烯烃硼氢化反应机理的进一步探讨  

Further Discussion on the Mechanism of Hydroboration of Olefins

作　　者：张磊 周建国 周永柱 Lei Zhang;Jianguo Zhou;Yongzhu Zhou(School of Science,Tianjin Chengjian University,Tianjin 300384,China;School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China.)

机构地区：[1]天津城建大学理学院,天津300384 [2]天津大学化工学院,天津300072

出　　处：《大学化学》2021年第6期212-216,共5页University Chemistry

基　　金：天津城建大学教学改革与研究课题(2019JG1956)。

摘　　要：烯烃的硼氢化反应是一步完成的协同加成反应,一般认为反应需经历四中心环状过渡态。我们采用量子化学计算模拟了丙烯的硼氢化反应机理,计算出的过渡态与所谓的四中心环状结构并不相符,因为硼原子与双键的两个碳原子都存在一定的键合作用,并且氢原子发生迁移的程度是微弱的,这些与文献报道的过渡态特征相符。通过进一步理论计算,我们发现硼氢化反应或许需要经历某些类似于四中心环状的结构,它们对应于过渡态之后、产物之前的一些瞬间状态。最后,通过分子轨道相互作用模型解读硼氢化反应的机理。Hydroboration of olefins is a concerted addition reaction involving only one step.It is generally considered to proceed via a four-center cyclic transition state.We performed theoretical studies on the reaction mechanism of the hydroboration of propene using quantum chemistry calculations,which led to a unique transition state that was inconsistent with the so-called four-center cyclic structure.In the computed transition state,the boron atom is bonded to both of the olefinic carbon atoms,and the degree of the hydrogen shift event is very low.All of these observations are consistent with those reported in the literature.Further theoretical studies revealed that the reaction might involve certain structures similar to the four-center cyclic structure,appearing as the transient states between the transition state and the product.Finally,the reaction mechanism of hydroboration was analyzed from the perspective of the orbital interaction model.

关 键 词：硼氢化 反应机理 过渡态 轨道相互作用 烯烃 

分 类 号：G64[文化科学—高等教育学] O6[文化科学—教育学]