Chemistry Reference
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present on the product. The mechanism of this reaction is illustrated below using
arrow pushing.
d. The Swern oxidation
Hint: The oxygen atom in dimethyl sulfoxide is nucleophilic.
In this topic, there have been many references to oxidation and reduction reactions.
While these reactions are not within the scope of the discussions of this topic, their
mechanisms do involve the processes presented herein. In the case of the Swern
oxidation, the first step is an addition-elimination reaction between dimethyl sulfox-
ide and oxallyl chloride. This process, illustrated below using arrow pushing,
involves addition of the sulfoxide oxygen to a carbonyl with subsequent elimination
of a chloride anion.
The second stage of the Swern oxidation, illustrated below, involves a nucleophilic
displacement of the oxallyl group from the sulfur. In this step, the nucleophile is a
chloride anion, and the reaction is facilitated by the decomposition of the leaving
group into carbon dioxide gas, carbon monoxide gas, and a chloride anion.
The third stage of this reaction involves another nucleophilic displacement. In this
step, the nucleophile is an alcohol and the leaving group is a chloride anion. This
