Study on Ranking and Characteristic of Vinyl Cations as Carbocation

本研究的目的是二价乙烯基阳离子如何与三价碳正离子连接以及乙烯基阳离子的特征。1)气相中苯乙炔衍生物的质子化反应生成乙烯基阳离子。用芳代取代反应的线性关系方程评价了各种乙烯基阳离子的热力学。b取代乙烯基阳离子的r值与相应的乙烯基阳离子的稳定性呈线性关系，并与三价苯基阳离子相关。2)测定了乙烯基衍生物在乙醇水溶液中溶解的溶剂效应。通过制备具有亲水性炮基的乙烯基衍生物，克服了溶解度的问题。还需进一步调查。3)激光闪光光解芳基取代卤化乙烯可生成乙烯基阳离子。乙烯基阳离子的行为可以通过测量其在不同溶剂溶解条件下的衰变速率来跟踪。对溶剂混合物的亲核性进行了评价。对甲氧基苯基阳离子的取代基之间由于与亲核试剂之间的空间排斥力而存在较大的差异。

The purpose of this study is how a divalent vinyl cation is connected with trivalent carbocations and how characteristic a vinyl cation is.1) Protonation to phenylacetylene derivatives in gas phase generates vinyl cations. The thermodynamics of various vinyl cations were evaluated with equation of linear relationship of aromatic substitution reaction. The r-values of b-substituted vinyl cations gave linear relationship with stability of the corresponding vinyl cations and also related with trivalent benzylic cations.2) Solvent effect of solvolysis of vinyl derivatives were measured in aqueous ethanol. The problem of solubility was overcome with preparation of vinyl derivatives which have a hydrophilic ammmono group. Further investigation has to be done in extension.3) A vinyl cation can be generated by laser flash photolysis of aryl-substituted vinyl halides. The behavior of a vinyl cation can be followed by measuring its decay rates under various solvolytic conditions. The nucleophilicity of solvent mixture is evaluated. There is large difference between beta-substituents of alpha-p-methoxyphenylvinyl cations due to steric repulsion between the beta-substituent and nucleophiles.