Lithium Carbenoids and Related Species: Structure and Reactions

锂类胡萝卜素和相关物质：结构和反应

• 批准号: 1258670
• 负责人: Lawrence Pratt
• 金额: $ 22.35万
• 依托单位: CUNY Medgar Evers College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1258670&HistoricalAwards=false
• 关键词: Lithium; Carbenoids; Related; Species; Structure

The Chemical Structure, Dynamics and Mechanisms Program supports Professors Lawrence M. Pratt, at Fisk University in Nashville TN, and Marcus A. Tius at the University of Hawaii who will continue their efforts to better understand the structures and reaction mechanisms of lithium carbenoids. The project will use a combination of computational quantum chemistry and NMR spectroscopy to determine the structure of lithium carbenoids in solution, and their tendency to form mixed aggregates with other lithium compounds. Mixed aggregates are well known in organolithium chemistry, and they sometimes have dramatic effects on reactivity and selectivity. The reaction mechanisms studied to date have often been quite complex, and would be very difficult to elucidate without the use of computational chemistry. Preliminary work completed during the initial grant period has shown which computational methods are most appropriate for the problems in this study. The predictions of the reaction products, obtained from the calculated mechanisms, will be tested in the laboratory of the Tius synthetic group. Frequently, two or more reaction mechanisms are operating concurrently, and changing the reaction conditions may enhance or suppress one mechanism. This sometimes results in improved reaction selectivity, purer products, and reductions in the production of toxic wastes. It may also show that the reagents being investigated are not ideal for a particular reaction, and may spur the search for alternate synthetic methods.With the support of the Chemical Structure, Dynamics and Mechanisms Program in the Chemistry Division at the National Science Foundation, Professors Lawrence M. Pratt, at Fisk University in Nashville TN, and Marcus A. Tius at the University of Hawaii will contribute to further understanding of lithium carbenoid reactions that can lead to a wider application in synthetic organic reactions. Organolithium reagents are ubiquitous in modern synthesis but little is known about the factors affecting their structure and reactivity. Broader impacts are in student education and training, with the largest impact on minority students. Fisk University is a Historically Black College/University (HBCU), with about 98% African-American and about 70% female students. The University of Hawaii is a collaborating institution, and is also committed to the inclusion of minorities in science. Louisiana Tech University is also a collaborating institution, with a large African-American student population and some joint faculty appointments with Grambling State University, another HBCU. A major impact of this research will be to revitalize the graduate (MS) program at Fisk, which had been hurt by economic conditions in recent years. A goal of this project is to help those students bridge into a program of their choice, possibly at one of the several research universities collaborating with Professor Pratt on this and other projects.

化学结构、动力学和机理项目为田纳西州纳什维尔菲斯克大学的 Lawrence M. Pratt 教授和夏威夷大学的 Marcus A. Tius 教授提供支持，他们将继续努力更好地了解类胡萝卜素的结构和反应机制。该项目将结合计算量子化学和核磁共振波谱来确定溶液中类胡萝卜素锂的结构，以及它们与其他锂化合物形成混合聚集体的倾向。混合聚集体在有机锂化学中众所周知，它们有时对反应性和选择性具有显着影响。迄今为止研究的反应机制通常相当复杂，如果不使用计算化学就很难阐明。在初始资助期间完成的初步工作表明哪种计算方法最适合本研究中的问题。根据计算机理得出的反应产物预测将在 Tius 合成小组的实验室进行测试。 通常，两种或多种反应机制同时运行，改变反应条件可能会增强或抑制一种机制。这有时会提高反应选择性、提高产品纯度并减少有毒废物的产生。它还可能表明正在研究的试剂对于特定反应并不理想，并且可能会刺激寻找替代合成方法。在美国国家科学基金会化学部化学结构、动力学和机制项目的支持下，教授们田纳西州纳什维尔菲斯克大学的劳伦斯·M·普拉特 (Lawrence M. Pratt) 和夏威夷大学的马库斯·A·提乌斯 (Marcus A. Tius) 将有助于进一步了解类胡萝卜素反应，从而在合成有机反应中得到更广泛的应用。有机锂试剂在现代合成中无处不在，但人们对影响其结构和反应性的因素知之甚少。更广泛的影响在于学生教育和培训，其中对少数族裔学生的影响最大。菲斯克大学是一所传统黑人学院/大学 (HBCU)，约 98% 为非裔美国人，约 70% 为女性学生。夏威夷大学是一个合作机构，也致力于将少数族裔纳入科学领域。路易斯安那理工大学也是一所合作机构，拥有大量非裔美国学生，并与另一所 HBCU 格兰布林州立大学联合任命了一些教师。这项研究的一个主要影响将是重振菲斯克大学的研究生（MS）项目，该项目近年来受到经济状况的影响。该项目的目标是帮助这些学生进入他们选择的项目，可能是与普拉特教授合作开展该项目和其他项目的几所研究型大学之一。