Hydrochloric Acid → 1-Ethyl-6,8-difluoro-1,4-dihydro-4-oxo-7-[3-(4-aminobenzenesulfonamido)-1-pyrrolidinyl]-3-quinolinecarboxylic acid

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Reaction Steps

To the compound obtained in Example 14 is added a mixture solution made up of 100 ml of 2N hydrochloric acid and 10 ml of ethanol, and the resulting mixture is refluxed for 4 hours while heating. After cooling, the reaction mixture is neutralized with 2N sodium hydroxide solution and concentrated under reduced pressure. The residue is added to water which is then adjusted to pH 13 with 2N sodium hydroxide solution to dissolve, and any undissolved matter, if present, is removed. The solution is adjusted to pH 7 with acetic acid. Precipitating crystals are collected by filtration and washed. To the washed crystals is added water, pH adjusted to 3 to dissolve, and any undissolved matter, if present, is removed. The solution is then adjusted to pH 7 with 2N sodium hydroxide solution and precipitating crystals are collected by filtration and washed with water. Recrystallization from DMF-methanol gives 1.07 g of the titled compound. Melting point 214°-216° C.

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