Continuous production method of high-purity acetylacetone

Abstract

The invention discloses a continuous production method of high-purity acetylacetone, carries out azeotropic distillation with salt water to separate coarse acetylacetone liquid containing acetic acid, acetic anhydride and high-boiling product, and in such a way to continuously produce high-purity acetylacetone. The steps are as follows: in a deacidifying and deanhydriding tower T1, azeotropic mixture formed by acetylacetone and water are steamed out from the tower top, are misphased in a phase splitter S1; the water layer flows back, and the oil layer flows through the deanhydriding tower T1 and a treating column T3, thus obtaining high purity acetylacetone; the water containing cyclamate at the column bottom of the deacidifying and deanhydriding tower T1 is discharged into soda solution and a reactor R1, with the pH value of the mixture solution of 5 to 8; after flowing through a salt separator S2, the salt water with low concentration is poured into the deacidifying and deanhydriding tower T1 from the tower top; after simple recrystallization, the acetate is separated from the salt separator S2, thus obtaining high purity acetate of the byproduct. The continuous production method of high-purity acetylacetone has the advantages of continuous and steady production, little consumption, good separation effect of acetic anhydride from high-boiling products; in addition, the product purity reaches to 99.9 percent, waste water discharging is beneficial for environmental protection and the invention can be used for producing acetate byproducts.

Description

technical field [0001] The invention belongs to the technical field of chemical separation, and in particular relates to a method for continuously producing high-purity acetylacetone from a crude acetylacetone solution. Background technique [0002] Acetylacetone is an important chemical and pharmaceutical intermediate, which can be used to synthesize sulfonamide drugs, feed additives and catalysts, etc. With the development of society, the purity requirements for acetylacetone are getting higher and higher, and the purity requirement of superior products reaches 99.9%. , which also puts forward higher requirements for the continuous distillation process of acetylacetone. The crude acetylacetone solution obtained by the isomerization of isopropenyl acetate method also contains acetic acid, acetic anhydride and a small amount of high boilers. These impurities are close to the boiling point of acetylacetone. At present, there is no satisfactory method to The above-mentioned i...

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Problems solved by technology

[0003] British patent GB1354180 adopts the method of fractional distillation, changes the degree of vacuum, and extracts acetic acid, acetic anhydride and acetylacetone step by step. This method not only cannot realize continuous production, but also because the boiling points are close, acetic acid and acetic anhydride are not easy to separate, and the purity of acetylacetone products is not high. High; GB795843 adopts the method of passing crude acetylacetone into 3mol / LNH3 solution to remove acetic acid and acetic anhydride. Since acetylacetone has a certain solubility in water, the solubility at 30°C is 15%, and the solubility at 80°C is 34%. A large amount of acetylacetone will flow away with the waste water, and the product loss will be large; Japanese patent JP1056640 uses a small amount of water to react to remove acetic anhydride, and then water and acetic acid are extracted from the top of the tower as low boiling substances, because water and acetic anhydride react slowly at room temperature , especially a small amount of water is difficult to completely react acetic anhydride, and it is also difficult to separate acetic acid and acetylacetone, and acetylacetone cannot meet the requirements of high purity; The boiling agent separates acetylacetone. This method can completely convert acetic anhydride into acetic acid, and can effectively remove acetic acid when the content of acetic acid is low. However, a large amount of waste water is generated during the production process, and a large amount of acetylacetone is dissolved in the high-temperature waste water at the bottom of the tower kettle. , leading to product loss, which does not meet environmental protection requirements; and in the case of relatively large acetic acid and acetic anhydride content, the removal efficiency of acetic acid decreases, and acetic acid enters the final product, affecting the purity of the final product acetylacetone

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