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

探索烯烃加成机理；

• 批准号: 0111421
• 负责人: Donna Nelson
• 金额: $ 6万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2004-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0111421&HistoricalAwards=false
• 关键词: Exploring; Mechanism; Additions; Alkenes; Extending

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.

提案的目标有两个。第一种是扩展PI开发的一种技术，用于关联烯烃加成反应的可测量特征，以获得机械上和综合上有用的信息。PI已经在足够多的系统中应用了这项技术，以确定其可行性，但其范围尚未确定。该技术使(1)在速率决定步骤中确定空间效应和电子效应的相对大小的过程，(2)为了合成目的而预测取代基对反应速率的影响的相对简单的方法，以及(3)在某些情况下在可选的所提出的反应机理之间进行选择的方法。要推广的简单技术是将所研究的烯烃加成反应的相对速率(LogKrel)的对数与烯烃的可测量特征关联(绘制)，如电离势(IPs)、它们的最高占据分子轨道能量(HOMO)，在某些情况下它们的最低空置分子轨道能量(Lumos)。以前已经有过利用IP和LOG KREL比较、表格和曲线图的机理研究；这项技术的不同之处在于它侧重于立体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，以便展开数据点和便于可视化。许多已研究和将要研究的反应是基本反应，出现在本科有机化学教材中。令人惊讶的是，其中许多化合物的相对反应性根本没有被研究过，在某些情况下，由于使用太少的数据点或含有取代基的烯烃而没有足够广泛的电子效应，因此得出了错误的结论。这个项目将促进对这些基本反应的理解，并使化学家在合成中使用加成反应受益，因为相对反应性数据将使预测分子中存在多于一个双键时的位置选择性成为可能，但希望只有一个双键发生反应。第二个目标是增加天然代表不足少数(URM)在化学中的参与。赠款的直接影响将是有限的，因为它的期限很短(一年)，但随后的资金可以继续努力实现这些目标。