H₂‐Free Re‐Based Catalytic Dehydroxylation of Aldaric Acid to Muconic and Adipic Acid Esters

Abstract

As one of the most demanded dicarboxylic acids, adipic acid can be directly produced from renewable sources. Hexoses from (hemi)cellulose are oxidized to aldaric acids and subsequently catalytically dehydroxylated. Hitherto performed homogeneously,w ep resent the first heterogeneous catalytic process for converting an aldaric acid into muconic and adipic acid. The contribution of leached Re from the solid prereduced catalyst was also investigated with hot-filtration test and found to be inactive for dehydroxylation. Corrosive or hazardous (HBr/H 2 )reagents are avoided and simple alcohols and solid Re/C catalysts in an inert atmosphere are used. At 120 8 8C, thec arboxylic groups are protected by esterification, which prevents lactonization in the absence of water or acidic sites.Dehydroxylation and partial hydrogenation yield monohexenoates (93 %). Forc omplete hydrogenation to adipate, a1 6% higher activation barrier necessitates higher temperatures.

Deoxydehydration and Catalytic Transfer Hydrogenation: New Strategy to Valorize Tartaric Acid and Succinic Acid to γ-Butyrolactone and Tetrahydrofuran

“…Rhenium-catalyzed DODH produced high yields (> 85%) of FA or its ester from TA or its ester in the presence of various reductants including alcohol [19,35,36], metal [37], H 2 [38], and triphenylphosphine [39]. Similarly, DODH has been employed to convert C6 sugar acids and their derivatives to valuable bio-based products [35,[40][41][42][43].…”

YUCOMAT 2023: An International Advisory Board Member’s Digest

“…Temperature was an equally important parameter in the process, as it affected the type of hydration in the cement. Among the posters on catalysis, Brigita Hočevar from the National Institute of Chemistry in Ljubljana described a rigorous study of testing a dozen different metals supported on different substrates for the production of adipic acid from bio-based sources [112], concluding that, first of all, water is a poor choice of solvent per se for this type of catalytic reaction and that methanol presents a more effective choice and, second of all, that the choice of the support is crucial, as out of a number of different combinations of metals and substrates, only rhenium on the carbon support yielded satisfactory results.…”

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“…Reactions for upgrading biobased polyhydroxylated compounds by the selective removal of hydroxy groups are of great interest, for example, in deoxydehydration, [133][134][135][136][137] hydrodeoxygenation, [138,139] didehydroxylation, [140] or dehydrative epoxidation [141] of vicinal diols. While impressive advances have been achieved with various chemocatalysts, both transition metalbased and metal-free, further research and development is clearly needed for improving the selectivity, outcome, and sustainability of these reactions, such as high-performing, stable, and sustainable catalysts, additives, and solvents, in order to design industrially viable biobased processes.…”