Crystallisation of tetracycline hydrochloride - accelerated by subjecting to high-frequency vibrations, with purer, less toxic prod. formed

摘要

Process for preparing tetracycline hydrochloride (I) comprises treating a suspension of tetracycline (II) in organic solvent with conc. HCl and irradiating the resulting soln. with high-frequency vibrations, esp. of 10,000-400,000 Hz at flux density 0.5-10.5 W/sq.cm. By this irradiation crystallisation of (I) is 10-13 times quicker, and a purer product is obtained in higher yields. (I) is deposited as small, micronised crystals (particularly suitable for ointments, syrups etc.) and not as conglomerates enclosing solvent and acid. The activity of the mother liquor is 2000-4000 units/ml lower than for a control; that of (I) is higher than for a control and is close to the theoretical. (I) is esp. useful for preparation of tetraolean, and has a reduced toxicity.