反应详情

Methyl 4-methyl-2,6-diacetoxybenzoate (14.9 grams, 56.0 mmoles) was dissolved in carbon tetrachloride (200 mL), and N-bromosuccinimide (11.1 grams, 62.2 mmoles) and benzoyl peroxide (0.2 grams, 0.8 mmoles) were added. The mixture was refluxed under nitrogen. After 3.5 hours, an additional portion (0.2 grams) of N-bromosuccinimide was added. Reflux was continued for an additional hour. The reaction mixture was cooled to room temperature and then in ice for 1 hour, and the solid removed by filtration. The filtrate was evaporated to dryness. Hexanes (250 mL) was added to the residue, and the mixture was boiled until dissolution was obtained. The hexanes solution was concentrated to about 75 mL when a solid just began to precipitate. The mixture was heated to dissolve the solid, and the solution was allowed to cool slowly to room temperature. White crystals formed slowly, and the mixture was chilled in ice for 2 hours to complete crystallization. The solid was filtered, washed with cold hexanes (100 mL), and dried in vacuo to afford 11.9 grams (62% yield) of methyl 4-bromomethyl-2,6-diacetoxy-benzoate (m.p. 93°-95° C., open capillary, uncorrected). The product was contaminated with a small amount of methyl 2,6-diacetoxy-4-dibromomethylbenzoate, which did not interfere with subsequent reactions.

1. temperatureThe mixture was refluxed under nitrogen
2. temperatureReflux
3. waitwas continued for an additional hour
4. waitin ice for 1 hour
5. customthe solid removed by filtration
6. customThe filtrate was evaporated to dryness
7. additionHexanes (250 mL) was added to the residue
8. dissolutionthe mixture was boiled until dissolution
9. customwas obtained
10. concentrationThe hexanes solution was concentrated to about 75 mL when a solid
11. customto precipitate
12. temperatureThe mixture was heated
13. dissolutionto dissolve the solid
14. temperatureto cool slowly to room temperature
15. customWhite crystals formed slowly
16. temperaturethe mixture was chilled in ice for 2 hours
17. customcrystallization
18. filtrationThe solid was filtered
19. washwashed with cold hexanes (100 mL)
20. customdried in vacuo