Refining process and equipment for batch production of bentazone

Abstract

The invention discloses a refining process for batch production of bentazone. The process comprises the following steps: by using phthalic anhydride as a raw material, carrying out amination, alkalinehydrolysis, oxidation, acidification and amidation to obtain o-benzamide, salifying 2-methylpyridine and sulfur trioxide to obtain 2-methylpyridine sulfonate, and carrying out sulfonation reaction onthe o-aminobenzamide and the 2-methylpyridine sulfonate to obtain the bentazone, and performing cyclization with phosphorus oxychloride to obtain bentazone. According to the bentazone refining process provided by the invention, the raw material utilization rate can be effectively improved, the product purity is improved, the fineness of the bentazone preparation process is improved through the steps of amination, alkaline hydrolysis, oxidation, acidification, amidation, salification, sulfonation, cyclization and the like, impurities in the product are reduced to the maximum extent, the problem of high impurity content in the product prepared by a central one-pot method in the prior art are solved, the yield of bentazone prepared by the method can reach 88.6%, and the purity reaches 99.5%.

Description

technical field [0001] The invention belongs to the technical field of chemical preparation, and in particular relates to a refining process and equipment for batch production of bentazone. Background technique [0002] Bentazon, also known as 3-isopropyl-(1H)-benzo-2,1,3-thiadiazin-4-one-2,2-dioxide, is a product researched and developed by German BASF company in 1968. A selective water and dry field post-emergence herbicide. Because of its strong adaptability to crops, safety and low toxicity, wide herbicidal spectrum, and can be mixed with other herbicides, it has been widely used in soybean fields, corn fields and rice fields in my country to prevent Cyperaceae and broad-leaved weeds. my country's herbicide market occupies an important position. [0003] The existing patent technology center also discloses a variety of methods for synthesizing and preparing bendazone, such as in the German patent DE2105687, it is recorded that anthranilic acid and isopropylsulfonyl chlo...

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Problems solved by technology

[0003] The existing patent technology center also discloses a variety of methods for synthesizing and preparing bendazone, such as in the German patent DE2105687, it is recorded that anthranilic acid and isopropylsulfonyl chloride are reacted, and then the product is obtained by phosgene ring closure. The above-mentioned methods all use the intermediate of isopropylsulfamoyl chloride, which is highly corrosive, unstable, difficult to synthesize, high in boiling point, difficult to purify and analyze quantitatively, and directly affects the bentazone product yield, cost and quality

[0004] Chinese patent CN101863858A discloses a synthetic method of bentazone, first using phthalic anhydride as the main raw material, through amination, degradation and esterification to obtain methyl anthranilate, and then using methyl anthranilate , chlorosulfonic acid, isopropylamine and phosphorus oxychloride are raw materials, and triethylamine is used as an anacid agent, and a one-pot method is used to prepare methyl o-isopropylaminosulfonamidobenzoate, and finally o-isopropylaminosulfonamidobenzoic acid The methyl ester is then subjected to sodium alkoxide cyclization and acidification reaction to synthesize bentazone. In this patent, bentazone is prepared by one-step method, which simplifies the preparation process and shortens the preparation time. However, the disadvantage of the one-pot preparation is that the waste is difficult to separate and recycle. Utilization, on the one hand, resources cannot be fully utilized, on the other hand, there are still serious environmental pollution problems after discharge

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