Method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid

Abstract

The invention provides a novel method for synthesizing 2-nitro-4-methylsulfonylbenzoic acid. Paratoluensulfonyl chloride is taken as a starting material, and the 2-nitro-4-methylsulfonylbenzoic acid is obtained at a high yield through the steps of methylation, halogenation, nitration and oxidation respectively. The synthesizing route is as follows: the method has the advantages that the problems of industrial three-waste pollution, high production cost, heavy metal pollution, complex operation and the like in a conventional process are solved; and the method has the characteristics of high yield and product purity, cleanness, safety, low production cost and capability of being popularized to large-scale industrial production, and has great importance in clean production.

Description

technical field [0001] The invention belongs to the field of organic synthesis, in particular to a new synthesis method of 2-nitro-4-thiamphenicol benzoic acid. Background technique [0002] 2-Nitro-4-thiamphenicol benzoic acid, referred to as NMSBA, is an important intermediate widely used in medicine and pesticides, especially in the synthesis of mesotrione. Its structural formula is as follows: [0003] [0004] Mesotrione (also known as mesotrione) is a systemic, selective, pre-emergence or post-emergence herbicide developed by Swiss Syngenta in the mid-1970s. , high activity, strong miscibility, low toxicity, environmental friendliness, safety to subsequent crops, and flexible use have achieved considerable success abroad, while the domestic synthesis process is still immature. In addition, mesotrione The administrative protection period in China expired in August 2012. Its excellent effect of controlling weeds in cornfields and rich economic benefits has attracted th...

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Problems solved by technology

[0007] This synthetic method is widely seen in domestic and foreign patents, but this synthetic method has many problems for industrial production

For example: U.S. Patent US5591890 introduces the air oxidation method under the catalysis of cobalt salt, but this method has the pollution problem of metal wastewater, and the production efficiency is low, and the yield is only about 70%.

U.S. Patent No. 5,424,481 introduces the nitric acid oxidation method using vanadium pentoxide as a catalyst. This method is commonly used in industrial production at present, but there is serious nitrogen oxide pollution in this method, and it is difficult to treat the waste acid solution and highly toxic chemicals. Problems such as the use of vanadium pentoxide lead to a large amount of industrial waste and dangerous operation

The world patent WO2004058698 reports an oxidation method using hydrogen peroxide. In this method, the amount of hydrogen peroxide is nearly 30 times that of raw materials, and the amount of sulfuric acid is nearly 20 times that of raw materials. This results in large waste water, low production efficiency, and high production costs. The problem

The world patent WO2007099450 reports the method of using hydrogen peroxide under the catalysis of metal vanadium salt and metal cerium salt as an oxidizing agent. Although the amount of hydrogen peroxide is effectively reduced, in addition to the pollution of metal salt wastewater, its yield is also greatly reduced, only 40%. about

In addition, regarding the synthesis of 2-nitro-4-thiamphenicol benzoic acid, there are also a large number of reports in Chinese patents, such as the ozone-nitric acid oxidation method under the catalysis of vanadium pentoxide reported in Chinese patent CN101177369. This method still cannot avoid acidity Wastewater and nitrogen oxides three wastes pollution and other issues

Chinese patent CN101503383 has introduced the use of fuming sulfuric acid and hydrogen peroxide to make persulfuric acid as an oxidizing agent. Although the oxidation efficiency of hydrogen peroxide has been improved to a certain extent, the pollution problem of waste acid still exists when 70% of sulfuric acid is used mechanically as a solvent. The preparation increases the complexity of its operation, the production cost is high, and the purity is low

The nitric acid oxidation method reported in Chinese patent CN101921215, the generation of a large amount of waste acid water, the use of potassium dichromate and potassium permanganate, etc., bring more serious pollution problems. Chinese patent CN102584650 introduces CuO / Al 2 o 3 The carrier-catalyzed hydrogen peroxide oxidation method, in which the preparation of the catalyst undoubtedly increases its production cost, and the yield of this method can only reach about 79% after deducting the recovered raw materials, and the production efficiency is low

Analyzing various methods, we found that there are some problems in them, such as: using nitric acid as an oxidizing reagent, the reaction is violent, prone to side reactions, and a large amount of nitrogen oxides are produced, which seriously pollutes the air; using sulfuric acid as a reaction medium, a large amount of acidic wastewater The production of heavy metal salts will seriously pollute the environment; the use of a large number of catalysts will easily cause re-pollution; the use of heavy metal salts, the production of heavy metal waste liquid will pollute the environment; complex operations and other disadvantages

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