The @A00512@ of an @E02130@ to a position in an aromatic compound already carrying a @S06076@ (other than hydrogen). The @E02130@ 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:
I03251.pngwhere E + is an @E02020@ and Z is a substituent (other than hydrogen).