Jianli Wang,Miao Zhang,Zhi Zheng,Fengwen Yu,Jianbing Ji
The effectiveness of indirect oxidation of glycerol to prepare 1,3-dihydroxyacetone (DHA) was further verified in this work. The oxidation of the 1,3-acetalized glycerol (5-hydroxyl-2-phenyl-1,3-dioxane, HPD) to 1,3-acetalized dihydroxyacetone (2-phenyl-1,3-dioxan-5-one, PDO) was successfully achieved by Montanari oxidation system (NaClO/NaBr/Magnetic recyclable TEMPO). The magnetic polystyrene nanosphere immobilized TEMPO catalyst (1.02 mmol g −1 nitroxyl radical) was readily prepared and characterized by elemental analysis, particle size analysis, and TEM. The catalyst can be used as recyclable and efficient catalyst for HPD oxidation, and high catalytic activity for up to five cycles was obtained. The target product DHA can be efficiently separated by biphasic extraction without complicated purification. The overall yield of DHA was 95.3%, and 78.1% yield with >99% purity after crystallization.
Peter Kisszekelyi,Rifan Hardian,Hakkim Vovusha,Binglin Chen,Xianhai Zeng,Udo Schwingenschlögl,Jozsef Kupai,Gyorgy Szekely
Graphical Up the tempo : An efficient TEMPO-based electrocatalytic transformation of biomass-based C 6 -platform chemical 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) is reported. The molecular design and comparison of homogeneous (native, size-enlarged) and solid-supported (SiliaCAT, TurboBeads) TEMPOs is discussed for the oxidation in the ElectraSyn reactor with cost-effective electrodes and green solvents. Computational modeling reveals the synergistic effect of the catalyst/base system and facilitated the catalyst design. The catalytic transformation of bio-derived compounds, specifically 5-hydroxymethylfurfural (HMF), into value-added chemicals may provide sustainable alternatives to crude oil and natural gas-based products. HMF can be obtained from fructose and successfully converted to 2,5-diformylfuran (DFF) by an environmentally friendly organic electrosynthesis performed in an ElectraSyn reactor, using cost-effective and sustainable graphite (anode) and stainless-steel (cathode) electrodes in an undivided cell, eliminating the need for conventional precious metal electrodes. In this work, the electrocatalysis of HMF is performed by using green solvents such as acetonitrile, γ-valerolactone, as well as PolarClean, which is used in electrocatalysis for the first time. The reaction parameters and the synergistic effects of the TEMPO catalyst and 2,6-lutidine base are explored both experimentally and through computation modeling. The molecular design and synthesis of a size-enlarged C 3 -symmetric tris-TEMPO catalyst are also performed to facilitate a sustainable reaction work-up through nanofiltration. The obtained performance is then compared with those obtained by heterogeneous TEMPO alternatives recovered by using an external magnetic field and microfiltration. Results show that this new method of electrocatalytic oxidation of HMF to DFF can be achieved with excellent selectivity, good yield, and excellent catalyst recovery.
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