Patent ID: 6441225
Filing Date: 2002-08-27
Classification: B01J,C07C,C08G

Abstract:
A method to recover dicarboxylic or tricarboxylic aromatic acid from salts of such acids, the method comprising the steps of:providing an aqueous solution of a salt of a dicarboxylic or tricarboxylic aromatic acid, the aqueous solution having a pH of about 7 or greater; contacting the aqueous solution with sufficient carbon dioxide to lower the pH of the aqueous solution resulting in precipitation of at least a portion of the dicarboxylic or tricarboxylic aromatic acid; separating precipitated dicarboxylic or tricarboxylic aromatic acid from the solution; recovering carbon dioxide from the solution; and contacting the separated precipitated dicarboxylic or tricarboxylic aromatic acid with oxalic acid under conditions effective to disproportionate any monosalt of the dicarboxylic or tricarboxylic aromatic acid present to a mixture of disalt and dicarboxylic or tricarboxylic aromatic acid.