Hydrochloric Acid → 1-Cyclopropyl-6,7-difluoro-8-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

Participants

Reaction Steps

To ethyl 1-cyclopropyl-6,7-difluoro-8-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylate (2.2 g) was added conc. hydrochloric acid (5 ml), water (2 ml) and acetic acid (20 ml), and the mixture is refluxed for 2 hours. After cooling, the precipitated crystals are separated by filtration, and washed with water, ethanol and diethyl ether in this order to give 1-cyclopropyl-6,7-difluoro-8-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (1.8 g) as a white crystal, m.p. 240°-243° C.

Provenance & Evidence