1,3,5,7-Naphthalenetetracarboxylic acids and process for preparation thereof
AssigneeTeijin Limited
InventorsGentaro Yamashita, Yasushi Tsuru, Kiyoshi Yamamoto, Moriharu Yamamoto, Nobuo Sakaiya, Toshihiro Aoyama, Tadao Komoriya
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Abstract
A novel 1,3,5,7-naphthalenetetracarboxylic acid, an alkali salt thereof, or an ester thereof, and a novel process for preparation thereof, and method of effective purification thereof.
Claims14
A compound of the formula ##SPC9##
- wherein the X's may be the same or different and are selected from the group consisting of hydrogen atoms, alkali metals, alkyl having 1 to 12 carbon atoms and allyl.
A process for preparing an alkali metal 1,3,5,7-naphthalenetetracarboxylate of the formula ##SPC11##
- wherein M is an alkali metal, which comprises heating a mixture of at least one alkali metal naphthalenecarboxylate of the formula ##SPC12##
- wherein n is an integer of 1 to 4;
- and M is an alkali metal with the proviso that when n is 4, the four --COOM groups are not present simultaneously at the 1,3,5,7-positions, and 1-40% by weight, based on the weight of the mixture, of said alkali metal 1,3,5,7-naphthalenetatracarboxylate to a temperature of at least 350.degree.C. in an atmosphere of an inert gas and in the presence of a catalyst selected from the group consisting of the halides, oxides, sulfates, carbonates and carboxylates of zinc or cadmium and recovering the resulting alkali metal 1,3,5,7-naphthalenetetracarboxylate from the reaction mixture.
A process for preparing an alkali metal 1,3,5,7-naphthalenetetracarboxylate of high purity, which comprises heating at least one alkali metal naphthalenecarboxylate of the formula ##SPC13##
- wherein n is an integer of 1 to 4;
- and M is an alkali metal with the proviso that when n is 4, the four --COOM groups are not present simultaneously in the 1,3,5,7-positions, to a temperature of at least 350.degree.C. in an atmosphere of an inert gas, dissolving the reaction mixture obtained in water, adjusing the alkali ion concentration of the resulting aqueous solution to at least 6 g-alkali ion/ 1000 g-water, hot filtering the solid substance precipitated, then precipitating an alkali metal 1,3,5,7-naphthalenetetracarboxylate from the resulting filtrate, and recovering the alkali metal salt precipitated from the formed slurry.
A process for preparing a 3,7-dialkali 1,3,5,7-naphthalenetetracarboxylate of the formula ##SPC14##
- wherein M is an alkali metal, which comprises bringing a tetraalkali metal 1,3,5,7-naphthalenetetracarboxylate of the formula ##SPC15##
- wherein M is the same as defined above, into contact with a mineral acid in an amount of not more than 2.5 equivalents per mol of the tetraalkali metal 1,3,5,7-carboxylate or an organic acid having a pKa value of not more than 5.4 in an aqueous medium.
A process for preparing a 3,7-dialkali metal 1,3,5,7-naphthalenetetracarboxylate, which comprises reacting 1,3,5,7-naphthalenetetracarboxylic acid or a monoalkali metal salt thereof or a mixture of said acid and said salt with a tetraalkali metal 1,3,5,7-naphthalenetetracarboxylate.
Dependencies are inferred from the claim text.