1-Cyclopropyl-7-(4-ethylpiperazin-1-yl)-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid--hydrogen chloride (1/1)

Preparation1. Crude Process: Dissolve enrofloxacin in 1/20 times its volume of water and heat to 90°C. Add hydrochloric acid and act for 30 minutes. Adjust the pH to 3-4 and remove impurities by hot filtration. Adjust the pH to 1 with hydrochloric acid, cool to precipitate crystals, and centrifuge to obtain enrofloxacin hydrochloride. 2. Refined Process: Dissolve crude enrofloxacin hydrochloride in an appropriate amount of distilled water, add 4% activated carbon for decolorization, filter, allow to crystallize naturally, and dry at 80°C for 10 hours to obtain pure enrofloxacin hydrochloride.