritate mucous membranes.^[1] Nitrogen trichloride was trademarked as Agene and used to artificially bleach and age flour. It has the same effect as that of tear gas, but has never been used as such.^[2]

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°.^[3] The Pauling electronegativities are very similar for nitrogen (3.04) and chlorine (3.16).

Reactions

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.

Nitrogen trichloride is hydrolyzed by hot water to release ammonia and hypochlorous acid.

NCl₃ + 3 H₂O → NH₃ + 3 HOCl

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 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]

References

1. ^ 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
2. ^ George Clifford White: The handbook of chlorination and alternative disinfectants. 4th Edition, Wiley, 1999, ISBN 9780471292074, p. 322
3. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
4. ^ 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. 

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. 
• 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. 

External links

• OSHA - Nitrogen trichloride