Synthesis of 4-phenylethynylphthalic anhydride, a useful end-capping agent for polyimides

Article abstract of DOI:10.3184/174751912X13366326240908

Hydrolysis and bromination of phthalic anhydride in water gave a mixture of the monosodium salt of 4-bromophthalic acid. These were reacted with phenylacetylene under Sonogashira coupling reaction conditions in an aqueous medium. Acidification afforded 4-phenylethynylphthalic acid and then dehydration of this gave 4-phenylethynylphthalic anhydride in 76% overall yield. Compared with traditional synthetic methods, this method has the advantage of low cost, convenient manipulation and is environmentally friendly.