A method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation

Abstract

The present application relates to the technical field of herbicide production, and in particular to a method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation, which comprises synthesizing a four-component oxide catalyst Zn9Fe3BiMo 12 O5, S200 2-chloro-3-methyl-4-methylsulfonyl acetophenone, four-component oxide catalyst Zn9Fe3BiMo 12 O5 and N,N-dimethyl sulfoxide are added to the autoclave, an oxidant is added and heated to perform an oxidation reaction, and 2-chloro-3-methyl-4-methylsulfonylbenzoic acid is obtained after filtering, adjusting the base, washing, adjusting the acid, extracting, and distilling. When the filtrate is obtained by filtering in step S200, a four-component oxide catalyst Zn9Fe3BiMo is obtained. 12 O 51 , washed with water and ethanol in turn, dried to remove most of the water and then used for the next reaction. The application has the effects of complete reaction of raw materials, less three wastes generated by the reaction and easy recovery of the catalyst.

Description

Technical Field

[0001] The present application relates to the technical field of herbicide production, and in particular to a method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation. Background Art

[0002] Farmland weeds are one of the main causes of low grain yields, so herbicides are now being used more and more widely. There are many types of herbicides, which can be generally divided into HPPD inhibitors, ACC inhibitors and ALS / AHAS inhibitors according to their targets. Since the discovery of the directional target of hydroxyphenylpyruvate oxygenase (HPPD) in the 1980s, triketone herbicides as HPPD inhibitor herbicides have begun to develop by leaps and bounds. In the 1990s, Zeneca developed and marketed the first triketone herbicide, sulfotrione. In 2007, Bayer developed the triketone cornfield herbicide tampron, which has high herbicidal activity and can kill some weeds that are resistant to marketed herbicides. Since 2014, the annual sales of this product have been more than US$200 million. In 2008, Bayer launched furansulfotrione, which is mainly used in corn fields and rice fields.

[0003]

[0004] In the synthetic route of tampronil and furansulfuron, 2-chloro-3-methyl-4-methylsulfonylbenzoic acid is an important intermediate, which is usually obtained by oxidation with sodium hypochlorite using 2-chloro-3-methyl-4-methylsulfonylacetophenone as raw material. However, this method has the problem of incomplete reaction and large amount of waste water. Chinese patent CN112194603 reports a method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation of 2-chloro-3-methyl-4-methylsulfonylacetophenone, which uses a clean oxidant for oxidation, and produces less three wastes, but the homogeneous catalytic system used has the problem of difficulty in catalyst recovery. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid in high yield by using 2-chloro-3-methyl-4-methylsulfonylacetophenone as a raw material and oxygen as a clean oxidant.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for synthesizing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid as shown in formula (I), wherein the method comprises: using 2-chloro-3-methyl-4-methylsulfonylacetophenone as shown in formula (II) as a raw material, and using four-component oxide Zn9Fe3BiMo12 O 51 As a catalyst, oxygen is used as an oxidant, and the reaction is carried out in N,N-dimethyl sulfoxide at a certain oxygen pressure and temperature. After the reaction is completed, the catalyst is filtered, separated, washed, and dried, and can be reused. The filtrate is post-treated to obtain 2-chloro-3-methyl-4-methylsulfonylbenzoic acid as shown in formula (I).

[0008]

[0009] In the present invention, the 2-chloro-3-methyl-4-methylsulfonyl acetophenone and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The mass ratio is: 1:0.4~0.1.

[0010] In the present invention, the recommended mass dosage of the N,N-dimethyl sulfoxide is 20 to 70 times that of 2-chloro-3-methyl-4-methylsulfonylacetophenone.

[0011] In the present invention, the pressure of the oxygen is 0.4-0.6 MPa.

[0012] In the present invention, the reaction temperature is 130°C to 150°C.

[0013] In the present invention, the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 After centrifugal separation, the product is washed with water and ethanol in turn, and can be used for the next reaction after drying.

[0014] The reaction solution was analyzed by liquid chromatography, and the conversion rate of the raw material 2-chloro-3-methyl-4-methylsulfonylacetophenone and the yield of the product 2-chloro-3-methyl-4-methylsulfonylbenzoic acid were determined by external standard method.

[0015] The post-treatment method of the reaction filtrate is: adjusting the pH of the filtrate to alkaline with sodium hydroxide solution, washing with ethyl acetate three times, adjusting the pH of the aqueous phase to acidic with hydrochloric acid solution, and then extracting with ether three times, combining the three ether extracts, and distilling off the ether under reduced pressure to obtain the product 2-chloro-3-methyl-4-methylsulfonylbenzoic acid.

[0016] More specifically, it is recommended that the method of the present invention be carried out according to the following steps: 2-chloro-3-methyl-4-methylsulfonylacetophenone, Zn9Fe3BiMo 12 O 51and N,N-dimethyl sulfoxide, with 0.4-0.6MPa oxygen as oxidant, react at 130-150℃ for a period of time, release the pressure, the catalyst can be reused after separation by filtration, washing and drying, analyze the filtrate by liquid chromatography, adjust the pH to about 11 with sodium hydroxide solution, wash three times with ethyl acetate, adjust the pH value of the aqueous phase to about 2 with hydrochloric acid solution, extract three times with ether, combine the three ether extracts, and remove the ether under reduced pressure to obtain the product 2-chloro-3-methyl-4-methylsulfonylbenzoic acid; 2-chloro-3-methyl-4-methylsulfonylacetophenone and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The mass ratio of 2-chloro-3-methyl-4-methylsulfonylacetophenone is 1:0.4-0.1; the recommended mass dosage of N,N-dimethyl sulfoxide is 20-70 times that of 2-chloro-3-methyl-4-methylsulfonylacetophenone.

[0017] The synthetic method of the present invention has the following beneficial effects: the conversion rate of the raw material 2-chloro-3-methyl-4-methylsulfonyl acetophenone is good, the yield of the product 2-chloro-3-methyl-4-methylsulfonyl benzoic acid is high, and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 Reusable. DETAILED DESCRIPTION

[0018] The present invention is further described below through specific implementation modes, but the protection scope of the present invention is not limited thereto.

[0019] Embodiment 1:

[0020] 7.4 g (18 mmol) of Fe(NO3)3·9H2O and 16.0 g (54 mmol) of Zn(NO3)2·6H2O were weighed and dissolved in 150 mL of deionized water, and the solution was labeled solution a; 3.0 g (6 mmol) of Bi(NO3)3·5H2O was weighed and dissolved in a mixture of 14 mL of deionized water and 6 mL of concentrated nitric acid, and the solution was labeled solution b; 12.8 g (10 mmol) of (NH4)6Mo7O 24 ·4H2O, dissolve it in 100mL of deionized water, and mark this solution as solution c; after mixing solution a and solution b evenly, slowly pour them into the vigorously stirred solution c, heat the mixed solution to 70℃, stir it open for 5h, the water evaporates almost completely, and a large amount of solid precipitates at the bottom of the container. Collect the precipitate and dry it in a vacuum drying oven at 175℃ for 8h; calcine the dried solid in air for 4h, the calcination temperature is 550℃, and the heating rate is 5℃ / min. After cooling, collect the catalyst and grind it into powder to obtain Zn9Fe3BiMo 12 O 51Catalyst; in a 100mL polytetrafluoroethylene-lined autoclave, add 5mmol of 2-chloro-3-methyl-4-methylsulfonylacetophenone, Zn9Fe3BiMo 12 O 51 (0.125g) and 35mL of N,N-dimethyl sulfoxide, seal the autoclave, replace the air in the autoclave with oxygen, fill with oxygen until the pressure gauge is 0.5MPa, put the autoclave into an oil bath preheated to 140°C, and react for 14h. After cooling and depressurization, the catalyst is separated by filtration, and the filtrate is analyzed by liquid chromatography. The conversion rate of 2-chloro-3-methyl-4-methylsulfonyl acetophenone is 99%, and the yield of the product 2-chloro-3-methyl-4-methylsulfonyl benzoic acid is 98%. Then the filtrate is adjusted to pH 11 with sodium hydroxide solution, washed three times with ethyl acetate, and the aqueous phase is adjusted to pH 2 with hydrochloric acid solution, and then extracted three times with ether, the three ether extracts are combined, and the ether is evaporated under reduced pressure to obtain the product 2-chloro-3-methyl-4-methylsulfonyl benzoic acid. The solid obtained by filtration is washed with water and ethanol in turn, and the recovered Sixiang oxide catalyst Zn9Fe3BiMo is obtained after drying. 12 O 51 Can be used for next reaction.

[0021] NMR characterization data:

[0022] 1 H NMR (400MHz, d6-DMSO) δ7.98 (d, J = 8.2 Hz, 1H), 7.73 (d, J = 8.2 Hz, 1H), 3.31 (s, 3H), 2.72 (s, 1H); 13 C NMR (101MHz, d6-DMSO) δ166.9,142.0,138.4,136.5,132.7,127.4,126.8,43.3,16.9.

[0023] The difference between Example 2-3 and Comparative Example 1-2 and Example 1 is that the pressure of the oxygen introduced in step S200 is different, as shown in the following table:

[0024] Example 2 Example 3 Comparative Example 1 Comparative Example 2 Air pressure(MPa) 0.4 0.6 0.3 0.7

[0025] The difference between Examples 4-5 and Comparative Examples 3-4 and Example 1 is that the temperature for the oxidation reaction in step S200 is different as shown in the following table:

[0026]

[0027]

[0028] The difference between Examples 6-8 and Comparative Examples 5-6 and Example 1 is that in step S200, 2-chloro-3-methyl-4-methylsulfonylacetophenone and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The mass ratios are different, as shown in the following table:

[0029] Example 6 Example 7 Example 8 Example 9 Comparative Example 5 Comparative Example 6 Quality Ratio 1:0.12 1:0.2 1:0.3 1:0.4 1:0.05 1:0.5

[0030] The difference between Examples 10-14 and Comparative Examples 7-8 and Example 1 is that the mass amount of N,N-dimethyl sulfoxide in step S200 is different in multiples of 2-chloro-3-methyl-4-methylsulfonylacetophenone, as shown in the following table:

[0031]

[0032] The difference between Examples 15-17 and Example 1 is that the four-element oxide catalyst Zn9Fe3BiMo 12 O 51 The number of reuses is shown in the following table:

[0033] Embodiment 15 Example 16 Embodiment 17 Reuse times 1 2 3

[0034] Detection Methods

[0035] The filtrate obtained in step S300 was analyzed by liquid chromatography to obtain the yield (%) of 2-chloro-3-methyl-4-methylsulfonylbenzoic acid and the conversion rate (%) of 2-chloro-3-methyl-4-methylsulfonylacetophenone. The test results are shown in the following table:

[0036]

[0037] Conclusion: It can be seen from the data of Examples 1-3 and Comparative Examples 1-2 in the above table that the reaction yield is higher when the oxygen pressure is 0.4-0.6, and the yield drops sharply when the oxygen pressure is less than 0.4. When the oxygen pressure is greater than 0.6, the yield reaches 100%, but the product selectivity decreases, and further increasing the oxygen pressure has little effect, indicating that the appropriate range of oxygen pressure for the reaction is 0.4-0.6.

[0038]

[0039]

[0040] Conclusion: According to the data of Examples 1, 4, 5 and Comparative Examples 3 and 4 in the above table, the reaction yield is higher when the reaction temperature is 130-150°C, with the highest at 140°C. When the reaction temperature is less than 130°C, the yield drops significantly, and when the temperature is greater than 160°C, the product selectivity decreases, indicating that the suitable range of the reaction temperature for the reaction is 130-150°C.

[0041]

[0042] Conclusion: According to the data of Examples 1, 6, 7, 8, 9 and Comparative Examples 5 and 6 in the above table, the reaction yield is 2-chloro-3-methyl-4-methylsulfonylacetophenone and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The mass ratio of 1:0.1-1:0.4 is high, among which the mass ratio is 1:0.1, and the yield of the reaction gradually decreases with the increase of the amount of catalyst. When the mass ratio is less than 1:0.1 or greater than 1:0.4, the yield drops sharply, indicating that the 2-chloro-3-methyl-4-methylsulfonyl acetophenone and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The suitable range of the mass ratio is 1:0.1-1:0.4.

[0043]

[0044]

[0045] Conclusion: According to the data of Examples 1, 10-14 and Comparative Examples 7 and 8 in the above table, the reaction yield is higher when the mass dosage of N, N-dimethyl sulfoxide is 20-70 times of 2-chloro-3-methyl-4-methylsulfonyl acetophenone, wherein the maximum is 30 times, the yield decreases slightly when the multiple is less than 30, and the yield remains basically the same when the multiple is 30-70, and the yield decreases significantly when the multiple is less than 20 or greater than 70, indicating that the suitable range of the mass dosage of N, N-dimethyl sulfoxide in the reaction is 20-70 times of 2-chloro-3-methyl-4-methylsulfonyl acetophenone.

[0046]

[0047] Conclusion: From the data of Examples 1, 15-17 in the above table, it can be seen that the reaction yield increases with the catalyst Zn9Fe3BiMo 12 O 51 The reaction yield decreased with the increase of the reuse times. When the reuse times were 3 times or less, the reaction yield was higher, indicating that the catalyst Zn9Fe3BiMo 12 O 51 It has good reuse effect.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation, comprising the following steps: S100: Preparation of four-component oxide catalyst Zn9Fe3BiMo 12 O 51 ; S200: 2-chloro-3-methyl-4-methylsulfonyl acetophenone, four-component oxide catalyst Zn9Fe3BiMo 12 O 51 , N,N-dimethyl sulfoxide is added into the autoclave, an oxidant is added and the autoclave is heated to carry out an oxidation reaction; S300: releasing the pressure and filtering the liquid material to obtain a filtrate, adjusting the pH of the filtrate with a sodium hydroxide solution until the filtrate is alkaline, washing it with ethyl acetate three times, and adjusting the pH of the aqueous phase with a hydrochloric acid solution until the aqueous phase is acidic; S400: extracting the acidic aqueous phase in S300 three times with diethyl ether, combining the three diethyl ether extracts, and removing the diethyl ether under reduced pressure to obtain the product 2-chloro-3-methyl-4-methylsulfonylbenzoic acid; S500: Four-component oxide catalyst Zn9Fe3BiMo 12 O 51 Recycling; Step S300 filters the filtrate to obtain the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 , washed with water and ethanol in turn, dried to remove most of the water and then used for the next reaction; In step S100, the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The synthesis method is: S101: Dissolve Fe(NO3)3•9H2O and Zn(NO3)2•6H2O in deionized water and label the solution as solution a, where the mass fraction of Fe(NO3)3•9H2O is 4.3% and the mass fraction of Zn(NO3)2•6H2O is 9.2%; S102: Dissolve Bi(NO3)3•5H2O in a nitric acid solution, and mark the solution as solution b, wherein the concentration of the nitric acid solution is 25%, the mass fraction of Bi(NO3)3•5H2O is 11.8%, and the volume ratio of solution a to solution b in step S101 is 15:2; S103: Take (NH4)6Mo7O 24 •4H2O is dissolved in deionized water and the solution is labeled solution c, where (NH4)6Mo7O 24 • The mass fraction of 4H2O is 11.3%, and the volume ratio of solution a to solution c in step S101 is 3:2; S104: After mixing solution a and solution b evenly, slowly pour them into the vigorously stirred solution c, heat the mixed solution to 70°C, and stir in an open air until the water is almost completely evaporated and a large amount of solid is precipitated at the bottom of the container. Collect the precipitate and dry it in a vacuum drying oven at 175°C for 8 h; S105: The dried solid was calcined in air for 4 h at a calcination temperature of 550 °C and a heating rate of 5 °C / min. After cooling, the catalyst was collected and ground into powder to obtain Zn9Fe3BiMo 12 O 51 catalyst; The oxidant added to the autoclave in step S200 is oxygen, and the pressure of the oxygen is 0.4-0.6 MPa; The temperature for the oxidation reaction in step S200 is 130-150°C.

2. The method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation according to claim 1, characterized in that: In step S200, 2-chloro-3-methyl-4-methylsulfonyl acetophenone and the four-component oxide catalyst Zn9Fe3BiMo 12 O 51 The mass ratio is 1:0.4-1:0.

1.

3. The method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation according to claim 1, characterized in that: The mass amount of N,N-dimethyl sulfoxide in step S200 is 20-70 times that of 2-chloro-3-methyl-4-methylsulfonylacetophenone.

4. The method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation according to claim 1, characterized in that: The end point of the pH adjusted by sodium hydroxide in step S300 is 10.5-11.

5.

5. The method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid by catalytic oxidation according to claim 1, characterized in that: The end point of adjusting the pH of the hydrochloric acid solution in step S300 is 1.5-2.5.

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