反应详情

温度

8 °C

5-Formyl-2,4-dimethyl-1H-pyrrole-3-carboxylic acid ethyl ester (806 g), potassium hydroxide (548 g), water (2400 mL) and methanol (300 mL) were refluxed for two hours with stirring and then cooled to 8° C. The mixture was extracted twice with dichloromethane. The aqueous layer was adjusted to pH 4 with 1000 mL of 10 N hydrochloric acid keeping the temperature under 15° C. Water was added to facilitate stirring. The solid was collected by vacuum filtration, washed three times with water and dried under vacuum at 50° C. to give 5-formyl-2,4-dimethyl-1H-pyrrole-3-carboxylic (645 g, 93.5% yield) acid as a yellow solid. NMR (DMSO-d6) δ2.40, 2.43 (2×s, 2×3H, 2×CH3), 9.57 (s, 1H, CHO), 12.07 (br s, 2H, NH+COOH). MS m/z 168 [M+1].

1. extractionThe mixture was extracted twice with dichloromethane
2. customunder 15° C
3. additionWater was added
4. stirringto facilitate stirring
5. filtrationThe solid was collected by vacuum filtration
6. washwashed three times with water
7. customdried under vacuum at 50° C.