Method for purifying tetracycline

Claim 1

A METHOD OF ISOLATING TETRACYCLINE FROM A FERMENTATION BROTH CONTAINING THE SAME AND APPRECIABLE QUANTITIES OF CHLORTETRACYCLINE, WHICH COMPRISES ACIDIFYING SAID BROTH; FILTERING THE BROTH; TREATING THE FILTRATE WITH AN INORGANIC METAL COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE RELATIVELY WATER-INSOLUBLE SALTS AND BASES OF THE LIGHT METALS OF GROUPS IIA AND IIIB OF THE PERIODIC TABLE AT A PH IN THE RANGE OF ABOUT 9 TO ABOUT 10 SAID COMPOUND BEING PRESENT IN A CONCENTRATION GREATER THAN ABOUT 0.005 GRAM OF COMPOUND PER MILLILITER OF FILTRATE, WHEREBY AN INSOLUBLE ASSOCIATION OF TETRACYCLINE AND INORGANIC COMPOUND PRECIPITATES; SEPARATING THE PRECIPITATE; MIXING THE PRECIPITATE WITH AN ORGANIC SOLVENT FOR TETRACYCLINE THEREBY FORMING A MIXTURE COMPRISING WATER, ORGANIC SOLVENT, INORGANIC METAL COMPOUND AND TETRACYCLINE; ACIDIFYING THE MIXTURE TO A PH IN THE RANGE OF ABOUT 1.5 TO ABOUT 2.5 WITH AN ACID WHICH FORMS AN INSOLUBLE SALT WITH THE CATION OF THE INORGANIC METAL COMPOUND IN SAID SOLVENT AT SAID ACID PH; REMOVING THE INSOLUBLE SALT; AND RECOVERING THE TETRACYCLINE FROM THE SOLVENT BY ADJUSTING THE PH THEREOF TO THE RANGE OF ABOUT 4 TO ABOUT 4.5, WHEREBY TETRACYCLINE PRECIPITATES.

Claim 2

A METHOD OF ISOLATING TETRACYCLINE FROM A FERMENTATION BROTH CONTAINING THE SAME AND APPRECIABLE QUANTITIES OF CHLORTETRACYCLINE, WHICH COMPRISES ACIDIFYING SAID BROTH; FILTERING THE BROTH; TREATING THE FILTRATE WITH AN INORGANIC METAL COMPOUND SELECTED FROM THE GROUP CONSISTING OF THE RELATIVELY WATER-INSOLUBLE SALTS AND BASES OF THE LIGHT METALS OF GROUPS IIA AND IIIB OF THE PERIODIC TABLE AT A PH IN THE RANGE OF ABOUT 9 TO ABOUT 10 SAID COMPOUND BEING PRESENT IN A CONCENTRATION GREATER THAN ABOUT 0.005 GRAM OF COMPOUND PER MILLILITER OF FILTRATE, WHEREBY AN INSOLUBLE ASSOCIATION OF TETRACYCLINE AND INORGANIC COMPOUND PRECIPITATES; SEPARATING THE PRECIPITATE; MIXING THE PRECIPITATE WITH AN ORGANIC SOLVENT FOR TETRACYCLINE THEREBY FORMING A MIXTURE COMPRISING WATER, ORGANIC SOLVENT, INORGANIC METAL COMPOUND AND TETRACYCLINE; ACIDIFYING THE MIXTURE TO A PH IN THE RANGE OF ABOUT 1.5 TO ABOUT 2.5 WITH AN ACID WHICH FORMS AN INSOLUBLE SALT WITH THE CATION OF THE INORGANIC METAL COMPOUND IN SAID SOLVENT AT SAID ACID PH; REMOVING THE INSOLUBLE SALT; AND RECOVERING THE TETRACYCLINE FROM THE SOLVENT BY ADJUSTING THE PH THEREOF TO THE RANGE OF ABOUT 4 TO ABOUT 4.5, WHEREBY TETRACYCLINE PRECIPITATES.