Editing Quaternary ammonium cation (section)

==Reactions==
Quaternary ammonium cations are unreactive toward even strong [[electrophile]]s, [[oxidant]]s, and [[acid]]s. They also are stable toward most [[nucleophile]]s. The latter is indicated by the stability of the [[hydroxide]] salts such as [[tetramethylammonium hydroxide]] and [[tetrabutylammonium hydroxide]] even at elevated temperatures. The halflife of Me<sub>4</sub>NOH in 6M NaOH at 160 °C is >61 h.<ref>{{cite journal | vauthors = Marino MG, Kreuer KD | title = Alkaline stability of quaternary ammonium cations for alkaline fuel cell membranes and ionic liquids | journal = ChemSusChem | volume = 8 | issue = 3 | pages = 513–523 | date = February 2015 | pmid = 25431246 | doi = 10.1002/cssc.201403022 | bibcode = 2015ChSCh...8..513M }}</ref>

Because of their resilience, many unusual anions have been isolated as the quaternary ammonium salts. Examples include [[tetramethylammonium pentafluoroxenate]], containing the highly reactive pentafluoroxenate ({{chem|XeF|5|−}}) ion. [[Permanganate]] can be solubilized in [[Organic compound|organic]] [[solvents]], when deployed as its {{chem|N[[butyl|Bu]]|4|+}} salt.<ref>{{cite journal | title = Purple benzene: Solubilization of anions in organic solvents | vauthors = Herriott AW | journal = Journal of Chemical Education| year = 1977 | volume = 54 | issue = 4 | page = 229 | doi = 10.1021/ed054p229.1| bibcode = 1977JChEd..54Q.229H }}</ref><ref>{{Cite journal | vauthors = Doheny Jr AJ, Ganem B | title = Purple benzene revisited | journal = Journal of Chemical Education| year = 1980 | volume = 57 | pages = 308 | doi = 10.1021/ed057p308.1 | issue = 4|bibcode=1980JChEd..57..308D }}</ref>

With exceptionally strong bases, quat cations degrade. They undergo [[Sommelet–Hauser rearrangement]]<ref>{{OrgSynth | collvol = 4 | collvolpages = 585 | year = 1963 | title = 2-Methylbenzyldimethylamine |  vauthors = Brasen WR, Hauser CR |prep=cv4p0585}}</ref> and [[Stevens rearrangement]],<ref>{{cite book| doi = 10.1002/0471264180.or018.04 | chapter = The Base-Promoted Rearrangements of Quaternary Ammonium Salts | title = Organic Reactions | pages = 403–464 | year = 2011 | vauthors = Pine SH | isbn = 978-0471264187}}</ref> as well as dealkylation under harsh conditions or in presence of strong nucleophiles, like thiolates. Quaternary ammonium cations containing N−C−C−H units can also undergo the [[Hofmann elimination]] and [[Emde degradation]].

[[Image:Benzalkonium chloride Structure V.1.svg|thumb|[[Benzalkonium chloride]] is a common type of quat salt used as a [[biocide]], a [[cationic]] [[surfactant]], and as a [[phase transfer agent]].<ref>{{Cite book |doi = 10.1002/14356007.q03_q01|chapter = Antimicrobial Surfaces|title = Ullmann's Encyclopedia of Industrial Chemistry|pages = 1–13|year = 2013| vauthors = Lackner M, Guggenbichler JP |isbn = 9783527306732}}</ref>  ADBACs are a [[mixture]] of alkylbenzyldimethylammonium chlorides, in which the alkyl group has various even-numbered alkyl chain lengths.]]