Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1997-07-10
1998-06-23
Killos, Paul J.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C07C 6334
Patent
active
057707669
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD AND BACKGROUND
The present invention relates to a method of separation and purification of hydroxynaphthalenecarboxylic acids.
Hydroxynaphthalenecarboxylic acids such as 2-hydroxynaphthalene-6-carboxylic acid are important raw materials of aromatic polyesters, and indispensable especially to the production of liquid crystalline polymers excellent in workability and fluidity, and resins or fibers having a high elasticity and a high heat resistance. Further, 2-hydroxynaphthalene-3-carboxylic acid and 2-hydroxynaphthalene-3,6-dicarboxylic acid are useful as raw materials for azo type pigments or dyes.
2-hydroxynaphthalene-6-carboxylic acid (referred to as "BON6" hereinafter) and 2-hydroxynaphthalene-3-carboxylic acid (referred to as "BON3" hereinafter) have been produced from the reaction of alkaline salts of .beta.-naphthol and carbon dioxide by Kolbe-Schmitt reaction (Japanese Patent Application KOKAI Sho. 57-95939, Japanese Patent Application KOKAI Sho. 57-97244, Japanese Patent Application KOKAI Sho. 58-99436, and Japanese Patent Application KOKAI Sho. 63-146843 etc.). The reaction mixtures obtained according to the above reaction contain isomers such as BON3, BON6 and other impurities in addition to objective products.
Recently, it has been found that 2-hydroxynaphthalene-3,6-dicarboxylic acid (referred to as "BON3,6" hereinafter) can be obtained in high yield by the reaction of potassium salt of 2-naphthol and carbon dioxide under a specific condition, but substantial amounts of BON6 and BON3 are still contained in the reaction mixture.
As these hydroxynaphthalenecarboxylic acids vary in the use and property, the purification of the products is indispensable, and various purification processes therefor have been proposed.
For example, as a method for the separation and purification of BON6, the process has been proposed in which water is added to the reaction mixture and the pH value is adjusted at approximately 3-4 with a mineral acid such as hydrochloric acid, sulfuric acid and the like to deposit a crude BON6, and then the crude product is washed with water-alcohol solvent such as diluted methanol to separate BON6 and BON3.
Other method such that crude BON6 are subjected to crystallization in an aqueous solution containing aliphatic ethers (Japanese Patent Application KOKAI Hei 1-216955), and the BON6 is separated by the crystallization as the dioxane adduct so as to obtain the BON6 from the adduct (Japanese Patent Application KOKAI Hei 2-15046 and KOKAI Hei 2-218643).
Similar methods have been used for the separation of BON3,6 from BON3 and BON6, but these methods were not sufficient and it was impossible to obtain separated and purified products in a high purity from the reaction mixtures containing impurities in much amount.
DISCLOSURE OF THE INVENTION
The present invention relates to a method of separation and purification of hydroxynaphthalenecarboxylic acids, which comprises treating a solution containing a mixture of various kinds of hydroxynaphthalenecarboxylic acids with a nonionic porous synthetic adsorbent having as a basic structure aromatic copolymers mainly composed of styrene and divinylbenzene or methacrylic copolymers mainly composed of monomethacrylates and dimethacrylates, and separating into each hydroxynaphthalenecarboxylic acid.
In the present specification, "treatment with adsorbents" means a process including a previous dissolution of hydroxynaphthalenecarboxylic acids in a solvent, an adsorption of the solution obtained, and a selective extraction with a solvent or an elution through a column packed with an adsorbent.
In the present specification, "hydroxynaphthalenecarboxylic acids" include not only hydroxynaphthalene monocarboxylic acids but also polycarboxylic acids such as dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids and the like.
The nonionic porous synthetic adsorbents having as the basic structure aromatic copolymers mainly composed of styrene and divinylbenzene or methacrylic copolymers mainly composed of monomethacrylates and dim
Kitayama Masaya
Mori Shigeji
Uchiyama Yoshiro
Ueno Ryuzo
Yanagawase Kuniyo
Kabushiki Kaisha Ueno Seiyaku Oyo Kenkyujo
Killos Paul J.
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