反应详情

A mixture of 2-methoxy-5-sulfamoylbenzoic acid (58 g, 0.25 mole), 48% hydrobromic acid (150 ml), and acetic acid (150 ml) was heated to reflux for five hours. The progress of reaction was checked by thin layer chromatography (silica gel, 7:2:1 ethylacetate/methanol/29% ammonium hydroxide). Upon cooling, a solid crystallized out which was collected by filtration, and rinsed with cold water. This solid was dissolved in hot water (≤85° C.) and filtered through Celite® and recrystallized from the cool filtrate. Some of the recrystallized material was crystallized once more by dissolving in methanol, filtering, and mixing with excess amount of 1,1,1-trichloroethane. The mixture was evaporated to remove most of the methanol, and the resulting crystallizing mixture was stirred in ice bath. The solid was collected by filtration and rinsed with 1,1,1-trichloroethane, vacuum pumped at room temperature overnight to give a white solid, mp 234°-235° C.

1. temperaturewas heated
2. temperatureto reflux for five hours
3. customThe progress of reaction
4. temperatureUpon cooling
5. customa solid crystallized out which
6. filtrationwas collected by filtration
7. washrinsed with cold water
8. dissolutionThis solid was dissolved in hot water (≤85° C.)
9. filtrationfiltered through Celite®
10. customrecrystallized from the cool filtrate
11. customSome of the recrystallized material was crystallized once more
12. dissolutionby dissolving in methanol
13. filtrationfiltering
14. additionmixing with excess amount of 1,1,1-trichloroethane
15. customThe mixture was evaporated
16. customto remove most of the methanol
17. customthe resulting crystallizing mixture
18. filtrationThe solid was collected by filtration
19. washrinsed with 1,1,1-trichloroethane, vacuum
20. customto give a white solid, mp 234°-235° C.