摘要
取代基对分子反应中心的影响,除了通过电子效应和立体效应以外,还能在分子内发生另一种直接作用,即分子内某些取代基可与反应中心作用,形成过渡态或环形中间体而影响某一反应。这类取代基一般带有π电子或未共享电子对,在分子内充当亲核试剂,发生分子内的亲核取代。这种在同一分子内,亲核的取代基参与反应中心取代反应的现象。邻基参与在有机化学中,特别是在亲核取代,消除和重排中普遍存在,它对反应速度和反应产物等影响很大,是有机化学中一种较重要的效应。
The effect of substituent on the reaction center of the molecule can produce another direct action in the intermolecule besides by the electronic effect and stereo effect, that is to say, some substituent of the molecule can react on the reaction center to form the transition state or cyclic intermediate so that it can influence certain reaction. This kind of substituent usually contains π elctrons or the unshared electron pair, acts as a nucleophile in the molecule and produces intramolecular nucleophilic displacement. This neighboring group participation in organic chemistry, especially in nucleophilie displacement, elimination and rearrangment, is in common existence. It has tremendous effect on the reaction rate and reaction products. So this is an important effect in organic chemistry.
关键词
邻基效应
取代基
亲核取代
neighboring group participation
sustituent
intramolecular nucleophilic displacement
