for the following products
3,3',4,4'-Biphenyltetracarboxylic dianhydride | 3,4,3',4'-Biphenyltetracarboxylic dianhydride (BPDA) | 4,4'-Biphthalic anhydride | BPDA | [5,5'-Biisobenzofuran]-1,1',3,3'-tetraone and 3,3',4,4'-Diphenyltetracarboxylic dianhydride
