Method of improving content of 2-hydroxy-3-naphthoic acid produced in gas-solid phase method

Abstract

The invention discloses a method of improving content of 2-hydroxy-3-naphthoic acid produced in a gas-solid phase method; the method comprises the steps: performing a salt forming reaction to concentrated alkaline and 2-naphthol, performing a carboxylation reaction with carbon dioxide and then obtaining the finished 2-hydroxy-3-naphthoic acid after a series of steps of resin separation, neutralization reaction, cooling and filter pressing, resin absorption, acidification reaction and centrifugal drying. A resin absorption procedure is added between the filter pressing procedure and the acidification procedure, so that the residual 2-naphthol in the filtrate after the filter pressing can be removed and the content of 2-hydroxy-3-naphthoic acid is greatly increased; meanwhile, the concentrated solution produced after the desorption of absorbed saturated resin is recovered, the 2-naphthol and the 2-hydroxy-3-naphthoic acid are obtained and the recovery of the 2-naphthol is realized; meanwhile, the source consumption is reduced. The method is simple, is simple and convenient in operation, good in stability and high reliability.

Description

technical field [0001] The invention relates to a production method of organic chemical products, in particular to a method for increasing the content of 2-hydroxy-3-naphthoic acid produced by a gas-solid phase method. Background technique [0002] 2-Hydroxy-3-naphthoic acid is widely used as an important intermediate of dyes, organic pigments and medicines. 2-Hydroxy-3-naphthoic acid is the raw material of organic pigments and ice-dyed phenol. 2-Hydroxy-3-naphthoic acid also has the function of stabilizing vitamin B in medicine. In the synthetic fiber industry, 2-hydroxy-3-naphthoic acid can be condensed with formaldehyde to obtain bis 2-hydroxy-3-naphthoic acid, which is the raw material for the preparation of polyester fibers and polyamide fibers. [0003] Industrially, 2-hydroxy-3-naphthoic acid is produced by Kolbe-schmitt reaction, that is, 2-naphthol sodium salt and titanium dioxide undergo electrophilic substitution to generate 2,3-acid disodium salt, and then neutr...

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Problems solved by technology

At present, the synthesis process is mainly divided into solid-phase method and solvent method. Although the two methods have their own advantages, the 2-hydroxy-3-naphthoic acid produced generally has a common problem: 2-hydroxy-3-naphthoic acid Naphthoic acid products are unstable in quality, dark in color, small in size and low in content, which affects its export competitiveness

Because 2-naphthol has a certain solubility in water, there will be a certain amount of 2-naphthol in the mother liquor of 2-hydroxyl-3-naphthoic acid, after adding acid in the acid precipitation process, with the increase of acid value, 2- The solubility of naphthol will also reduce and separate out, so inevitably contain a small amount of 2-naphthol in 2-hydroxyl-3-naphthoic acid, thereby affecting the purity of 2-hydroxyl-3-naphthoic acid, limiting 2- Demand for hydroxy-3-naphthoic acid in high-end industries

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