PROCESS OF REFINING F SERIES PROSTAGLANDINS

In the present invention, there is disclosed a refining process of F series prostaglandins of the general formula I, in which R represents an alkyl group containing 1 to 8 carbon atoms or a phenoxyl group being optionally substituted with a halogen or a haloalkyl, wherein the process is characterized in that 1.1 to 1.5 equivalents of 0.2 to 2.0 molar aqueous solution of alkali metal hydroxide are added at a temperature ranging from 0 to 85 degC to a solution of a raw acid of the general formula I in an alcohol having 1 to 4 carbon atoms or an ether that is miscible with water, the obtained mixture is agitated for a period of 0.5 to 48 hours, the reaction mixture is then acidified with an inorganic acid to give pH 3.0 to 4.5, the released acid of the general formula I is extracted into a water immiscible organic solvent, the obtained extract is then washed with a saturated salt brine, dried with inorganic desiccant and after filtering off the extract, the required product is isolated by vacuum evaporation of solvents. Due to the action of alkalis, a nearly complete removal of contaminant of the type of acid alkyl esters of the general formula I, being present in the starting material, takes place. In the same time, a partial or complete removal of some minor unidentified compounds takes place or they can be transformed to contaminants that can be easily separated by chromatography.