A method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation

Abstract

The present application relates to a kind of 2-nitro-4-methylsulfonyl benzoic acid prepared by catalytic oxidation method, which is to use 2-nitro-4-methylsulfonyl toluene as raw material, with concentrated sulfuric acid as solvent, with peroxysulfuric acid as oxidant, with main catalyst monomer as catalyst or with main catalyst and cocatalyst to form compound or mixture as catalyst, catalytic oxidation reaction is carried out, the obtained reaction liquid is cooled and then is subjected to alkali solution acid separation, and 2-nitro-4-methylsulfonyl benzoic acid is obtained;The main catalyst is the compound containing selenate ion or selenite ion;The cocatalyst is one of copper salt, manganese salt, cobalt salt and magnesium salt.The present application is simple to operate, and the reaction condition is mild, and the yield of the obtained 2-nitro-4-methylsulfonyl benzoic acid is high and the purity is high.

Description

Technical Field

[0001] This invention relates to the fields of fine chemical synthesis and herbicides, and particularly to a method for the catalytic oxidation preparation of 2-nitro-4-methylsulfonylbenzoic acid. Background Technology

[0002] 2-Nitro-4-methylsulfonylbenzoic acid is an important organic synthesis intermediate, widely used in dyes, pharmaceuticals, and pesticides, especially in the pesticide field. Therefore, developing new synthetic processes for 2-nitro-4-methylsulfonylbenzoic acid is crucial. However, in existing technologies, low catalyst selectivity, poor catalytic efficiency, and low yield have been key factors restricting the synthesis of 2-nitro-4-methylsulfonylbenzoic acid.

[0003] CN115784948A discloses a method for preparing 2-nitro-4-methylsulfonylbenzoic acid by reacting manganese dioxide as a catalyst at 160℃-180℃. However, this method suffers from limitations such as low catalyst activity, high reaction temperature, and high energy consumption. CN103073461A discloses a method for preparing 2-nitro-4-methylsulfonylbenzoic acid by oxidation with nitric acid as an oxidant. However, this method requires a large amount of nitric acid and generates nitrogen oxide waste gas that is difficult to treat, making it environmentally unfriendly. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation with mild reaction conditions and high catalytic efficiency.

[0005] To address the aforementioned problems, the present invention provides a method for the catalytic oxidation preparation of 2-nitro-4-methylsulfonylbenzoic acid, characterized in that: the method uses 2-nitro-4-methylsulfonyltoluene as a raw material, concentrated sulfuric acid as a solvent, peroxysulfuric acid as an oxidant, and a main catalyst monomer as a catalyst or a compound or mixture formed by the main catalyst and a co-catalyst as a catalyst to carry out a catalytic oxidation reaction. The resulting reaction solution is cooled and then subjected to alkali dissolution and acid precipitation to obtain 2-nitro-4-methylsulfonylbenzoic acid; the main catalyst is a compound containing selenate ions or selenite ions; and the co-catalyst is one or more of copper salts, manganese salts, cobalt salts, and magnesium salts.

[0006] The method involves placing 2-nitro-4-methylsulfonyl toluene in a reactor, adding concentrated sulfuric acid and stirring to dissolve it, then adding a catalyst, initially heating to 80℃~120℃, then adding the oxidant within 3 hours, maintaining the temperature for 0.5~3.5 hours, followed by alkali dissolution and acid precipitation to obtain 2-nitro-4-methylsulfonyl benzoic acid.

[0007] The concentrated sulfuric acid has a mass concentration of 80% to 98%.

[0008] The molar ratio of the oxidant to the 2-nitro-4-methylsulfonyl toluene is 3~6:1.

[0009] The amount of the main catalyst is 0.5-20% of the mass of 2-nitro-4-methylsulfonyl toluene, the amount of the co-catalyst is 0.1-15% of the mass of 2-nitro-4-methylsulfonyl toluene, and the mass ratio of the main catalyst to the co-catalyst is 1:0-5.

[0010] The alkaline dissolution and acid precipitation process uses a sodium hydroxide solution with a mass concentration of 5% to 50%, and the acid precipitation process uses one of hydrochloric acid, phosphoric acid, or sulfuric acid solutions with a mass concentration of 10% to 35%.

[0011] The main catalyst is one of sodium selenate, selenic acid, selenite, copper selenate, manganese selenite, and magnesium selenite; the co-catalyst is one of copper sulfate, cobalt acetate, manganese nitrate, and magnesium nitrate.

[0012] Compared with the prior art, the present invention has the following advantages: 1. This invention is simple to operate, has mild reaction conditions, and is safe and environmentally friendly.

[0013] 2. Using the method of the present invention, 2-nitro-4-methylsulfonylbenzoic acid with high yield and high purity can be obtained. Detailed Implementation

[0014] A method for the catalytic oxidation preparation of 2-nitro-4-methylsulfonylbenzoic acid is disclosed. This method involves using 2-nitro-4-methylsulfonyltoluene as a raw material, concentrated sulfuric acid as a solvent, persulfate as an oxidant, and a main catalyst monomer or a compound or mixture of a main catalyst and a co-catalyst as a catalyst. The resulting reaction solution is cooled and then subjected to alkali dissolution and acid precipitation to obtain 2-nitro-4-methylsulfonylbenzoic acid. The main catalyst is a compound containing selenate or selenite ions; the co-catalyst is one or more of copper, manganese, cobalt, and magnesium salts. The specific method is as follows: 2-Nitro-4-methylsulfonyltoluene was placed in a reactor, concentrated sulfuric acid was added and stirred to dissolve it, then a catalyst was added, and the temperature was raised to 80℃~120℃. The oxidant was then added within 3 hours, and the temperature was maintained for 0.5~3.5 hours. After alkali dissolution and acid precipitation, 2-nitro-4-methylsulfonylbenzoic acid was obtained.

[0015] The concentration of concentrated sulfuric acid is 80% to 98%, with a preferred concentration of 90% to 98%.

[0016] The molar ratio of the oxidant to 2-nitro-4-methylsulfonyl toluene is 3~6:1.

[0017] The amount of the main catalyst is 0.5-20% of the mass of 2-nitro-4-methylsulfonyl toluene, preferably 2-12%, more preferably 3-8%. The amount of the co-catalyst is 0.1-15% of the mass of 2-nitro-4-methylsulfonyl toluene, preferably 0.1-10%, more preferably 0.5-8%. The mass ratio (g / g) of the main catalyst to the co-catalyst is 1:0-5, preferably 1:0-3, more preferably 1:0-2.

[0018] The main catalyst is one of sodium selenate, selenic acid, selenite, copper selenate, manganese selenite, and magnesium selenite; the co-catalyst is one of copper sulfate, cobalt acetate, manganese nitrate, and magnesium nitrate.

[0019] In the alkaline dissolution and acid precipitation process, the alkaline dissolution uses a sodium hydroxide solution with a mass concentration of 5% to 50%, preferably 10% to 25%; the acid precipitation uses one of hydrochloric acid, phosphoric acid, or sulfuric acid solutions with a mass concentration of 10% to 35%, preferably hydrochloric acid.

[0020] Example 1 Weigh 0.215 g of sodium selenate and add it to a 250 mL beaker. Add 50 mL of water and then 0.65 g of copper sulfate. Stir and heat to 80 °C until dissolved. After 1 hour, calcine the solution in a muffle furnace at 200 °C until all moisture is removed to obtain catalyst a for later use.

[0021] In a three-necked flask, 0.5 mol of 80% concentrated sulfuric acid and 0.05 mol of 2-nitro-4-methylsulfonyl toluene were added and stirred until dissolved. 1 g of catalyst a was added, and the temperature was raised to 90 °C. Peroxysulfuric acid (0.2 mol) was slowly added with stirring, and the oxidant was added dropwise over 3 hours. The reaction was then continued at 90 °C with stirring for another 3 hours. After cooling and standing, the product 2-nitro-4-methylsulfonyl benzoic acid was obtained by alkali dissolution with 10% sodium hydroxide solution and acid precipitation with 35% hydrochloric acid solution.

[0022] Example 2 Weigh 2.15g of selenic acid and add it to a 250ml beaker. Add 50ml of water and then 3.9g of copper sulfate. Stir and heat to 80℃ until dissolved. After 1 hour, calcine the solution in a muffle furnace at 200℃ until all moisture is removed to obtain catalyst b for later use.

[0023] In a three-necked flask, 0.5 mol of 98% concentrated sulfuric acid and 0.05 mol of 2-nitro-4-methylsulfonyl toluene were added and stirred until dissolved. 1 g of catalyst b was added, and the temperature was raised to 120 °C. Peroxysulfuric acid (0.15 mol) was slowly added with stirring. The oxidant was added dropwise over 3 hours, and the reaction was continued at 120 °C with stirring for 1.5 hours. After cooling and standing, the product 2-nitro-4-methylsulfonyl benzoic acid was obtained by alkali dissolution with 25% sodium hydroxide solution and acid precipitation with 35% hydrochloric acid solution.

[0024] Example 3 Weigh 1g of catalyst c selenite and add it to a three-necked flask. Add 0.5mol of 98% concentrated sulfuric acid and 0.05mol of 2-nitro-4-methylsulfonyl toluene and stir to dissolve. Heat to 100℃ and slowly add 0.3mol of peroxysulfuric acid while stirring. The oxidant is added dropwise over 3 hours. Then, continue stirring at 100℃ for 2 hours. After cooling and standing, dissolve in 15% sodium hydroxide solution and precipitate with 20% phosphoric acid solution to obtain the product 2-nitro-4-methylsulfonyl benzoic acid.

[0025] Example 4 In a three-necked flask, 0.5 mol of 98% concentrated sulfuric acid and 0.05 mol of 2-nitro-4-methylsulfonyl toluene were added and stirred to dissolve. Catalyst d (0.65 g selenite and 1.3 g copper sulfate) was added, and the temperature was raised to 100 °C to dissolve the catalyst. Peroxysulfuric acid (0.3 mol) was slowly added while stirring, and the oxidant was added dropwise over 3 hours. The reaction was then continued at 100 °C with stirring for another 3 hours. After cooling and standing, the product 2-nitro-4-methylsulfonyl benzoic acid was obtained by alkali dissolution with 15% sodium hydroxide solution and acid precipitation with 35% hydrochloric acid solution.

[0026] Example 5 In a three-necked flask, 0.5 mol of 98% concentrated sulfuric acid and 0.05 mol of 2-nitro-4-methylsulfonyl toluene were added and stirred to dissolve. Catalyst e (2.5 g selenite and 3.0 g cobalt acetate) was added, and the temperature was raised to 120 °C to dissolve the catalyst. Peroxysulfuric acid (0.3 mol) was slowly added while stirring, and the oxidant was added dropwise over 3 hours. The reaction was then continued at 120 °C with stirring for another 3 hours. After cooling and standing, the product 2-nitro-4-methylsulfonyl benzoic acid was obtained by alkali dissolution with 10% sodium hydroxide solution and acid precipitation with 35% hydrochloric acid solution.

[0027] Example 6 Weigh 1.3g of selenite and add it to a 250ml beaker. Add 50ml of water and then 2.5g of manganese nitrate. Stir and heat to 80℃ until dissolved. After 1 hour, place the solution in a muffle furnace at 200℃ and calcine until all moisture is removed to obtain catalyst f, manganese selenite, for later use.

[0028] In a three-necked flask, 0.5 mol of 98% concentrated sulfuric acid and 0.05 mol of 2-nitro-4-methylsulfonyl toluene were added and stirred until dissolved. 1 g of catalyst f was added, and the temperature was raised to 95 °C. Peroxysulfuric acid (0.3 mol) was slowly added while stirring, and the reaction was continued at 95 °C for 2.5 hours with stirring. After cooling and standing, the mixture was dissolved in 10% sodium hydroxide solution and precipitated with 35% hydrochloric acid solution to obtain the product 2-nitro-4-methylsulfonyl benzoic acid.

[0029] Example 7 Weigh 2.5g of copper selenite and add it to a 250ml beaker. Add 50ml of water and then 12.5g of magnesium nitrate. Stir and heat to 80℃ until dissolved. After 1 hour, place the solution in a muffle furnace at 200℃ and calcine until all moisture is removed to obtain catalyst magnesium selenite for later use.

[0030] In a three-necked flask, 0.5 mol of 90% concentrated sulfuric acid and 0.05 mol of 2-nitro-4-methylsulfonyl toluene were added and stirred until dissolved. 1 g of catalyst J was added, and the temperature was raised to 100 °C. Peroxysulfuric acid (0.25 mol) was slowly added while stirring, and the reaction was continued at 100 °C for 1 hour with stirring. After cooling and standing, the product 2-nitro-4-methylsulfonyl benzoic acid was obtained by alkali dissolution with 50% sodium hydroxide solution and acid precipitation with 10% hydrochloric acid solution.

[0031] The yields and purities of the catalysts in Examples 1-7 are shown in Table 1.

[0032] Table 1 Catalyst Yield and Purity As can be seen from Table 1, using the catalyst combination and reaction conditions of the present invention, the yield of the product 2-nitro-4-methylsulfonylbenzoic acid is ≥89%, and the purity of the product can reach ≥99%, which proves that the present invention has a competitive advantage in related fields.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any simple modifications, equivalent changes, or alterations made to the above examples based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for the catalytic oxidation preparation of 2-nitro-4-methylsulfonylbenzoic acid, characterized in that: This method refers to using 2-nitro-4-methylsulfonyltoluene as a raw material, concentrated sulfuric acid as a solvent, peroxysulfuric acid as an oxidant, and a main catalyst monomer as a catalyst or a compound or mixture formed by the main catalyst and a co-catalyst as a catalyst to carry out a catalytic oxidation reaction. After cooling, the resulting reaction solution is dissolved in alkali and precipitated with acid to obtain 2-nitro-4-methylsulfonylbenzoic acid. The main catalyst is a compound containing selenate ions or selenite ions. The co-catalyst is one or more of copper salts, manganese salts, cobalt salts, and magnesium salts.

2. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation as described in claim 1, characterized in that: The method involves placing 2-nitro-4-methylsulfonyl toluene in a reactor, adding concentrated sulfuric acid and stirring to dissolve it, then adding a catalyst, initially heating to 80℃~120℃, then adding the oxidant within 3 hours, maintaining the temperature for 0.5~3.5 hours, followed by alkali dissolution and acid precipitation to obtain 2-nitro-4-methylsulfonyl benzoic acid.

3. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation as described in claim 1 or 2, characterized in that: The concentrated sulfuric acid has a mass concentration of 80% to 98%.

4. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation as described in claim 1 or 2, characterized in that: The molar ratio of the oxidant to the 2-nitro-4-methylsulfonyl toluene is 3~6:

1.

5. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation as described in claim 1, characterized in that: The amount of the main catalyst is 0.5-20% of the mass of 2-nitro-4-methylsulfonyl toluene, the amount of the co-catalyst is 0.1-15% of the mass of 2-nitro-4-methylsulfonyl toluene, and the mass ratio of the main catalyst to the co-catalyst is 1:0-5.

6. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation as described in claim 1 or 2, characterized in that: The alkaline dissolution and acid precipitation process uses a sodium hydroxide solution with a mass concentration of 5% to 50%, and the acid precipitation process uses one of hydrochloric acid, phosphoric acid, or sulfuric acid solutions with a mass concentration of 10% to 35%.

7. The method for preparing 2-nitro-4-methylsulfonylbenzoic acid by catalytic oxidation as described in claim 1 or 5, characterized in that: The main catalyst is one of sodium selenate, selenic acid, selenite, copper selenate, manganese selenite, and magnesium selenite; the co-catalyst is one of copper sulfate, cobalt acetate, manganese nitrate, and magnesium nitrate.

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