Preparation method of 2-methoxy-6-methylbenzoic acid

A kind of technology of methyl benzoic acid and methyl benzoate is applied in the field of preparation of 2-methoxy-6-methyl benzoic acid, and can solve the difficulty of 2-methoxy-6-methyl benzoic acid source , the lack of reports, etc.

Inactive Publication Date: 2021-07-06
JIANGSU YONGAN CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the existing process, the source of 2-methoxy-6-methylbenzoic acid is difficult and there are few reports, so it is of great significance to develop a new synthesis process

Method used

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  • Preparation method of 2-methoxy-6-methylbenzoic acid
  • Preparation method of 2-methoxy-6-methylbenzoic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] (1) Reductive hydrogenation

[0035] Add 2-methyl-6-nitrobenzoic acid (500 g), platinum carbon (platinum content: 2%, 50 g), methanol (2000 g), into the autoclave, replace with nitrogen, and pass hydrogen to a pressure of 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.

[0036] (2) Diazotization hydrolysis

[0037] 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 8-12 hours until the reaction is complete (HPLC: 2-hydroxy-6-methylbenzoic acid+2-methoxy-6-methylbenzoic acid<1 %).

[003...

Embodiment 2

[0046] (1) Reductive hydrogenation

[0047] Add 2-methyl-6-nitrobenzoic acid (450 g), platinum carbon (platinum content: 2%, 9.0 g), methanol (1350 g), into the autoclave, nitrogen replacement, and 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.

[0048] (2) Diazotization hydrolysis

[0049] The reduction mother liquor (1 / 3 amount) obtained in step (1) is cooled to 5-10°C, and 317.3 g of nitrosyl sulfuric acid (mass concentration 40%, 1.2 eq.) is added dropwise under temperature control. After the addition is completed, the temperature is slowly raised to 50-60 ℃, control the heating time not less than 30min, after stirring for 1 hour, raise the temperature to 64-66℃ and reflux for 12-16 hours until t...

Embodiment 3

[0055] diazotization hydrolysis

[0056] The reduction mother liquor (1 / 3 amount) obtained in step (1) of Example 2 was cooled to 10-15°C, and 277.6 g of sodium nitrite solution (mass concentration 40%, 1.05 eq.) was added dropwise under temperature control, and the addition was completed 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: 2-hydroxy-6-methylbenzoic acid + 2-methoxy-6-methyl benzoic acid <1%).

[0057] 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.

[0058] The aqueous layer was extracted with MIBK 100ml, the organic layer was separated and concentrated, and then combined with the oil layer to obtain 141 g of crude product of methyl 2-hydroxy-6-methylbenzoate (HPLC: methyl 2-hydroxy-6-methylbenzoate: 45.6%; 2-methoxy-6-meth...

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Abstract

The invention discloses a synthesis process of 2-methoxy-6-methylbenzoic acid, which comprises the following steps: (1) reduction hydrogenation reaction: by taking 2-methyl-6-nitrobenzoic acid or methyl 2-methyl-6-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 2-amino-6-methylbenzoic acid or methyl 2-amino-6-methylbenzoate; (2) diazotization, hydrolysis and esterification one-pot reaction: by taking the reduction product as a raw material, and methanol as a solvent, performing diazotization, hydrolysis and esterification reaction under the action of a diazotization reagent to prepare methyl 2-hydroxy-6-methylbenzoate; (3) methylation reaction: with methyl 2-hydroxy-6-methylbenzoate as a raw material and dimethyl sulfate as a methylation reagent, carrying out methylation reaction in the presence of alkali to prepare methyl 2-methoxy-6-methylbenzoate; and (4) hydrolysis reaction: mixing the methyl 2-methoxy-6-methylbenzoate 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, and conducting filtering and drying to obtain the 2-methoxy-6-methylbenzoic acid.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, relates to the synthesis of organic intermediates, in particular to a preparation method of 2-methoxy-6-methylbenzoic acid. Background technique [0002] 2-methoxy-6-methylbenzoic acid is a key synthetic intermediate of the pesticide fungicide metrafenone. Metrafenone was first produced as a benzophenone-type fungicide metrafenone by the American Cyanoamine Company (now owned by BASF, Germany). Actin, the cytoskeleton of the pathogen, is destroyed and disintegrated, resulting in abnormal branching of the mycelium and slowing down the growth, so as to achieve the purpose of preventing and controlling powdery mildew. It has excellent activity against powdery mildew and eye spot disease on grains, melons, beans, grapes and other crops. It was launched in the UK in 2004. In the following year, BASF temporarily registered 98% of metrafenone technical and 42% of benzoin in my country. Bacter...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C65/21C07C51/09C07C69/92C07C67/31C07C69/84C07C67/08C07C229/56C07C227/04
CPCC07C51/09C07C67/31C07C67/08C07C227/04
Inventor 耿敬坤方浙能姚林夕张燕超苗君慧王博涛季品俊
Owner JIANGSU YONGAN CHEM CO LTD
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