Clean and efficient preparation method of 1, 6-Cleve's acid and 1, 7-Cleve's acid

Abstract

The invention provides a clean and efficient preparation method of 1, 6-Cleve's acid and 1, 7-Cleve's acid. The method comprises the following steps of: carrying out hydrogenation reduction reaction on an aqueous solution of a mixture of 5-nitro-2-naphthalenesulfonic acid magnesium salt and 8-nitro-2-naphthalenesulfonic acid magnesium salt under the action of a catalyst to obtain an aqueous solution of 5-amino-2-naphthalenesulfonic acid magnesium salt and 8-amino-2-naphthalenesulfonic acid magnesium salt; filtering the reduced mixed solution to remove the catalyst, then concentrating the remaining solution to 40-120g / L, preferably to 60-80g / L, conducting crystallization, and then performing filtering to obtain a filter cake which is 5-amino-2-naphthalenesulfonic acid magnesium salt (1, 6-Cleve's acid magnesium salt) and filtrate which is an 8-amino-2-naphthalenesulfonic acid magnesium salt (1, 7-Cleve's acid magnesium salt) solution; and respectively adding acid into the filtrate and the filter cake to carry out acid precipitation to obtain 1, 6-Cleve's acid and 1, 7-Cleve's acid. According to the preparation method provided by the invention, a large amount of iron mud and heavy metal pollution are avoided, environmental friendliness is realized, no waste is generated, the environmental pollution is reduced, the product yield is improved, and the product yield can reach 85-99%.

Description

technical field [0001] The invention belongs to the field of synthesis of dye intermediates, in particular to a clean and efficient preparation method of 1,6 and 1,7-cliffic acids. Background technique [0002] Cliffic acid includes three different products, 1,6-cliffic acid, 1,7-cliffic acid and mixed ciffic acid, all of which are very important dye intermediates. Among them, 1,6-cliffic acid is used to prepare azo dyes and sulfur dyes, such as the production of direct fast blue BGL, sulfur blue CV, direct fast red RGL, direct black 80, etc.; 1,7-cliffic acid is mainly It is used to prepare direct light fast blue B2R, BGL, gray LBN, brown RTL and sulfide CD, etc.; mixed clevic acid can be used to produce direct black FF, etc. The dyes produced by these products have many varieties, are widely used, have large market demand, and have high economic value. [0003] It is mentioned in "Compendium of Dyestuff Production Process" that the traditional production process of 1,6- ...

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Problems solved by technology

[0005] It can be seen from the above that the reduction reaction in the traditional process is carried out with iron powder under acidic conditions. Although the process is simple, it will produce a large amount of iron sludge containing organic matter and salty wastewater, which not only makes post-processing difficult and high cost , and a large amount of waste has seriously polluted the environment, and the pressure on environmental protection is great

The patent (CN 107602422 A) uses hydrazine hydrate solution instead of iron powder. Although this process avoids the production of iron sludge, but because hydrazine hydrate is a highly toxic chemical, and has carcinogenicity and strong corrosiveness, it is not a kind of Particularly ideal cleaning raw material, the patent also does not separate the mixed Cliff acids

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