Ethanol → 4-Chloro-3,7-dimethylindole-2-carboxylic acid

In 20 ml of ethanol and 5 ml of water were dissolved 1.50 g (6.0 mmol) of ethyl 4-chloro-7-methylindole-2-carboxylate and 0.5 g (9.0 mmol) of potassium hydroxide. The reaction mixture was refluxed for 4 hours. The solution was concentrated and then 1N HCl aqueous solution was added. The precipitates were separated by filtration, dissolved in 50 ml of diethyl ether and extracted with 30 ml of aqueous sodium hydrogencarbonate solution three times. The extract was washed with 30 ml of diethyl ether. The water layers were made acid with 1N HCl aqueous solution and extracted with 30 ml of diethyl ether three times. The extract was dried over anhydrous magnesium sulfate and concentrated to provide 0.91 g of beige crystals. Yield: 68%

1. temperatureThe reaction mixture was refluxed for 4 hours
2. concentrationThe solution was concentrated
3. addition1N HCl aqueous solution was added
4. customThe precipitates were separated by filtration
5. dissolutiondissolved in 50 ml of diethyl ether
6. extractionextracted with 30 ml of aqueous sodium hydrogencarbonate solution three times
7. washThe extract was washed with 30 ml of diethyl ether
8. extractionextracted with 30 ml of diethyl ether three times
9. dry with materialThe extract was dried over anhydrous magnesium sulfate
10. concentrationconcentrated

ORD record

ord-73c82cc3ae974eb8ad2df65408101ee8

Source dataset

uspto-grants-1999_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05866594