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

NSF化学部的化学合成计划支持Gerald B教授的研究、教育和推广计划。路易斯维尔大学的哈蒙德说。该项目旨在寻求对依赖于离子（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（离解），或者它们可以形成接触离子对（它们几乎没有分离）。 一些溶剂容易支持离子的解离（例如，食盐水）。 其它溶剂不允许离子解离（例如，油中食盐）。 本研究旨在了解溶剂的性质如何影响离子的形成和分离，以及离子分离如何影响反应产物的形成。 实验结果与各种计算工作相结合，以预测溶液中的离子/离子对的结构。哈蒙德博士通过他的“目标卓越：西班牙裔拉丁裔学生倡议”激励西班牙裔学生进入化学和其他科学领域，该倡议为大学带来了杰出的西班牙裔化学作为榜样。 他还与拉丁美洲大学化学系的教师建立联系，以吸引高素质的研究活跃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，主办本科生暑期研究，并与中国东华大学徐波教授合作。 在化学部化学催化计划的资助下，Gerald B博士。肯塔基州路易斯维尔大学的哈蒙德正在研究离子反应。 在离子反应中，离子可以解离或它们可以形成包含离子对。 本研究探讨了在低介电常数和低溶剂化能力溶剂中，接触离子对如何与化学反应中的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，他的研究产生了各种金属和非金属基团的反离子的亲和力尺度，并实现了一种新的接触离子对辅助亲核取代过程（SNip）。这种概念上新的亲核取代途径使得在常规SN 2或SN 1反应失败的那些情况下具有反应性。SNip过程的计算研究进行。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试剂，以促进SNIP过程。哈蒙德博士热衷于通过暑期研究实习，专注于招募代表性不足的学生进入技术领域的推广计划。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.