反应详情

To a solution of 20.0 g (0.16 mole) of 4-hydroxy-6-methyl-2-pyrone in 250 ml of methanol was added 1.0 g of 5% palladium on carbon as the hydrogenation catalyst. Hydrogenation was carried out at room temperature under a pressure of 20 kg/cm2 for 7 hours. The catalyst was removed by filtration and the solvent was removed by evaporation under a reduced pressure. The precipitated crystal was recovered by filtration and recrystallized from ethanol to obtain 14.8 g (yield: 73%) of 4-hydroxy-5,6-dihydro-6-methyl-2-pyrone in the form of a crystal, m.p. 103°-104° C.

1. customThe catalyst was removed by filtration
2. customthe solvent was removed by evaporation under a reduced pressure
3. filtrationThe precipitated crystal was recovered by filtration
4. customrecrystallized from ethanol