反应详情

A 5 liter flask was set up and equipped with stirrer, thermometer, reflux condenser and nitrogen inlet. Succinic anhydride (373 grams), benzoin (531 grams) and pyridine (300 milliliters; 296 grams) were introduced. The flask was purged with nitrogen and the reaction mixture heated to 90°-95° C. The mixture was stirred for one and a half hours at this temperature. Glacial acetic acid (1300 milliliters) and ammonium acetate (385 grams) were added to the reaction mixture and the mixture reheated to 90°-95° C. Stirring was continued and this temperature was maintained for a further 2 hours. The mixture was filtered, rinsing through with glacial acetic acid (150 milliliters). Distilled water (750 milliliters) was added and the mixture reheated to 90°-95° C. before gradual cooling with stirring to 15° C. over 1 hour. After filtering and washing with a mixture of acetic acid and distilled water in a ratio of 2:1 (600 milliliters), the product was slurried with distilled water (1000 milliliters). After filtering and washing with distilled water (2×400 milliliters), the product was dried at 90°-100° C. under vacuum. 702 Grams (67% yield) of β-(4,5-diphenyloxazol-2-yl)propionic acid were obtained as a white crystalline powder, m.p. 163°-165° C. The material was investigated for quality by TLC. The product had high purity and merely showed a number of very faint trace impurities.

1. customA 5 liter flask was set up
2. customequipped with stirrer
3. temperaturethermometer, reflux condenser and nitrogen inlet
4. customThe flask was purged with nitrogen
5. temperaturethe reaction mixture heated to 90°-95° C
6. additionGlacial acetic acid (1300 milliliters) and ammonium acetate (385 grams) were added to the reaction mixture
7. customreheated to 90°-95° C
8. stirringStirring
9. temperaturethis temperature was maintained for a further 2 hours
10. filtrationThe mixture was filtered
11. washrinsing through with glacial acetic acid (150 milliliters)
12. additionDistilled water (750 milliliters) was added
13. customreheated to 90°-95° C.
14. temperaturebefore gradual cooling
15. stirringwith stirring to 15° C. over 1 hour
16. filtrationAfter filtering
17. washwashing with a mixture of acetic acid
18. distillationdistilled water in a ratio of 2:1 (600 milliliters)
19. filtrationAfter filtering
20. washwashing with distilled water (2×400 milliliters)
21. customthe product was dried at 90°-100° C. under vacuum