Structure of the dibenzoylphthalic acids obtained by condensation of pyromellitic dianhydride with benzene

Conclusions A method has been developed for the isolation of 2,4-dibenzoylisophthalic and 2,5-dibenzoylterephthalic acids from the mixtures formed during the Friedel-Crafts condensation of pyromellitic dianhydride with benzene. The structure of the acids obtained has been investigated by PMR and DR speetroscopy. The ability of 2,5-dibenzoylterephthalic acid to undergo tautomeric interconversions (normal or cyclic forms) has been discovered.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 368–372, February, 1976.