Synthesis of higher carboxylic acids from ethers, CO₂ and H₂

Synthesis of higher carboxylic acids using CO₂ and H₂ is of great importance, because CO₂ is an attractive renewable C1 resource and H₂ is a cheap and clean reductant. Herein we report a route to produce higher carboxylic acids via reaction of ethers with CO₂ and H₂. We show that the reaction can be efficiently catalyzed by an IrI₄ catalyst with LiI as promoter at 170 °C, 5 MPa of CO₂ and 2 MPa of H₂. The catalytic system applies to various ether substrates. The mechanistic study indicates that the ethers are converted to olefins, which are further transformed into alkyl iodides. The higher carboxylic acids are produced by carbonylation of alkyl iodides with CO generated in situ via RWGS reaction. This report offers an alternative strategy of higher carboxylic acid synthesis and CO₂ transformation.