Editing Hydroxide (section)

===As a nucleophilic reagent===
[[File:AcylSubstitution.svg|thumb|300px|Nucleophilic acyl substitution with an anionic [[nucleophile]] (Nu<sup>&minus;</sup>) and [[leaving group]] (L<sup>&minus;</sup>)]]
The hydroxide ion is intermediate in [[nucleophilicity]] between the [[fluoride]] ion F<sup>−</sup>, and the [[azanide|amide]] ion {{chem|NH|2|−}}.<ref>{{cite journal|last=Mullins|first=J. J.|year=2008|title=Six Pillars of Organic Chemistry|journal=[[J. Chem. Educ.]]|volume=85|issue=1|page=83|doi=10.1021/ed085p83|bibcode= 2008JChEd..85...83M}}[http://bastoslab.com/2010/wp-content/uploads/2010/09/ed085p83.pdf pdf] {{Webarchive|url=https://web.archive.org/web/20110707213623/http://bastoslab.com/2010/wp-content/uploads/2010/09/ed085p83.pdf |date=2011-07-07 }}</ref> [[Ester hydrolysis]] under alkaline conditions (also known as [[base hydrolysis]])
:R<sup>1</sup>C(O)OR<sup>2</sup> + OH<sup>&minus;</sup> {{eqm}} R<sup>1</sup>CO(O)H + <sup>&minus;</sup>OR<sup>2</sup> {{eqm}} R<sup>1</sup>CO<sub>2</sub><sup>&minus;</sup> + HOR<sup>2</sup>
is an example of a hydroxide ion serving as a nucleophile.<ref name=Hardinger>{{cite web|url = http://www.chem.ucla.edu/~harding/IGOC/S/saponification.html|title = Illustrated Glossary of Organic Chemistry: Saponification|year = 2017|first = Steven A.|last = Hardinger|publisher = [[UCLA College of Letters and Science|Department of Chemistry & Biochemistry, UCLA]]|access-date = April 10, 2023}}</ref> 

Early methods for [[saponification|manufacturing soap]] treated [[triglyceride]]s from animal fat (the ester) with [[lye]].  

Other cases where hydroxide can act as a nucleophilic reagent are [[amide]] hydrolysis, the [[Cannizzaro reaction]], [[nucleophilic aliphatic substitution]], [[nucleophilic aromatic substitution]], and in [[elimination reaction]]s. The reaction medium for KOH and NaOH is usually water but with a [[phase-transfer catalyst]] the hydroxide anion can be shuttled into an organic solvent as well, for example in the generation of the reactive intermediate [[dichlorocarbene]].