反应详情

温度

50 °C

2,4-Dimethyl-5-ethoxycarbonyl-3-(2-ethoxycarbonylethyl)-pyrrole (1.07 kg) and 3.2 L 5 N sodium hydroxide were mechanically stirred in a 12 L three-neck round bottom flask equipped with a reflux condenser and an addition funnel and heated in an oil bath. The mixture was refluxed for 3 hours after which time the internal temperature was 96° C., all solids were dissolved and thin layer chromatography showed hydrolysis to be complete. The heating bath was removed and the mixture cooled to 50° C. in a water bath. 12N Hydrochloric acid (˜1.3 L) was slowly added. After about 50% of the acid was added gas evolution began and the temperature reached 60° C. As more acid was added, gas evolution increased and a yellow precipitate formed. The final pH was adjusted to 3.5 with hydrochloric acid. The mixture was cooled in an ice bath to 8° C. The solids were collected by vacuum filtration, washed twice with 0.5 L of distilled water and dried for 48 hours in a vacuum oven at 55-60° C. to give 677 g (101% yield) of 3-(2-carboxyethyl)-2,4-dimethylpyrrole.

1. customequipped with a reflux condenser and an addition funnel
2. temperatureheated in an oil bath
3. temperatureThe mixture was refluxed for 3 hours after which time the internal temperature
4. customwas 96° C.
5. dissolutionall solids were dissolved
6. customhydrolysis
7. customThe heating bath was removed
8. addition12N Hydrochloric acid (˜1.3 L) was slowly added
9. additionAfter about 50% of the acid was added gas evolution
10. customreached 60° C
11. additionAs more acid was added
12. temperaturegas evolution increased
13. customa yellow precipitate formed
14. temperatureThe mixture was cooled in an ice bath to 8° C
15. filtrationThe solids were collected by vacuum filtration
16. washwashed twice with 0.5 L of distilled water
17. customdried for 48 hours in a vacuum oven at 55-60° C.