Swern

Definition

The Swern oxidation, also known as the Swern-Moffatt oxidation, is a chemical reaction used to convert alcohols into aldehydes or ketones. It is a powerful and versatile method for the oxidation of alcohols, particularly those that are sterically hindered or sensitive to basic conditions.

5 Must Know Facts For Your Next Test

1. The Swern oxidation is a two-step process that involves the activation of DMSO with oxalyl chloride, followed by the addition of the alcohol to form the desired aldehyde or ketone.
2. The Swern oxidation is particularly useful for the oxidation of sterically hindered alcohols, as it avoids the use of strong bases or oxidizing agents that could cause unwanted side reactions.
3. The reaction is typically carried out at low temperatures (around -78°C) to control the reactivity and prevent side reactions.
4. The Swern oxidation is compatible with a wide range of functional groups, making it a versatile method for the synthesis of aldehydes and ketones.
5. The mechanism of the Swern oxidation involves the formation of an activated dimethylsulfonium chloride species, which then reacts with the alcohol to form the desired carbonyl compound.

Review Questions

• Describe the key steps involved in the Swern oxidation reaction.
  • The Swern oxidation is a two-step process. First, oxalyl chloride reacts with dimethyl sulfoxide (DMSO) to form an activated dimethylsulfonium chloride species. In the second step, the alcohol is added, and this activated species then oxidizes the alcohol to form the desired aldehyde or ketone. The reaction is typically carried out at low temperatures to control the reactivity and prevent side reactions.
• Explain why the Swern oxidation is particularly useful for the oxidation of sterically hindered alcohols.
  • The Swern oxidation is preferred for the oxidation of sterically hindered alcohols because it avoids the use of strong bases or oxidizing agents that could cause unwanted side reactions. The activation of DMSO with oxalyl chloride creates a milder and more selective oxidizing species, which can effectively oxidize even bulky alcohols without compromising the integrity of other functional groups present in the molecule.
• Analyze the versatility of the Swern oxidation in the context of organic synthesis.
  • The Swern oxidation is a highly versatile method for the synthesis of aldehydes and ketones. It is compatible with a wide range of functional groups, making it a useful tool in the arsenal of organic chemists. The ability to selectively oxidize alcohols, even those that are sterically hindered, without the need for harsh conditions or reagents, allows for the efficient and controlled preparation of a variety of carbonyl compounds, which are essential building blocks in the synthesis of more complex organic molecules. The versatility of the Swern oxidation makes it a valuable reaction in the field of organic synthesis.

Related terms

Oxidation: The process of increasing the oxidation state of a molecule, typically by the addition of oxygen or the removal of hydrogen.

Dimethyl Sulfoxide (DMSO): A polar aprotic solvent used in the Swern oxidation as the oxidizing agent, along with oxalyl chloride.

Oxalyl Chloride: A reagent used in the Swern oxidation, which reacts with DMSO to form an activated dimethylsulfonium chloride species that then oxidizes the alcohol.