One-Step Electrocatalytic Approach Applied to the Synthesis of ß-Propiolactones from CO2 and Dienes.

ß-Lactones are common substructures in a variety of natural products and drugs, and they serve as versatile synthetic intermediates in the production of valuable chemical derivatives. Traditional ß-lactone synthesis relies on laborious multi-step synthetic methods that use toxic compounds, sophisticated catalysts, expensive, and/or reactive chemicals. Based on the in situ electrochemical formation of metal-based nanoclusters, this paper describes the development of a one-step, room temperature electrocatalytic method for the formation of stable ß-lactone from CO2 and dienes. This one-step "electrosynthesis" method results in the formation of a new class of ß-lactone with high selectivity (up to 100%) and activity (up to 80% yields with respect to the reacted diene) by regulating the applied potential and current density. This work paves the way for more sustainable and environmentally friendly reaction pathways based on the in situ formation of nanoclusters as organic electrosynthesis catalysts.

Modeling the HCOOH/CO2 Electrocatalytic Reaction: When Details Are Key.

Our first principles simulations of the electrooxidation of formic acid over nickel identify the reorientation of the formate intermediate and the desorption of CO2 as the rate-limiting steps. Although they are not associated with an electron transfer, these barriers are strongly modified when the electrochemical potential is explicitly accounted for and when modeling the influence of the solvent. Hence, such a level of modeling is key to understand the kinetic limitations that penalize the reaction.

Impacts of electrode potentials and solvents on the electroreduction of CO2: a comparison of theoretical approaches.

Since CO2 is a readily available feedstock throughout the world, the utilization of CO2 as a C1 building block for the synthesis of valuable chemicals is a highly attractive concept. However, due to its very nature of energy depleted "carbon sink", CO2 has a very low reactivity. Electrocatalysis offers the most attractive means to activate CO2 through reduction: the electron is the "cleanest" reducing agent whose energy can be tuned to the thermodynamic optimum. Under protic conditions, the reduction of CO2 over many metal electrodes results in formic acid. Thus, to open the road to its utilization as a C1 building block, the presence of water should be avoided to allow a more diverse chemistry, in particular for C-C bond formation with alkenes. Under those conditions, the intrinsic reactivity of CO2 can generate carbonates and oxalates by C-O and C-C bond formation, respectively. On Ni(111), almost exclusively carbonates and carbon monoxide are evidenced experimentally. Despite recent progress in modelling electrocatalytic reactions, determining the actual mechanism and selectivities between competing reaction pathways is still not straight forward. As a simple but important example of the intrinsic reactivity of CO2 under aprotic conditions, we highlight the shortcomings of the popular linear free energy relationship for electrode potentials (LFER-EP). Going beyond this zeroth order approximation by charging the surface and thus explicitly including the electrochemical potential into the electronic structure computations allows us to access more detailed insights, shedding light on coverage effects and on the influence of counterions.