Aerobic Oxidation of Xylose to Xylaric Acid in Water over Pt Catalysts

Abstract

Energy-efficient catalytic conversion of biomass intermediates to functional chemicals can make bio-products viable. Herein, we report an efficient and low temperature aerobic oxidation of xylose to xylaric acid, a promising bio-based chemical for the production of glutaric acid, over commercial catalysts in water. Among several heterogeneous catalysts investigated, Pt/C exhibits the best activity. Systematic variation of reaction parameters in the pH range of 2.5 to 10 suggests that the reaction is fast at higher temperatures but high C-C scission of intermediate C -oxidized products to low carbon carboxylic acids undermines xylaric acid selectivity. The C-C cleavage is also high in basic solution. The oxidation at neutral pH and 60 °C achieves the highest xylaric acid yield (64 %). O pressure and Pt amount have significant influence on the reactivity. Decarboxylation of short chain carboxylic acids results in formation of CO , causing some carbon loss; however, such decarboxylation is slow in the presence of xylose. The catalyst retained comparable activity, in terms of product selectivity, after five cycles with no sign of Pt leaching.

Sustainable access to renewable N-containing chemicals from reductive amination of biomass-derived platform compounds

“…Various carboxylic acids including lactic acid [182], succinic acid [183], glucaric acid [184], xylaric acid [185], itaconic acid [186] and formic acid [187] can be obtained from biomass-derived carbohydrates in high yields. Amongst these, lactic acid stands out due to the high market demand of biodegradable poly(lactic acid) and its function as a versatile intermediate for the production of many commodity chemicals [188,189].…”

Exploiting Nature's Most Abundant Polymers: Developing New Pathways for the Conversion of Cellulose, Hemicellulose, Lignin and Chitin into Platform Molecules (and Beyond)

“…The oxidation of D ‐xylose ( 54 ) so as to form the 1°‐PM xylonic acid ( 64 ) (Figure 10) and, in some instances, the two‐fold oxidation product xylaric acid ( 65 ), has not been well studied but can be accomplished by various chemical and biological methods [6] . It has been suggested that compound 65 may serve, through three‐fold deoxygenation, as a precursor to glutaric acid ( 66 ) for which there is great demand industrially as a precursor to various polymers [45] …”

Chemical and Enzymatic Routes for Lignocellulosic Bioproducts via Carbon Extension and Deoxygenation

“…One such example is glucaric acid ( 25 ), a key ingredient for hyper-branched polyesters and food additives . Selective oxidation of the two terminal oxygens of glucose over Pt/C formed glucaric acid and xylaric acid ( 27 ) from xylose. , Mechanistically, the oxidation pathway follows the HMF oxidation described above. The key challenge is C–C cleavage of C 6 or C 5 species to low carbon acids, which has been partly addressed by designing effective catalysts, for example, Bi-doped Au nanoparticles (AuBi/C), or tuning the reaction parameters .…”