PRODUCTION OF ALKYLBENZOIC ACID

PROBLEM TO BE SOLVED: To produce the subject compound in a high grade without causing the abnormal operation of an installation, while by-producing a small amount of a dicarboxylic acid, by oxidizing an alkylbenzene compound with molecular oxygen in a liquid phase, recovering the alkylbenzene from the obtained reaction product, removing impurities from the recovered alkylbenzene and subsequently reusing the purified compound as the raw material. SOLUTION: This method for producing the alkylbenzoic acid comprises oxidizing an alkylbenzene compound (A) having two or more 1-3C alkyl groups with a molecular oxygen-containing gas in the presence of a soluble heavy metal catalyst in a liquid phase, recovering the compound (A) from the reaction product solution, removing the contained impurities from the recovered component (A) by a distillation treatment, a water-washing treatment, a washing treatment using a 8-14pH alkaline aqueous solution, a treatment using an anion exchange resin, a treatment using a solid adsorbent, a treatment using an alkali solid substance, etc., and subsequently reusing the purified recovered component A. In the method, one carboxyl group of the component A is converted into the carboxyl group.