for the following products
2,2-bis-[4-(3,4-Dicarboxyphenoxy) phenyl] propane dianhydride | 4,4'-Bisphenol a dianhydride | 5,5'-((1-Methylethylidene)bis(4,1-phenyleneoxy))bis-1,3-isobenzofurandione | BPADA and 4,4'-(4,4'-Isopropylidenediphenoxy)bis-(phthalic anhydride)
