The Study on the Mechanism of Conjugative Stabilization of Phenyl Cations

苯基阳离子是高活性的重要合成中间体，本课题是研究苯基阳离子共轭稳定机理的结构-反应关系的基础性研究。1)对取代苯基阳离子的优化结构进行了半经验和从头计算，结果表明，具有给电子基团的高度稳定的取代苯基阳离子具有“非平面”结构，其稳定性与非平面性密切相关。2) 2-丙基苯基氯光溶剂通过2-丙基苯基阳离子中间体得到与2-丙基苯二氮离子热分解类似的产物。3)考察了溶剂、间取代基的给电子能力和生成物的电子亲和性对三氟乙烯芳酯和氯化物光溶解过程中芳基自由基和芳基阳离子中间产物比例的影响，其中芳基自由基从溶剂中抽氢和溶剂对芳基阳离子的亲核附合是竞争性的。4)在邻羟基氯化物的光溶解过程中，中间氧化苯基阳离子的环收缩与亲核溶剂对羟基苯基阳离子的侵蚀是竞争性的。通过计算对实验结果进行了验证。

This is a fundamental research to investigate the structure-reactivity relationship of phenyl cations, which are highly reactive and important intermediates for synthesis, with respect to the mechanism of the conjugative stabilization of phenyl cations.1)Semi-empirical and ab initio calculations on the optimized structures of substituted phenyl cations revealed that highly stabilized phenyl cations with electron-donating groups at meta position have "non-planar" structures, whose stability and nonplanality are closely related.2)Photosolvolysis of 2-propylphenyl chloride gave rise to the products via 2-propylphenyl cation intermediate which were similarly obtained in the thermal decomposition of 2-propylbenzenediazonium ions.3)The effects of solvents, electron-donating ability of meta-substituents, and electron-affinity of leaving grous on the ratio of two products via aryl radical and aryl cation intermediates were investigated in the photo-solvolysis of aryl triflates and chlorides, where hydrogen abstraction of aryl radicals from solvent and nucleophilic attach of solvent on aryl cations occured competitively.4)In the photo-solvolysis of ortho-hydroxyphenyl chloride ring contraction of the intermediate oxido-phenyl cations occured competitively with the nucleophilic solvent attack on the hydroxyphenyl cations. The experimental results were investigated by computational calculations.