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Method for synthesizing 2,3,5,6-tetrafluorophenol

A technology of tetrafluorophenol and pentafluorobenzoic acid, applied in chemical instruments and methods, preparation of organic compounds, organic chemistry and other directions, can solve the problems of high cost, complicated operation, increased cost and the like, and achieves less environmental pollution and convenient operation. Effect

Active Publication Date: 2021-08-06
宁夏忠同生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method realizes 2,3,5,6-tetrafluorophenol through a two-step reaction, the operation is cumbersome, and solvent extraction is used in the preparation of 4-hydroxy-2,3,5,6-tetrafluorobenzoic acid, and the cost is relatively high; More N,N-dimethylaniline is used in the decarboxylation of 4-hydroxy-2,3,5,6-tetrafluorobenzoic acid, and the decarboxylation reaction is carried out at 160°C, which not only increases the cost but also consumes a certain amount of energy. Increase

Method used

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  • Method for synthesizing 2,3,5,6-tetrafluorophenol

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Effect test

Embodiment 1

[0025] 404 grams of DMF and 202.3 grams of sodium acetate were charged into a 1L glass reactor. Add 106.0 g of pentafluorobenzoic acid at a temperature of 50-55°C. Heated and refluxed for 6 hours. HPLC detects that the raw material content of the reaction solution is lower than 1.0%, and drops below 80° C., and 350.0 grams of 30% concentrated hydrochloric acid is added to the kettle to adjust the pH to be less than 1. Then the temperature was raised to reflux for 5 hours. After the reflux is completed, steam distillation is carried out to separate the lower organic matter. The organic matter in the lower layer was rectified to obtain 74.0 g of 2,3,5,6-tetrafluorophenol, which turned into white crystals after cooling down. The yield was 89%, and the HPLC purity was 99.9%.

Embodiment 2

[0027] 305 g of DMSO and 202.3 g of sodium acetate were charged into a 1 L glass reactor. Add 106.0 g of pentafluorobenzoic acid at a temperature of 50-55°C. The temperature was raised to reflux for 2 hours. HPLC detects that the raw material content of the reaction solution is lower than 1.0%, and drops below 80° C., and 350.0 grams of 30% concentrated hydrochloric acid is added to the kettle to adjust the pH to be less than 1. Then the temperature was raised to reflux for 5 hours. After the reflux is completed, steam distillation is carried out to separate the lower organic matter. The organic matter in the lower layer was rectified to obtain 76.6 g of 2,3,5,6-tetrafluorophenol, which turned into white crystals after cooling down. The yield was 92%, and the HPLC purity was 99.8%.

Embodiment 3

[0029] Put 800 grams of water and 202.3 grams of sodium acetate into a 1L glass reactor. Add 106.0 g of pentafluorobenzoic acid at a temperature of 55-60°C. Heated and refluxed for 40 hours. HPLC detects that the raw material content of the reaction solution is lower than 1.0%, and drops below 80° C., and 350.0 grams of 30% concentrated hydrochloric acid is added to the kettle to adjust the pH to be less than 1. Then the temperature was raised to reflux for 5 hours. After the reflux is completed, steam distillation is carried out to separate the lower organic matter. The organic matter in the lower layer was rectified to obtain 73.2 g of 2,3,5,6-tetrafluorophenol, which turned into white crystals after cooling down. The yield was 88%, and the HPLC purity was 99.8%.

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Abstract

The invention discloses a method for synthesizing 2,3,5,6-tetrafluorophenol, belonging to the field of fine chemical engineering. According to the invention, short-chain sodium aliphatate with large steric hindrance and pentafluorobenzoic acid are subjected to a reflux reaction in a polar solvent; after the reaction is finished, strong acid hydrolysis decarboxylation and steam distillation are performed; and a water vapor distillation product is rectified to obtain 2,3,5,6-tetrafluorophenol, the purity of 2,3,5,6-tetrafluorophenol is 99.8% or above, and the yield of 2,3,5,6-tetrafluorophenol is 88% or above. The method has the remarkable characteristics of simplicity and convenience in operation and small environmental pollution, and has a relatively good economic value in preparation of a 2,3,5,6-tetrafluorophenol product.

Description

technical field [0001] The invention relates to a method for synthesizing 2,3,5,6-tetrafluorophenol, which belongs to the technical field of fine chemicals. Background technique [0002] 2,3,5,6-Tetrafluorophenol is a widely used fine chemical intermediate, mainly used in the field of pharmaceutical intermediates and new materials. There are two main methods of synthesis. [0003] CN104926617A reported that 1,2,4,5-tetrafluorobenzene reacted with borate ester under the action of organolithium reagent to obtain 2,3,5,6-tetrafluorophenylboronic acid / ester; then obtained 2,3 ,5,6-Tetrafluorophenol, the total yield is 86%, and the purity is 99.7%. In this method, the reaction temperature needs to be controlled below -50°C in an anhydrous and oxygen-free environment. At the same time, an organolithium reagent with a risk of fire is used in the synthesis. Therefore, the synthesis cost of this method is high and there are potential safety hazards. [0004] CN108069832A has repor...

Claims

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Application Information

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IPC IPC(8): C07C37/055C07C37/50C07C37/76C07C39/27C07C67/11C07C69/63
CPCC07C37/0555C07C37/50C07C37/76C07C67/11C07C69/63C07C39/27
Inventor 张同斌刘英亮王涛李锋耿艺文孙艳萍姜殿平
Owner 宁夏忠同生物科技有限公司