Scale-up preparation, column chromatography-free purification of protected carbonyl-containing biomass molecules and their derivatizations

Abstract

Recently, the protection strategy has received significant attention due to improved product selectivity and process efficiency for biomass conversion. In this work, an effective route to protect the carbonyl group of biomass-based furans with 1,3-propylene glycol followed by a simple but effective purification process is first established. Sulfamic acid, a commercially available, low-cost heterogeneous Brønsted acid catalyst, under different reaction conditions, exhibited excellent acetalization performance at gram level with good recyclability. Then, an efficient column chromatography-free purification protocol was established to give gram-level, high-purity acetal products by bypassing large eluent use, long processing times, and poor separation of strong polarity molecules by column chromatography. We further examined the protection group effect on selectivity during the hydrodeoxygenation, deoxygenation, or ring hydrogenation of biomass-derived furanic compounds over supports with different acidity/basicity under a reducing atmosphere that differs from previous reports that were typically focused on aerobic oxidation. Finally, the positive effect of the protection strategy on the photocatalytic oxidation of HMF is reported. Overall, our work greatly expands the application potential of the protection strategy via proposing an effective scale-up preparation method for commercially unavailable substrates and exploring more reaction types, especially under a reducing atmosphere. A grander blueprint to explore the protection strategy in biomass conversion can be imagined.