Preparation method of 2-nitro-4-methylsulfonylbenzoic acid

Abstract

The invention belongs to the field of compound preparation, and particularly relates to a preparation method of 2-nitro-4-methylsulfonylbenzoic acid. The method comprises the following steps: by taking 2-nitro-4-methylsulfonyltoluene as a raw material, carrying out high-temperature pressurized reaction in a nitric acid and sulfuric acid system, producing water at the same time, and after the reaction is finished, filtering, layering and drying to obtain the 2-nitro-4-methylsulfonylbenzoic acid. The invention provides a method for preparing 2-nitro-4-methylsulfonylbenzoic acid on the basis of nitric acid oxidation without adding a metal catalyst. According to the method, toxic vanadium pentoxide is not used as a catalyst, the recovery treatment of the catalyst is reduced, the use amount of sulfuric acid can be reduced to 25% of the original use amount, and the extracted water is used for tail gas absorption treatment and nitric acid recovery, so that the reaction safety is improved to a great extent, the use amount of raw materials is reduced, the environmental influence is reduced, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of compound preparation, and specifically relates to a method for preparing 2-nitro-4-methylsulfonylbenzoic acid. Background Art

[0002] As an important organic intermediate, 2-nitro-4-methylsulfonylbenzoic acid is widely used in pesticides, dyes, medicines and other fields. Mesotrione is a highly effective herbicide for corn fields. It is highly effective and low in toxicity. It is not only safe for corn crops, but also safe for the ecological environment. It conforms to the current development trend, and has received more and more attention and is widely used. As an important intermediate in the synthesis of mesotrione, it is of great significance to develop a green and efficient synthesis process for 2-nitro-4-methylsulfonylbenzoic acid.

[0003] In the current preparation method, 2-nitro-4-methylsulfonyltoluene is used to prepare 2-nitro-4-methylsulfonylbenzoic acid. The main oxidants used are nitric acid, sodium dichromate, hydrogen peroxide, etc., and specific metal catalysts are also required, such as vanadium pentoxide, metal manganese salts, and metal cobalt salts. However, the metal catalysts are difficult to recover and some have certain toxicity.

[0004] Under sulfuric acid / nitric acid system, using vanadium pentoxide as catalyst, o-nitro-p-methylsulfonylbenzoic acid is synthesized. But the method uses high concentration of nitric acid, which can easily produce by-products in the reaction process, and produces a large amount of nitrogen oxide tail gas, which easily pollutes the air. The catalyst vanadium pentoxide used belongs to a poisonous catalyst, and recycling is difficult (CN1090843A, CN103073461B), the amount of spent acid produced is relatively large, and the processing cost is high. In addition, some preparation methods pass into oxygen to react, and the safety risk is relatively high.

[0005] The method of preparing 2-nitro-4-methylsulfonylbenzoic acid using potassium dichromate or potassium permanganate as an oxidant will produce a large amount of chromium-containing waste acid water or manganese dioxide waste residue, which has a great impact on the environment and is difficult to dispose of the waste.

[0006] U.S. Patent No. 5,591,890 reports a method for preparing 2-nitro-4-methylsulfonylbenzoic acid using air as an oxidant. This method uses cobalt acetate as a catalyst, but the oxidation effect is relatively poor, the yield is low, and the equipment is easily corroded.

[0007] In general, these preparation methods generally have the disadvantages of large amount of three wastes generated, poor reaction selectivity, high production cost and limited yield. Summary of the invention

[0008] To solve the above problems, the object of the present invention is to provide a method for preparing 2-nitro-4-methylsulfonylbenzoic acid.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A preparation method of 2-nitro-4-methylsulfonylbenzoic acid comprises the following steps: using 2-nitro-4-methylsulfonyltoluene as a raw material, subjecting the raw material to a high temperature and pressure reaction in a nitric acid and sulfuric acid system, and simultaneously producing water; filtering, layering and drying the raw material after the reaction is completed to obtain the 2-nitro-4-methylsulfonylbenzoic acid.

[0011] Furthermore, 2-nitro-4-methylsulfonyltoluene is used as a raw material, sulfuric acid is added and the temperature is increased, and then nitric acid is added dropwise, and water is produced at the same time. After the reaction is completed, the temperature is lowered, the filter is filtered, a solvent is added to the filter cake, and the filter cake is allowed to stand for stratification. After the water layer is acidified, it is filtered and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid.

[0012] Furthermore, 2-nitro-4-methylsulfonyltoluene is used as a raw material, sulfuric acid is added and the temperature is raised to 140-160° C., and then nitric acid is added dropwise, and water is produced at the same time. When the nitric acid is added dropwise, the pressure of the reaction system is controlled to be 0.1-0.5 MPa, the dropping time is 3-8 hours, and the reaction is completed after 2-6 hours of heat preservation; after the reaction is completed, the temperature is lowered to 75-80° C., water is added and the temperature is further lowered to 5-10° C., and the filter is filtered with suction, a solvent is added to the filter cake, the temperature is raised to 35-50° C., and then liquid alkali is added dropwise, and the layer is allowed to stand for stratification. After the water layer is acidified with hydrochloric acid, the temperature is lowered to 5° C., and then the filter is filtered with suction, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid.

[0013] The weight ratio of the sulfuric acid to 2-nitro-4-methylsulfonyltoluene is 0.1-10:1, preferably 0.25:1; and the concentration of the sulfuric acid is 70%-98%.

[0014] The concentration of nitric acid is 40% to 75%, preferably 60%; the weight ratio of nitric acid to 2-nitro-4-methylsulfonyltoluene is 3 to 10:1, preferably 4.5:1.

[0015] After the reaction is completed, the weight ratio of water added to 2-nitro-4-methylsulfonyltoluene is 1 to 5:1, preferably 2:1.

[0016] The solvent added to the filter cake is one or more of chloroform, dichloroethane and toluene, preferably chloroform.

[0017] The weight ratio of the solvent to 2-nitro-4-methylsulfonyltoluene is 1 to 5:1, preferably 2:1.

[0018] The temperature at which the solubilizing agent is heated is preferably 45°C.

[0019] The method of the present invention has the following advantages:

[0020] The present invention proposes a method for preparing 2-nitro-4-methylsulfonylbenzoic acid based on nitric acid oxidation without adding a metal catalyst. The method does not use toxic vanadium pentoxide as a catalyst, reduces the recovery and treatment of the catalyst, and the amount of sulfuric acid can be reduced to 25% of the original amount. The produced water is used for tail gas absorption treatment and nitric acid recovery, which greatly improves the safety of the reaction, reduces the amount of raw materials, reduces environmental impact, and is suitable for industrial production. Specifically:

[0021] 1) The present invention does not use metal catalysts, thus avoiding the use of toxic metals;

[0022] 2) The amount of sulfuric acid and nitric acid used in the reaction of the present invention is reduced;

[0023] 3) The water produced by the present invention is used as tail gas absorption water to further recover nitric acid for reuse, thereby reducing the consumption of nitric acid;

[0024] 4) The reaction conversion rate and yield of the present invention are high, reaching more than 95%. The yields of the currently reported preparation methods are basically less than 90%, and the present invention has great industrial application prospects. DETAILED DESCRIPTION

[0025] Example 1

[0026] 40g 2-nitro-4-methylsulfonyltoluene and 10g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 180g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 44.7g, content 99.4%, yield 97.5%.

[0027] Example 2

[0028] 40g 2-nitro-4-methylsulfonyltoluene and 20g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 180g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 44.7g, content 99.1%, yield 97.1%.

[0029] Example 3

[0030] 40g 2-nitro-4-methylsulfonyltoluene and 10g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 120g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 44.5g, content 98.9%, yield 96.5%.

[0031] Example 4

[0032] 40g 2-nitro-4-methylsulfonyltoluene and 10g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 270g 40% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 44.2g, content 99.2%, yield 96.1%.

[0033] Example 5

[0034] 40g 2-nitro-4-methylsulfonyltoluene and 10g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 150°C, the pressure was 0.2MPa, 180g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 43.9g, content 98.7%, yield 95.1%.

[0035] Example 6

[0036] 40g 2-nitro-4-methylsulfonyltoluene and 10g 98% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 180g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 44.0g, content 99.4%, yield 97.2%.

[0037] Example 7

[0038] 120g 2-nitro-4-methylsulfonyltoluene and 30g 80% sulfuric acid were added into the reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 540g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 240g water was added, the temperature was further lowered to 10°C, suction filtered, 240g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 90g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 105g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, yielding 132.4g, with a content of 99.2% and a yield of 97.6%.

[0039] Recovery of nitric acid: Add 120 g of produced water into another kettle. During the reaction, pass the tail gas in the reactor into the kettle, and introduce oxygen at the same time. Raise the temperature to 40°C and stir. After the reaction is completed, cool down. The nitric acid content in the water is 40%.

[0040] Example 8

[0041] Apply to recover nitric acid.

[0042] 40g of 2-nitro-4-methylsulfonyltoluene and 20g of 98% sulfuric acid were added to the reactor, the temperature was raised to 140°C, the pressure was 0.2MPa, 200g of 40% nitric acid recovered in Example 7 was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, and after the addition was completed, the temperature was kept for 6 hours. After the reaction was completed, the temperature was lowered to 80°C, 80g of water was added, the temperature was continued to be lowered to 10°C, and suction was filtered. 80g of chloroform was added to the filter cake, the temperature was raised to 45°C, and after the complete dissolution, 30g of 30% sodium hydroxide solution was added dropwise. After the addition was completed, the mixture was allowed to stand for stratification, 35g of 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction was filtered, the mixture was washed with water, and the 2-nitro-4-methylsulfonylbenzoic acid was obtained, with a yield of 42.0g, a content of 98.4%, and a yield of 90.7%.

[0043] Comparative Example 1

[0044] The difference from Example 1 is that the amount of sulfuric acid used is 2 g, and the other conditions are the same as those in Example 1, specifically:

[0045] 40g 2-nitro-4-methylsulfonyltoluene and 2g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 180g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 28.4g, content 99.1%, yield 61.7%.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that the usage amount of nitric acid is 80g, and the other conditions are the same as those in Example 1, specifically:

[0048] 40g 2-nitro-4-methylsulfonyltoluene and 10g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 140°C, the pressure was 0.2MPa, 80g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 30.4g, content 99.0%, yield 66.0%.

[0049] Comparative Example 3

[0050] The difference from Example 1 is that the reaction temperature is 120° C., and the other conditions are the same as those in Example 1, specifically:

[0051] 40g 2-nitro-4-methylsulfonyltoluene and 10g 80% sulfuric acid were added into a reaction kettle, the temperature was raised to 120°C, the pressure was 0.2MPa, 180g 60% nitric acid was added dropwise, the pressure was maintained, water was produced while adding dropwise, the addition was continued for 5 hours, after the addition was completed, the temperature was kept for 6 hours, after the reaction was completed, the temperature was lowered to 80°C, 80g water was added, the temperature was continued to be lowered to 10°C, suction filtered, 80g chloroform was added to the filter cake, the temperature was raised to 45°C, after the complete dissolution, 30g 30% sodium hydroxide solution was added dropwise, the addition was completed, the separation was allowed to stand, 35g 30% hydrochloric acid was added dropwise to the water layer, the pH was adjusted to less than 1, the temperature was lowered to 5°C, suction filtered, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid, 21.8g, content 99.0%, yield 47.3%.

[0052] As can be seen from the above embodiments and comparative examples, the method for preparing 2-nitro-4-methylsulfonylbenzoic acid based on nitric acid oxidation in the embodiment of the present invention does not use toxic metal catalysts, reduces the recovery of the catalyst, and reduces the amount of sulfuric acid to 25% of the original amount. The water produced is used for tail gas absorption and treatment, and nitric acid is recovered, which greatly improves the safety of the reaction, reduces the amount of raw materials, reduces environmental impact, and is suitable for industrial production. Comparative Examples 1-2 have incomplete reactions due to the changes in the amounts of sulfuric acid and nitric acid, resulting in a decrease in reaction yield. Comparative Example 3 has incomplete conversion due to the low reaction temperature, so the reaction yield is significantly reduced. Therefore, the specific reaction conditions of the embodiment of the present invention can ensure that the reaction yield can reach more than 95%, and the amount of sulfuric acid can be significantly reduced.

Claims

1. A method for preparing 2-nitro-4-methylsulfonylbenzoic acid, characterized in that: 2-nitro-4-methylsulfonyltoluene is used as a raw material, and a high temperature and pressure reaction is carried out in a nitric acid and sulfuric acid system, and water is produced at the same time. After the reaction is completed, 2-nitro-4-methylsulfonylbenzoic acid is obtained by filtering, layering and drying.

2. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, wherein: Take 2-nitro-4-methylsulfonyltoluene as raw material, add sulfuric acid and heat up, then add nitric acid dropwise, and produce water at the same time. After the reaction is completed, cool down, filter with suction, add solvent to the filter cake, let stand to separate the layers, acidify the water layer, filter with suction and dry to obtain 2-nitro-4-methylsulfonylbenzoic acid.

3. The preparation method of 2-nitro-4-methylsulfonylbenzoic acid according to claim 1, characterized in that: 2-nitro-4-methylsulfonyltoluene is used as a raw material, sulfuric acid is added and the temperature is raised to 140-160°C, then nitric acid is added dropwise, and water is produced at the same time. When the nitric acid is added dropwise, the pressure of the reaction system is controlled to be 0.1-0.5MPa, the dropping time is 3-8 hours, and the temperature is kept for 2-6 hours to complete the reaction; after the reaction is completed, the temperature is lowered to 75-80°C, water is added and the temperature is further lowered to 5-10°C, and the filter is filtered by suction, a solvent is added to the filter cake, the temperature is raised to 35-50°C, and then liquid alkali is added dropwise, and the layer is allowed to stand for stratification. After the water layer is acidified with hydrochloric acid, the temperature is lowered to 5°C, and then the filter is filtered by suction, washed with water, and dried to obtain 2-nitro-4-methylsulfonylbenzoic acid.

4. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 3, wherein: The weight ratio of the sulfuric acid to 2-nitro-4-methylsulfonyltoluene is 0.1-10:1; and the concentration of the sulfuric acid is 70%-98%.

5. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 3, wherein: The weight ratio of the nitric acid to 2-nitro-4-methylsulfonyltoluene is 3-10:1; the concentration of the nitric acid is 40%-75%.

6. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 3, wherein: After the reaction is completed, the weight ratio of water added to 2-nitro-4-methylsulfonyltoluene is 1 to 5:

1.

7. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 3, wherein: The solvent added to the filter cake is one or more of chloroform, dichloroethane and toluene.

8. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid according to claim 3, wherein: The weight ratio of the solvent to 2-nitro-4-methylsulfonyltoluene is 1 to 5:1.