CAS: Atom-Economical Decarbonylative Processes Using Low-Cost Heterogeneous Catalysts

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With the support of the Chemical Synthesis program in the Division of Chemistry, Adelina Voutchkova-Kostal of George Washington University is studying efficient and minimally wasteful methods to prepare complex molecules from renewable starting materials containing carbonyl (C=O) groups. The methods of interest involve chemical reactions in which the carbonyl group controls the site of the initial transformation before it is ultimately lost during the course of product formation. Promoting the desired 'decarbonylative' reactions will rely on the design of tunable clay-based catalysts which are anticipated to be directly applicable to both small and large-scale synthetic processes. The methodology developed is expected to find use in fine chemical synthesis, the conversion of biomass to value-added materials, and in future manufacturing processes aimed at facilitating a sustainable chemical economy. The broader impacts of the funded project will extend to societal benefits accrued by the participation of Dr. Voutchkova-Kostal and her coworkers in outreach and educational activities that include the mentoring of middle and high school students from the local area and the provision of summer research experiences for undergraduate students from across the country. In addition to these programs, which will help to broaden the participation of underrepresented groups in science, technology, engineering, and mathematics (STEM) fields, all students engaging with the Voutchkova-Kostal research group will gain transferrable skills and valuable experiences in the evaluation of the environmental impacts of chemical manufacturing processes.By their avoidance of traditional organohalide starting materials, decarbonylation and decarbonylative coupling reactions have the potential to minimize halogenated waste, allow for the use of aldehydes from renewable biomass sources, and facilitate new selective C-C bond forming reactions. Notwithstanding these advantages, such processes have yet to find universal application in organic synthesis. To help to address this deficiency, the funded research focuses on the development of a suite of atom-economical and chemoselective decarbonylative transformations based on a low-cost and tunable Pd-layered double hydroxide (Pd-LDH) heterogeneous catalyst platform. Specifically, three types of reaction are being pursued: (i) chemoselective methods for decarbonylation of carbonyl group-containing substrates, (ii) decarbonylative aldol condensation processes, and (iii) decarbonylative analogs of the Suzuki and Heck cross-coupling reactions. The high-loading of precious metal complexes typically required for conventional homogenous catalysis-based decarbonylation chemistry, makes such reactions poorly chemoselective and both expensive and environmentally non-sustainable to implement. By contrast, the approach being explored aims to overcome these challenges by the use of easy-to-handle solid supported catalysts that offer expanded use of decarbonylation as an atom-economical strategy for selective C-C bond formation and defunctionalization. At a fundamental level, the studies will help to enable the rational design of supported catalysts that can outperform homogeneous analogues in function, while minimizing environmental impact.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.