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

在化学系化学合成项目和刺激竞争性研究既定项目（EPSCoR）的支持下，爱荷华州大学的佛罗伦萨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。该研究的重点是化学键的断裂，这些化学键在医学，农业，工程和商业中常用的材料类型中无处不在。在这些转化过程中，关键的硼试剂本身会降解为无害的硼酸-一种在洗衣粉等家用产品中发现的低毒性化学品。将在各种重要情况下对所制定的方法进行评估，包括：（1）目前未再循环的环氧树脂塑料的受控解构（解聚），以及（2）全氟烷基和多氟烷基物质的分解，这些物质是作为持久性污染物出现的，会引起严重的健康问题。除了在塑料回收和PFAS补救领域提供预期的技术进步外，资助项目的更广泛影响还扩展到社会的利益，因为威廉姆斯博士和她的同事们参与了各种活动，以改善化学教育的获得，并提高爱荷华州大学的多样性，公平性和包容性。例如，一个广泛使用的基于智能手机的应用程序的持续开发，以促进本科生在有机化学入门课程的学习正在进行中，威廉姆斯博士正在带头创建一个美国化学学会女化学家委员会（ACS WCC）章在她的机构。总的来说，这些举措预计将使化学科学对不同的学生群体更容易理解和包容，并增加对重要的有机化学相关主题的普遍参与。根据该奖项，爱荷华州大学的威廉姆斯团队将专注于开发硼介导的反应，用于传统惰性的C-O，C-F，和C-H键，并在复杂的分子环境中演示和评估这些过程。这项工作建立在从威廉姆斯实验室的早期发现中获得的见解的基础上，该发现揭示了三卤化硼介导的C-F和C-O键裂解反应的可调性，以及后者在木质纤维素聚合物分离中的成功应用。新的研究旨在扩大对C-F和C-O裂解背景下驱动化学选择性的关键参数的理解，探索扩展到C-H官能化的新型（基于自由基的）反应性机制，并评估这些反应对上述PFAS和环氧树脂塑料降解的潜力。将采用实验设计（DoE）方法来揭示以前没有意识到的醚键的化学和区域选择性裂解的机理和操作细微差别。最后，值得注意的是，参与资助项目的本科生和研究生将接受教育和实验培训，为他们将来为国家的STEM（科学、技术、工程和数学）劳动力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价值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.