We recently reported biomass-derived tetrahydrofuran-2,5-dicarboxylic acid (THFDCA) as a potential renewable feedstock for adipic acid (AA) production by combining HI and molecular H₂ in organic acid solvents. However, the volatile and corrosive nature of HI, the catalyst, presents challenges in industrial implementation. In this work, we demonstrate an improved, less corrosive system with comparable AA yields (∼87%) using Nafion and an iodide salt, e.g., LiI, NaI and KI. Kinetic and reactivity studies indicate that the activation of THFDCA's etheric C–O bond proceeds either by direct protonation at the surface of the solid acid or by liquid-phase protons which are transported from the surface of the solid acid to the bulk solvent through an ion-exchange process. The combination of a solid acid and an iodide salt functions as a controlled release mechanism for protons without sacrificing the effectiveness of HI, while significantly reducing the corrosiveness of the reaction mixture. Further, the spent Nafion can easily be separated from the reaction mixture and regenerated by ion-exchange with minimal loss in reactivity.

中文翻译：

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由生物质衍生的四氢呋喃-2,5-二羧酸中的固体酸和碘盐的组合催化己二酸的生产†

我们最近报道了生物质衍生的四氢呋喃-2,5-二羧酸（THFDCA）作为通过在有机酸溶剂中结合HI和分子H ₂来生产己二酸（AA）的潜在可再生原料。然而，作为催化剂的HI的挥发性和腐蚀性，在工业实施中提出了挑战。在这项工作中，我们证明了使用Nafion和碘盐，例如，具有相当的AA收率（〜87％）的改进的，腐蚀性较小的系统。，LiI，NaI和KI。动力学和反应性研究表明，THFDCA的醚化C–O键的活化通过固体酸表面的直接质子化或液相质子进行，液相质子通过离子从固体酸的表面转移至本体溶剂交换过程。固体酸和碘化物盐的组合起质子的控制释放机制的作用，而不会牺牲HI的有效性，同时显着降低了反应混合物的腐蚀性。此外，用过的Nafion可以容易地从反应混合物中分离出来，并通过离子交换而再生，而反应活性的损失最小。