Direct synthesis of α,ω-dicarboxylic acids via dicarbonylation of cyclic ethers

Abstract

α,ω-Dicarboxylic acids are important intermediates for the preparation of polyamides, polyesters and polyurethanes. However, their production pathways are limited and usually suffer from low efficiency and environmental problems. Here, we report an innovative approach to synthesize C+2 dicarboxylic acids directly from cyclic ethers by dicarbonylation. Different from the general findings that C+1 monocarboxylic acids are produced by carbonylation of cyclic ethers involving alkene intermediates, in this work, by manipulating the reaction system with RhCl3 and iodine in acetic acid, diiodide-substituted intermediates were selectively formed and subsequently converted to dicarboxylic acids in the presence of H2 and CO. As high as 84% yield of adipic acid was obtained directly from tetrahydrofuran. This catalytic system is applicable not only to a wide variety of cyclic ethers but also to different primary diols to synthesize C2-elongated α,ω-dicarboxylic acids. This work provides a novel dicarbonylation strategy for the efficient synthesis of adipic acid, glutaric acid and other important α,ω-dicarboxylic acids (such as 1,7-heptanedioic acid and 1,8-octanedioic acid) that are still not easily synthesized by other methods.