Efficient Production of 5‑Hydroxymethylfurfural Enhanced by Liquid–Liquid Extraction in a Membrane Dispersion Microreactor

Aimed at efficient production of 5-hydroxymethylfurfural (HMF) in a green and sustainable way, dehydrogenation of fructose was enhanced by liquid–liquid extraction in a membrane dispersion microreactor. On account of the high mass-transfer rate resulted from dripping flow, the obtained HMF was readily extracted from the aqueous phase to the organic phase, effectively preventing the sequence side reaction and leading to high HMF selectivity. Enhanced by efficient extraction, the reaction duration decreased from 60 min in a traditional stirred reactor to 4 min in the microreactor, leading to an increase in the space-time yield by 3 orders of magnitude. The effects of total volume flow rate, droplet size, and phase ratio relating to extraction efficiency and HMF yield were systematically investigated. The highest extraction efficiency of nearly 100% coupled with the HMF yield of 93.0% was achieved at the phase ratio of 2 with volume flow rate of 600 mL/h. Overall, this work not only delineates an efficient strategy for synthesizing HMF but also opens a new avenue for reaction systems with subsequent side reaction, which suffer from low selectivity of the intermediates due to the in-line separation bottleneck under conditions of limited mass transfer

Efficient Production of 5‑Hydroxymethylfurfural Enhanced by Liquid–Liquid Extraction in a Membrane Dispersion Microreactor

Aimed at efficient production of 5-hydroxymethylfurfural (HMF) in a green and sustainable way, dehydrogenation of fructose was enhanced by liquid–liquid extraction in a membrane dispersion microreactor. On account of the high mass-transfer rate resulted from dripping flow, the obtained HMF was readily extracted from the aqueous phase to the organic phase, effectively preventing the sequence side reaction and leading to high HMF selectivity. Enhanced by efficient extraction, the reaction duration decreased from 60 min in a traditional stirred reactor to 4 min in the microreactor, leading to an increase in the space-time yield by 3 orders of magnitude. The effects of total volume flow rate, droplet size, and phase ratio relating to extraction efficiency and HMF yield were systematically investigated. The highest extraction efficiency of nearly 100% coupled with the HMF yield of 93.0% was achieved at the phase ratio of 2 with volume flow rate of 600 mL/h. Overall, this work not only delineates an efficient strategy for synthesizing HMF but also opens a new avenue for reaction systems with subsequent side reaction, which suffer from low selectivity of the intermediates due to the in-line separation bottleneck under conditions of limited mass transfer

Highly Selective Production of <i>p</i>‑Xylene from 2,5-Dimethylfuran over Hierarchical NbO_<i>x</i>‑Based Catalyst

A hierarchical NbO_<i>x</i>-based catalyst with both Brønsted acid and Lewis acid sites was synthesized in the absence of corrosive hydrofluoric acid, exhibiting high catalytic activity for biobased <i>p</i>-xylene (PX) production from 2,5-dimethylfuran (DMF). The as-prepared composite was composed of Nb₂O₅ and NbOPO₄ crystals, and the densities of Brønsted acid and Lewis acid were determined to be 232.9 and 80.4 μmol/g, respectively. The well-balanced Brønsted/Lewis acidity and the hierarchical structure with small mesopores (3 nm) and large mesopores (48 nm) contributed to the high activity and stability: a conversion of 87.2% with the PX selectivity of 92.7%, and a carbon balance of 94.6% was achieved after 6 h of reaction at 523 K. In comparison with Sn-Beta, NbO_<i>x</i>-based catalyst prepared in this work showed obvious advantages in suppressing carbon deposition: 90.9 and 54.7 mmol of PX were obtained over the NbO_<i>x</i>-based catalyst and the Sn-Beta, respectively, after 24 h. Spent catalysts were regenerated through calcination at high temperature and they proved to be recyclable: a decrease of 3.7% in DMF conversion and no loss in PX selectivity could be evidenced over five consecutive runs. Overall, NbO_<i>x</i>-based catalyst which is synthesized through the green and sustainable approach is sufficiently stable, active, and regenerable, and provides an alternative candidate for efficient PX production

Visible-Light-Promoted α‑C(sp³)–H Amination of Ethers with Azoles and Amides

A visible-light-induced highly efficient C(sp3)–H amination of ethers with amides and azoles has been presented under mild conditions via a nitrogen- and carbon-centered radical coupling process. This protocol successfully utilizes 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tert-butyl nitrite (TBN) as cocatalysts to deliver the aminated products of ethers under aerobic conditions. Notably, the developed reaction features the corresponding products in good yields (up to 93%) with a wide substrate scope. The mechanistic study indicates that C–N bond formation proceeds via a direct radical cross-coupling process. Preliminary biological activity analysis indicates that the resulting products have good and selective inhibitory activity on osteosarcoma (OS) cell lines and are promising for use as hits for drug discovery