Rearrangement Reactions of Alkyl Carbocation

Carbocation rearrangements can be defined “as the movement of the carbocation from an unstable state to a more stable state by making use of different structural reorganizational shifts within the molecule”. Alkyl carbocation is a carbocation comprising an alkyl group. They are the most common carbocation.

For example:

Alkyl Carbocation

Carbocation Rearrangement

Carbocation Rearrangement occurs whenever the alcohols are converted into several carbocations and this phenomenon is termed as carbocation rearrangement. In simple carbocation comprises +ve charge in a molecule that is connected to 3 more groups and holds a sextet. Carbocation rearrangement can be carried out to a reaction that does not involve alcohol. There are 2 types of carbocation rearrangements namely Alkyl and Hybrid Shift.

Alkyl Shift

An alkyl shift occurs when a carbocation does not contain a hydrogen atom that is present on the adjacent carbon atom that is readily available for rearrangement. There are some cases where a hybrid shift does not lead to a stable carbocation. For instance, consider the following case.

Alkyl Carbocation

Suppose if alkyl group migrates there would be a chance for formation of tertiary carbocation that is more stable.

Alkyl Carbocation

When a carbon attached to four carbons are present adjacent to secondary carbocation then there would be a possibility for the occurrence of alkyl shift.

Alkyl Carbocation

This alkyl occurs when a carbon-carbon bond donates a pair of electrons to the empty p-orbital on the carbocation. It can occur potentially at any time when carbocation is formed.


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