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

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.