Method for making polyetherimides

A method of preparing a polyetherimide, said method comprising reacting at least one aromatic diamine with a purified oxybisphthalic anhydride, said purified oxybisphthalic anhydride having structure (IV)

• said oxybisphthalic anhydride having been purified by a method, said method comprising the steps of:
• a. providing a first solution comprising at least one oxybisphthalic anhydride (IV), ortho-dichlorobenzene solvent, and a hexaalkylguanidinium halide phase transfer catalyst;
• and
• b. contacting the first solution with a silica, said silica having a total pore volume of about 0.5 milliliters/gram or greater, and a cumulative pore volume distribution of about 20 percent or greater of particles having a pore diameter in a range between about 3 nanometers and about 20 nanometers;
• said contacting being carried out at a temperature in a range between about 50° C. and about 250° C. to provide a second solution of the oxybisphthalic anhydride (IV) which is substantially free of said phase transfer catalyst.

A method of preparing a polyetherimide, said method comprising reacting at least one aromatic diamine with a purified oxybisphthalic anhydride, said purified oxybisphthalic anhydride having structure (IV)

• said oxybisphthalic anhydride having been prepared by a method, said method comprising the steps (a)-(e)
• a. contacting in a reaction mixture at least one substituted phthalic anhydride in at least one solvent in the presence of at least one organic phase transfer catalyst and at least one inorganic carbonate salt to provide a first product mixture comprising at least one oxybisphthalic anhydride, at least one solvent, and at least one inorganic salt selected from the group consisting of alkali metal halide salts, alkaline earth metal halide salts, and mixtures thereof, said oxybisphthalic anhydride being present in said first product mixture in an amount corresponding to at least 25 percent by weight of a total weight of said first product mixture, said substituted phthalic anhydride having structure VI
• wherein Z is 0 and X1 is selected from the group consisting of fluoro, chloro, bromo, iodo, and nitro groups;
• b. diluting said first product mixture with at least one solvent, to provide a second product mixture, wherein the oxybisphthalic anhydride is present in an amount corresponding to less than 25 percent by weight of a total weight of the second product mixture;
• c. dissolving substantially all of the oxybisphthalic anhydride present in the second product mixture to provide a third product mixture, said third product mixture comprising less than 25 ppm water, and wherein said oxybisphthalic anhydride is present in an amount corresponding to less than 25 percent by weight of a total weight of the third product mixture;
• and
• d. filtering the third product mixture at a temperature above the crystallization point temperature of the oxybisphthalic anhydride to provide a first solution of the oxybisphthalic anhydride;
• and
• e. contacting the first solution with a silica, said silica having a total pore volume of about 0.5 milliliters/gram or greater, and a cumulative pore volume distribution of about 20 percent or greater of particles having a pore diameter in a range between about 3 nanometers and about 20 nanometers, said contacting being carried out at a temperature in a range between about 50° C. and about 250° C. to provide a second solution of the oxybisphthalic anhydride IV which is substantially free of said organic phase transfer catalyst.