氮杂炔正离子与2,3-二甲基丁烯反应机理研究

用半经验量子化学AM1方法研究氮杂炔正离子R1-C≡N-R2] 与2,3-二甲基丁烯的反应机理.优化得到各驻点的几何构型,通过振动分析对过渡态进行了确认,解析了反应路径,并用同一方法研究当R1和R2分别被不同的烷烃基取代的反应情况.结果表明反应体系有两个过渡态,ts1为C2-C3接近时的过渡态;ts2为氢原子的迁移,最后得到产物.不同烷烃基取代有相同的反应机理,支链越多的烷烃基的相对能量越高,由于苯基为一平面结构,能量反而较支链烷烃基团低.

Theoretical Studies on Reaction Mechanism between Nitrilium and 2, 3 - Dimethyl Butanes

The mechanism of addition reactions between nitrilium and 2,3-dimethyl butanes has been studied by using AM1 semi empirical quantum chemistry method. The geometries and the energies of the stationary points in the reaction processes were calculated using the AM1 semi empirical quantum chemistry method in this paper.The transition states have further been confirmed by the vibration frequency.Based on the above calculation,the reactions have been studied by the same method when the R1 and R2 in reactants are substituted separately by different paraffin base substitution response situation.The results indicate that,the reaction occurs via two transition states: ts1 is condsponding to the approach of C2-C3 atom;ts2 involves a hydrogen migration process,and finally the relatively stable product can be obtained.The different derivatives have the same reaction mechanism,the reactant with more branched chain paraffin has a higher energy.The compound with benzene as alkylation has a relatively low energy because the benzyl is a planar.