What is it about?
Conventional conversion of alkenes to carbonates relies on two separate reaction steps: oxidation of the alkene to the epoxide, followed by cycloaddition of carbon dioxide. In this work, we demonstrate how these two fundamentally different reactions can be successfully integrated into a single-step conversion using molecular oxygen, carbon dioxide and a simple organocatalyst. More importantly, we investigate the underlying principles that enable this one-pot reaction. Through detailed kinetic analysis and mechanistic studies, we show that radical epoxidation is the limiting key step, while CO₂ fixation proceeds readily with a substantially lower activation barrier once the epoxide intermediate has formed. This kinetic separation provides the foundation for integrating oxidation and carbon dioxide incorporation into a single process. The study thus establishes a general concept for integration consecutive reaction steps into a single process, combining the use of molecular oxygen as a benign oxidant with CO₂ utilisation while avoiding hazardous peroxide oxidants, transition-metal catalysts and the isolation of reaction intermediates. Highlights - Integration of oxidation and CO₂ fixation in a single reactor. - Metal-free one-pot oxidative carboxylation using molecular oxygen and carbon dioxide. - Mechanistic and kinetic understanding of the coupled reaction network. - Identification of epoxidation as the rate-determining step. - Insights into the influence of gas composition and phase behaviour on integrated reaction performance. - Demonstration of the concept by direct synthesis of styrene carbonate.
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Why is it important?
Most research on CO₂ utilisation focuses on developing new catalysts or improving catalytic performance. Our work addresses a complementary challenge: the rational, science-based integration of consecutive reaction steps into a single process. The concept extends beyond the conventional synthesis of cyclic carbonates. It illustrates how mechanistic understanding, reaction kinetics and reactor engineering can be combined to design integrated reaction networks that simplify chemical processes and make carbon utilisation more efficient. We believe that this systems-oriented design philosophy will become increasingly important as CO₂ conversion technologies advance from laboratory demonstrations to industrial implementation.
Perspectives
Future CO₂ utilisation will benefit from the rational integration of catalytic reaction steps into efficient process concepts. Understanding the interplay between oxidation and carbon dioxide incorporation provides the scientific basis for developing integrated CCU processes. By expanding the portfolio of sustainable routes to cyclic carbonates — important intermediates for polycarbonate production and other value-added chemicals — this work illustrates how mechanistic insight can guide the design of future carbon utilisation technologies.
Prof. Dr. Thomas Ernst Müller
Ruhr-Universitat Bochum
Read the Original
This page is a summary of: Sustainable One-Pot Metal-Free Oxidative Carboxylation of Styrenes with Molecular Oxygen and Carbon Dioxide, ACS Sustainable Chemistry & Engineering, August 2025, American Chemical Society (ACS),
DOI: 10.1021/acssuschemeng.5c03968.
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