Patent ID: 7524986

Claim:
A method for producing an aromatic carboxylic acid, by oxidizing an aromatic compound B with oxygen in the presence of a catalytic nitrogen-containing cyclic compound A to thereby yield a corresponding aromatic carboxylic acid, the aromatic compound B having one or more hydrocarbon groups alone as substituents on its aromatic ring, and the catalytic nitrogen-containing cyclic compound A having a skeleton represented by following Formula (i): wherein X represents oxygen atom or an —OR group, and wherein R represents hydrogen atom or a hydroxyl-protecting group, as a constitutive member of its ring, the method comprising the step of carrying out a reaction at: a concentration of the aromatic compound B in the reaction system of 3.0 percent by weight or less; a molar ratio of the catalytic nitrogen-containing cyclic compound A to the aromatic compound B in the reaction system of 0.01 or more; an oxygen concentration in an offgas of 1% to 8% with the oxygen to be fed to the reaction system being an oxygen-containing gas containing oxygen in an amount of 10% to 50%; and a pressure of oxygen to be fed to the reaction system being 0.1 MPa to 4 MPa, while continuously feeding the catalytic nitrogen-containing cyclic compound A, the aromatic compound B, a reaction solvent, and oxygen to a reactor and continuously extracting a reaction mixture from the reactor.