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Dissertation
Boron-mediated C–O and C–F bond cleavage: valorization of lignin and degradation of PFAS
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2025
DOI: 10.25820/etd.008235
Abstract
Boron Lewis acids form strong bonds with oxygen and fluorine, enabling activation of robust C–O and C–F bonds— key functionalities found in pharmaceuticals, polymers, and chemical-resistant materials. A notable example is lignocellulose, the structural component of plant cell walls and the most abundant biopolymer on Earth. It comprises lignin, cellulose, and hemicellulose. While cellulose is routinely extracted for use in textiles and films, common isolation methods rely on harsh conditions that degrade lignin through condensation or crosslinking, limiting its potential as a renewable source of aromatic monomers. This work explores how boron Lewis acids can selectively separate polysaccharides from lignocellulose under mild conditions, yielding a lignin sample that closely resembles its native structure.
Chapter one reviews general strategies for activating C–O and C–F bonds, focusing on the selective cleavage of aryl alkyl ethers— common in lignin, natural products, and protecting groups. It also outlines C–F bond cleavage approaches relevant to PFAS degradation. Chapter two details a previously developed method in our laboratory using a BBr3/BCl3 system for regioand chemoselective cleavage of dialkyl ethers, efficiently removing polysaccharides from lignocellulose while preserving low-crosslinked lignin.
Chapter three describes efforts to optimize this separation protocol for sustainability and scalability, replacing BCl3 with regenerable triaryl borates and demonstrating full recycling of boron waste. The conclusion proposes future directions, including applying boron Lewis acids to promote halogen exchange in PFAS, transforming resistant C–F bonds into more reactive and degradable forms.
Details
- Title: Subtitle
- Boron-mediated C–O and C–F bond cleavage: valorization of lignin and degradation of PFAS
- Creators
- Theodora Ephrosinie Leventis
- Contributors
- Florence J. Williams (Advisor)Scott R. Daly (Committee Member)Louis Messerle (Committee Member)F. Christopher Pigge (Committee Member)Amanda J. Haes (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Chemistry
- Date degree season
- Autumn 2025
- DOI
- 10.25820/etd.008235
- Publisher
- University of Iowa
- Number of pages
- xxxii, 214 pages
- Copyright
- Copyright 2025 Theodora E. Leventis
- Language
- English
- Date submitted
- 08/06/2025
- Description illustrations
- Illustrations, graphs, charts, tables
- Description bibliographic
- Includes bibliographical references (pages 104-122).
- Public Abstract (ETD)
This work explores the use of boron-based chemical tools to break apart some of the strongest bonds in nature, specifically carbon oxygen (C O) and carbon fluorine (C F) bonds. These bonds are found in a variety of materials from plant biomass to synthetic industrial pollutants. By using boron compounds known as Lewis acids, we can efficiently separate lignocellulose the structural material in plants into its useful components: lignin, cellulose, and hemicellulose. Importantly, this is done without damaging their structures, which is essential for creating new bio-based materials and fuels.
To make the process more environmentally friendly, we use recyclable forms of boron, allowing these reactions to be renewable and sustainable. In a second application, the same boron chemistry is used to activate the C F bonds in PFAS, a group of toxic and long-lasting chemicals often called "forever chemicals." By converting these stable bonds into more reactive ones, this method may provide a promising new pathway for breaking down harmful pollutants.
- Academic Unit
- Chemistry
- Record Identifier
- 9985135148202771
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