Chloramines

Chloramines refer to derivatives of ammonia and organic amines wherein one or more N−H bonds have been replaced by N−Cl bonds.^[1][2] Two classes of compounds are considered: inorganic chloramines and organic chloramines. Chloramines are the most widely used members of the halamines.^[3]

Inorganic chloramines

Inorganic chloramines comprise three compounds: monochloramine (NH₂Cl), dichloramine (NHCl₂), and nitrogen trichloride (NCl₃). Monochloramine is of broad significance as a disinfectant for water.^[4]

Inorganic chloramines are produced by the reaction of ammonia and hypochlorous acid or chlorine. An urban legend claims that mixing household bleach (aqueous sodium hypochlorite) with ammonia-based cleaners releases chlorine gas or mustard gas; in reality, the gas produced by the reaction is a mixture of inorganic chloramines.

Organic chloramines

N-Chloropiperidine is a rare example of an organic chloramine.^[5]

Chloramine-T is often referred to as a chloramine, but it is really a salt (CH₃C₆H₄SO₂NClNa) derived from a chloramine.^[6]

Organic chloramines feature the NCl functional group attached to an organic substituent. Examples include N-chloromorpholine (ClN(CH₂CH₂)₂O), N-chloropiperidine, and N-chloroquinuclidinium chloride.^[7]

Chloramines are commonly produced by the action of sodium hypochlorite on secondary amines:

R₂NH + NaOCl → R₂NCl + NaOH

Tert-butyl hypochlorite can be used instead of bleach:^[8]

R₂NH + t-BuOCl → R₂NCl + t-BuOH

Swimming pools

Chloramines are formed by reaction of chlorine used to disinfect swimming pools with ammonia and urea introduced into the pools by human perspiration, saliva, mucus, urine, and other biologic substances, and by insects and other pests.^[9] Chloramines, especially trichloramine, are responsible for most of the "chlorine smell" of pools, as well as for skin, eye, and respiratory irritation.^[10]

References

1. Berliner, J. F. T. (1931). "The Chemistry of Chloramines". American Water Works Association. 23 (9): 1320−1333. doi:10.1002/j.1551-8833.1931.tb17955.x. JSTOR 41228138. Retrieved 4 October 2023.
2. Kovacic, Peter; Lowery, Michael K.; Field, Kurt W. (1970). "Chemistry of N-bromamines and N-chloramines". Chemical Reviews. 70 (6): 639−665. doi:10.1021/cr60268a002. Retrieved 4 October 2023.
3. Dong, Alideertu; Wang, Yan-Jie; Gao, Yangyang; Gao, Tianyi; Gao, Ge (2017). "Chemical Insights into Antibacterial N -Halamines". Chemical Reviews. 117 (6): 4806–4862. doi:10.1021/acs.chemrev.6b00687. PMID 28252944.
4. Lawrence, Stephen A. (2004). Amines: Synthesis, Properties and Applications. Cambridge University Press. p. 172. ISBN 9780521782845.
5. Claxton, George P.; Allen, Lloyd; Grisar, J. Martin (1977). "2,3,4,5-Tetrahydropyridine Trimer". Organic Syntheses. 56: 118. doi:10.15227/orgsyn.056.0118.
6. Campbell, Malcolm M.; Johnson, Graham. (1978). "Chloramine T and Related N-halogeno-N-metallo Reagents". Chemical Reviews. 78: 65–79. doi:10.1021/cr60311a005.
7. Lindsay Smith, J. R.; McKeer, L. C.; Taylor, J. M. "4-Chlorination of Electron-Rich Benzenoid Compounds: 2,4-Dichloromethoxybenzene". Organic Syntheses. 67: 222. doi:10.15227/orgsyn.067.0222.
8. Herranz, Eugenio; Sharpless, K. Barry (1983). "Osmium-catalyzed Vicinal Oxyamination of Olefins by N-chloro-N-Argentocarbamates: Ethyl Threo-[1-(2-hydroxy-1,2-diphenylethyl)]carbamate". Org. Synth. 61: 93. doi:10.15227/orgsyn.061.0093.
9. "Controlling Chloramines in Indoor Swimming Pools". NSW Government Health. 3 December 2012. Retrieved 20 February 2013.
10. Bessonneau, Vincent; Derbez, Mickaël; Clément, Michel; Thomas, Olivier (2011). "Determinants of chlorination by-products in indoor swimming pools". International Journal of Hygiene and Environmental Health. 215 (1): 76–85. doi:10.1016/j.ijheh.2011.07.009. ISSN 1438-4639. PMID 21862402.