1,2:3,4-Di-O-isopropylidene-alpha-D-galactopyranose

PreparationIn a dry reaction flask, 16 mL of 36 M H₂SO₄ was added to 1600 mL of freshly distilled acetone, ensuring the reaction mixture was kept at 0 °C during the dropwise addition. The solution was then heated to room temperature and stirred for 10 minutes. D-galactose (20 g, 111 mmol) was added to the solution and the mixture was stirred vigorously for 18 hours. After the reaction was complete, the dark yellow solution was neutralized with anhydrous Na₂CO₃ and then filtered. Activated carbon and 20 g of Na₂CO₃ were added to the filtrate, and the mixture was heated to reflux. The mixture was filtered again, and the filtrate was concentrated to dryness using a rotary evaporator. The residue was purified by silica gel column chromatography to obtain the target product, 1,2:3,4-Di-O-isopropylidene-D-galactopyranose.