氮杂炔正离子与二环[2,2,1]-2-庚烯反应的微观机理研究

Theoretical analysis of micro-mechanisms on the addition reactions of nitriliums with bicyclo[2,2,1]-hept-2-ene

采用DFT理论,在B3LYP/6-31G**水平下研究了氮杂炔正离子[R—C≡N—CH(R1R2)]+与二环[2,2,1]-2-庚烯的反应机理.优化得到各驻点的几何构型,通过振动分析和内禀反应坐标对过渡态进行了确认,解析了反应路径.并在同一水平上研究了当R,R1和R2分别为不同烷烃取代基的同分异构体时,得到不同产物的反应情况,找出这类反应随取代基不同的变化规律.结果表明:该反应体系有TSa和TSb两条路径,产物主要通过能量较低的过渡态TSa路径反应;当取代基为直链烷烃基团时,反应位垒较小,有利于反应进行.

The mechanisms on addition reactions of nitrilium [ R—C≡N—CH（R1 R2 ）]^ ＋ with bicycle[ 2,2, 1 ]-hept-2-ene have been studied using the density function theory B3LYP method at 6-31G^＊＊ level. The influence of different substituents to the addition reaction also has been investigated to research into the reaction law. The geometries and the energies of the stationary points in the reaction processes were calculated. The transition states have further been confirmed by intrinsic reaction coordinates （IRC） and characterized by the number of imaginary vibrational frequency. The obtained results show that the titled reaction were consist of two similar parallel reactions Path 1 and Path 2,and generate the product Pa and Pb vis TSa and TSb, respectively. The reaction process of the Path 1 is much more favorable than that of the Path 2. The energy barrier of reaction is higher when the substituent is branch-alkyl, and the reactions take place easily for straight-alkyl.