Carbon-carbon coupling reactions often utilize transition metal catalysts, which can be expensive and deactivate over time. Finding routes to carbon-carbon coupling reactions through use of heterogeneous organocatalysts is an attractive alternative. Utilizing polymers as a support for cooperative acid-base catalysts provides a level of tunability unmatched with alternative oxide support systems. Linear polymers as well as rigid, porous organic polymers (POP) were synthesized containing amine bases and weak acids and examined for cooperative aldol catalysis. Both types of polymer catalysts provide a potential recoverable handle for recycle and reuse, while offering enhanced active site mobility and flexibility compared to organic functionalized oxides. Further reactivity can be controlled through higher active sites loadings within the POP, as well as the chain length and monomer content of the linear polymer catalysts.<br/>Linear polymer catalysts were prepared with varying acid monomer strength and acid to base ratios to examine optimal configurations for enhancing cooperativity between functional groups, as well as placement within the chain of these groups. A significant enhancement in the rate of the aldol condensation is seen when pairing of weakly acidic species with a primary amine are present on a linear polymer chain. All of the polymer catalysts are currently being explored for further cooperatively catalyzed reactions, as well as stability and recyclability. This work is instructive in identifying fundamentals of cooperative catalysis on acid-base bifunctional polymer supports that will provide a baseline for further engineering of superior catalysts.

Bifunctional polymer architectures for cooperative catalysis: Tunable acid-base polymers for the aldol condensation

251st National Meeting (2016)

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