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