PRODUCTION OF 2,6-NAPHTHALENE DICARBOXYLIC ACID

• Main Authors: SAITO NOBORU, IIDA TOSHIYA, HASEBE REN
• Format: Patent
• Language: English
• Published: 14.04.1998
• Edition: 6
• Subjects: ACYCLIC OR CARBOCYCLIC COMPOUNDS; APPARATUS THEREFOR; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; GENERAL METHODS OF ORGANIC CHEMISTRY; METALLURGY; ORGANIC CHEMISTRY; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; THEIR RELEVANT APPARATUS; TRANSPORTING

PROBLEM TO BE SOLVED: To provide a method for producing the subject compound in a high yield, to obtain the compound to recover and to reutilize a catalyst by oxidizing a 2,6-dialkylnaphthalene with molecular oxygen in the presence of the transition metal catalyst in a liquid phase and subsequently washing the reaction product under constant conditions. SOLUTION: This method for producing 2,6-naphthalene dicarboxylic acid (2,6-NDCA) comprises oxidizing a 2,6-dialkylnaphthalene with molecular oxygen in the presence of a catalyst containing a transition metal (e.g. Mn) in a solvent containing a 1-3C organic acid (e.g. acetic acid) in a concentration of >=50wt.%, and subsequently washing the reaction product with water or an aqueous salt solution having a pH of >=5 as a washing liquid until the pH of the used washing liquid becomes 4-8. The 2,6-NDCA is useful as a raw material for polyethylene naphthalate giving films and various kinds of molded products excellent in mechanical strengths, heat resistance and dimensional stability. Such the washing enables to transfer the transition metal salt of by-produced trimellitic acid to the side of the washing liquid, thereby permitting to obtain the 2,6-NDCA in a high purity.