Reacción #54181

Ecuación de reacción

chlorine

water

1(2-furyl)-1-ethanol

chlorine

→

3-hydroxy-2-methyl-γ-pyrone

Disolventes

tetrahydrofuran

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroIn a 3-neck round bottom flask equipped with a magnetic stirring bar, a gas inlet tube
2. 2
   TemperaturaThe solution was cooled to a temperature of 0° to 10° C
3. 3
   workup.ADDITIONwas added via the gas inlet tube
4. 4
   workup.ADDITIONThe rate of addition
5. 5
   Temperaturawhile maintaining the reaction temperature below 10° C
6. 6
   TemperaturaThe reaction mixture was heated
7. 7
   Temperaturato reflux
8. 8
   Otrothe tetrahydrofuran removed by distillation
9. 9
   Otroa temperature of about 105° C., a condenser
10. 10
    workup.ADDITIONwas added
11. 11
    FiltraciónThe reaction mixture was then filtered hot
12. 12
    Temperaturacooled
13. 13
    OtroCrystallization and filtration

Procedimiento

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.

Fuente