反応 #54181
ord-a2c4903d580241c0b095cdc1bbcb2419
反応条件
後処理
- 1その他In a 3-neck round bottom flask equipped with a magnetic stirring bar, a gas inlet tube
- 2温度The solution was cooled to a temperature of 0° to 10° C
- 3workup.ADDITIONwas added via the gas inlet tube
- 4workup.ADDITIONThe rate of addition
- 5温度while maintaining the reaction temperature below 10° C
- 6温度The reaction mixture was heated
- 7温度to reflux
- 8その他the tetrahydrofuran removed by distillation
- 9その他a temperature of about 105° C., a condenser
- 10workup.ADDITIONwas added
- 11ろ過The reaction mixture was then filtered hot
- 12温度cooled
- 13その他Crystallization and filtration
実験手順
In a 3-neck round bottom flask equipped with a magnetic stirring bar, a gas inlet tube, a thermometer and an addition funnel was added 20 ml of tetrahydrofuran and 50 ml of water. The solution was cooled to a temperature of 0° to 10° C. The addition funnel was charged with a solution of 1(2-furyl)-1-ethanol (0.089 moles) in 20 ml of tetrahydrofuran and this was added dropwise to the stirred reaction flask while chlorine (0.30 mole) was added via the gas inlet tube. The rate of addition was such that all the alcohol was added in the first 1.3-1.5 equivalents of chlorine (approximately 30 minutes) while maintaining the reaction temperature below 10° C. The reaction mixture was heated to reflux and the tetrahydrofuran removed by distillation. When the reaction mixture reached a temperature of about 105° C., a condenser was added and the refluxing continued for about 2 hours. The reaction mixture was then filtered hot, cooled, the pH adjusted to 2.2 and the reaction mixture was cooled to 5° C. Crystallization and filtration yielded 3.43 grams of crude 3-hydroxy-2-methyl-γ-pyrone (maltol). The aqueous filtrate was extracted with CHCl3 to obtain a second crop of 2.58 g of maltol. Distillation of the combined solids and recrystallization from methanol gave 5.5 g (49%) of pure white maltol, m.p. 159.5°-160.5° C.