Date on Master's Thesis/Doctoral Dissertation
micellar catalysis; photocatalysis; halosequestration
Strategies for manipulation of chemical phases were explored with emphasis on synthetic chemistry applications. Some strategies are fairly divergent from their origin, but all ultimately began from investigations of micellar media. Accordingly, Chapter 1 reviews the historical development of micellar catalytic processes. Chapters 2 and 3 detail development of synthetic methods in micellar solutions of designer surfactant PS-750-M. PS-750-M was designed to create benign micellar solutions which effectively mimic toxic organic solvents; it contains a proline-based linker between its hydrophobic and hydrophilic regions which imparts increased polarity to the micellar core. Chapter 2 details an interfacial nucleophilic substitution of perfluoroarenes by sulfinate salt nucleophiles. Chapter 3 covers the development of sustainable, operationally simple conditions for palladium-catalyzed arylation of polar nitroalkanes. Both reactions were selected for the significant polarity differences between the coupling partners involved. Successful development of these methods thus helped to validate the original surfactant design strategy while also elucidating PS-750-M’s properties. Chapter 4 extends upon the work presented in Chapter 3 but ultimately focuses on manipulation of non-micellar phases for the sequestration of halides and concomitant enhancement the nitroalkane arylation. Halides are common byproducts of coupling reactions, but they can also inhibit catalysts. Tetramethylammonium chloride and similar compounds were explored as halosequestrants. The influence of the reaction medium on sequestration was explored. In particular, tetramethylammonium chloride was found to form a beneficial supramolecular hydrate structure when used with specific relative loadings of K3PO4 and water. Leveraging these phase manipulations, nitroalkane arylation was made to proceed ten times faster with only one tenth the catalyst loading. Chapter 5 explores the properties and applications of a polymeric photocatalyst. Low-molecular-weight polymer was prepared in a micellar medium. High-molecular-weight polymer remained solution-processable and could be applied as a surface coating. Irradiation of the "backside" catalyst face not in contact with the reaction mixture proved viable, thereby enabling new approaches to photocatalysis which may resolve industrial scalability issues. Benchmarking showed the polymer was superior to small-molecule organophotocatalysts. Synthesis of small-molecule models of polymer substructures revealed that the motif of dual chromophores in fixed proximity was key to the enhanced catalytic activity.
Smith, Justin Douglas, "(Pseudo)phase tuning in the service of synthesis: technologies for sustainable catalysis." (2020). Electronic Theses and Dissertations. Paper 3518.
Retrieved from https://ir.library.louisville.edu/etd/3518