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Method for preparing 2-chloro-3-methyl-4-methylsulfonyl benzoic acid

A technology for methanesulfonyl benzoic acid and methanesulfonyl acetophenone is applied in the field of preparing 2-chloro-3-methyl-4-methanesulfonyl benzoic acid, and can solve the problems of complex operation process, high toxicity and easy generation of excessive oxides etc.

Inactive Publication Date: 2021-09-14
利民化学有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Patent CN104292137 uses tetrahydrofuran as a solvent when preparing 2-chloro-3-methyl-4-methanesulfonylbenzoic acid, and the yield is low, only 72%
Dioxane and tetrahydrofuran are extremely flammable, irritating, carcinogenic, and highly toxic. They are prone to produce peroxides during storage and recycling, and there is a safety risk of explosion.
Acetonitrile is a moderately toxic regulated chemical, which is likely to cause chronic poisoning accidents during production and is not easy to recycle
[0006] In summary, the current method uses aprotic polar solvents such as dioxane, acetonitrile, and tetrahydrofuran, which are highly toxic and miscible with water, to react with excess sodium hypochlorite solution to prepare 2-chloro-3-methyl-4- Methylsulfonylbenzoic acid has the disadvantages of low reaction yield, high solvent cost, complicated operation process, and difficult solvent recovery. At the same time, dioxane and tetrahydrofuran will produce peroxides in the process of recovery and recycling, and there is a risk of explosion. Safety risks are not conducive to the improvement of intrinsic safety and cannot realize green and clean production

Method used

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  • Method for preparing 2-chloro-3-methyl-4-methylsulfonyl benzoic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Weigh 1mol of 2-chloro-3-methyl-4-methylsulfonylacetophenone, 10mol of 6% sodium hypochlorite aqueous solution (calculated as sodium hypochlorite), and 0.1mol of benzyltriethylammonium chloride are added to the reaction flask, and the temperature is slowly raised to 100°C, keep warm for 0.5h. After the reaction, cool down to 30°C, add 36% hydrochloric acid dropwise to acidify to PH = 1, stir and crystallize for 4 hours, filter, wash the filter cake with 2% aqueous hydrochloric acid, and dry to obtain white powdery solid 2-chloro-3- Methyl-4-methylsulfonylbenzoic acid 247.5g, content 97.9%, yield 97.5%.

[0028] According to the above reaction conditions and steps, using benzyltriethylammonium chloride as a phase transfer catalyst, the influence of catalysts with different molar equivalents on the reaction results is shown in Table 1.

[0029] The impact of table 1 catalyst dosage on reaction result

[0030] batch number Catalyst molar equivalent Product ...

Embodiment 2

[0033] Weigh 1mol of 2-chloro-3-methyl-4-methylsulfonylacetophenone, 3mol of 15% sodium hypobromite aqueous solution (calculated as sodium hypobromite), and 0.05mol of tetrabutylammonium bromide into the reaction flask , control the temperature to 5°C, and keep the reaction for 8h. After the reaction, cool down to -10°C, add 40% hydrobromic acid dropwise to acidify to PH = 1, stir and crystallize for 0.5h, filter, wash the filter cake with 20% hydrobromic acid aqueous solution, and dry to obtain a white powdery solid 246.2 g of 2-chloro-3-methyl-4-methylsulfonylbenzoic acid, content 97.0%, yield 96.1%.

[0034] According to the reaction conditions and steps in Example 2, the impact of different ionic catalyst types on the reaction results is shown in Table 2, and the impact of non-ionic catalyst types on the reaction results is shown in Table 3.

[0035] Table 2 The impact of the type of ionic catalyst on the reaction result

[0036] batch number Types of Ionic C...

Embodiment 3

[0045] Weigh 1 mol of 2-chloro-3-methyl-4-methylsulfonylacetophenone, 5 mol of 10% sodium hypochlorite aqueous solution (calculated as sodium hypochlorite), and 0.01 mol of tetrabutylammonium bisulfate into the reaction flask, and slowly heat up to 55°C , insulation reaction 3h. After the reaction, cool down to 10°C, add 98% sulfuric acid dropwise to acidify to PH = 1, stir and crystallize for 2 hours, filter, wash the filter cake with 10% aqueous sulfuric acid, and dry to obtain white powdery solid 2-chloro-3- Methyl-4-methylsulfonylbenzoic acid 242.1g, content 97.8%, yield 95.3%.

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Abstract

The invention discloses a method for preparing 2-chloro-3-methyl-4-methylsulfonyl benzoic acid, which comprises the following step: in a water phase, carrying out haloform reaction on 2-chloro-3-methyl-4-methylsulfonyl acetophenone and sodium hypohalide under the action of a phase transfer catalyst to obtain the 2-chloro-3-methyl-4-methylsulfonyl benzoic acid. According to the preparation method provided by the invention, toxic and high-risk solvents are not needed, solvent recovery operation and safety risks do not exist, and the production cost is reduced; and meanwhile, side reactions are reduced, the product yield and content are greatly improved, the method is green and environment-friendly, and the intrinsic safety is improved.

Description

technical field [0001] The present invention relates to a kind of method for preparing 2-chloro-3-methyl-4-methylsulfonylbenzoic acid, specifically, utilize phase transfer catalytic reaction to prepare 2-chloro-3-methyl-4- Methanesulfonylbenzoic acid method. Background technique [0002] 2-Chloro-3-methyl-4-methylsulfonylbenzoic acid, CAS No. 106904-09-0, English name 2-Chloro-3-methyl-4-methylsulfonylbenzoic acid, is an important intermediate for the synthesis of tembotrione . Ebitrione is a triketone HPPD inhibitor herbicide, mainly used for the control of gramineous weeds, broad-leaved weeds, malignant weeds and resistant weeds in corn fields and rice fields, and has very high herbicidal activity. Huge capacity. [0003] At present, the synthesis of 2-chloro-3-methyl-4-methylsulfonylbenzoic acid needs to dissolve 2-chloro-3-methyl-4-methylsulfonylacetophenone in dioxane, acetonitrile, tetrahydrofuran and other aprotic In polar solvents, it can be obtained by haloform ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C317/44C07C315/04
CPCC07C315/04C07C317/44
Inventor 李新生徐宁孙敬权许宜伟孙丽梅李林虎
Owner 利民化学有限责任公司
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