Preparation method for 5-acetoacetamidobenzimidazolone

Abstract

The invention discloses a preparation method for 5-acetoacetamidobenzimidazolone. The preparation method comprises the following steps: with water as a solvent, adding 5-aminobenzimidazolone, a sodiumhydrosulfide solution and active carbon into the water, carrying out mixing, carrying out a reaction at a certain temperature for a certain period of time, and carrying out filtering so as to obtainan intermediate filtrate; and dropwise adding diketene into the intermediate filtrate at a certain temperature, keeping the temperature for a certain period of time, and carrying out cooling, filtering and drying so as to obtain the 5-acetoacetamidobenzimidazolone. According to the invention, by adoption of the sodium hydrosulfide solution, dissolution of the 5-aminobenzimidazolone can be accelerated, and oxidation of the 5-aminobenzimidazolone can be prevented; H2S gas generated by hydrolyzing of the sodium hydrosulfide at a high temperature can generate the sodium hydrosulfide solution afterbeing absorbed by the sodium hydroxide solution, so the H2S can be recycled, and emission of waste gas is avoided; the water is used as the solvent, so the cost of alcohol used as the solvent is reduced, the potential safety hazard during product drying is avoided, and the reaction time is short. The preparation method provided by the invention has the following advantages: a product purity is larger than or equal to 99.2%; the yield of the product is larger than or equal to 85%; the quality is guaranteed; and the yield is improved.

Description

technical field [0001] The invention belongs to the technical field of fine chemical technology, and in particular relates to a preparation method of 5-acetoacetamidobenzimidazolone. 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-aminobenzimidazolone is an important r...

AI Technical Summary

Problems solved by technology

5-aminobenzimidazolone is an important raw material, the amino group is easily oxidized, and its solubility in water is low. Therefore, most of the existing processes are to dissolve 5-aminobenzimidazolone under acidic conditions in alcohol solvents, and at the same time add antioxidants to avoid the formation of amino groups. oxidation

Chinese patent CN101307023A discloses a method for preparing 5-acetoacetamidobenzimidazolone with 5-aminobenzimidazolone and diketene, phosphoric acid, liquid caustic soda, and water. The 5-acetoacetamidobenzimidazolone produced by the process Although the product has high purity, the total yield is only 75%, and there is still a lot of room for improvement. The addition of concentrated phosphoric acid produces a large amount of phosphorus-containing wastewater in the production process, which increases the cost of environmental protection in the later stage, which is not conducive to the concept of green chemistry. Therefore, solving the problems existing in the existing synthetic 5-acetoacetamido benzimidazolone process is of great significance for protecting the environment and reducing production costs