Preparation of Benzenetetracarboxylic Acids by the Cobalt-Catalyzed Carbonylation of Schiff Bases from Benzenedicarbaldehydes and Subsequent Oxidation

Article abstract of DOI:10.1021/jo00158a020

Schiff bases (3a-d and 4a-c), synthesized from benzenedicarbaldehydes (terephthalaldehyde and isophthalaldehyde) and primary amines (methylamine, ethylamine, butylamine, and aniline), were carbonylated in the presence of Co2(CO)8 under an elevated pressure at 200-290 deg C to give dicarbonylated products, benzodipyrrolediones (5a-d, 10a-c, and 11a-c), in high yields. 1,2,3,4-Benzenetetracarboxylic acid (prehnitic acid) and 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid) were prepared selectively by the oxidation of the benzodipyrrolediones with nitric acid.Structu ral analysis of the benzodipyrrolediones by NMR spectra and the mechanism of the carbonylation reaction are discussed.