Author: Christine Lucky

Publisher:

Published: 2024

Total Pages: 0

ISBN-13:

Electrochemistry provides an attractive route to a sustainable chemical industry by replacing fossil fuel-derived heat with renewable electricity as the driving force for chemical synthesis. However, most studies focus on the transformation of inorganic species, while decarbonizing high-volume petrochemical transformations requires the manipulation of C(sp3)-H and C(sp3)-C(sp3) bonds. This dissertation demonstrates two approaches that leverage the unique properties of electrochemical reactions to activate the C-H and C-C bonds in small organic molecules. First, we present an outer-sphere approach to activate C(sp3)-H bonds for the sustainable synthesis of ethylene oxide from ethanol. In this two-step transformation, ethanol was first chlorinated to 2 chloroethanol using electrochemically generated chlorine radicals before reacting with OH- to form ethylene oxide in a convergent synthesis. The formation of the thermodynamically unfavorable chlorination product, 2 chloroethanol, was promoted by applying kinetic control over the chlorination site by increasing the reaction temperature. The overall process selectivity was also controlled by the catalyst material and the applied potential which dictate the rate of competitive side reactions to form acetic acid. This halide-mediated approach is generalizable to the production of other valuable chemicals through modification of the anodic chemistry. Then, we detail how mildly oxidative potentials cleave C-C bonds in short-chain alkanes on a Pt catalyst to provide insight into the inner-sphere reactivity of organic molecules at electrochemical interfaces. While this reaction does not occur at a constant potential, it can be facilitated by changing the potential throughout the reaction. The variation provides independent control over substrate adsorption, C-C bond cleavage, and reductive product desorption. Using this technique, we showed that mildly oxidizing potentials transform butane adsorbates to *CO through *CHx fragments, which can be desorbed as methane. Identifying the branchpoint between C-C fragmentation and oxygenation allowed us to design pulsed potential approaches to promote selective C-C cleavage and provide design criteria for improved fuel cell catalysts. The manipulation of adsorbed species through the applied potential is widely applicable for reaction control and investigation. By establishing the fundamental basis for these electrochemical C(sp3)-H and C(sp3)-C(sp3) bond transformations, our findings lay the groundwork for future sustainable synthesis and electrocatalytic energy storage technologies.