Recent Advances in Direct Elimination of Carboxylic Acids to Olefins.

The direct elimination of carboxylic acids to olefins offers an atom-economical and sustainable strategy for synthesizing valuable alkenes from abundant, stable, and inexpensive precursors. This review systematically summarizes recent advances (through 2025) in reaction systems and mechanistic studies in this transformation, encompassing thermal, transition metal catalysis (e.g., Rh, Pd, Ir, Ni, Cu, Fe), photochemical, and electrochemical pathways. Within this framework, we highlight progress in catalyst design-including ligand optimization and the development of earth-abundant metal and rare metal catalysts-activation modes (e.g., through the formation of anhydrides, or via direct decarboxylation), and the implementation of greener reaction conditions. While significant progress has been made in thermal and transition metal-catalyzed methods, challenges persist, including cost, metal recovery, and the need for harsh conditions. Emerging photochemical and electrochemical approaches provide milder and more environmentally benign alternatives; however, issues regarding selectivity, scalability, and reagent sustainability demand further investigation. This overview aims to serve as a comprehensive knowledge base and practical reaction guide, inspiring future research to overcome existing limitations and advance the practical, sustainable synthesis of olefins via elimination of carboxylic acids.