2-氯吡啶光氯化取代反应机理的量子化学研究  

Theoretical Study on Substitute Mechanism of Chlorine Radical with 2-Chloropyridine

作　　者：曹映玉[1] 杨恩翠[1] 华芳[1] 杨琨[1] 赵妍[1] 王万得[1] 郝金库[1] 

机构地区：[1]天津师范大学化学与生命科学学院,天津300074

出　　处：《天津师范大学学报（自然科学版）》2004年第1期8-11,14,共5页Journal of Tianjin Normal University：Natural Science Edition

基　　金：天津市自然科学基金资助项目(003602011);天津市教委基金资助项目(990710);天津师范大学青年基金资助项目

摘　　要：用PM3方法研究了2-氯吡啶光氯化取代反应的过渡态.研究结果表明,生成2,6-二氯吡啶、2,5-二氯吡啶、2,4-二氯吡啶、2,3-二氯吡啶不同产物的每一个反应通道都存在两个过渡态;反应体系沿反应坐标的变化为反应物→反应物络合物→第1过渡态→中间体→第2过渡态→产物络合物→产物;第2过渡态为主过渡态,生成2,6-二氯吡啶反应路径主过渡态的能量及活化能最低,分别为-139612.06和135.39kJ/mol,反应优先生成2,6-二氯吡啶.生成二氯吡啶反应过程中吡啶环反应部位CCl键的形成主要与共轭双键断裂同步,而CH键的断裂主要与共轭双键的重新形成同步.The substitute mechanism of 2-chloropyridine reacting with chlorine radical was studied theoretically by semi-empirical method- PM3. The results showed that there were two transition states in each reaction path for obtaining 2,3-,2,4-,2,5-and 2,6-dichloropyridine respecively. The energy of chief transition state and activation barrier of leading to 2,6-dichloropyridine were lowest among four reaction paths, which is -139 612.06 and 135.39 kJ/mol respectively. Thus, 2,6-dichloropyridine was prior product. The formation ofC (Cl) and the breaking of conjugate double bond was mainly synchronous during the process of producing the dichloropyridine, so did the breaking of C H bond and the re-formation of conjugate double bond.

关 键 词：2-氯吡啶 光氯化 取代反应 量子化学 过渡态 PM3 氯代吡啶 

分 类 号：O626[理学—有机化学] O641.121[理学—化学]