Editing Quaternary ammonium cation (section)

== Synthesis ==
Quaternary ammonium compounds are prepared by the [[alkylation]] of [[tertiary amine]].  Industrial production of commodity quat salts usually involves hydrogenation of [[fatty nitrile]]s, which can generate primary or secondary amines. These amines are then treated with [[methyl chloride]].<ref name=KO>{{cite book |doi=10.1002/0471238961.0113131523051920.a01.pub2|chapter=Ammonium Compounds |title=Kirk-Othmer Encyclopedia of Chemical Technology |year=2003 |last1=Weston |first1=Charles W. |last2=Papcun |first2=John R. |last3=Dery |first3=Maurice |isbn=0471238961 }}</ref>

The quaternization of alkyl amines by [[halocarbon|alkyl halides]] is widely documented.<ref name=OS>{{cite journal|title=o-Methylbenzyl Alcohol| vauthors = Brasen WR, Hauser CR |journal=  Organic Syntheses |year=1954 |volume=34 |page=58 |doi= 10.15227/orgsyn.034.0058}}</ref> In older literature this is often called a [[Menshutkin reaction]], however modern chemists usually refer to it simply as '''quaternization'''.<ref>{{cite book | vauthors = Smith MB, March J |author2-link= Jerry March | year = 2001 | title = Advanced Organic Chemistry: Reactions, Mechanisms, and Structure | edition = 5th | location = New York, NY | publisher = Wiley-Interscience | isbn = 0-471-58589-0}}</ref> The reaction can be used to produce a compound with unequal alkyl chain lengths; for example when making [[Surfactant#Cationic head groups|cationic surfactants]] one of the alkyl groups on the amine is typically longer than the others.<ref>{{Ullmann| vauthors = Kosswig K |title=Surfactants|doi=10.1002/14356007.a25_747}}</ref> A typical synthesis is for [[benzalkonium chloride]] from a long-chain alkyldimethylamine and [[benzyl chloride]]:

:{{chem2 | CH3(CH2)_{n}N(CH3)2 + ClCH2C6H5 -> [CH3(CH2)_{n}N(CH3)2CH2C6H5]+Cl- }}