migratory aptitude

The term is applied to characterize the relative tendency of a group to participate in a @R05194@. In nucleophilic rearrangements ( @M03920@ to an electron-deficient centre), the migratory aptitude of a group is loosely related to its capacity to stabilize a partial positive charge, but exceptions are known, and the position of hydrogen in the series is often unpredictable.
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1141 [Terms] [Paper]