Method for purifying bisimides

A method for purifying an oxybisphthalimide having structure (II)

• wherein R1 is a C1-C8 aliphatic radical, a C3-C12 cycloaliphatic radical, or a C3-C12 aromatic radical;
• said method comprising the steps of:
• (a) providing a first solution comprising at least one oxybisphthalimide (II), ortho-dichlorobenzene solvent, and a hexaalkylguanidinium halide phase transfer catalyst;
• and
• (b) contacting the first solution with a silica, said silica having 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 oxybisphthalimide (II) which is substantially free of said phase transfer catalyst.

A method for the preparation of an oxybisphthalimide having structure (II)

• wherein R1 is a C1-C8 aliphatic radical, a C3-C12 cycloaliphatic radical, or a C3-C12 aromatic radical;
• said method comprising steps (a)-(e)
• (a) contacting in a reaction mixture at least one substituted phthalimide 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 oxybisphthalimide, 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 oxybisphthalimide 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 phthalimide having structure VI
• wherein Z is NR1, wherein R1 is a C1-C8 aliphatic radical, a C3-C12 cycloaliphatic radical, or a C3-C12aromatic radical;
• 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 oxybisphthalimide 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 oxybisphthalimide 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 oxybisphthalimide 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 oxybisphthalimide to provide a first solution of the oxybisphthalimide;
• 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 oxybisphthalimide (II) which is substantially free of said organic phase transfer catalyst.