What is the Difference Between Wittig Reaction and Wittig Rearrangement?

The Wittig reaction and Wittig rearrangement are both important chemical reactions in organic chemistry. They are named after Nobel Prize-winning chemist Georg Wittig. Here are the key differences between the two:

Wittig Reaction:

• The Wittig reaction is a coupling reaction that involves the coupling of aldehydes.
• It is useful in the production of alkenes in organic synthesis processes.
• The nature of the produced alkene depends on the stability of the ylide, with unstabilized ylides giving Z-alkenes and stabilized ylides giving E-alkenes.
• The formation of E-alkenes is highly selective in this reaction.

Wittig Rearrangement:

• The Wittig rearrangement is a transformation of one form into another form depending on the stability.
• There are two main types of Wittig rearrangement: 1,2-Wittig rearrangement and 2,3-Wittig rearrangement.
• The 1,2-Wittig rearrangement involves the rearrangement of an ether with an alkyllithium compound, forming an alkoxy lithium salt as an intermediate and an alcohol as the final product.
• When the ether contains a good leaving group and electron-withdrawing group, such as a cyanide group, this group is eliminated during the rearrangement, forming the corresponding ketone.

In summary, the Wittig reaction is a coupling reaction used to produce alkenes, while the Wittig rearrangement is a transformation reaction involving the rearrangement of ethers.

Comparative Table: Wittig Reaction vs Wittig Rearrangement

The Wittig reaction and Wittig rearrangement are both important processes in organic chemistry, but they have distinct differences. Here is a comparison table highlighting their key differences:

The Wittig reaction is widely used in organic synthesis for the preparation of alkenes, while the Wittig rearrangement is a transformation of one form into another form depending on the stability of the ylide.