反应详情

温度

10 °C

Concentrated sulfuric acid (60 mL) was stirred mechanically and cooled in an ice/water bath. To this was gradually added 5-fluoro-2-methylbenzoxazole (9), (20 g, 0.132 Moles), at such a rate that the temperature stayed at 15–20° C., over a 15–20 minute period. A solution of concentrated sulfuric acid (11 mL), and concentrated nitric acid (10 mL), was prepared and added drop by drop to the benzoxazole solution at such a rate that the temperature was maintained at approximately 10° C. When this acid solution had been added the cooling bath was removed and the mixture allowed to stir at room temperature for 1 hour. At the end of this period the solution was carefully poured onto ice with good stirring. Sufficient water was then added to get good mixing. The solid was filtered off, washed well with water and air-dried. Yield 16.0 g.

1. temperaturecooled in an ice/water bath
2. waitat such a rate that the temperature stayed at 15–20° C., over a 15–20 minute period
3. additionWhen this acid solution had been added the cooling bath
4. customwas removed
5. additionAt the end of this period the solution was carefully poured onto ice with good stirring
6. additionSufficient water was then added
7. customto get good mixing
8. filtrationThe solid was filtered off
9. washwashed well with water
10. customair-dried