Methods for producing and purifying 2-aryl-3,3-bis(4-hydroxyaryl)phthalimidine compounds, the purified monomers, and polymers derived therefrom
View Patent ↗Disclosed is 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 a hydrogen, a C 1-25 hydrocarbyl group, or a halogen, and wherein the method comprises dissolving a 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. Subsequent trituration with aqueous methanol and recrystallization from isopropanol can result in product having undetectable levels of phenolphthalein derivatives.
1. A method for producing a highly purified 2-aryl-3,3-bis(4-hydroxyaryl)phthalimidine of formula (I)
wherein R 1 is hydrogen or a C 1-3 alkyl group and R 2 is hydrogen, a C 1-3 alkyl 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 1-3 alkyl group, or a halogen,
a primary aryl amine of formula (III),
wherein R 1 is hydrogen or a C 1-3 alkyl 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 solution comprising an alkali metal hydroxide, an alkaline earth hydroxide, or a combination comprising at least one of the foregoing metal hydroxides;
precipitating the dissolved, crude phthalimidine compound from the aqueous base solution by adding a mineral 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, washing the isolated phthalimidine compound with dilute acid, then with water, and drying the washed phthalimidine compound to provide a purified phthalimidine compound of formula (I);
triturating the purified phthalimidine compound of formula (I) with an aqueous C 1-3 alcohol to provide a triturated phthalimidine compound; and
washing the triturated phthalimidine compound with aqueous alcohol, then hot water preheated to a temperature of 60 to 80° C.; and
drying the washed phthalimidine compound to provide the 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.