Cation Radicals in Solution

有机合成计划支持教授内森L。鲍尔德 溶液中阳离子自由基化学的研究。 牛津大学化学系的鲍尔德教授说， 得克萨斯州奥斯汀，正在开发一个方便的机械标准， 区分烯烃π键的亲电加成与加成 通过初始电子转移反应进行。 形成 通过亲电试剂加成到芳基乙烯基上的均苄基阳离子 醚和硫化物，其中烯烃与芳族化合物绝缘， 由于杂原子，环与Hammett σ相关， 值，而这种基板的单电子氧化与 Hammett-Brown sigma-plus值。 相反，当烯烃是 直接连接到芳环，质子化和电离 优先与sigma-plus相关。 鲍尔德教授正在开发 一组独特的取代基参数， 阳离子自由基形成的相关性，允许区分 苯乙烯的亲电反应和电子转移反应之间 衍生物. 一种新的加聚策略， 连续阳离子自由基反应提供了一种有吸引力的途径， 狄尔斯-阿尔德和其他环加成聚合物，并将探讨 机械地和作为新材料的合成方法。 Nathan L.教授鲍尔德，化学系的， 得克萨斯大学奥斯汀分校，有机合成的支持下， 程序，进行的形成和反应化学的研究， 两类活性分子，一类（阳离子）带有净正电荷， 另一个（“阳离子自由基”）具有正电荷， 除所含电子外还含有一个未成对电子的 在分子中形成化学键。 他正在开发一套 参数来描述可能导致形成 这两类分子中的任何一种， 分子导致简单的阳离子和阳离子自由基。 的 Bauld教授强调了这些不寻常物种的重要性。 一种新的高分子材料成型方法的研究 基于阳离子自由基的反应。 这种化学反应 提供新的材料和温和的路线，以已知的材料显示 一系列重要属性。

The Organic Synthesis Program supports Professor Nathan L. Bauld's investigations of the chemistry of cation radicals in solution. Professor Bauld, of the Department of Chemistry of the University of Texas at Austin, is developing a convenient mechanistic criterion for distinguishing electrophilic additions to alkene pi bonds from additions proceeding via initial electron transfer reactions. Formation of homobenzylic cations through addition of electrophiles to aryl vinyl ethers and sulfides, wherein the alkene is insulated from the aromatic ring by virtue of the heteroatom, correlates with the Hammett sigma value, while one-electron oxidation of such substrates correlates with the Hammett-Brown sigma-plus value. In contrast, when the alkene is directly attached to an aryl ring, both protonation and ionization correlate preferentially with sigma-plus. Professor Bauld is developing a unique set of substituent parameters which promise significantly better correlations for cation radical formation, permitting the distinction between electrophilic and electron transfer reactions of styrene derivatives. A new addition polymerization strategy based upon sequential cation radical reactions offers an attractive route to Diels-Alder and other cycloaddition polymers and will be explored mechanistically and as a method for the synthesis of new materials. Professor Nathan L. Bauld, of the Department of Chemistry of the University of Texas at Austin, with support from the Organic Synthesis Program, carries out studies of the formation and reaction chemistry of two classes of reactive molecules, one (`cations`) bearing a net positive charge, the other (`cation radicals`) having a positive charge and also containing an unpaired electron in addition to those electrons involved in forming the chemical bonds in the molecule. He is developing a set of parameters to describe the reactions which can lead to the formation of either of these classes of molecules, determining which types of molecules lead to simple cations and which to cation radicals. The importance of these unusual species is highlighted by Professor Bauld's investigations of a new method for the formation of polymeric materials based upon the reactions of cation radicals. This chemistry promises to afford both new materials and milder routes to known materials displaying a range of important properties.