A kind of synthetic method of 2-nitro-3-methylbenzoic acid

Abstract

The invention discloses a method for synthesizing 2-nitro-3-methylbenzoic acid. The method comprises that powdery meta-methylbenzoic acid and nitric acid undergo a reaction at -30 to -15 DEG C to produce a nitrification reaction solution, and the nitrification reaction solution is separated and purified to form a 2-nitro-3-methylbenzoic acid product. The method has simple processes, is easy to operate, has a high conversion rate of m-methylbenzoic acid, has high selectivity of 2-nitro-3-methylbenzoic acid, and has obvious environmental protection effects and significant economic benefits.

Description

technical field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method for synthesizing 2-nitro-3-methylbenzoic acid. Background technique

[0002] 2-nitro-3-methylbenzoic acid is the core starting material for the production of the blockbuster insecticides chlorantraniliprole and cyantraniliprole. At present, its synthesis method has the following two categories:

[0003] The first category: JP05132450 report, using 2-nitro-m-xylene as raw material, prepared by oxidation method, the chemical reaction that occurs is:

[0004]

[0005] The disadvantage of this method is that the source of raw materials is limited, the price is expensive, and the cost is high. At the same time, since the oxidation process itself belongs to a typical free radical reaction mechanism, various intermediate products are inevitably generated, resulting in difficulties in subsequent separation and purification.

[0006] The second category: using m-tolu...

Examples

Embodiment 1

[0043] Put 500 g of concentrated nitric acid with a mass fraction of 92% into a four-necked glass bottle with a volume of 1000 mL, start mechanical stirring, and cool down to -15°C. Add 50g of toluic acid powder with an average particle size of 180 microns into a glass bottle for reaction, keep stirring during the reaction and control the reaction temperature at -15°C, and stop the reaction after 10 minutes of reaction to obtain the main product 2-nitro- The nitration reaction liquid of 3-methylbenzoic acid, through HPLC analysis, the conversion ratio of raw material m-toluic acid is 99.1%, the selectivity of target product 2-nitro-3-methylbenzoic acid is 75.2%, to the obtained nitration Water was added to the reaction liquid, and filtered to obtain 2-nitro-3-methylbenzoic acid product with a purity of 99.2%.

Embodiment 2

[0045] Put 500 g of concentrated nitric acid with a mass fraction of 94% into a four-neck glass bottle with a volume of 1000 mL, turn on mechanical stirring, and cool down to -17°C. Add 66.6g of toluic acid powder with an average particle size of 160 microns into a glass bottle for reaction. During the reaction, keep stirring and control the reaction temperature -17°C. After 120 minutes of reaction, the reaction is terminated, and the main product is 2-nitro The nitration reaction solution of -3-methylbenzoic acid was analyzed by HPLC, the conversion rate of raw material m-methylbenzoic acid was 99.3%, and the selectivity of target product 2-nitro-3-methylbenzoic acid was 78.4%. Add water to the obtained nitration reaction solution, and filter to obtain 2-nitro-3-methylbenzoic acid product with a purity of 99.4%.

Embodiment 3

[0047] Put 500 g of concentrated nitric acid with a mass fraction of 96% into a four-neck glass bottle with a volume of 1000 mL, turn on mechanical stirring, and cool down to -17.8°C. Add 74.7g of toluic acid powder with an average particle size of 150 microns into a glass bottle for reaction. During the reaction, keep stirring and control the reaction temperature -17.8°C. After 35 minutes, the reaction is terminated, and the main product is 2-nitro -The nitration reaction liquid of 3-methylbenzoic acid, analyzed by HPLC, the conversion rate of raw material m-toluic acid is 99.4%, the selectivity of target product 2-nitro-3-methylbenzoic acid is 79.8%. Add water to the obtained nitration reaction solution, and filter to obtain 2-nitro-3-methylbenzoic acid product with a purity of 99.3%.

technical field

[0001] The invention relates to the technical field of fine chemicals, in particular to a method for synthesizing 2-nitro-3-methylbenzoic acid. Background technique

[0002] 2-nitro-3-methylbenzoic acid is the core starting material for the production of the blockbuster insecticides chlorantraniliprole and cyantraniliprole. At present, its synthesis method has the following two categories:

[0003] The first category: JP05132450 report, using 2-nitro-m-xylene as raw material, prepared by oxidation method, the chemical reaction that occurs is:

[0004]

[0005] The disadvantage of this method is that the source of raw materials is limited, the price is expensive, and the cost is high. At the same time, since the oxidation process itself belongs to a typical free radical reaction mechanism, various intermediate products are inevitably generated, resulting in difficulties in subsequent separation and purification.

[0006] The second category: using m-tolu...

Examples

Embodiment 1

[0043] Put 500 g of concentrated nitric acid with a mass fraction of 92% into a four-necked glass bottle with a volume of 1000 mL, start mechanical stirring, and cool down to -15°C. Add 50g of toluic acid powder with an average particle size of 180 microns into a glass bottle for reaction, keep stirring during the reaction and control the reaction temperature at -15°C, and stop the reaction after 10 minutes of reaction to obtain the main product 2-nitro- The nitration reaction liquid of 3-methylbenzoic acid, through HPLC analysis, the conversion ratio of raw material m-toluic acid is 99.1%, the selectivity of target product 2-nitro-3-methylbenzoic acid is 75.2%, to the obtained nitration Water was added to the reaction liquid, and filtered to obtain 2-nitro-3-methylbenzoic acid product with a purity of 99.2%.

Embodiment 2

[0045] Put 500 g of concentrated nitric acid with a mass fraction of 94% into a four-neck glass bottle with a volume of 1000 mL, turn on mechanical stirring, and cool down to -17°C. Add 66.6g of toluic acid powder with an average particle size of 160 microns into a glass bottle for reaction. During the reaction, keep stirring and control the reaction temperature -17°C. After 120 minutes of reaction, the reaction is terminated, and the main product is 2-nitro The nitration reaction solution of -3-methylbenzoic acid was analyzed by HPLC, the conversion rate of raw material m-methylbenzoic acid was 99.3%, and the selectivity of target product 2-nitro-3-methylbenzoic acid was 78.4%. Add water to the obtained nitration reaction solution, and filter to obtain 2-nitro-3-methylbenzoic acid product with a purity of 99.4%.

Embodiment 3

[0047] Put 500 g of concentrated nitric acid with a mass fraction of 96% into a four-neck glass bottle with a volume of 1000 mL, turn on mechanical stirring, and cool down to -17.8°C. Add 74.7g of toluic acid powder with an average particle size of 150 microns into a glass bottle for reaction. During the reaction, keep stirring and control the reaction temperature -17.8°C. After 35 minutes, the reaction is terminated, and the main product is 2-nitro -The nitration reaction liquid of 3-methylbenzoic acid, analyzed by HPLC, the conversion rate of raw material m-toluic acid is 99.4%, the selectivity of target product 2-nitro-3-methylbenzoic acid is 79.8%. Add water to the obtained nitration reaction solution, and filter to obtain 2-nitro-3-methylbenzoic acid product with a purity of 99.3%.

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