Nitrogen trichloride

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Nitrogen trichloride

Nitrogen, N   Chlorine, Cl
Names
Other names Trichloramine Agene Nitrogen(III) chloride Trichloroazane Trichlorine nitride
Identifiers
CAS Number	10025-85-1 checkY
3D model (JSmol)	Interactive image
ChEBI	CHEBI:37382 checkY
ChemSpider	55361 checkY
EC Number	Template:Chembox ECNumber/format Template:Chembox ECNumber/format Template:Chembox ECNumber/format Template:Chembox ECNumber/format Template:Chembox ECNumber/format Template:Chembox ECNumber/format
Gmelin Reference	1840
PubChem CID	61437
RTECS number	Template:Chembox RTECS/format Template:Chembox RTECS/format Template:Chembox RTECS/format Template:Chembox RTECS/format Template:Chembox RTECS/format Template:Chembox RTECS/format
UNII	VA681HRW8W checkY
InChI InChI=1S/Cl3N/c1-4(2)3 checkY Key: QEHKBHWEUPXBCW-UHFFFAOYSA-N checkY InChI=1/Cl3N/c1-4(2)3 Key: QEHKBHWEUPXBCW-UHFFFAOYAZ
SMILES ClN(Cl)Cl
Properties
Chemical formula	NCl3
Molar mass	120.36 g·mol−1
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)
Solubility in water	immiscible slowly decomposes
Solubility	soluble in benzene, chloroform, CCl4, CS2, PCl3
Structure
Crystal structure	orthorhombic (below −40 °C)
Molecular shape	trigonal pyramidal
Dipole moment	0.6 D
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	232 kJ/mol
Hazards
NFPA 704 (fire diamond)	2 0 3 OX
Autoignition temperature	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). ☒N verify (what is checkY☒N ?) Infobox references

Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl₃. This yellow, oily, and explosive liquid is most commonly encountered as a product 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.

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, NH₂Cl and NHCl₂, 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, NCl₃ is a pyramidal molecule. The N-Cl distances are 1.42 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 NCl₃ 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.

$\mathrm{N}\mathrm{C}\mathrm{l}{\phantom{A}}_3+3\mathrm{H}{\phantom{A}}_2\mathrm{O}⟶\mathrm{N}\mathrm{H}{\phantom{A}}_3+3\mathrm{H}\mathrm{C}\mathrm{l}+\frac{3}{2}\mathrm{O}{\phantom{A}}_2$

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

$2\mathrm{N}\mathrm{C}\mathrm{l}{\phantom{A}}_3⟶\mathrm{N}{\phantom{A}}_2+3\mathrm{C}\mathrm{l}{\phantom{A}}_2$

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 membranes — it 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 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.

See also

• List of food contamination incidents
• Nitrogen tribromide
• Nitrogen triiodide

Further reading

• Jander, J. (1976). "Recent Chemistry and Structure Investigation of Nitrogen Triiodide, Tribromide, Trichloride, and Related Compounds". Advances in Inorganic Chemistry. Advances in Inorganic Chemistry and Radiochemistry. 19: 1–63. doi:10.1016/S0065-2792(08)60070-9. ISBN 9780120236190.
• 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.

External links

• OSHA - Nitrogen trichloride
• Nitrogen Trichloride - Health References