Method for preparing 1-amino-4-naphthalene sulfonic acid sodium salt

Abstract

The invention discloses a method for preparing 1-amino-4-naphthalene sulfonic acid sodium salt. The method includes the steps that (1) a reduction sulfonization reaction is conducted, specifically, water, an organic solvent, 1-nitronaphthalene and a reduction sulfonization reagent are sequentially added into a reactor, the temperature is increased to 108-114 DEG C for a backflow reaction, and thereaction is conducted for 6-9 h to the reaction endpoint; (2) cooling desalting is conducted, specifically, a material obtained in the step (1) is cooled to 0-10 DEG C, an inorganic salt is precipitated, then suction filtration or filter pressing is conducted, and filter liquor I is collected; (3) material acidizing is conducted, specifically, the filter liquor I collected in the step (2) is addedinto the reactor, sulfuric acid is added to adjust the pH of the filter liquor to be 1-2, the temperature is increased to 50-60 DEG C, then suction filtration or filter pressing is conducted, a filter cake 2 and filter liquor 2 are collected; (4) alkaline-adding neutralization is conducted, specifically, bottom water is added into the reactor, then the filter cake 2 collected in the step (3) is added, the temperature is increased to 20-50 DEG C, and inorganic base is added to adjust the pH of a solution to be 7-8, so that the filter cake is completely dissolved; and (5) concentration crystallization is conducted, and thus a target product, namely 1-amino-4-naphthalene sulfonic acid sodium salt, is obtained. The method has the characteristics of simple production process, low energy consumption, less waste water, high product selectivity and high purity.

Description

technical field [0001] The invention relates to a production method of a chemical dye intermediate, in particular to a production method of sodium 1-amino-4-naphthalenesulfonate. Background technique [0002] Sodium 1-amino-4-naphthalenesulfonate (sodium 1,4-acid for short) is widely used in chemical industry, medical treatment, dyestuff and other fields. At present, its main production process is the traditional solid-phase sulfonation method and solvent sulfonation method. Regardless of the solid-phase sulfonation method or the solvent sulfonation method, the source 1-nitronaphthalene is generally hydrogenated and reduced to obtain 1-naphthylamine, and 1-naphthylamine is then subjected to high-temperature transposition sulfonation to obtain sodium 1,4 acid. The synthetic route is relatively complicated. Among them, 1-naphthylamine belongs to Class 3 carcinogens and has certain carcinogenicity; and in the process of synthesizing 1-naphthylamine by high-pressure hydrogenati...

AI Technical Summary

Problems solved by technology

[0006] For the current traditional solid-phase sulfonation and solvent sulfonation methods to prepare sodium 1,4-acid, the process route is cumbersome, there are potential safety hazards in the preparation of intermediate products, a large amount of waste water is produced during the production process, and the intermediate products are strongly carcinogenic , high sulfonation reaction temperature, high energy consumption, easy carbonization of the product, easy loss of solvent and difficult recovery, etc., the present invention provides a kind of 1-nitronaphthalene and reducing sulfonating agent through the reduction sulfonation reaction of 1-nitronaphthalene and reducing sulfonating agent. The method of sodium 1-amino-4-naphthalenesulfonate, the method has simple production process, low energy consumption, less waste water, higher product selectivity and purity

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