Sulfonium 2295918 201883683 2008-03-29T20:25:59Z Cacycle 83784 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>&minus;</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>&minus;</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}} [[de:Sulfonium]] [[ja:スルホニウム]] [[pt:Sulfônio]]