Synthesis process of 2-methyl-3-methoxybenzoic acid

A technology of methoxybenzoic acid and toluic acid, which is applied in the field of synthesis of organic pesticide intermediates, can solve problems such as difficult to meet the production demand of the pesticide methoxyfenozide, unstable product quality, corrosion of equipment and pipelines, and achieve Product quality is stable and controllable, meets quality requirements, and reduces usage

Inactive Publication Date: 2021-10-19
JIANGSU YONGAN CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method also has the disadvantages of many reaction steps and complicated separation and purification.
And in the process of preparing methoxyfenozide from 3-methoxyl-2-methylbenzoic acid obtained by this method, it is necessary to carry out vacuum distillation operation to intermediate 3-methoxyl-2-methylbenzoyl chloride , acyl chlorides severely corrode the equipment and...

Method used

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  • Synthesis process of 2-methyl-3-methoxybenzoic acid
  • Synthesis process of 2-methyl-3-methoxybenzoic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] (1) Reductive hydrogenation

[0043] 3-nitro-2-methylbenzoic acid (500 g), platinum carbon (platinum content 2%, 50 g), methanol (2000 g), add to the autoclave, replace with nitrogen, and pass hydrogen to 1.0-1.3 MPa , raise the temperature to 70-80°C, control the temperature and control the reaction pressure until the reaction is complete (raw material <0.5%), continue to stir for 60 min, filter while hot, collect the catalyst for mechanical use, and directly carry out diazotization hydrolysis of the mother liquor.

[0044] (2) Diazotization hydrolysis

[0045] The temperature of the reduction mother liquor obtained in step (1) is lowered to 0-5°C, and 900 g of nitrosyl sulfuric acid (weight percentage: 40%, 1.02 eq.) is added dropwise under temperature control. 30min, after stirring for 1 hour, heat up to 64-66°C and reflux for 4-8 hours until the reaction is complete (HPLC: 3-hydroxy-2-methylbenzoic acid+3-methoxy-2-methylbenzoic acid<1 %).

[0046] The temperatur...

Embodiment 2

[0054] (1) Reductive hydrogenation

[0055] Add 3-nitro-2-methylbenzoic acid (450 g), platinum carbon (platinum content 2%, 9.0 g), methanol (1350 g), into the autoclave, nitrogen replacement, hydrogen pressure to 0.9-1.1 MPa , raise the temperature to 60-70°C, control the temperature and control the reaction pressure until the reaction is complete (raw material <0.5%), continue to stir for 30 min, filter while hot, divide the mother liquor into three parts while hot, and directly carry out diazotization hydrolysis.

[0056] (2) Diazotization hydrolysis

[0057] Add 92.2 g (1.2 eq.) of sulfuric acid to the reduction mother liquor (1 / 3 amount) obtained in step (1), cool down to 5-10°C, and add 126.6 g of sodium nitrite solution dropwise under temperature control (sodium nitrite: 63.6 g, 1.2 eq. .; Water: 63 g), after adding, slowly raise the temperature to 50-60°C, control the heating time for not less than 30min, stir for 1 hour, then raise the temperature to 64-66°C and refl...

Embodiment 3

[0063] diazotization hydrolysis

[0064] Add 150.6 g (2.0 eq.) of sulfuric acid to the reduction mother liquor obtained in step (1) of Example 2, add 150.6 g (2.0 eq.) of sulfuric acid, lower the temperature to 20-30°C, and add 155.7 g of sodium nitrite solution dropwise under temperature control (sodium nitrite: 55.7 g, 1.05 eq.; water: 100 g), after the addition, slowly raise the temperature to 50-60°C, stir for 1 hour, then raise the temperature to 64-66°C and reflux for 8-16 hours until the reaction is complete (HPLC: 3-hydroxy -2-methylbenzoic acid + 3-methoxy-2-methylbenzoic acid <1%).

[0065] Raise the temperature to 85-100°C, recover about 360 g of methanol by atmospheric distillation, add 400 g of water, let stand to separate layers, and separate 105 g of oil layer.

[0066] The aqueous layer was extracted with MIBK 100ml, the organic layer was separated and concentrated, and then combined with the oil layer to obtain 138 g of crude 3-hydroxy-2-methylbenzoate (HPLC:...

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Abstract

The invention discloses a synthesis process of 2-methyl-3-methoxybenzoic acid, which comprises the following steps: (1) reductive hydrogenation reaction: by taking 2-methyl-3-nitrobenzoic acid or methyl 2-methyl-3-nitrobenzoate as a raw material, methanol as a solvent, hydrogen as a hydrogen source and palladium on carbon or platinum on carbon as a catalyst, carrying out hydrogenation reduction to prepare 3-amino-2-methyl benzoic acid or methyl 3-amino-2-methyl benzoate; (2) diazotization, hydrolysis and esterification one-pot reaction: by taking the reduction product as a raw material and methanol as a solvent, under the action of a diazotization reagent, performing diazotization, hydrolysis and esterification reaction to prepare methyl 3-hydroxy-2-methyl benzoate; (3) methylation reaction: by taking methyl 3-hydroxy-2-methyl benzoate as a raw material and dimethyl sulfate as a methylation reagent, carrying out methylation reaction in the presence of alkali to prepare methyl 3-methoxy-2-methyl benzoate; and (4) hydrolysis reaction: mixing the methyl 3-methoxy-2-methyl benzoate with alkali and water, conducting heating for hydrolysis, conducting cooling after the reaction is completed, adjusting the pH value to 1-3 by using acid, separating out a product, conducting filtering, and conducting drying to obtain 3-methoxy-2-methyl benzoic acid.

Description

technical field [0001] The invention belongs to the technical field of synthesis of organic pesticide intermediates, in particular to a synthesis process of 2-methyl-3-methoxybenzoic acid. Background technique [0002] 2-Methyl-3-methoxybenzoic acid is an important intermediate of the high-efficiency and low-toxicity pesticide methoxyfenozide. The traditional preparation process depends on the different starting materials. The following three methods are important: [0003] Method 1: Use 2,6-dichlorotoluene as a raw material to obtain 3-methoxy-2-methylbenzoic acid through etherification, Grignard reaction, hydrolysis, or Grignard reaction, hydrolysis, and etherification. This method adopts the highly toxic reagent sodium cyanide and the grid reaction, which has high safety risks, unstable yield and product quality, and is not conducive to industrialization. [0004] Method 2: Using 2-methyl-3-nitrobenzoic acid as a raw material, synthesize 3-methoxy-2-methylbenzoic acid th...

Claims

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Application Information

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IPC IPC(8): C07C59/64C07C51/09
CPCC07C51/09C07C67/31C07C227/04C07C59/64C07C69/92C07C229/60
Inventor 耿敬坤方浙能姚林夕季品俊张燕超苗君慧王博涛
Owner JIANGSU YONGAN CHEM CO LTD
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