Process for purification of naphthalenedicarboxylic acid
AssigneeMitsubishi Petrochemical Co., Ltd.
InventorsHiroshi Iwane, Takahiro Sugawara, Miwa Shirasaki
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Abstract
A process for purifying a crude naphthalenedicarboxylic acid containing impurities and coloring substances obtained by the oxidation of a di-substituted naphthalene, dispense with the use of a large amount of alkali or acid, and producing a naphthalenedicarboxylic acid having a high purity and good color effectively and in a high recovery is disclosed, which comprises dissolving the crude naphthalenedicarboxylic acid in a mixed solvent comprising an amine compound and an alcohol and conducting crystallization.
Claims16
A process for producing a naphthalenedicarboxylic acid which comprises dissolving a crude naphthalenedicarboxylic acid in a mixed solvent comprising an amine compound and an alcohol and conducting crystallization, said crude naphthalenedicarboxylic acid being one obtained by the oxidation of a di-substituted naphthalene, wherein the proportion of the amine compound to the alcohol in the mixed solvent is in the range of from 1:99 to 99:1 by weight, and wherein the mixed solvent is used in an amount from 0.5 to 100 times by weight the amount of the crude naphthalenedicarboxylic acid.
A process for producing a high-purity naphthalenedicarboxylic acid which comprises dissolving a crude naphthalenedicarboxylic acid in a mixed solvent comprising an amine compound and an alcohol and then cooling the resulting solution to a temperature lower by at least 30.degree. C. than the temperature at which the crude naphthalenedicarboxylic acid was dissolved in the mixed solvent, thereby to precipitate an amine salt of the naphthalenedicarboxylic acid, wherein the proportion of the amine compound to the alcohol in the mixed solvent is in the range of from 1:99 to 99:1 by weight, and wherein the mixed solvent is used in an amount from 0.5 to 100 times by weight the amount of the crude naphthalenedicarboxylic acid.
A process for producing a high-purity naphthalenedicarboxylic acid which comprises dissolving a crude naphthalenedicarboxylic acid in a mixed solvent comprising an amine compound and an alcohol and then adding an acid to the resulting solution thereby to precipitate the naphthalenedicarboxylic acid.
Dependencies are inferred from the claim text.