Patent ID: 7514524

Claim:
A method comprising: reacting a phenolphthalein material and a primary hydrocarbyl amine in the presence of an acid catalyst to form a reaction mixture comprising 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, wherein the phenolphthalein material comprises greater than or equal to 95 weight percent phenolphthalein, based on the total weight of phenolphthalein material; quenching the reaction mixture; treating the quenched reaction mixture to obtain a first solid; triturating the first solid with a triturating solvent and washing to obtain a second solid, wherein the second solid comprises greater than or equal to 97 weight percent 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine, based on the total weight of the second solid; and wherein the 2-hydrocarbyl-3,3-bis(4-hydroxyaryl)phthalimidine has a formula of: wherein R 1 is selected from the group consisting of a hydrogen, and a hydrocarbyl group, and R 2 is selected from the group consisting of a hydrogen, a hydrocarbyl group, and a halogen.