The @[email protected] of an @[email protected] to a position in an aromatic compound already carrying a @[email protected] (other than hydrogen). The @[email protected] may displace that substituent group but may also itself be expelled or migrate to a different position in a subsequent step. The term 'ipso-substitution' is not used, since it is synonymous with substitution. For example:
where E + is an @[email protected] and Z is a substituent (other than hydrogen).
See also:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1128 [Terms] [Paper]