Tunable Multi‐Phase System for Highly Chemo‐Selective Oxidation of Hydroxymethyl‐Furfural

Abstract

Three different multiphase systems (MP 1–3) comprised of two immiscible liquids, with or without an ionic liquid (IL: methyltrioctyl ammonium chloride), were investigated for the oxidation of 5‐hydroxymethyl‐furfural (HMF) over 5 % Ru/C as a catalyst and air (8 bar) as an oxidant. These conditions proved versatile for an excellent control of the reaction selectivity to 4 distinct products derived from full or partial oxidation of the carbonyl and alcohol functions of HMF, and each one achieved in 87–96 % isolated yield at complete conversion. MP1 based on water and isooctane, yielded 2,5‐furandicarboxylic acid (FDCA, 91 % yield). In MP2, obtained by adding the IL to MP1, the oxidation proceeded towards the formation of 5‐formyl‐2‐furancarboxylic acid (FFCA, 87–89 % yield). MP2 also proved successful in the design of a one pot–two step oxidation/reduction sequence to prepare 5‐hydroxymethyl‐2‐furancarboxylic acid (HMFCA, 85 % yield). In MP3, the use of an acetonitrile/cyclooctane biphase yielded 2,5‐diformylfuran (DFF, 96 % yield). All the multiphase systems MP 1–3 allowed a perfect segregation of the catalyst in a single phase (either the hydrocarbon or the IL) distinct from the one containing HMF and its oxidation products. This was crucial not only for the catalyst/product separation but also for the recycle of Ru/C that was possible under all the tested conditions. Accordingly, MP‐reaction were run in a semicontinuous mode without removing the catalyst from the reactor nor resorting to conventional separation and activation techniques. Negligible Ru leaching, less than 0.96 ppb, was measured in all cases.

Controlled alcohol oxidation reactions by supported non-noble metal nanoparticles on chitin-derived N-doped carbons

“…The cost of the catalyst in a liquid-phase reaction may represent up to a third of the total cost of the process, implying that its loss by leaching or other reasons is critical, and its recovery and reuse are crucial. 60,61 The stability and reusability of the Mo-N/C catalyst were therefore investigated by designing recycling experiments under the conditions shown in Fig. 8b [benzyl alcohol (1 mmol), Mo-N/C (50 mg), acetonitrile (1 mL), 130 °C, 20 bar, 24 h].…”

High-Yield Synthesis of 1-Hydroxyhexane-2,5-dione via Hydrogenation/Hydrolysis of 5-Hydroxymethyl-furfural in Ionic Liquid-Assisted Multi-Phase Systems

“…For these reasons and with the aim to design protocols as accessible as possible, commercial 5% Ru/C was exclusively used throughout this study. This catalyst was characterized for its structural, morphological, and acidic properties in recent papers by our group. ,,, …”

“…Based on our long-standing expertise on the chemical upgradation of bio-based molecules through multiphase (MP)-based protocols for the hydrogenation and reductive amination of levulinic acid, , hydrogenation of sugars and sugar-like substrates, and oxidation of HMF, we have recently demonstrated that the same MP conditions could be successfully used for the synthesis of HHD from HMF. At 100 °C and 50 bar of H 2 , in an MP system comprising water, isooctane, methyltrioctylphosphonium bis­(trifluoromethyl) sulfonimide ([P 8881 ]­[NTf 2 ]) as an ionic liquid (IL), and commercial 5 wt % Ru/C as the catalyst, HHD was achieved from HMF with 99% selectivity and 75% isolated yield .…”

Continuous Flow Hydrogenation of Lignin‐model Aromatic Compounds over Carbon‐supported Noble Metals

“…On a last note on this subject, previous studies of our group proved that the same commercial sample of Ru/C used in this work, did not undergo any leaching under a variety of conditions for both hydrogenation and oxidation processes, in the presence of water and/or organic solvents. [60,67]…”