Exploring Mechanism of Additions to Alkenes; Extending a New Technique by Four Reactions

提案有两个目标。第一个是扩展PI开发的一项技术的发展，该技术用于将烯烃加成反应的可测量特征相关联，以便获得机械和合成上有用的信息。PI已将该技术应用于足够多的系统，以确定其可行性，但其范围尚未确定。该技术实现了(1)在速率决定步骤中确定空间和电子效应的相对大小的程序，(2)一种相对简单的方法来预测取代基对合成目的的反应速率的影响，以及(3)在某些情况下在不同的建议反应机制之间进行选择的方法。要扩展的简单技术是将所研究的烯烃加成反应的相对速率（log krel）的对数与烯烃的可测量特征（如电离势（IPs）、最高已占据分子轨道能（HOMOs）和某些情况下最低未占据分子轨道能（LUMOs））相关联（绘图）。之前有一些机制研究利用了IP和log krel的比较、表格和图；这种技术的不同之处在于，它侧重于空间效应和电子效应的分离，它需要更多的数据点和烯烃中具有各种电子效应的取代基，以便分散数据点并促进可视化。许多已经研究和将要研究的反应是基本反应，出现在本科有机化学课本中。令人惊讶的是，其中许多的相对反应性根本没有被研究过，在某些情况下，由于使用的数据点太少，或者没有足够大范围的电子效应，就得出了错误的结论。该项目将促进对这些基本反应的理解，并有利于化学家在合成中使用加成反应，因为相对反应性数据将能够预测分子中存在多个双键时的位点选择性，但希望仅影响一个双键的反应。第二个目标是增加本地未被充分代表的少数民族（urm）在化学中的参与。由于资助期限较短（一年），直接影响有限，但后续资金可以继续努力实现目标。

There are two proposal objectives. The first is to extend development of a technique, which has been developed by the PI, for correlating measurable characteristics in addition reactions of alkenes in order to gain information useful mechanistically and synthetically. The PI has applied the technique to enough systems to establish its viability, but its range is not determined. The technique enables (1) a procedure to determine relative magnitudes of steric and electronic effects in the rate-determining step, (2) a relatively simple way to predict the effects of substituents on reaction rates for synthetic purposes, and (3) a method to choose between alternative proposed reaction mechanisms in some cases. The simple technique to be extended is correlating (plotting) the logs of the relative rates (log krel) of the alkene addition reactions studied versus measurable characteristics of the alkenes, such as ionization potentials (IPs), their highest occupied molecular orbital energies (HOMOs), and in some cases their lowest unoccupied molecular orbital energies (LUMOs). There have been previous mechanistic studies making use of IP vs log krel comparisons, tables, and plots; this technique differs in that it focuses on the separation of steric versus electronic effects, and it requires more data points and substituents with a variety of electronic effects in the alkenes in order to spread out the data points and to facilitate visualization.Many of the reactions studied and to be studied are fundamental reactions, which appear in undergraduate organic chemistry texts. Surprisingly, the relative reactivities of many of these have not been studied at all, and in some cases, erroneous conclusions have been drawn by using too few data points or alkenes bearing substituents without a wide enough range of electronic effects. This project will advance the understanding of these fundamental reactions and benefit chemists using addition reactions in synthesis, because relative reactivity data will enable prediction of site selectivity when more than one double bond is present in the molecule, but it is desired to effect reaction at only one.The second objective is to increase the participation of native under-represented minorities (URMs) in chemistry. The direct influence of the grant will be limited due to its short (one year) duration, but subsequent funding can continue efforts toward the goals.