Patent ID: 7790832

Claim:
A method for purifying a 2-aryl-3,3-bis(hydroxyaryl)phthalimidine compound, the method comprising: contacting a crude 2-aryl-3,3-bis(hydroxyaryl)phthalimidine compound with a solid acidic material, an organic acid chloride, an organic anhydride, a solution of a mineral acid in a polar organic solvent, a solution of an organosulfonic acid having 2 or more carbon atoms in an organic solvent, acetic acid, or a combination thereof, to remove a 2-aryl-3-(aminoaryl)-3-(hydroxyaryl)phthalimidine compound having a formula: wherein each R 1 is independently selected from the group consisting of a hydrocarbyl radical, a nitro radical, and a halogen atom; “a” is an integer from 0 to 4; and Ar 1 and Ar 2 are independently at each occurrence an aromatic radical; and producing a purified 2-aryl-3,3-bis(hydroxyaryl)phthalimidine product comprising less than 200 parts per million of the 2-aryl-3-(aminoaryl)-3-(hydroxyaryl)phthalimidine compound.