Patent ID: 6641734
Filing Date: 2003-11-04
Classification: C07C

Abstract:
A process for purifying an organic acid, comprising:providing an aqueous feed stream comprising a product organic acid and at least one strong contaminant, wherein the molar concentration of the product organic acid is at least 20 times greater than the molar concentration of the strong contaminant; contacting the aqueous feed stream with a first immiscible basic extractant that has a selectivity for the strong contaminant relative to the product organic acid that is greater than about 3, whereby the majority of the strong contaminant and less than about 33 wt % of the product organic acid become complexed with the first immiscible basic extractant; separating the complexed first immiscible basic extractant from the aqueous stream, thereby producing a first effluent stream that comprises product organic acid and that has a greater ratio of product organic acid to strong contaminant than the aqueous feed stream did; and contacting the complexed first immiscible basic extractant with a displacing acid, wherein the first immiscible basic extractant has a greater affinity for the displacing acid than it does for the strong contaminant or the product organic acid, and wherein the displacing acid is present in sufficient amount to cause product organic acid to be selectively displaced from the complexed first immiscible basic extractant, thereby, over time, producing a second effluent stream that comprises a major amount of product organic acid and displacing strong contaminant from the complexed first immiscible basic extractant, thereby following production of the second effluent stream with the production of a third effluent stream that comprises a major amount of strong contaminant and that is separated from the second effluent stream; wherein the total amount of product organic acid present in the first effluent stream and in the second effluent stream is at least about 900/0 by weight of the product organic acid that was present in the feed stream.