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Method for synthesizing 3,4-difluoro-2-methylbenzoic acid

A technique for the synthesis of toluic acid and its synthesis method, which is applied in the fields of chemical instruments and methods, separation/purification of carboxylic acid compounds, preparation of carboxylate, etc., and can solve the problems of multiple synthesis steps, high price of bromine, unfavorable atom economy, etc. problem, to achieve the effect of simple synthesis process and cost reduction

Inactive Publication Date: 2019-09-06
HUNAN NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The route of using difluorotoluene as a raw material through bromination and Grignard reaction has a higher yield per step, but there are many synthesis steps, bromine atoms are not introduced into the target molecule, and the price of bromine is relatively high. Therefore, from the perspective of atom economy is disadvantageous from the point of view of
Moreover, the preparation and reaction of the Grignard reagent in the route require anhydrous and oxygen-free conditions, which require high production equipment and operations.

Method used

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  • Method for synthesizing 3,4-difluoro-2-methylbenzoic acid
  • Method for synthesizing 3,4-difluoro-2-methylbenzoic acid
  • Method for synthesizing 3,4-difluoro-2-methylbenzoic acid

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Embodiment 1

[0008] Embodiment 1: in the three-necked flask that electric stirrer is housed, thermometer and airway tube, add 12.8g (0.1mol) 2,3-difluorotoluene and 13.1g (0.1mol) anhydrous aluminum trichloride, pass into Carbon dioxide gas, turn on the stirring device. Observe the temperature change, when the reaction temperature rises to the highest (about 28 °C) and then falls back, place the three-necked flask in a water bath, and the temperature of the water bath is stabilized at 28 °C. The reaction was stopped after 10 h. The mixture in the three-necked flask was slowly poured into ice water with constant stirring. The obtained white precipitate was suction filtered. After suction filtration, the white solid was dispersed in 50 mL of petroleum ether, stirred, and suction filtered. The solid was taken, and the filtrate was recovered for later use. Suspend the above white powder in 20 mL of methanol, add 2 mL of concentrated HCl, stir at 45 °C for 30 min, then filter with suction, ...

Embodiment 2

[0009] Embodiment 2: Add 8.96g (0.07mol) 2,3-difluorotoluene and 13.1g (0.1mol) anhydrous aluminum trichloride in the three-necked flask that electric stirring device is housed, thermometer and airway, pass into Carbon dioxide gas, turn on the stirring device. Observe the temperature change. When the reaction temperature rises to the highest level (about 30 °C) and then falls back, place the three-necked flask in a water bath, and the temperature of the water bath is stabilized at 30 °C. After the reaction was carried out for 10 h, the reaction was stopped. The mixture in the three-necked flask was slowly poured into ice water with constant stirring. The obtained white precipitate was suction filtered. After suction filtration, the white solid was dispersed in 50 mL of petroleum ether, stirred, and suction filtered. The solid was taken, and the filtrate was recovered for later use. Suspend the above white powder in 20 mL of methanol, add 2 mL of concentrated HCl, stir at 4...

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Abstract

The invention discloses a method for preparing 3,4-difluoro-2-methylbenzoic acid. 2,3-difluorotoluene used as a starting material reacts with carbon dioxide in the presence of anhydrous aluminum trichloride to obtain the 3,4-difluoro-2-methylbenzoic acid. The synthesis method is simple, economical and practical, allows the desired product to be obtained in one step, and allows the reaction to be carried out at room temperature or in a warm water bath, so the method has the advantages of low energy consumption, easiness in operation, high yield, low cost and great application prospect.

Description

technical field [0001] The present invention relates to the synthesis method of 3,4-difluoro-2-methylbenzoic acid. Background technique [0002] 3,4-difluoro-2-methylbenzoic acid is an important intermediate in the synthesis of ATP-competitive mTOR selective inhibitor XL388. Patent US5374606A reports a synthesis of 3,4-difluoro-2-methylbenzoic acid The method uses 3,4-difluorobenzoic acid as a raw material, and reacts with methyl iodide under the action of butyllithium to obtain the target compound. The reaction needs to be performed at low temperature (-78°C). The flammability of butyllithium and the high price of methyl iodide make this synthetic route unsuitable for industrial production. US2005054733A1 also discloses a method for synthesizing 3,4-difluoro-2-methylbenzoic acid. This patent uses 2,3-difluorotoluene as raw material, reacts with bromine under the catalysis of iron powder, and extracts and other post-treatments Distillation under reduced pressure after oper...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/15C07C63/70C07C51/43C07C51/42
CPCC07C51/15C07C51/42C07C51/43C07C63/70
Inventor 郑子建田晒校徐广宇
Owner HUNAN NORMAL UNIVERSITY
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