Process for extractively separating a mixture containing phosphoric acid monoalkylesters into its components

摘要

The invention relates to a process for separating a mixture containing phosphoric acid monoalkylesters, phosphoric acid dialkylesters and minor proportions of diphosphoric acid dialkylesters, each with 6 to 12 carbon atoms in the alkyl radical, by extractively distributing them between an aliphatic or aromatic hydrocarbon as an unpolar solvent and a polar solvent. To this end, the invention provides: for the ester mixture to be admixed with the quantity of water stoichiometrically necessary for hydrolyzing the P-O-P-bond of the diphosphoric acid dialkylester with the resultant formation of the phosphoric acid monoalkylester; for the whole to be maintained for at least 1 hour at temperatures higher than 60 DEG C.; for the partially hydrolyzed ester mixture to be treated in a countercurrent apparatus comprising n-stages with the solvents immiscible or partially miscible with one another so as to ensure introduction of pure solvent into stage 1 and stage n, respectively, and the introduction of partially hydrolyzed mixture into one of the stages 2 to (n-1), n standing for a whole number of at least 3.