Manganese and Ruthenium Catalysis for Sustainable C–H Functionalizations and Polymer Synthesis
by Isaac-Johannes Maksso
Date of Examination:2024-09-25
Date of issue:2024-10-28
Advisor:Prof. Dr. Lutz Ackermann
Referee:Prof. Dr. Lutz Ackermann
Referee:Prof. Dr. Konrad Koszinowski
Referee:Prof. Dr. Philipp Vana
Referee:Prof. Dr. Dr. h.c. Lutz Tietze
Referee:Prof. Dr. Daniel Jun. Obenchain
Referee:Dr. Daniel Janßen-Müller
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Abstract
English
The ever-growing scarcity of resources, energy crises, and environmental pollution demand the development of sustainable chemical processes for C–C bond formations and efficient post-consumer plastic waste recycling. While previous work has often relied on late transition metals, chemical oxidants, or toxic and sensitive organometallic reagents, the potential of manganese- or ruthenium-catalyzed C–H functionalizations under photochemical or electrochemical conditions for polymer synthesis and polymer up-cycling remains underexplored. This thesis investigates eco-friendly manganese- and ruthenium-catalyzed methods for C–H functionalizations, polymer synthesis, and polymer up-cycling under mild photochemical and electrochemical conditions, utilizing potentially renewable energy sources and avoiding hazardous reagents. A key achievement is the development of a manganese-catalyzed C–H alkylation using a transient directing group (TDG) approach, enabling the intramolecular C–H alkylation of indoles. Furthermore, a photo-induced ruthenium-catalyzed C–H arylation polymerization (CHAP) with high functional group tolerance and novel electrochemical methods for polymer up-cycling were developed. Additionally, manganese-electrocatalyzed C–H azidation was applied to a broad range of commodity polymers and post-consumer plastic waste, preserving polymer integrity while achieving significant functionalization. The highly efficient 1,3-dipolar cycloaddition proved to convert the azido-decorated polymers effectively and enables the selective introduction of designated material properties by chemical design. Overall, this research showcases innovative C–H functionalization strategies using earth-abundant manganese and cost-effective ruthenium catalysts, emphasizing their potential for sustainable chemistry and effective plastic waste recycling.
Keywords: Catalysis; Polymers; Up-Cycling; C–H Activation; Electrochemistry; Green Hydrogen; Photochemistry; Synthesis; Ruthenium; Manganese; Material Science