阅读说明：本技术 一种2-硝基-4-甲砜基苯甲酸的制备方法 (Preparation method of 2-nitro-4-methylsulfonylbenzoic acid ) 是由 陈宝明 韦自强 孔禄 张磊 刘华珍 姚金莉 王海洋 殷平 殷凤山 于 2020-07-09 设计创作，主要内容包括：一种2-硝基-4-甲砜基苯甲酸的制备方法,以硝酸氧化方案为基础,将对甲砜基甲苯溶于氯代烷溶剂中,将硝酸滴加至质量分数为80～90wt％的硫酸中,将对甲砜基甲苯的氯代烷溶液和混酸溶液同时、持续地加入反应体系,进行硝化反应,将硝化反应的料液经过处理后,实现硫酸的多次套用,既可套用至硝化反应,又能套用于氧化反应,氧化反应中的硫酸又可多次套用,2-硝基-4-甲砜基苯甲酸总摩尔收率可达到90％以上,含量为99％以上。利用本发明,可使2-硝基-4-甲砜基苯甲酸生产中的废酸量减少90％以上,五氧化二钒的用量减少90％以上,极大减少了三废产生,工艺安全环保,三废量小,适用于工业化大生产。(A preparation method of 2-nitro-4-methylsulfonylbenzoic acid is based on a nitric acid oxidation scheme, p-methylsulfonyltoluene is dissolved in a chloroalkane solvent, nitric acid is dropwise added into sulfuric acid with the mass fraction of 80-90 wt%, the chloroalkane solution and mixed acid solution of the p-methylsulfonyltoluene are simultaneously and continuously added into a reaction system for nitration reaction, the feed liquid of the nitration reaction is treated, multiple reuse of the sulfuric acid is realized, the sulfuric acid can be reused for both nitration reaction and oxidation reaction, the sulfuric acid in the oxidation reaction can be reused for multiple times, the total molar yield of the 2-nitro-4-methylsulfonylbenzoic acid can reach more than 90%, and the content is more than 99%. The method can reduce the amount of waste acid in the production of 2-nitro-4-methylsulfonylbenzoic acid by more than 90 percent, reduce the amount of vanadium pentoxide by more than 90 percent, greatly reduce the generation of three wastes, has safe and environment-friendly process and small amount of three wastes, and is suitable for industrial mass production.)

1. A preparation method of 2-nitro-4-methylsulfonylbenzoic acid comprises the following steps:

1) nitration reaction

Dissolving p-methylsulfonyl toluene in a chloroalkane solvent for later use; dropwise adding nitric acid into sulfuric acid with the mass fraction of 80-90 wt% to obtain a mixed acid solution for later use;

simultaneously and continuously adding the chloroalkane solution and the mixed acid solution of the p-methylsulfonyltoluene into a reaction system for nitration reaction, and controlling the adding amount of the two solutions simultaneously entering the reaction system to keep the reaction temperature at 10-30 ℃;

standing after the reaction is finished, reacting and discharging, layering feed liquid, separating liquid, and mechanically applying the separated lower sulfuric acid liquid to the subsequent nitration reaction of the methylsulfonyl toluene; adding water into the separated upper layer organic phase, heating and azeotropically evaporating a chloroalkane solvent, separating out a white solid, and filtering to obtain a wet 2-nitro-4-methylsulfonyl toluene product;

2) oxidation reaction

Adding the 2-nitro-4-methylsulfonyl toluene obtained in the step 1) into a sulfuric acid solution with the mass fraction of 60-70 wt%, adding a vanadium pentoxide catalyst, heating to 135-160 ℃, dropwise adding nitric acid, and carrying out an oxidation reaction;

and after the reaction is finished, cooling, filtering, pulping and washing a filter cake by using hot water at the temperature of 70-100 ℃, cooling to room temperature, and filtering to obtain a 2-nitro-4-methylsulfonylbenzoic acid product.

2. The method of producing 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein the nitration reaction of step 1) is a continuous reaction.

3. The process for producing 2-nitro-4-methylsulfonylbenzoic acid according to claim 2, wherein the continuous reaction is carried out in a tubular reactor.

4. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein the sulfuric acid separated from the nitration reaction in step 1) is reused, the final waste sulfuric acid is subjected to negative pressure distillation to remove the residual chloroalkane solvent, and water is added to dilute the waste sulfuric acid to a sulfuric acid solution with a mass fraction of 60-70 wt%.

5. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein in step 2), the sulfuric acid solution with the mass fraction of 60-70 wt% is obtained by treating the reaction solution in step 1).

6. The preparation method of 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein in the step 2), the filtrates after the reaction are combined, concentrated to a sulfuric acid solution with a mass fraction of 60-70 wt%, and applied to the subsequent oxidation reaction of 2-nitro-4-methylsulfonyltoluene.

7. The preparation method of 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein in step 2), after concentrating to 60-70 wt% sulfuric acid solution, potassium hydroxide is added to the finally produced waste sulfuric acid to adjust the pH value to be neutral, potassium chlorate is added, stirring is performed at 70-80 ℃ to react, then ammonium sulfate is added to the reaction product at room temperature to react, ammonium vanadate solid is removed by filtration, the filtrate is concentrated to crystallize, filtered and dried to obtain a byproduct potassium sulfate salt, and the ammonium metavanadate solid obtained by filtration is burned to remove ammonia to obtain vanadium pentoxide which is reused for oxidation reaction.

8. The preparation method of 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein in step 1), the molar ratio of the amount of nitric acid used in the nitration reaction to p-methylsulfonyltoluene is 1-1.5: 1, the molar ratio of sulfuric acid to p-methylsulfonyltoluene is 4-8: the weight ratio of the chloroalkane solvent to the p-methylsulfonyltoluene is chloroalkane: 5-10% of p-methylsulfonyl toluene: 1.

9. the method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein in step 2), the molar ratio of the materials is: nitric acid: sulfuric acid: catalyst: 3-8% of p-methylsulfonyl toluene: 4-8: 0.01-0.05: 1, when pulping and washing, the using amount of hot water is 1-3 times of the weight of p-methylsulfonyl toluene.

10. The method for producing 2-nitro-4-methylsulfonylbenzoic acid according to any one of claims 1 to 9, wherein the chlorinated alkane solvent in step 1) is one of dichloromethane, trichloromethane and dichloroethane.

Technical Field

The invention belongs to the field of herbicide intermediate preparation, and particularly relates to a preparation method of 2-nitro-4-methylsulfonylbenzoic acid.

Background

The p-hydroxyphenylpyruvate dioxygenase (HPPD) is a key enzyme in a plastoquinone and tocopherol biosynthesis pathway necessary for the normal growth of plants, can catalyze the biochemical process from tyrosine to plastoquinone in plants, and is one of the most important herbicide action targets at present.

Mesotrione can inhibit hydroxyphenylpyruvate dioxygenase (HPPD), finally influences the biosynthesis of carotenoid, is a broad-spectrum, systemic, selective and contact herbicide, is mainly absorbed by leaf surfaces and roots, conducted to the top and the base in xylem and phloem and distributed in the whole plant, and the selectivity of mesotrione is derived from different metabolic actions in crops and weeds, the mesotrione is metabolized to be 4-hydroxy derivatives in the crops, or the crop can absorb the leaf surfaces of the mesotrione slower than the weeds, and the leaf surfaces of the weeds are whitened after the herbicide is applied, so that meristematic tissue necrosis is caused.

Mesotrione is mainly used for corn, and can also be used for lawn, sugarcane, rice, onion, sorghum, other small crops and the like, has the characteristics of high efficiency, low toxicity, safety for corn crops, environmental ecological safety and the like, accords with the current development trend, and is more and more widely concerned and valued.

The main synthetic route of mesotrione is prepared by using 2-nitro-4-methylsulfonylbenzoic acid as a starting raw material through acyl chlorination, esterification and rearrangement reactions, and the reaction principle is as follows:

thus, 2-nitro-4-methylsulfonylbenzoic acid is a key intermediate for its preparation of mesotrione, and currently, there are three major preparation schemes for 2-nitro-4-methylsulfonylbenzoic acid.

The first scheme is as follows:

the research on the synthesis of 2-nitro-4-methylsulfonylbenzoic acid by a sodium dichromate oxidation method, namely a fine chemical intermediate, 6.2005, volume 35, stage 3, 50-56, uses p-methylsulfonyltoluene as a raw material, firstly performs a mixed acid nitration reaction, performs post-treatment to prepare 2-nitro-4-methylsulfonyltoluene, and then performs oxidation by sodium dichromate or potassium permanganate to prepare 2-nitro-4-methylsulfonylbenzoic acid.

Scheme II:

taking p-methylsulfonyl toluene as a raw material, firstly carrying out mixed acid nitration reaction, carrying out aftertreatment to obtain 2-nitro-4-methylsulfonyl toluene, and then carrying out oxidation by using oxygen or air, wherein U.S. Pat. No. 5,5591890 reports that cobalt acetate is used as a catalyst, and air is used as an oxidant to be oxidized in acetic acid; the Chinese patent application CN201110288563 takes metalloporphyrin as a catalyst to prepare 2-nitro-4-methylsulfonylbenzoic acid through oxidation, but the oxidation of air or oxygen has the problems of low oxidation capacity, high-pressure reaction, poor final oxidation effect, low yield, corrosion resistance of equipment and the like.

The third scheme is as follows:

chinese patent application CN201510133705 reports a nitric acid oxidation scheme, wherein p-methylsulfonyl toluene is used as a raw material, mixed acid is firstly subjected to nitration reaction, water is directly added after the nitration reaction is finished to perform oxidation reaction, nitric acid is used as an oxidant, and vanadium pentoxide is used as a catalyst.

In summary, in the existing synthesis method of 2-nitro-4-methylsulfonylbenzoic acid, the process for preparing 2-nitro-4-methylsulfonylbenzoic acid by oxidizing 2-nitro-4-methylsulfonyltoluene generally has the defects of large amount of three wastes, poor selectivity, high production cost and the like.

Disclosure of Invention

The invention aims to provide a preparation method of 2-nitro-4-methylsulfonylbenzoic acid, which solves the problems of large three-waste amount, poor selectivity, high production cost and the like in the preparation process of the intermediate 2-nitro-4-methylsulfonylbenzoic acid, and develops a green, environment-friendly and safe preparation scheme on the basis of a nitric acid oxidation scheme, so that the reuse of waste acid and solvent in two-step reaction is realized, the generated waste acid can be reduced by more than 90% after repeated reuse, the reaction safety is improved, the process is safe and environment-friendly, the three-waste amount is small, and the preparation method is suitable for industrial production.

In order to achieve the purpose, the invention provides the following technical scheme:

a preparation method of 2-nitro-4-methylsulfonylbenzoic acid comprises the following steps:

1) nitration reaction

Dissolving p-methylsulfonyl toluene in a chloroalkane solvent for later use; dropwise adding nitric acid into sulfuric acid with the mass fraction of 80-90 wt% to obtain a mixed acid solution for later use;

simultaneously and continuously adding the chloroalkane solution and the mixed acid solution of the p-methylsulfonyltoluene into a reaction system for nitration reaction, and controlling the adding amount of the two solutions simultaneously entering the reaction system to keep the reaction temperature at 10-30 ℃;

standing after the reaction is finished, reacting and discharging, layering feed liquid, separating liquid, and mechanically applying the separated lower sulfuric acid liquid to the subsequent nitration reaction of the methylsulfonyl toluene; adding water into the separated upper layer organic phase, heating and azeotropically evaporating a chloroalkane solvent, separating out a white solid, and filtering to obtain a wet 2-nitro-4-methylsulfonyl toluene product;

2) oxidation reaction

Adding the 2-nitro-4-methylsulfonyl toluene obtained in the step 1) into a sulfuric acid solution with the mass fraction of 60-70 wt%, adding a vanadium pentoxide catalyst, heating to 135-160 ℃, dropwise adding nitric acid, and carrying out an oxidation reaction;

and after the reaction is finished, cooling, filtering, pulping and washing a filter cake by using hot water at the temperature of 70-100 ℃, cooling to room temperature, and filtering to obtain a 2-nitro-4-methylsulfonylbenzoic acid product.

Further, the nitration reaction of step 1) is a continuous reaction.

Preferably, the continuous reaction is carried out in a tubular reactor.

Further, after the sulfuric acid separated by the nitration reaction in the step 1) is reused, the final waste sulfuric acid is subjected to negative pressure evaporation to remove the residual chloroalkane solvent, and then water is added to dilute the sulfuric acid solution until the mass fraction is 60-70 wt%.

In the step 2), the sulfuric acid solution with the mass fraction of 60-70 wt% is obtained by treating the reaction material liquid in the step 1).

Further, in the step 2), combining the filtrates after the reaction is finished, concentrating the filtrates to a sulfuric acid solution with the mass fraction of 60-70 wt%, applying the sulfuric acid solution for the subsequent oxidation reaction of the 2-nitro-4-methylsulfonyl toluene, and discharging the distilled water after the biochemical treatment is qualified.

And in the step 2), after concentrating until a sulfuric acid solution with the mass fraction of 60-70 wt% is used, adding potassium hydroxide into finally generated waste sulfuric acid to adjust the pH value to be neutral, then adding potassium chlorate, stirring and reacting at 70-80 ℃, then cooling to room temperature, adding ammonium sulfate for reaction, filtering to remove ammonium vanadate solid, concentrating, crystallizing, filtering and drying the filtrate to obtain a byproduct potassium sulfate salt, and burning and deaminating the filtered ammonium metavanadate solid to obtain vanadium pentoxide which is reused for oxidation reaction.

Preferably, the chloroalkane solvent in step 1) is one of dichloromethane, trichloromethane and dichloroethane.

In the step 1), the weight ratio of the chloroalkane solvent to the p-methylsulfonyltoluene is chloroalkane: 5-10% of p-methylsulfonyl toluene: 1.

further, in the step 1), the molar ratio of the amount of the nitric acid to the p-methylsulfonyl toluene in the nitration reaction is 1-1.5: 1, the molar ratio of sulfuric acid to p-methylsulfonyltoluene is 4-8: 1.

in the step 2), the molar ratio of the materials is as follows: nitric acid: sulfuric acid: catalyst: 3-8% of p-methylsulfonyl toluene: 4-8: 0.01-0.05: 1, when pulping and washing, the using amount of hot water is 1-3 times of the weight of p-methylsulfonyl toluene.

The inventor finds that sulfuric acid is difficult to apply mechanically in the conventional nitration reaction for preparing 2-nitro-4-methylsulfonylbenzoic acid, because the nitration reaction is difficult to be smoothly performed if more nitration products are dissolved in the sulfuric acid in the nitration reaction; according to the invention, a chloroalkane solvent is added in a nitration reaction, the concentration of sulfuric acid is adjusted, 80-90 wt% of sulfuric acid is adopted, a product is dissolved in the chloroalkane solvent to the maximum extent, the chloroalkane solvent and a mixed acid solution are fed at a constant speed and simultaneously, standing reaction is carried out after the reaction is finished, discharging is carried out, a feed liquid is layered and separated, the separated lower-layer sulfuric acid solution is directly applied to the subsequent nitration reaction of methyl sulfone-based toluene, water is added into the separated organic phase, the chloroalkane solvent is azeotropically distilled, a nitration product is separated out, the nitration product is directly applied to the next oxidation reaction after filtration, the yield is quite high, the molar yield of the two-step reaction is more than 90%, the sulfuric acid application of the nitration reaction is realized, the sulfuric acid application of the nitration reaction can be.

In the oxidation reaction, the sulfuric acid solution concentrated to 60-70 wt% in the post-treatment contains the vanadium pentoxide catalyst, and when the sulfuric acid solution is applied to the subsequent oxidation reaction of 2-nitro-4-methylsulfonyl toluene, the vanadium pentoxide catalyst is not required to be added, so that the using amount of the catalyst is greatly reduced in the production process, the final waste sulfuric acid is adjusted to be neutral by potassium hydroxide after multiple applications, and the obtained ammonium metavanadate can be used for preparing vanadium pentoxide after the treatment of potassium chlorate and ammonium sulfate, so that the atom utilization rate is improved.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, a new reaction system is arranged, so that the waste acid can be reused in the nitration reaction and the oxidation reaction, the waste acid generated in the nitration reaction can be reused for the oxidation reaction after a solvent is removed by distillation, the waste acid generated in the oxidation reaction can be reused for the oxidation reaction after post-treatment and concentration, and the vanadium pentoxide as a catalyst can be reused for the oxidation reaction along with sulfuric acid, so that the waste acid amount generated by the existing production factory can be reduced by more than 90%, the vanadium pentoxide as a catalyst can be reduced by more than 90%, and the generation of three wastes can be greatly reduced.

Adding potassium hydroxide into the waste sulfuric acid finally generated by the process to adjust the pH value to be neutral, oxidizing, settling, filtering to remove ammonium vanadate solid, concentrating, crystallizing, filtering and drying the filtrate to obtain a byproduct potassium sulfate for export sales; filtering to obtain ammonium vanadate solid, and reusing the prepared vanadium pentoxide after high-temperature deamination for oxidation reaction.

When the technical scheme of the invention is used for continuous reaction, the reaction volume in unit time is small, the stable controllability of the reaction is increased, the reaction safety is improved, and the equipment investment is reduced.

The method realizes the recycling of the sulfuric acid, the total molar yield of the 2-nitro-4-methylsulfonylbenzoic acid can reach about 90 percent, the content is 99 percent, the process is safe, green and environment-friendly, the amount of three wastes is small, and the method is suitable for industrial production.

Detailed Description

The present invention is further illustrated by the following specific examples.