Method of synthesizing, purifying and refining 2,6-naphthalene disulfonic acid

Abstract

The invention discloses a method of synthesizing, purifying and refining 2,6-naphthalene disulfonic acid. The method comprises the following steps of 1) sulfonation and solventing-out: heating refinednaphthalene and concentrated sulfuric acid for sulphonation to produce 2,6-naphthalene disulfonic acid and 2,7-naphthalene disulfonic acid, and performing solventing-out with water and filtering to obtain a 2,6-naphthalene disulfonic acid filter cake and a 2,7-naphthalene disulfonic acid mother liquor; 2) washing: by taking ammonia water with the mass percentage being 0.08-0.20 percent or a 0.15-0.28 percent ammonium sulfate aqueous solution as a washing reagent, washing the 2,6-naphthalene disulfonic acid filter cake to obtain a 1-grade 2,6-naphthalene disulfonic acid filter cake and a 1-grade refined filtrate, performing circulation washing on the 2,6-naphthalene disulfonic acid filter cake for 2-4 times at this way to obtain a 2,6-naphthalene disulfonic acid product with the purity larger than 99 percent; and 3) washing solution indiscriminate application: enabling the 1-grade refined filtrate to return for indiscriminate application to a solventing-out procedure in the step 1) and / or a washing procedure in the step 2), and enabling the residual refined filtrate to return for indiscriminate application to the washing procedure in the step 2). The method provided by the invention realizes the purposes of acquiring high-quality 2,6-naphthalene disulfonic acid with separation, refining and purification, increasing the yield of 2,7-naphthalene disulfonic acid and lowering wastewater discharge.

Description

(1) Technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a method for synthesizing and purifying 2,6-naphthalene disulfonic acid. (2) Background technology [0002] 2,6-Naphthalene disulfonic acid is an important chemical intermediate, mainly used in dyes, pharmaceuticals and concrete additives. For example, it synthesizes 2,6-naphthalene disulfonic acid dihydroxynaphthalene through alkali fusion. This product has high added value and broad market prospects. It has a wide range of applications in the fields of fibers, packaging containers, electronic components, dyes and medicines, especially It is an important monomer for preparing various polyester materials and liquid crystal polyester resins. As another example, by controlling the reaction conditions, partial alkali fusion can be carried out to form Scher's salt, which is a raw material mainly used for the manufacture of dyes such as acid blue, acid bordeaux, edibl...

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Problems solved by technology

[0003] At present, the preparation method of 2,6-naphthalene disulfonic acid is mainly a series of operations such as heating reaction of naphthalene and concentrated sulfuric acid, adding water and p-phenylenediamine to precipitate it to obtain a solid, further drying, grinding, filtering, washing and recrystallization Finally, the finished product of 2,6-naphthalene disulfonic acid is obtained, but the production process of this method is more complicated

Patent CN101412685A discloses the method of using sodium chloride to crystallize 2,6-naphthalene disulfonic acid, but sodium chloride has higher requirements on the use of process equipment; patent CN101412686A discloses the method of using sodium sulfate to refine 2,6-naphthalene disulfonic acid , but the solubility of sodium sulfate is low at room temperature; and the solid purity of 2,6-naphthalene disulfonic acid in the above-mentioned technology is about 90% (liquid chromatography purity), all can not reach the requirement of high-quality products, and all in the above-mentioned technology Use a large amount of inorganic salts for salting-out refining, resulting in a large amount of wastewater that is difficult to treat

[0004] Shenyang Research Institute of Chemical Industry proposed that naphthalene and concentrated sulfuric acid / 20% fuming acid / 65% nicotinic acid can generate 2,6-naphthalene disulfonic acid and 2,7-naphthalene disulfonic acid under certain conditions. Obtain 2,6-naphthalene disulfonic acid-based filter cake and 2,7-naphthalene disulfonic acid-based mother liquor, wherein 2,7-naphthalene disulfonic acid can be used to prepare important dye intermediate H acid, but the obtained The filter cake 2,6-naphthalene disulfonic acid has low purity and more impurities, and the main residue is 2,7-naphthalene disulfonic acid, which is not conducive to the development of subsequent products

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