Editing Oxonium ion (section)

==Alkyloxonium==
Hydronium is one of a series of oxonium ions with the formula R<sub>''n''</sub>H<sub>3−''n''</sub>O<sup>+</sup>.
Oxygen is usually pyramidal with an sp<sup>3</sup> [[orbital hybridisation|hybridization]]. Those with ''n''&nbsp;=&nbsp;1 are called primary oxonium ions, an example being protonated alcohol (e.g. [[methanol]]). In acidic media, the oxonium [[functional group]] produced by protonating an alcohol can be a [[leaving group]] in the [[elimination reaction|E2 elimination]] reaction. The product is an [[alkene]]. Extreme acidity, heat, and dehydrating conditions are usually required. Other hydrocarbon oxonium ions are formed by [[protonation]] or [[alkylation]] of [[alcohol (chemistry)|alcohol]]s or [[ether]]s (R−C−{{overset|+|O}}−R<sub>1</sub>R<sub>2</sub>).

Secondary oxonium ions have the formula R<sub>2</sub>OH<sup>+</sup>, an example being protonated ethers.

Tertiary oxonium ions have the formula R<sub>3</sub>O<sup>+</sup>, an example being [[trimethyloxonium tetrafluoroborate|trimethyloxonium]].<ref>{{cite journal |title=Superelectrophiles |author=Olah, George A. |year=1993 |journal=Angew. Chem. Int. Ed. Engl. |volume=32 |issue=6 |pages=767–788 |doi=10.1002/anie.199307673}}</ref> Tertiary [[alkyl]]oxonium [[salt (chemistry)|salts]] are useful [[alkylating agent]]s. For example, [[triethyloxonium tetrafluoroborate]] ({{Chem|Et|3|O|+}})({{Chem|BF|4|-}}), a white crystalline solid, can be used, for example, to produce ethyl esters when the conditions of traditional Fischer [[esterification]] are unsuitable.<ref>{{cite journal |last1=Raber |first1=Douglas J. |last2=Gariano Jr |first2=Patrick |last3=Brod |first3=Albert O. |last4=Gariano |first4=Anne L. |last5=Guida |first5=Wayne C. |year=1977 |title=Esterification Of Carboxylic Acids With Trialkyloxonium Salts: Ethyl And Methyl 4-acetoxybenzoates |journal=Org. Synth. |volume=56 |page=59 |doi=10.15227/orgsyn.056.0059}}</ref> It is also used for preparation of enol ethers and related functional groups.<ref>{{cite journal |last1=Struble |first1=Justin R. |last2=Bode |first2=Jeffrey W. |year=2010 |title=Synthesis Of A ''N''-mesityl Substituted Aminoindanol-derived Triazolium Salt |journal=Org. Synth. |volume=87 |page=362 |doi=10.15227/orgsyn.087.0362 |doi-access=free}}</ref><ref>{{cite journal |last1=Hegedus |first1=Lous S. |last2=Mcguire |first2=Michael A. |last3=Schultze |first3=Lisa M. |year=1987 |title=1,3-Dimethyl-3-methoxy-4-phenylazetidinone |journal=Org. Synth. |volume=65 |page=140 |doi=10.15227/orgsyn.065.0140}}</ref>
{| class="wikitable" style="margin:1em auto; text-align:center;"
|[[File:Oxonium-ion-2D.png|100px]]||[[File:Trimethyloxonium-2D-skeletal.png|100px]]||[[File:Trimethyloxonium-3D-balls.png|100px]]||[[File:Trimethyloxonium-3D-vdW.png|100px]]
|-
|general [[trigonal pyramidal molecular geometry|pyramidal]]<br>oxonium ion||[[skeletal formula]] of the<br>[[trimethyloxonium]] cation||[[ball-and-stick model]]<br>of trimethyloxonium||[[space-filling model]]<br>of trimethyloxonium
|}

[[Oxatriquinane]] and [[oxatriquinacene]] are unusually stable oxonium ions, first described in 2008. Oxatriquinane does not react with boiling water or with [[Alcohol (chemistry)|alcohol]]s, [[thiol]]s, [[halide ion]]s, or [[amine]]s, although it does react with stronger [[nucleophile]]s such as [[hydroxide]], [[cyanide]], and [[azide]].