A liquid-liquid extraction method for separating carboxylate monofunctional perfluoropolyethers and carboxylate difunctional perfluoropolyethers

Abstract

The invention discloses a liquid-liquid extraction method for separating carboxylate monofunctional perfluoropolyethers and carboxylate difunctional perfluoropolyethers, which comprises: the mixture containing monocarboxylate end-group perfluoropolyether and dicarboxylate end-group perfluoropolyether are mixed in contact with light and heavy two-phase solvent, after extraction equilibrium, the two phases were separated and the solvent is removed, and the high-purity monocarboxylate end-group perfluoropolyether is obtained in heavy phase and dicarboxylate end-group perfluoropolyether is obtained in light phase. The light phase solvent comprises a diluent and a polar solvent containing fluorine atoms. The diluent is one or more of sulfolane, dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, water, ethylene glycol, acetonitrile, acetic acid, ethanol, methanol. A heavy phase solvent consists of a non-polar solvent containing fluorine atoms and a polar solvent containing fluorine atoms, or a non-polar solvent containing fluorine atoms and a non-polar solvent without fluorine atoms.

Dependencies are inferred from the claim text.