Chloramines
{{Short description|Class of chemical compounds}}
Chloramines refer to derivatives of ammonia and organic amines wherein one or more N−H bonds have been replaced by N−Cl bonds.{{cite journal |last1=Berliner |first1=J. F. T. |title=The Chemistry of Chloramines |journal=American Water Works Association |date=1931 |volume=23 |issue=9 |pages=1320−1333 |doi=10.1002/j.1551-8833.1931.tb17955.x |jstor=41228138 |url=https://www.jstor.org/stable/41228138 |access-date=4 October 2023|url-access=subscription }}{{cite journal |last1=Kovacic |first1=Peter |last2=Lowery |first2=Michael K. |last3=Field |first3=Kurt W. |title=Chemistry of N-bromamines and N-chloramines |journal=Chemical Reviews |date=1970 |volume=70 |issue=6 |pages=639−665 |doi=10.1021/cr60268a002 |url=https://pubs.acs.org/doi/pdf/10.1021/cr60268a002 |access-date=4 October 2023|url-access=subscription }} Two classes of compounds are considered: inorganic chloramines and organic chloramines. Chloramines are the most widely used members of the halamines.{{cite journal |doi=10.1021/acs.chemrev.6b00687 |title=Chemical Insights into Antibacterial N -Halamines |date=2017 |last1=Dong |first1=Alideertu |last2=Wang |first2=Yan-Jie |last3=Gao |first3=Yangyang |last4=Gao |first4=Tianyi |last5=Gao |first5=Ge |journal=Chemical Reviews |volume=117 |issue=6 |pages=4806–4862 |pmid=28252944 }}
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.{{cite book|last1=Lawrence|first1=Stephen A.|title=Amines: Synthesis, Properties and Applications|date=2004|publisher=Cambridge University Press|isbn=9780521782845|page=172|url=https://books.google.com/books?id=35xwBwjhe2MC&pg=PA172|language=en}}
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
image:N-chloropiperidine.png is a rare example of an organic chloramine.{{OrgSynth | first1= George P.|last1= Claxton |first2=Lloyd|last2= Allen|first3= J. Martin |last3=Grisar | title = 2,3,4,5-Tetrahydropyridine Trimer| volume = 56 | pages = 118| year = 1977| doi= 10.15227/orgsyn.056.0118}}]]
image:Chloramine T.svg is often referred to as a chloramine, but it is really a salt (CH3C6H4SO2NClNa) derived from a chloramine.{{cite journal|doi=10.1021/cr60311a005|title=Chloramine T and Related N-halogeno-N-metallo Reagents|journal=Chemical Reviews|volume=78|pages=65–79|year=1978|last1=Campbell|first1=Malcolm M.|last2=Johnson|first2=Graham.}}]]
Organic chloramines feature the NCl functional group attached to an organic substituent. The simplest organic chloramine is N-chloromethylamine, CH3NHCl;{{cite journal|doi=10.1016/j.watres.2016.11.065 |title=Formation and reactivity of inorganic and organic chloramines and bromamines during oxidative water treatment |date=2017 |last1=Heeb |first1=Michèle B. |last2=Kristiana |first2=Ina |last3=Trogolo |first3=Daniela |last4=Arey |first4=J. Samuel |last5=von Gunten |first5=Urs |journal=Water Research |volume=110 |pages=91–101 |pmid=27998787 }} notable examples include N-chloromorpholine (ClN(CH2CH2)2O), N-chloropiperidine, and N-chloroquinuclidinium chloride.{{OrgSynth|last1=Lindsay Smith |first1=J. R. |last2=McKeer |first2=L. C. |last3=Taylor |first3=J. M. |title=4-Chlorination of Electron-Rich Benzenoid Compounds: 2,4-Dichloromethoxybenzene |date=1989 |volume=67 |page=222 |doi=10.15227/orgsyn.067.0222}}
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:{{cite journal|title=Osmium-catalyzed Vicinal Oxyamination of Olefins by N-chloro-N-Argentocarbamates: Ethyl Threo-[1-(2-hydroxy-1,2-diphenylethyl)]carbamate|first1=Eugenio|last1=Herranz|first2=K. Barry|last2=Sharpless|journal=Org. Synth.|year=1983|volume=61|page=93|doi =10.15227/orgsyn.061.0093}}
:R2NH + t-BuOCl → R2NCl + t-BuOH
Very few chloramines are stable, and they easily decompose. In acid, they homolyze in the Hofmann–Löffler reaction; in base, they eliminate to the corresponding imines.
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.{{cite web|title=Controlling Chloramines in Indoor Swimming Pools|url=http://www.health.nsw.gov.au/environment/factsheets/Pages/chloramines.aspx|work=NSW Government Health|accessdate=20 February 2013|date=3 December 2012}} Chloramines, especially trichloramine, are responsible for most of the "chlorine smell" of pools,{{cite web |date=July 2006 |title=Chloramines: Understanding "Pool Smell" |url=https://chlorine.americanchemistry.com/Science-Center/Chlorine-Compound-of-the-Month-Library/Chloramines-Understanding-Pool-Smell/ |website=American Chemistry Council |url-status=dead |archive-url=https://web.archive.org/web/20191217170314/https://chlorine.americanchemistry.com/Science-Center/Chlorine-Compound-of-the-Month-Library/Chloramines-Understanding-Pool-Smell/ |archive-date=17 December 2019 |access-date=17 December 2019}} as well as for skin, eye, and respiratory irritation.{{cite journal | last1=Bessonneau | first1=Vincent | last2=Derbez | first2=Mickaël | last3=Clément | first3=Michel | last4=Thomas | first4=Olivier | title=Determinants of chlorination by-products in indoor swimming pools | journal=International Journal of Hygiene and Environmental Health | year=2011 | volume=215 | issue=1 | pages=76–85 | issn=1438-4639 | doi=10.1016/j.ijheh.2011.07.009 | pmid=21862402 }}