 Rearrangement reaction

A rearrangement reaction changes the connectivity of a molecule by moving atoms or groups within its framework. Its product is a constitutional isomer when the overall molecular formula is unchanged, although rearrangements can also occur as steps within a larger reaction.

A carbocation may undergo a hydride or alkyl shift that relocates its positive charge and changes the carbon skeleton. Rearrangements can also be concerted, without a free carbocation intermediate. Identifying which bonds break and form is therefore more informative than treating every rearrangement as the same mechanism.