α-Methyl Esterification of Natural Fatty Acid Methyl Esters Directly with CO₂

The α-methyl esterification of natural fatty acid methyl esters (FAMEs) is an essential approach for preparing high-value chemicals such as migration-resistant bioplasticizers, polyester precursors, and anionic surfactants. However, previous strategies are primarily based on time-consuming Claisen condensation, which utilizes petroleum-derived dimethyl carbonate (DMC) as a building block for α-methyl esterification, as well as a NaH/DMF deprotonation system with a highly explosive risk. Here, we present an efficient approach that harnesses carbon dioxide as a green C1 building block to facilitate rapid, nonexplosive α-methyl esterification of FAMEs, producing fatty acid dimethyl esters with high yield (>85%) at ambient temperature within 3 h. Various natural FAMEs, even those derived from waste cooking oil, are amenable to this approach. Our findings establish a robust strategy for α-methyl esterification of FAMEs, bringing the production of high-value chemicals from FAMEs one step closer to sustainability.