Hydrochloric Acid → Thieno[2,3-b]quinoline-4-carboxylic acid

Participants

Reaction Steps

1.0 g (4.1 mmol) methyl-thieno[2,3-b]quinoline-4-carboxylate 14, 12 ml ethanol and 60 mL 1N NaOH were mixed and heated at reflux for 75 minutes. After cooling the green solution was acidified with 4N HCl to pH ˜1-2, whereupon a solid precipitated. Then the reaction mixture was extracted with 200 mL diethylether. The organic layer was separated and extracted now with 150 mL of a sodium bicarbonate solution (5%), which was acidified another time with 4N HCl to give the product 15 as a crystalline solid. The precipitate was filtered off and dried under vacuum to give 760 mg of 15.

Provenance & Evidence