Active derivatives of the tetracycline antibiotics

Claim 1

THE PROCESS WHICH COMPRISES REACTING IN A SUBSTANTIALLY NON-AQUEOUS INERT SOLVENT A TETRACYCLINE ANTIBIOTIC SELECTED FROM THE GROUP CONSISTING OF TETRACYCLINE, OXYTETRACYCLINE, CHLORETETRACYCLINE, THE MINERAL ACID ADDITION SALTS THEREOF, THE P-TOLUENESULFONIC SALTS THEREOF, THE ALKALI METAL SALTS THEREOF, THE CALCUM SALTS THEREOF, AND THE BARIUM SALTS THEREOF WITH AT LEAST ONE MOLECULAR PROPORTION OF A CARBONYL COMPOUND TO OBTAIN THE 1:1 ADDUCT OF SAID TETRACYCLINE ANTIBIOTIC AND SAID CARBONYL COMPOUND, SAID CARBONYL COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF CHORAL, GLYOXAL, BROMAL, 1,2,3-INDANETRIONE, DIACETYL, ACETYL CYANIDE, ETHYL PYRUVATE, PYRUVALDEHYDE, BENZOYL CYANIDE, PHENYLGLYOXAL, ETHYL PHENYLPYRUVATE, DIETHYL OXALOCETATE, ETHYL 4-NITROPHENYLPYRUVATE, 5-NITROFURFURAL, AND 2-METHYL-3-FORMYQUINOXALINE-1,4-DIOXIDE, THE TEMPERATURE OF REACTION BEING FROM ABOUT 15* TO ABOUT 85*C. AND THE TIME OF REACTION BEING UP TO ABOUT 100 HOURS.