Breaking the equilibrium limit: synthesis of diethyl carbonate from CO2 using regenerable bis-/tris-triethoxysilane substrates†

Breaking the equilibrium limit is necessary to promote the production of diethyl carbonate (DEC) from CO₂ and alkoxysilanes. DEC yields are predicted to overcome the equilibrium limitation when substrates that generate oligomers as byproducts are used. In this study, we explored the catalytic synthesis of DEC using bis-/tris-triethoxysilane substrates over a Zr-based catalyst. Beyond-equilibrium DEC yields (>50% yield) are observed when typical substrates were used as the oligomer is obtained as a byproduct. For example, the isocyanate substrate solidified during DEC synthesis, yielding twice the amount of DEC generated from tetraethoxy orthosilicate. The isocyanate substrate was initially converted into an isocyanurate intermediate prior to polymerization to overcome the equilibrium limitation. The sustainability of this approach is highlighted by the feasibility of substrate regeneration from polymer byproducts. The demonstrated effectiveness of catalysis in promoting DEC from CO₂ can drive scientific and industrial advancements while maintaining sustainability.