Methods for purifying 2-aryl-3,3-bis(hydroxyaryl)phthalimidines
Methods for synthesizing and purifying 2-aryl-3,3-bis(4-hydroxyaryl)phthalimidine compounds are provided. The method includes heating a reaction mixture including a phenolphthalein, a primary aryl amine, and an acid catalyst to form a phthalimidine; precipitating the phthalimidine from the reaction mixture to provide a crude phthalimidine; providing a solution including the crude phthalimidine, an additive, and at least one solvent; contacting the solution with one or more purification agents to provide a treated solution; precipitating and recovering a phthalimidine adduct from the treated solution; and recovering a purified phthalimidine compound from the adduct.
1. A method of producing a purified 2-aryl-3,3-bis(4-hydroxyaryl)phthalimidine of formula (I),
wherein R 1 , at each occurrence, is selected from C 1 -C 25 hydrocarbyl; R 2 , at each occurrence, is selected from C 1 -C 25 hydrocarbyl and halogen; p is 0, 1, 2, 3, 4, or 5; and q is 0, 1, 2, 3, or 4; the method comprising:
(A) heating a reaction mixture comprising a phenolphthalein of formula (II), a primary aryl amine of formula (III), and an acid catalyst to form a phthalimidine of formula (I),
wherein R 1 , R 2 , p, and q are as defined above;
(B) precipitating the phthalimidine from the reaction mixture to provide a crude phthalimidine;
(C) providing a solution comprising the crude phthalimidine, urea, and at least one solvent;
(D) contacting the solution with one or more purification agents to provide a treated solution;
(E) precipitating and recovering a phthalimidine adduct from the treated solution; and
(F) recovering a purified compound of formula (I) from the adduct.
2. The method of claim 1 , wherein the compound of formula (I) is 2-phenyl-3,3-bis(4-hydroxyphenyl)phthalimidine (“PPPBP”).
3. The method of claim 1 , wherein the reaction mixture of (A) is heated to a temperature of 140° C. to 180° C.
4. The method of claim 1 , wherein (B) comprises quenching the reaction mixture of (A) by cooling the reaction mixture and adding an acid; filtering the precipitate; and washing the precipitate to provide the crude phthalimidine.
5. The method of claim 1 , wherein (D) comprises
contacting the solution with activated carbon; contacting the solution with an ion exchange resin; or a combination thereof.
6. The method of claim 1 , wherein (D) comprises contacting the solution with the one or more purification agents to provide the treated solution; and filtering the treated solution to remove the one or more purification agents.
7. The method of claim 1 , wherein the phthalimidine adduct of (E) is a phthalimidine-solvent adduct.
8. The method of claim 1 , wherein (E) includes one or more of:
filtering the treated solution to remove at least one of the one or more purification agents;
distilling the treated solution, optionally under reduced pressure, to remove at least a portion of the at least one solvent;
cooling the treated solution to precipitate the phthalimidine adduct;
filtering the treated solution to recover the precipitated phthalimidine adduct; and
triturating the phthalimidine adduct.
9. The method of claim 1 , wherein precipitating the phthalimidine adduct of (E) is performed at 10° C.
10. The method of claim 1 , wherein (F) includes washing the phthalimidine adduct with hot water, followed by drying to provide the purified compound of formula (I).
11. The method of claim 1 , wherein the yield of the purified compound of formula (I) is at least 80%.
12. The method of claim 1 , where the volumes of the at least one solvent solvent:starting material is 7:1 to 9:1, and the yield of purified compound of formula (I) is at least 90%.
13. The method of claim 1 , wherein the purified compound of formula (I) comprises less than 50 ppm of amino phenol impurities and less than 500 ppm of residual phenolphthalein of formula (II).
14. The method of claim 1 , wherein at least one of the one or more purification agents is recycled at least two times and used again in the method of any one of claims 1 - 13 , wherein the purity of the compound of formula (I) recovered using the recycled purification agent is greater than or equal to 99.85%.
15. The method of claim 1 , wherein at least one of the one or more purification agents used in the method is regenerated.
16. The method of claim 1 , wherein the cycle time for the process of (A)-(F) is 40 hours.
17. The method of claim 1 comprising a continuous process, the continuous process comprising one or more of:
subjecting one or more of the filtrates generated in (A) through (F) to distillation to recover one or more the solvents, and reusing the distilled solvents;
recycling at least one of the one or more purification agents used in the method and reusing the recycled purification agent; and
regenerating at least one of the one or more purification agents used in the reusing the regenerated purification agent.
18. The method of claim 1 , wherein the method does not include use of activated carbon.
19. A copolymer comprising repeating units derived from the purified compound of formula (I) according to claim 1 .
20. The copolymer of claim 19 , comprising further comprising repeating units derived from bisphenol-A.