Swern oxidation

In organic chemistry, the Swern oxidation also known as Moffatt-Swern, named after Daniel Swern, is a chemical reaction whereby a primary or secondary alcohol (−OH) is oxidized to an aldehyde (−CH=O) or ketone (>C=O) using oxalyl chloride, dimethyl sulfoxide (DMSO) and an organic base, such as triethylamine. It is one of the many oxidation reactions commonly referred to as 'activated DMSO' oxidations. The reaction is known for its mild character and wide tolerance of functional groups.

The by-products are dimethyl sulfide ((CH₃)₂S), carbon monoxide (CO), carbon dioxide (CO₂) and—when triethylamine is used as base—triethylammonium chloride (Et₃NHCl). Of the volatile by-products, dimethyl sulfide has a strong, pervasive odour and carbon monoxide is acutely toxic, so the reaction and the work-up needs to be performed in a fume hood. Dimethyl sulfide is a volatile liquid (B.P. 37 °C) with an unpleasant odour at even low concentrations.