Process for the purification of O,O-di(lower)alkyldithiophosphoric acids

摘要

A liquid-liquid extraction method for recovering O,O-di(lower)alkyldithiophosphoric acid of increased purity from a crude mixture in which it is contained comprises intimately contacting said mixture with an acidic aqueous solution to form two liquid phases whereby the concentration of the thiophosphoric acid in the aqueous phase is increased; separating the two phases; contacting the aqueous phase with a stable, water-immiscible, volatile, organic solvent to form two liquid phases whereby the concentration of the thiophosphoric acid in the organic solvent is increased; separating the two phases; and vaporizing the organic solvent to recover high purity O,O-di(lower)alkyl dithiophosphoric acid.