Study on Ranking and Characteristic of Vinyl Cations as Carbocation

这项研究的目的是研究二价乙烯基阳离子如何与三价碳阳离子连接，以及乙烯基阳离子在气相中质子化苯乙炔衍生物产生乙烯基阳离子的特征。用芳香族取代反应的线性关系方程估算了不同乙烯基阳离子的热力学。B取代的乙烯基阳离子的r值与相应的乙烯基阳离子的稳定性呈线性关系，也与三价苄基阳离子有关。2)测定了乙烯基衍生物在乙醇水溶液中的溶剂效应。通过制备具有亲水性氨基的乙烯基衍生物，克服了溶解性的问题。3)芳基取代的乙烯基卤化物可通过激光闪光光解生成乙烯基阳离子。通过测量乙烯基阳离子在不同溶解条件下的衰变速率，可以跟踪它的行为。对混合溶剂的亲核性进行了评价。由于空间排斥作用，α-对甲氧基苯基乙烯基阳离子的β-取代基与亲核试剂的β-取代基有很大差异。

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.