Migratory aptitude

Migratory aptitude is the relative ability of a migrating group to migrate in a rearrangement reaction.^[1] Migratory aptitudes vary in different reactions, depending on multiple factors.^[2]

In the Baeyer-Villiger reaction, the more substituted group, in general, migrates.^[3] In the pinacol rearrangement, the order of migratory aptitude has not been determined unambiguously,^[2] but some trends have been determined. For example, relative migratory aptitudes for alkyl substituents is Hydride >C(CH₃)₃> C₂H₅ > phenyl > CH₃.^[2] More bulky groups have more tendency to migrate.