Methods for producing aromatic carboxylic acids

Abstract

A method of this invention produces 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 includes 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, 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. This method can produce aromatic carboxylic acids with industrially good productivity without the need for special reaction facilities and without undergoing many steps.