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在实验及工业生产中常遇到的有机化学反应除离子型、自由基型反应外,还有一种在正常情况下添加酸碱或自由基催化剂都不能显著地改变其反应速度,反应历程中无高度极性的中间体(正负离子或自由基),而是在反应过渡态中键的断裂和形成是同时发生的,通常称为协同反应。大多数协同反应往往经历一环状过渡态,如环加成、电环合,——迁移反应,故又称周环反应。有关周环反应的机理,前线轨道理论,对称守
In the experimental and industrial production often encountered in organic chemical reactions in addition to ionic, free radical reaction, there is a normal addition of acid-base or free radical catalyst can not significantly change the reaction rate, the reaction process without height Polar intermediates (positive and negative ions or free radicals), but in the reaction transition state bond rupture and formation are simultaneous, commonly referred to as the synergistic reaction. Most of the synergistic reactions often experience a cyclic transition state, such as cycloaddition, cyclization, - migration reaction, it is also known as pericyclic reaction. The mechanism of pericyclic reaction, frontier orbital theory, symmetry keep