Method for reducing distillation residues of 5-acetylacetamidobenzimidazolone mother liquor

Abstract

The invention relates to a method for reducing distillation residues of 5-acetylacetamidobenzimidazolone mother liquor. The method comprises the following steps: with water as a solvent, adding mercaptoacetic acid, 5-aminobenzimidazolone and activated carbon, carrying out mixing, performing stirring for a certain time at a certain temperature, and conducting filtering to obtain a 5-aminobenzimidazolone filtrate; and dropwise adding diketene into the 5-aminobenzimidazolone filtrate at a certain temperature, keeping the temperature for a certain period of time to obtain 5-acetylacetamidobenzimidazolone, and distilling mother liquor for reuse. According to the invention, an organic acid solvent is used for replacing sodium hydrogen sulfite and phosphoric acid, so inorganic salt and phosphorus-containing substances in wastewater can be reduced; mercaptoacetic acid in the wastewater can be extracted by using the organic solvent and is recycled, so cost is reduced; and since the wastewater is subjected to MVR treatment and distillation before reuse, and the waste residue amount of the distilled wastewater is greatly reduced. The purity of an obtained product is greater than or equal to 99%, the yield of the product is greater than or equal to 80%, and the amount of acylation mother liquor distillation residues is reduced by about 30%, so quality and yield are ensured, environmental protection investment is reduced, and the purposes of energy conservation and emission reduction are achieved.

Description

technical field [0001] The invention belongs to the technical field of fine chemical technology, and in particular relates to a method for reducing distillation residue of 5-acetoacetamidobenzimidazolone mother liquor. Background technique [0002] 5-Acetoacetamidobenzimidazolone (AABI) is an important chemical intermediate, and its series of products are widely used in the fields of medicine, pesticides, special materials, etc., and the benzimidazole prepared by using it as a coupling component Ketone organic pigments have excellent properties such as heat resistance, light resistance, weather resistance, and solvent resistance, making them a huge market demand. However, the domestic production level of 5-acetoacetamidobenzimidazolone is not high, so this product has a good market prospect. [0003] The existing preparation method mainly uses 5-aminobenzimidazolone and diketene as raw materials to undergo acylation reaction to prepare 5-acetoacetamidobenzimidazolone. 5-am...

AI Technical Summary

Problems solved by technology

Chinese patent CN101307023A discloses a method for preparing 5-acetoacetamidobenzimidazolone with 5-aminobenzimidazolone and diketene, phosphoric acid, sodium bisulfite, and water. The 5-acetoacetamidobenzone Although the product purity of imidazolone is relatively high, the total yield is only 75%, and there is still a lot of room for improvement. The addition of concentrated phosphoric acid and sodium bisulfite produces a large amount of wastewater containing phosphorus and inorganic salts in the production process. Acylation of posts produces a large amount of wastewater every year, and the MVR wastewater treatment process produces a large amount of distillation residues every year. The problem of difficult and large volume of waste residues is becoming more and more obvious. The later stage of environmental protection treatment costs a lot, which is not conducive to the promotion of the concept of green chemistry; therefore, the solution to the existing synthetic The problems in the process of 5-acetoacetamidobenzimidazolone are very important for protecting the environment and reducing production costs