 The result is a ketone or aldehyde.In another definition all semipinacol rearrangements ""share a common reactive species in which an electrophilic carbon center, including but not limited to carbocations, is vicinal to an oxygen-containing carbon and can drive the 1,2-migration of a C–C or C–H bond to terminate the process, generating a carbonyl group" ".The rearrangement reaction can be classified into 4 types.