Water → 1-Cyclopropyl-6,7,8-trifluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

300 g of ethyl 1-cyclopropyl-6,7,8-trifluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylate, 106.8 g of water, and 426 g of acetic acid were introduced and 3.8 g of sulfuric acid were added. The mixture was heated at reflux for 3 hours. 310 ml of distillate were then distilled off until a bottom temperature of 109° C. was reached. The mixture was then cooled to 80° C. and 157.5 g of 4.8% strength by weight sodium acetate solution were added dropwise. The pH was then in the range 3 to 4. The mixture was then cooled to 20° C. and the solid was filtered off with suction. The solid was washed with 200 ml of water and dried in vacuo at 50° C. 270.3 g of 1-cyclopropyl-6,7,8-trifluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid were isolated, which corresponds to a yield of 99% of theory.

Provenance & Evidence