(166c) Electrochemical Separations for Sustainable Chemical Manufacturing: Homogeneous Catalyst Recycling and Enantioselective Separations

Chemical separations can often be one of the most energy- and waste-intensive steps in industry. Thermal-based separations often incur large energy costs, while traditional adsorption requires extensive chemical input for regeneration. Electrochemical control can play an important role in eliminating external chemical input and waste generation, as well as enhancing interfacial selectivity. However, most electrochemical separations have been focused on aqueous media applications, with limited attention devoted to value-added recovery in organic media for chemical manufacturing.

Here, we discuss two new applications of electrochemical separations for chemical manufacturing: the electrochemical recycling of organometallic catalysts from homogeneous-phase industrial reactions, and the design of chiral interfaces for enantioselective separations. First, we present a redox-mediated approach for the selective binding and release of key platinum-group organometallic catalysts, including Pt- and Pd-based hydrosilylation, Suzuki cross-coupling, and Wacker oxidation catalysts. Through electrochemical control, we are able to re-use these valuable catalysts post-reaction, preserving their reactivity for multiple cycles. We pursue a combination of mechanistic studies and electronic structure calculations to determine the catalytic intermediates being bound during reaction. Second, we discuss the bottom-up design of chiral redox-metallopolymers, to enable selective interactions with biologically-relevant enantiomers. We explore the binding mechanisms of the chiral electrodes with amino acids and pharmaceutical carboxylates, and highlight the role of supramolecular chirality for enhancing enantioselective recognition. Finally, we provide insights into the structure-function relationships between our chiral polymer and structural motifs from the target enantiomers.

Our work builds new capabilities of redox-electrodes for the discrimination of highly challenging isomer species, and points to emerging directions in electrochemical separations for fine chemical manufacturing.