| 摘要 |
1305860 Purification of doxycycline ALFA FARMACEUTICI SpA 17 Dec 1971 [31 March 1971] 58807/71 Heading C2A A process for purifying the 6-α-epimer of doxycycline of Formula I comprises precipitating 6-α-doxycycline 5-sul phosalicylate by means of sulphosalicylic acid from a solution of impure doxycycline (or a salt thereof) in an aqueous organic solvent containing from 20 to 70% by volume of water and from 80 to 30% by volume of N,N-dimethylformamide, N,N,-dimethylacetamide, dimethylsulphoxide or acetone. Such an aqueous organic solvent may preferably contain from 40 to 60% by volume of water. In a preferred process, 15 to 25 parts by volume of the aqueous organic solvent are used for each part by weight of 6α- doxycycline. The 6α-doxycycline 5-sulphosalicylate may be precipitated by adding to a solution containing doxycycline 5À5 to 6À5 moles of 5-sulphosalicylic acid per mole of 6α-doxycycline. The 5-sulphosalicylate salt produced may be converted into the free base of doxycycline or into another salt thereof. The process may be used for purifying doxycycline which has been produced by catalytic hydrogenation of methacycline. |
