芳香卤代物光致亲核取代反应的MO控制因素  

The MO Control Factor in Photoreaction of the Nucleophilic Substitution of Haloarenes

作　　者：杜汝励[1] 尹鹤群 

机构地区：[1]暨南大学化学系

出　　处：《暨南大学学报（自然科学与医学版）》1995年第3期61-66,共6页Journal of Jinan University(Natural Science & Medicine Edition)

基　　金：省自然科学基金资助项目

摘　　要：用光致亲核取代反应选择并合成了若干有代表性的底物芳香化合物，并计算参加反应的各底物的ＨＯＭＯ与ＬＵＭＯ轨道能级，阐述了光照条件下电子转移的制约因素。实验结果表明，在光诱导下烯醇负离子向卤代芳烃的电子转移过程是整个Ｓ＿ＲＮ１（单电子转移的单分子亲核取代反应）机理的关键，烯醇负离子的ＬＵＭＯ轨道能级愈高愈有利于反应的进行，而芳环的ＬＵＭＯ轨道能级愈低则更有利于反应的进行，当两轨道能级差大约为０７β时，反应很容易进行，且产率很高，而当两轨道能级差小于０．２β时，则反应不能发生。This work focuses on the research on photoreaction nucleophilic substitution of aromaticcompounds。After selecting and synthesizing some typical substrates,calculations for HOMO andLUMO orbital energy levels of all these substiates for the reaction is made and control factorsfor electronic transition under radiation are discussed。Experimental asults show that underphoto induction,the key step for S_RN 1 mechanism is the electronc transition from enolate tohaloarenes,The higher the LUMO orbital energy level of the enolate,the more helpful if is forthe reaction to proedeed,while fow LUMO orbital energy level of aromatic nucleus favous thetreaction,which can be effected easily with high yield,when the difference between thetwoorbital energy levels is around 0.7β.But it becomes impossible when this difference is lessthan 0.2β。

关 键 词：亲核取代反应 电子转移 卤代芳烃 轨道能级 

分 类 号：O625.2[理学—有机化学]