GB748724A - Desdimethylamino-oxytetracycline - Google Patents

Abstract

Desdimethylamino-oxytetracycline formula <FORM:0748724/IV(a)/1> is produced by reacting oxytetracycline with zinc in a mildly acidic medium consisting of (a) an aliphatic carboxylic acid having between one and three carbon atoms, e.g. acidic or propionic acid or (b) a dilute aqueous or dilute aqueous-alcoholic solution of a mineral acid containing not more than 5 per cent of the acid, e.g. hydrochloric, hydrobromic, sulphuric or phosphoric acid. A temperature of 0 DEG to 35 DEG C. is preferred. The oxytetracycline may be in the form of the amphoteric compound, the acid salt, e.g. the hydrochloride, or the metal salt, e.g. the sodium or potassium salt. In the case of the acid salt, it is preferred to add a base such as sodium acetate to the reaction mixture. Zinc is used in proportions of 0.5 to 3.0 on the oxytetracycline. In the case of mineral acid reactions the desdimethylamino-oxytetracycline is extracted from the reaction mixture by organic solvents such as chloroform, methylene chloride, carbon tetrachloride, diethyl ether or aliphatic water-immescible ethers. In the case of reactions in aliphatic acids, preferably in an inert atmosphere such as nitrogen, the residue obtained by evaporating the filtered reaction liquid to dryness is treated with water and then with ether. The ether insoluble is dissolved in alcohol, decomposed by strong mineral acid such as hydrochloric, further alcohol added and the desdimethylamino oxytetracycline precipitated by the addition of water. It is extracted with ether and recrystallized from acetone. Formula C20H19NO9, bound C 57.42 per cent, H=4.62 per cent, N 3.34 per cent; crystalline, melting at 217-218 DEG C.; [a ]25D= -137 DEG (1 per cent methanol), =47 DEG (1 per cent acetone); pKa 6.9 and 8.8 (50 per cent aqueous methanol). May be used in veterinary or pharmaceutical preparations (see Group VI).ALSO:Desdimethylamino oxytetracycline, produced by reacting oxytetracycline with zinc in a mildly acidic medium (see Group IV(b)), is incorporated into pharmaceutical or veterinary preparations for internal or external administration e.g. suspensions, elizirs, capsules and tablets.