谈到芳香取代反应,人们立刻会想到芳环上取代基的o~-、p-、m~-位上氢原子的取代反应。然而对另一类反应,即环上取代基本身的取代反应却少为人知。它是起始于试剂对芳环上取代基所在位置(ipso位)的进攻,进而置换了该取代基的反应。称作ipso取代反应。某些研究表明,试剂对氢原子所在位置的进攻与它对ipso位的进攻处于竞争状态,往 Speaking of aromatic substitution reaction, people immediately think of the aromatic ring on the o ~ -, p-, m ~ - position hydrogen atom substitution reaction. However, for the other type of reaction, the substituent substitution on the ring substituents is seldom known. It is the reaction that begins with the reagent’s position on the aryl ring (the ipso position), which in turn displaces the substituent. Referred to as ipso reaction. Some studies have shown that the attack of a reagent on the location of a hydrogen atom is in a state of competition with its attack on the ipso site,