Swern Oxidation
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The oxidation of a primary or secondary alcohol to afford, respectively, an aldehyde or a ketone, when treated with oxalyl chloride and dimethyl sulfoxide at very low temperature (below -60 ºC), followed by triethylamine, is known as Swern oxidation. The procedure is especially useful with primary alcohols because the product aldehyde is not oxidized to the corresponding carboxylic acid under the reaction conditions.
eg:
mechanism: