反应详情

2-Ethoxy-4-methoxybenzoic acid (9.5 g, 48.5 mmol) was added in portions to cold chlorosulfonic acid (60 mL, Aldrich) stirring at −3 to 0° C. (ice-acetone bath) over 15 min and warmed slowly to room temperature and heated to 60-65° C. for 40 min. The resulting dark solution was carefully poured with stirring into a large excess of ice and then 500 mL of dichloromethane was added. After stirring for 15 min, the layers were separated and the aqueous layer was extracted with dichloromethane (3×250 mL). The organic layers were washed with brine and dried over anhydrous magnesium sulfate. The solids were filtered off, and the filtrate was evaporated to a low volume. This was triturated with ether/hexane and filtered to give 5-chlorosulfonyl-2-ethoxy-4-methoxybenzoic acid as a colorless solid (13.4 g, 94%).

1. temperatureheated to 60-65° C. for 40 min
2. additionThe resulting dark solution was carefully poured
3. stirringAfter stirring for 15 min
4. customthe layers were separated
5. extractionthe aqueous layer was extracted with dichloromethane (3×250 mL)
6. washThe organic layers were washed with brine
7. dry with materialdried over anhydrous magnesium sulfate
8. filtrationThe solids were filtered off
9. customthe filtrate was evaporated to a low volume
10. customThis was triturated with ether/hexane
11. filtrationfiltered