Swern oxidation

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Here is a standard procedure for the Swern oxidation of an alcohol.


Swern oxidation.png

To a solution of oxalyl chloride (5 mmol) and 3 Å MS in CH2Cl2 (1 mL) at -78 °C under N2 was added dropwise a solution of DMSO (10 mmol) in CH2Cl2 (1 mL). After 15 min a solution of the alcohol in CH2Cl2 (3 mL) was slowly added dropwise. After 30 min, Et3N (15 mmol) was added dropwise. The reaction was stirred 30 min at -78 °C then slowly allowed to warm to rt.


  • Dichloromethane is usually the solvent of choice for this reaction, but Et2O or THF may also be used.
  • For secondary alcohols, warming the reaction to -40 °C after the addition of the alcohol for 20 min may help.
  • Bulkier amines such as diisopropylethylamine can be used instead of triethylamine in case of epimerization of the α-center


Swern oxidation mech.png