反应详情

Ice (50g.) was added slowly with stirring to 175 g. of concentrated sulfuric acid, keeping the temperature below 35°C. by means of an ice-salt bath. The temperature of the diluted acid was adjusted to 5°C., and 38.6 g. (0.460 mole) of tert.-butyl alcohol was slowly added with stirring, keeping the temperature between 5° and 10°C. 4-Hydroxy-3-mercapto-6-methyl-2-pyrone (36.4 g., 0.230 mole) was then added with vigorous stirring over a period of about 15 minutes, keeping the temperature of the reaction mixture at 5°C. The cooling bath was then removed from the reaction vessel, and stirring was continued for one hour, 20 minutes, while the temperature of the reaction mixture rose to 24°C. The mixture was then poured into ice water, and the gummy precipitate crystallized to a gray solid (weight 42.4 g. (86 percent), m.p. 108.5°-112.5°C.) upon standing at room temperature overnight. The crude product was suspended in 200 ml. of water and then dissolved by the addition of 100 ml. of 10% sodium hydroxide solution. The solution was stirred at room temperature for one hour with decolorizing charcoal, filtered and acidified with with dilute hydrochloric acid. The cream-colored solid precipitate (37.7 g., m.p. 116.5°C.) was collected on a filter, washed with water and dried. Recrystallization from 2-propanol gave the pure 3-tert.-butylthio-4-hydroxy-6-methyl-2-pyrone as white crystals, m.p. 117°-117.5°C.

1. customthe temperature below 35°C.
2. customwas adjusted to 5°C.
3. stirringwith stirring
4. customthe temperature between 5° and 10°C
5. stirringwith vigorous stirring over a period of about 15 minutes
6. customat 5°C
7. customThe cooling bath was then removed from the reaction vessel
8. stirringstirring
9. customrose to 24°C
10. additionThe mixture was then poured into ice water
11. customthe gummy precipitate crystallized to a gray solid (weight 42.4 g. (86 percent), m.p. 108.5°-112.5°C.)
12. waitupon standing at room temperature overnight
13. dissolutionof water and then dissolved by the addition of 100 ml
14. stirringThe solution was stirred at room temperature for one hour with decolorizing charcoal
15. filtrationfiltered
16. customThe cream-colored solid precipitate (37.7 g., m.p. 116.5°C.) was collected on a filter
17. washwashed with water
18. customdried
19. customRecrystallization from 2-propanol