Hydrochloric Acid → Minocycline Hydrochloride Dihydrate

Participants

Reaction Steps

Ten grams of a crude minocycline [HPLC. purity, 94.8% (percentage area)] was suspended at 15° to 20° C. in a mixed solvent of 30 ml of water and 45 ml of methanol and dissolved at a pH of 0.8 to 1.0 by adding conc. hydrochloric acid with stirring. Subsequently, 1 g of activated carbon and 10 mg of EDTA.2Na were added, and after 30 minutes' stirring, the activated carbon was separated by filtration. To the filtrate was added dropwise a 5% aqueous sodium hydroxide solution to adjust the pH of the filtrate to 4.0, whereby minocycline precipitated in the form of a hydrochloride. This hydrochloride was separated by filtration and dried in vacuo to obtain 11.0 g of a purified minocycline hydrochloride dihydrate [HPLC. purity, 99.4% (area percentage)].

Provenance & Evidence