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Roles of Contact Ion-Pairs as Promoters or Catalysts in Organic Reactions

接触离子对在有机反应中作为促进剂或催化剂的作用

基本信息

批准号：
1855972
负责人：
Gerald Hammond
金额：
$ 48.5万
依托单位：
University of Louisville Research Foundation Inc
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-01 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1855972&HistoricalAwards=false
关键词：
Roles Contact Ion Pairs Promoters

项目摘要

The Chemical Synthesis Program of the NSF Chemistry Division supports the research, education, and outreach programs of Professor Gerald B. Hammond of the University of Louisville. This project is seeks new understanding of chemical reactions that rely on the formation of ions (charged particles). In an ionic reaction, ions can separate (dissociate) or they can form contact ion pairs (where they are just barely separated). Some solvents easily support the dissociation of ions (e.g., table salt in water). Other solvents do not allow ions to dissociate (e.g., table salt in oil). This research seeks to understand how the properties of the solvent affect the ion formation and separation and subsequently, how ion separation impacts the formation of reaction products. Experimental results are combined with various computational efforts to predict the structures of the ions/ion pairs in solution. Dr. Hammond inspires Hispanic students to enter chemistry and other science fields through his "Targeting Excellence: Hispanic Latino Student Initiative" which brings prominent Hispanic chemistry to the University to serve as role models. He is also establishing links with faculty in chemistry departments from Latin American Universities to attract high caliber research-active scientists and students in collaborative projects. Professor Hammond works with the California State University, Fresno to host undergraduate students for summer research and also collaborates with Professor Bo Xu, of Donghua University, China. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Gerald B. Hammond, of the University of Louisville in Kentucky, is investigating ionic reactions. In an ionic reaction, ions can be dissociated or they can form contain ion pairs. This research examines how, in low dielectric constant and low solvation power solvents, contact ion pairs interact with reactants and catalysts in a chemical reaction. Ionic transformations cover a wide range of reaction types, from simple nucleophilic substitutions to complex cationic transition metal catalysis, but the understanding of counterion effects is mainly circumscribed to individual reactions. Toward this goal, his investigations generate affinity scales of counterions for various metal and non-metal groups and implement a new contact ion pair-assisted nucleophilic substitution process (SNip). This conceptually new nucleophilic substitution pathway enables reactivity in those instances where conventional SN2 or SN1 reactions fail. Computational studies of the SNip process are conducted. Also, under investigation is the design of ion pair promoters including chiral ion pair promoters and better electrophiles to facilitate the SNip process. Dr. Hammond is keenly engaged in outreach programs focused on underrepresented student recruitment into the technical fields through summer research internships.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

NSF化学部的化学合成计划支持路易斯维尔大学杰拉尔德·B·哈蒙德教授的研究、教育和推广计划。这个项目寻求对依赖于离子(带电粒子)形成的化学反应的新理解。在离子反应中，离子可以分离(解离)，也可以形成接触离子对(它们只是勉强分开)。一些溶剂很容易支持离子的离解(例如，水中的食盐)。其他溶剂不允许离子离解(例如，油中的食盐)。这项研究试图了解溶剂的性质如何影响离子的形成和分离，以及随后离子分离如何影响反应产物的形成。实验结果与各种计算结果相结合，预测了溶液中离子/离子对的结构。哈蒙德博士鼓励拉美裔学生进入化学和其他科学领域，通过他的“目标卓越：拉美裔拉美裔学生倡议”，将著名的拉美裔化学带到大学作为榜样。他还与拉丁美洲大学化学系的教职员工建立了联系，以吸引高素质的活跃于研究的科学家和学生参与合作项目。哈蒙德教授与加州州立大学弗雷斯诺分校合作，接待本科生进行暑期研究，并与东华大学中国教授合作。在化学系化学催化项目的资助下，肯塔基州路易斯维尔大学的杰拉尔德·B·哈蒙德博士正在研究离子反应。在离子反应中，离子可以解离，也可以形成含离子对。这项研究考察了在低介电常数和低溶剂化功率的溶剂中，接触离子对如何在化学反应中与反应物和催化剂相互作用。离子转化涵盖了广泛的反应类型，从简单的亲核取代到复杂的阳离子过渡金属催化，但对反离子效应的理解主要局限于单个反应。为了实现这一目标，他的研究为各种金属和非金属基团产生了反离子的亲和力标度，并实施了一种新的接触离子对辅助亲核取代过程(SNIP)。这一概念上新的亲核取代途径使传统SN2或SN1反应失败的情况下的反应成为可能。对剪接过程进行了计算研究。此外，正在研究的是离子对促进剂的设计，包括手性离子对促进剂和更好的亲电剂，以促进SNIP过程。哈蒙德博士热衷于通过暑期研究实习生招募人数不足的学生进入技术领域的外联计划。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。