Synthesis and antioxidant activity screening of new poly (imide-sulfonate) S have Schiff base linkage

A series of new poly (imide-sulfonate)s polyimides involving Schiff base moiety have synthesized via multistep synthesis. The first step involved reaction of pyromellitic anhydride with aniline producing bis (N-phenyl) pyromelltamic acid (1) which was subsequently dehydrated to the corresponding bis (N-phenyl) pyromelltimide (2) via fusion method. The synthesized imide (2) reacted with chlorosulfonic acid in the third step to produce bis N-(phenyl) pyromelletimide sulphonyl chloride (3). In the fourth step four diols was synthesized by condensation of 4,4'-methylenedianiline with four hydroxyl substituted aldehydes and ketones producing new diols (4-7) and these inturn were introduced successfully in condensation polymerization with monomer (3) affording the desired new polymers (8-11). The newly synthesized compounds and polymers were characterized through spectral data including FT-IR, ¹H-NMR and ¹³C-NMR. Antioxidant activity of new polymers (8-11) was measured using stable DPPH radicals.