Process for the preparation and recovery of oxydiphthalic anhydrides

摘要

Oxydiphthalic anhydrides of the formula <IMAGE> are prepared by reacting a halophthalic anhydride with potassium carbonate in: (1) a solvent-free reaction medium wherein the molar ratio of halophthalic anhydride:potassium carbonate is greater than 2:1; or (2) a high boiling solvent which improves the mixing of the components, and aids in subsequent purification of the product. The molar ratio of halophthalic anhydride to potassium carbonate is about 1.5:1 or greater. The oxydiphthalic anhydride can be purified by filtering or centrifuging a hot solution of the oxydiphthalic anhydride in a high boiling solvent to remove impurities, followed by cooling the solution to precipitate the oxydiphthalic anhydride, which can be removed from the solution by filtration or centrifuging.