Editing Swern oxidation (section)

==Mechanism==
The first step of the Swern oxidation is the low-temperature reaction of DMSO, '''1a''', formally as [[resonance (chemistry)|resonance]] contributor '''1b''', with oxalyl chloride, '''2'''. The first intermediate, '''3''', quickly decomposes giving off carbon dioxide and carbon monoxide and producing chloro(dimethyl)sulfonium chloride, '''4'''.

[[File:Dimethylchlorosulfonium Formation Mechanism.png|600px|center|Dimethylchlorosulfonium chloride formation.]]

After addition of the alcohol '''5''', the chloro(dimethyl)sulfonium chloride '''4''' reacts with the alcohol to give the key alkoxysulfonium ion intermediate, '''6'''. The addition of at least 2 equivalents of base — typically triethylamine — will [[deprotonation|deprotonate]] the alkoxysulfonium ion to give the sulfur [[ylide]] '''7'''. In a five-membered ring [[transition state]], the sulfur ylide '''7''' decomposes to give dimethyl sulfide and the desired [[carbonyl]] compound '''8'''.

[[File:Swern Oxidation Mechanism.png|600px|center|The mechanism of the Swern oxidation.]]