CAREER: Chemoselective Functionalization of Strong C-O, C-F and C-H Bonds Using Boron Chemistry

在化学系化学合成计划和既定的刺激竞争研究计划(EPSCoR)的支持下，爱荷华大学的弗洛伦斯·威廉姆斯正在研究简单含硼试剂以有用的方式解构化合物的能力，以创造增值材料和/或应对当代环境挑战。这项研究的重点是化学键的断裂，这种化学键普遍存在于医药、农业、工程和商业中常用的材料类型中。在这些转变过程中，关键的硼试剂本身被降解为无害的硼酸--一种存在于洗衣粉等家用产品中的低毒化学物质。将在各种重要背景下对开发的方法进行评估，包括：(1)对目前未回收的环氧树脂塑料进行受控解聚；(2)对全氟烷基物质和多氟烷基物质(PFA)进行分解，这些物质已作为持久性污染物出现，造成重大的健康问题。除了在塑料回收和全氟辛烷磺酸修复领域提供预期的技术进步外，该资助项目的更广泛影响还扩展到为社会带来的好处，因为威廉姆斯博士和她的同事参与了各种活动，以改善获得化学教育的机会，并增强爱荷华大学的多样性、公平性和包容性。例如，正在继续开发一款广泛可用的基于智能手机的应用程序，以促进本科生在有机化学入门课程中的学习，威廉姆斯博士正在带头在她的机构创建美国化学学会女性化学家委员会(ACSWCC)分会。综上所述，这些举措有望使不同群体的学生更容易接触和包容化学科学，并增加对重要有机化学相关主题的普遍参与。在这一奖项下，爱荷华大学的威廉姆斯团队将专注于为传统惰性C-O、Cü-F和C-H键的官能化而开发硼介导的反应，并在复杂的分子环境中展示和评估这些过程。这项工作建立在威廉姆斯实验室早期发现的洞察力基础上，该发现揭示了三卤化硼介导的C-F和C-O键断裂反应的可调性，并成功地将后者应用于木质纤维素聚合物的分离。新的研究旨在扩大对在C-F和C-O裂解环境中驱动化学选择性的关键参数的理解，探索扩展到C-H官能化的新的(基于自由基的)反应性机制，并评估这些反应对前述全氟辛烷磺酸和环氧树脂塑料降解的潜力。实验设计(DOE)方法将被用来揭示以前没有意识到的机制和操作上的细微差别，因为化学和区域选择性切割太空键。最后，在资助项目中工作的本科生和研究生将接受教育和实验培训，为他们未来为国家STEM(科学、技术、工程和数学)工作做出重大贡献做好准备。该奖项反映了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。

With the support of the Chemical Synthesis Program in the Division of Chemistry and the Established Program to Stimulate Competitive Research (EPSCoR), Florence Williams of the University of Iowa is studying the ability of simple boron-containing reagents to deconstruct chemical compounds in useful ways to create value-added materials and/or to tackle contemporary environmental challenges. The research focuses on cleavage of chemical bonds that are ubiquitous in types of materials commonly used in medicine, agriculture, engineering, and commerce. During the course of these transformations, the key boron reagents are themselves degraded into innocuous boric acid – a low toxicity chemical found in household products such as laundry detergent. The methodology developed will be evaluated in a variety of important contexts, including: (1) for the controlled deconstruction (depolymerization) of epoxy resin plastics, which are not currently recycled, and (2) for the breakdown of per- and poly-fluoroalkyl substances (PFAS), which have arisen as persistent pollutants that cause significant health concerns. In addition to offering anticipated technological advancements in the areas of plastics recycling and PFAS remediation, the broader impacts of the funded project extend to the benefits accrued to society as Dr. Williams and her coworkers engage in a variety of activities to improve access to chemical education and to enhance the diversity, equity, and inclusion landscape at the University of Iowa. For example, continued development of a widely available smart phone-based app to facilitate undergraduate student learning in introductory organic chemistry courses is in progress and Dr. Williams is spearheading the creation of an American Chemical Society Women Chemist's Committee (ACS WCC) chapter at her institution. Taken together, these initiatives are anticipated to make the science of chemistry more accessible and inclusive to a diverse population of students and to increase general engagement in important organic chemistry-related topics.Under this award, the Williams team at the University of Iowa will focus on the development of boron-mediated reactions for the functionalization of traditionally inert C–O, C¬–F, and C–H bonds and the demonstration and evaluation of these processes in complex molecular settings. The work builds on insights gained from earlier findings of the Williams laboratory which revealed the tunability of boron trihalide-mediated C–F and C–O bond cleavage reactions and successful application of the latter to lignocellulose polymer separation. New research is designed to expand understanding of the key parameters driving chemoselectivity in both C–F and C–O cleavage contexts, to explore novel (radical-based) mechanisms of reactivity that expand into C–H functionalization, and to evaluate the potential of these reactions for the aforementioned degradation of PFAS and epoxy resin plastics. A design of experiments (DoE) approach will be employed to reveal mechanistic and operational nuances not previously appreciated for the chemo- and regio-selective cleavage of ethereal bonds. Finally, it is noted that undergraduate and graduate students working on the funded project will receive educational and experimental training preparing them to make significant future contributions to the Nation's STEM (science, technology, engineering and mathematics) workforce.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.