Hydrochloric Acid → 1-Ethyl-6-fluoro-7-hydroxy-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid
Reaction equation
[CH2:1]([N:3]1[C:12]2[C:7](=[CH:8][C:9]([F:14])=[C:10](F)[CH:11]=2)[C:6](=[O:15])[C:5]([C:16]([O:18]CC)=[O:17])=[CH:4]1)[CH3:2].Cl.[OH-:22].[Na+]>>[CH2:1]([N:3]1[C:12]2[C:7](=[CH:8][C:9]([F:14])=[C:10]([OH:22])[CH:11]=2)[C:6](=[O:15])[C:5]([C:16]([OH:18])=[O:17])=[CH:4]1)[CH3:2]Participants
4
Procedure
A suspension of 1.2 g of ethyl 1-ethyl-6,7-difluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylate (European Offenlegungsschrift No. 230053, C.A. 108:112498) in 25 ml of 2N aqueous sodium hydroxide solution is heated at reflux for 4 hrs. After cooling to room temperature the reaction mixture is adjusted to pH 3 to 4 with 37% aqueous hydrochloric acid and the precipitate is filtered off under suction, washed with 200 ml of water and 200 ml of diethyl ether and dried. 980 mg (91%) of 1-ethyl-6-fluoro-7-hydroxy-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid are isolated as a colourless solid. M.p.>250°.