吡啶光氯化反应机理的量子化学研究(II)——PM3计算吡啶光氯化反应体系能量与反应动力学分析  

The Quantum Chemistry Study on Photochemical Chlorination of Pyridine (II) the Energy Calculation of the system by PM3 and Analysis of Kinetic Process

作　　者：郝金库[1] 杨恩翠[1] 赵增国[1] 王桂林[1] 施敏轶[1] 王玉新[1] 曹映玉[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：《天津师大学报（自然科学版）》2000年第3期1-6,共6页

基　　金：国家"八五"科技攻关基金项目!(85 5 0 42 10 1)

摘　　要：用量子化学方法 PM3结构参数全优化方法对吡啶光氯化反应所涉及的分子、自由基进行了能量计算 ,得到键解离能 ,并对反应活化能与动力学进行分析 .对吡啶光氯化反应 ,提出了氯自由基直接进攻吡啶环的碳原子和氯自由基首先夺取与吡啶环键链的氢原子两种不同的反应机理 .量化计算结果表明 :吡啶光氯化反应中夺氢反应机理所需的反应活化能较低 ,不同产物以生成2 -氯吡啶的活化能最低 ,为 1 74.0 8k J/mol,总反应级数为 1 .5级 ,对吡啶的分级数为 1级 .对氯气的分级数为 0 .5级 .All the equilibrium structures in the photochemical chlorination of pyridine were optimized by PM3.As a result,activation energies were calculated and kinetic process were discussed with bond dissociation energies. The Addition mechanism and abstraction mechanism were discussed. The activation energies in three reaction channels of getting 2 chloropyridine, 3 chloropyridine and 4 chloropyridine were compared,too. The results showed that: the abstraction mechanism dominated the photochemical chlorination of pyridine and produced 2 chloropyridine priorly, the activation energies of producing 2 chloropyridine was 174.08kJ/mol,the overall order is 1.5,1 for pyridine and 0.5 for Cl 2.

关 键 词：吡啶 光氯化反应 动力学 量子化学 

分 类 号：O626.32[理学—有机化学] O641.121[理学—化学]