Patent ID: 7446214

Claim:
A method for purifying an oxybisphthalic anhydride having structure (IV) said method comprising the steps of: a. providing a first solution comprising at least one oxybisphthalic anhydride (IV), at least one solvent, and at least one organic phase transfer catalyst; and b. contacting the first solution with a solid inorganic adsorbent material, said solid inorganic adsorbent material 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; to provide a second solution of the oxybisphthalic anhydride (IV), which is substantially free of the organic phase transfer catalyst.