硫代双烯酮与亚胺环加成反应机理的理论研究  

Theoretical Studies on the Mechanism of the Cycloaddition Reaction between Thioketene and Methylenimine

作　　者：王岩[1] 方德彩[1] 傅孝愿[1] 

机构地区：[1]北京师范大学化学系,北京100875

出　　处：《Chinese Journal of Chemical Physics》1999年第4期433-440,共8页化学物理学报（英文）

基　　金：国家自然科学基金!29603002;北京师范大学跨世纪人才基金

摘　　要：对硫代双烯酮与亚胺形成四员或六员环产物的环加成反应进行了理论研究．若反应为等摩尔比的，可以发生两个平行反应，分别形成氮杂及硫氮杂的四员环产物．这两个反应都是各经过一个两性离子中间体的分步反应，其中第二步为速控步骤．此外，以上两反应的中间体还可以与一个反应物分子继续反应形成两个不同的六员环产物;且这两个反应的活化势垒均比形成四员环产物的反应低，所得结果与实验一致．The cycloaddition reactions of thioketene and methylenimine forming four- or six-membered ring products were studied theoretically. For the equimolar (1:1) reactions (1) and (2), HF/6-31G* and Density Function Theory (DFT) B3LYP/6-31 + +G** methods were used, while for the mole ratio 1:2 or 2:1 reactions (3) and (4), only the RHF/6-31G* method was used to save CPU time. Bader type electron density topological analysis was used to studythe electronic structure of stationary points for the equimolar reactions (1) and (2). All the geometries of the stationary points on the reaction path have ho optimized by energy gradient technique, and an the transition states were characterized by vibration frequency analysis. In the case of equimolar reactions, two parallel reactions may proed with the formation of two different four-membered heterocyclic products. These two reactions are stepwise, proceeding via a zwitterionic intermediate respectively; the second step is the rate controlling one. In addition, the above two intermediates the can react further with another thioketene or methylenimine molecule respectively to form two six-memebered ring products, the barriers of these two reactions are 33.11 and 1.86kJ/mol respectively and they are lower than that of reactions forming four-membered ring product. This is consistent with experimental fact.

关 键 词：硫代双烯酮 亚胺 环加成 密度泛函法 拓扑分析 

分 类 号：O626[理学—有机化学]