Wittig Reaction Mechanism

TL;DR

The Wittig reaction is a useful method for converting ketones into alkenes by replacing the oxygen with a group attached to a methylene (CH2) group.

Transcript

in this video we're going to go over the wittig reaction and so here we have a ketone and we are going to react it with a phosphonium illid which looks like that what do you think the major product for this reaction will be the wittig reaction converts ketones into alkenes and one thing i like to do is rotate the ketone in such a way that the carbo... Read More

Key Insights

• 🔨 The Wittig reaction is a valuable tool for converting ketones into alkenes.
• 😒 The reaction involves the use of a phosphonium ylide to replace the oxygen of the ketone.
• 🏃 The product of the reaction can exist as a mixture of cis and trans isomers.
• 🧑‍🏭 The selectivity of the reaction can be influenced by various factors, including the starting ketone's stereochemistry and the structure of the ylide.
• 😨 Care should be taken when selecting the alkyl halide in the initial step of the reaction to avoid hindered SN2 reactions.
• 🛟 Triphenylphosphine is commonly used in the reaction and can serve as the starting material for the synthesis of the ylide.
• 🤙 In some cases, the Wittig reaction can produce a side product called triphenylphosphine oxide.

Questions & Answers

Q: What is the Wittig reaction?

The Wittig reaction is a chemical reaction that converts ketones into alkenes by replacing the oxygen atom of the ketone with a group attached to a methylene group.

Q: How is the major product determined in the Wittig reaction?

The major product is obtained by replacing the oxygen of the ketone with the group attached to the ylide used in the reaction.

Q: Can the Wittig reaction produce a mixture of isomers?

Yes, the Wittig reaction can produce both cis and trans isomers of the alkene product. The trans isomer is generally more stable.

Q: What factors affect the selectivity of the Wittig reaction?

The selectivity of the Wittig reaction can be influenced by the stereochemistry of the starting ketone and the structure of the ylide used in the reaction.

Summary & Key Takeaways

• The Wittig reaction involves reacting a ketone with a phosphonium ylide to form an alkene.

• The major product of the reaction is obtained by replacing the oxygen of the ketone with a group attached to the ylide.

• The reaction can produce a mixture of cis and trans isomers, with the trans isomer typically being more stable.