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Y是处于周期表右侧的某些原子,Z可以无,也可以是与Y相连的一个或多个原子或原子团。与动力学定律为Ad_E2或Ad_E3或其它复杂动力学定律无关,其过渡态有两种微观机理,即开放离子和桥型离子机理。开放离子机理允许单键自由旋转,本质上是非立体特殊性的或非立体选择性的,但可因离子对形成或结构特征等原因,给出立体特殊性或立体选择性的产物;但这种表观的立体特殊性或选择性,总可借改变溶剂的极性和反应条件,而使之表现非立体特殊
Y is some atom on the right side of the periodic table, Z may be absent, or it may be one or more atoms or radicals attached to Y. Independent of the kinetic law of Ad_E2 or Ad_E3 or other complex kinetic laws, there are two microscopic mechanisms of transition states, the open-ion and bridge-type ionic mechanisms. The open-ion mechanism allows a single bond to rotate freely, which is intrinsically non-stereoselective or non-stereoselective but may give stereospecific or stereoselective products due to ion pair formation or structural features; however, this Apparent three-dimensional specificity or selectivity, can always change the polarity of solvents and reaction conditions, leaving the performance of non-three-dimensional special