Schematic of the Swern oxidation. Reagents: primary or secondary alcohol, DMSO, oxalyl chloride, Et3N. Product: aldehyde, ketone.

The Swern oxidation is an organic reaction used to convert a primary alcohol to an aldehyde and a secon-dary alcohol to a ketone using DMSO, oxalyl chloride, and triethylamine. The mechanism begins with the activation of DSMO with oxalyl chloride which is then attacked by a chloride anion to form a chlorosulfo-nium cation and release both CO and CO2 gas. Formula of Methyl 3-fluoroisonicotinate 1627973-06-1 structure The alcohol then attacks the chlorosulfonium salt which releases the chloride anion and forms an alkoxysulfonium cation. Triethylamine then deprotonates the alkoxysulfonium at the alpha position to form a alkoxysulfonium ylide. A rearrangemnt then ensues which releases a molecule of dimethyl sulfide gas and results in the final aldehyde or ketone product. [1][2]

Mechanism

Mechanism of the Swern oxidation.

References:

1.
Omura, K.; Sharma, A. K.; Swern, D. J. Org. Chem. 1976, 41, 957–962.
2.
Huang, S. L.; Omura, K.; Swern, D. Synthesis 1978 297–299.