Preparation process for synthesizing 2,6-dihydroxynaphthalene

Abstract

The invention discloses a preparation process for synthesizing 2,6-dihydroxynaphthalene. The preparation process comprises specific steps as follows: (1) in an autoclave, adding 33-34 parts of 2,6-naphthalenedisulfonic acid disodium salt, 12-18 parts of sodium hydroxide and 50-52 parts of water, performing stirring and heating to 280-320 DEG C, and performing stirring for reaction at the temperature for 8-10 hours; (2) stirring the solution obtained after the reaction in the step (1) and cooling the solution to the room temperature, adding sulfuric acid with concentration of 40%-60%, and performing neutralization reaction until PH being 0.5-2; (3) filtering a suspension from the step (2), transferring filtered solids to a container, adding 150-152 parts of hexane, 0.1-0.15 parts of a copper salt catalyst and 1-1.5 parts of a phase transfer catalyst, performing stirring and heating to 30-60 DEG C, adding 12-50 parts of an oxidant with concentration of 20%-30%, and continuing reaction at30-70 DEG C for 2-4 hours to obtain a 2,6-dihydroxynaphthalene solution. The preparation process has the advantages that salt-containing wastewater is reduced, dosage of sodium hydroxide and potassium hydroxide is reduced, and the yield is significantly increased.

Description

technical field [0001] The invention belongs to the field of fine chemicals, and relates to a preparation process for synthesizing hydroxynaphthalene, in particular to a preparation process for synthesizing 2,6-dihydroxynaphthalene. Background technique [0002] 2,6-Dihydroxynaphthalene (CAS No.: 581-43-1) is widely used as dyes, pharmaceutical intermediates, analytical reagents, etc. At present, the method for industrially synthesizing 2,6-dihydroxynaphthalene is: use sodium 2,6-naphthalene disulfonate as a raw material, and the mixed reagent of sodium hydroxide and potassium hydroxide is an alkali-melting solvent, and carry out alkali-melting at high temperature. The 2,6-dihydroxynaphthalene was then acidified with concentrated sulfuric acid. The main problems in the existing process include: (1) a large excess of sodium hydroxide and potassium hydroxide needs to be used, and the molar amount of sodium hydroxide and potassium hydroxide usually used is more than 20 times t...

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Problems solved by technology

The main problems in the existing process include: (1) a large excess of sodium hydroxide and potassium hydroxide needs to be used, and the molar amount of sodium hydroxide and potassium hydroxide usually used is more than 20 times the molar amount of the substrate; (2) Neutralization of excess sodium hydroxide and potassium hydroxide requires the consumption of a large amount of sulfuric acid or hydrochloric acid, and generates a large amount of saline wastewater. The wastewater treatment cost is high; (3) The temperature of high-temperature alkali fusion is often above 350°C. Due to the severe reaction conditions, the process A large amount of tar will be produced as a by-product, and the yield of 2,6-dihydroxynaphthalene is very low

Patent CN201510185004.6 reports a method of using sodium 2,6-naphthalene disulfonate as a raw material, solid sodium hydroxide and nitrate mixture as an alkali fusion system for alkali fusion, and this method can also reduce sodium hydroxide and The use of potassium hydroxide, but with the addition of a large amount of nitrate and nitrite, these added salts will eventually form saline wastewater that is difficult to treat

Patents EP0479292 and JPH04338346 respectively report the use of potassium hydroxide as an alkali fusion reagent, under the auxiliary action of surfactant sodium oleate or sodium tetradecene sulfonate, and organic solvent hydrogenated terphenyl or aliphatic ring mixed oil Alkali fusion reaction, similarly, there are huge problems in the stability and use safety of surfactants and corresponding organic solvents at a reaction temperature of 330°C

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