Sulfonium
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201883683
2008-03-29T20:25:59Z
Cacycle
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also known as '''sulphonium ion''' and '''sulfanium ion'''
[[Image:Sulfonium ion.png|thumb|Sulfonium ion]]
A '''sulfonium ion''', also known as '''sulphonium ion''' and '''sulfanium ion''', is a positively charged [[sulfur]] [[ion]] carrying three [[alkyl]] [[functional group|groups]] as [[Substitution (chemistry)|substituents]] (S<sup>+</sup>R<sub>3</sub>). [[Ionic compound]]s consisting of a positively charged sulfonium [[cation]] and a negatively charged [[anion]] are called '''sulfonium salts'''.
Sulfonium compounds can be [[Chemical synthesis|synthesized]] from the reaction of dialkylsulfides with [[alkyl halide]]s:
: [[Dimethyl sulfide|CH<sub>3</sub>-S-CH<sub>3</sub>]] + [[Iodomethane|CH<sub>3</sub>-I]] → (CH<sub>3</sub>)<sub>3</sub>S<sup>+</sup> I<sup>−</sup> (trimethylsulfonium iodide)
In the above reaction, the alkylation of a sulfide, the sulfur atom has two lone electron pairs. Using those lone pairs, the sulfide acts as a nucleophile, and attacks the carbon of iodomethane. At the same time, as part of a concerted nucleophilic substitution mechanism (S<sub>N</sub>2), the iodide leaving group comes off; this leaves a positively charged trimethylsulfonium ion. This cation is attracted to the negatively charged iodide, so the two form an ionic bond, giving trimethylsulfonium iodide.<ref>Abdullah Rathur</ref>
== See also ==
*[[Sulfide]] R-S-R
*[[Sulfate]] R-SO<sub>4</sub>-R
*[[Sulfite]] R-SO<sub>3</sub>-R
*[[Sulfonic acid|Sulfonate]] R-SO<sub>3</sub><sup>−</sup>
*[[Onium compounds]]
== References ==
<references/>
== External links ==
* [http://www.iupac.org/goldbook/S06121.pdf IUPAC definition] (short pdf)
[[Category:Cations]]
[[Category:Organosulfur compounds]]
{{organic-chem-stub}}
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[[ja:スルホニウム]]
[[pt:Sulfônio]]