Methods for producing and purifying 2-aryl-3,3-bis(4-hydroxyaryl)phthalimidine compounds, the purified monomers, and polymers derived therefrom

1. A method for producing a purified 2-aryl-3,3-bis(4-hydroxyaryl) phthalimidine of formula (I)

wherein R 1 is hydrogen or a C 1-25 hydrocarbyl group and R 2 is hydrogen, a C 1-25 hydrocarbyl group, or a halogen, and wherein the method comprises:

heating a reaction mixture comprising

a phenolphthalein compound of formula (II)

wherein R 2 is hydrogen, a C 1-25 hydrocarbyl group, or a halogen,

a primary aryl amine of formula (III),

wherein R 1 is hydrogen or a C 1-25 hydrocarbyl group, and

an acid catalyst, to form a phthalimidine compound of formula (I);

precipitating the phthalimidine compound from the reaction mixture to provide a crude phthalimidine compound;

dissolving the crude phthalimidine compound in an aqueous base solution;

precipitating the dissolved, crude phthalimidine compound from the aqueous base solution by adding an acid in an amount effective to lower the pH of the solution to 9.0 to 12.0, to provide a semicrude phthalimidine compound; and

isolating the semicrude phthalimidine compound from the aqueous base solution, to provide the purified 2-aryl-3,3-bis (4-hydroxyaryl) phthalimidine of formula (I), and having a phenolphthalein compound content of less than 2,500 ppm, based on the weight of the purified 2-aryl-3,3-bis(4-hydroxyaryl) phthalimidine.

2. The method of claim 1 , wherein precipitating the phthalimidine compound from the reaction mixture comprises combining the reaction mixture with an acid and an antisolvent for the crude phthalimidine compound.

3. The method of claim 2 , wherein acid is a mineral acid and the antisolvent is water.

4. The method of claim 1 , wherein the base is an alkali metal hydroxide, an alkaline earth metal hydroxide, or a combination comprising at least one of the foregoing metal hydroxides.

5. The method of claim 1 , wherein the aqueous base solution is an aqueous sodium hydroxide solution.

6. The method of claim 1 , further comprising contacting the aqueous base solution comprising the dissolved, crude phthalimidine compound with a solid absorbent; and

removing the solid absorbent from the contacted aqueous base solution, prior to precipitating to form the semicrude phthalimidine compound.

7. The method of claim 1 , wherein the acid is a mineral acid.

8. The method of claim 7 , wherein the acid is hydrochloric acid with a molarity from 3 to 9.

9. The method of claim 1 , further comprising washing the isolated phthalimidine compound with dilute acid, then with water, and drying the washed phthalimidine compound to provide the purified 2-aryl-3,3-bis(4-hydroxyaryl) phthalimidine of formula (I).

10. The method of claim 1 , further comprising triturating the purified phthalimidine of formula (I) to provide a highly purified 2-aryl-3,3-bis(4-hydroxyaryl) phthalimidine of formula (I), having a phenolphthalein compound content of less than 100 ppm, based on the weight of the 2-aryl-3,3 -bis(4-hydroxyaryl) phthalimidine.

11. The method of claim 10 , wherein the triturating is performed with aqueous methanol.

12. The method of claim 10 , further washing the purified phthalimidine of formula (I) with water preheated to a temperature of 50 to 90° C.

13. A purified 2-aryl-3,3-bis(4-hydroxyaryl) phthalimidine produced by the method of claim 1 .

14. A highly purified 2-aryl-3,3-bis(4-hydroxyaryl) phthalimidine produced by the method of claim 10 .