Patent ID: 8134016
Filing Date: 2012-03-13
Classification: C07D

Abstract:
1. A method of purifying a dianhydride, said method comprising the steps of: a. providing a first solution comprising at least one dianhydride, 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 dianhydride, which is substantially free of the organic phase transfer catalyst, wherein the solid inorganic adsorbent material is selected from the group consisting of silica, alumina, zeolites, inorganic ion exchange compounds and mixtures thereof.