Preparation method of 2,5-dichlorophenol

A technology of dichlorophenol and p-dichlorobenzene, which is applied in the field of preparation of 2,5-dichlorophenol, can solve the problems of not being suitable for large-scale industrial production, difficult separation of mixed phenols, and low conversion rate of raw materials, etc., to achieve suitable Large-scale industrial production, less waste production and high yield

Inactive Publication Date: 2015-05-06
ANHUI XUELANG BIOTECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, there are three main processes for preparing 2,5-dichlorophenol. The patent US4326882 proposes to use 2,5-dichloroaniline as a raw material to prepare 2,5-dichlorophenol through diazotization and hydrolysis. This process It is currently the most mature 2,5-dichlorophenol production process. Its biggest disadvantage is that the route is long, a large amount of waste water is generated, and the pollution is serious; the patent US2799714 proposes to use 1,2,4-trichlorobenzene as raw material, alkali Mixed dichlorophenols were obtained by hydrolysis under neutral conditions, and then separated to obtain 2,5-dichlorophenols
The process route is simple, but the separation of mixed phenols is difficult and the yield is not high; patents such as US6586624, US6323377, and CN1793096A propose to use p-dichlorobenzene as a raw material to directly carry out hydroxylation reaction with hydrogen peroxide to prepare 2,5-dichlorophenol. This process is a green process, but the conversion rate of raw materials is very low, so it is not suitable for large-scale industrial production

Method used

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  • Preparation method of 2,5-dichlorophenol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] (1) Add 14.7g of p-dichlorobenzene and 26.6g of anhydrous aluminum trichloride to a 250ml three-neck flask, heat up to 65°C while stirring, add 8.6g of acetyl chloride dropwise, heat up to 115°C after 2 hours, and continue the reaction 6h. Slowly add 50ml of ice water, then add 100ml of dichloromethane for extraction, separate the dichloromethane phase and distill out the dichloromethane, carry out vacuum distillation with an oil pump, collect the fractions at about 70°C, and obtain 2,5-dichlorophenethyl The ketone was 14.2g, the yield was 75%, and the content detected by gas chromatography was 99%.

[0022] (2) Add 60 ml of a mixed solvent of dichloromethane and acetone with a volume ratio of 2:1 to a 250 ml three-necked flask at room temperature, then add 2.46 g of scandium trifluoromethanesulfonate as a catalyst, and 50 ml of 30% peracetic acid as an oxidizing agent. After stirring evenly, 18.9 g of 2,5-dichloroacetophenone was added dropwise, and the dropwise addit...

Embodiment 2

[0025] (1) Add 14.7g of p-dichlorobenzene and 33.3g of anhydrous aluminum trichloride to a 250ml three-neck flask, heat up to 65°C while stirring, add 11.8g of acetyl chloride dropwise, and heat up to 100°C after 2 hours of dripping, continue the reaction 5h. Slowly add 50ml of ice water, then add 100ml of dichloromethane for extraction, separate the dichloromethane phase and distill out the dichloromethane, carry out vacuum distillation with an oil pump, collect the fractions at about 70°C, and obtain 2,5-dichlorophenethyl The ketone was 18.0 g, the yield was 95%, and the content detected by gas chromatography was 99%.

[0026] (2) Add 105ml of a mixed solvent of dichloromethane and acetone at a volume ratio of 20:1 to a 250ml three-necked flask at room temperature, add 2.46g of scandium trifluoromethanesulfonate as a catalyst, and 46g of 75% m-chloroperoxybenzoic acid as an oxidizing agent. After stirring evenly, 18.9 g of 2,5-dichloroacetophenone was added dropwise, and th...

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Abstract

The invention discloses a preparation method of 2,5-dichlorophenol and relates to the technical field of pesticide intermediate synthesis. The preparation method comprises the following steps: with p-dichlorobenzene as a start raw material, performing a Friedel-Crafts acylation reaction between the p-dichlorobenzene and acetyl chloride in the presence of aluminum trichloride to obtain 2,5-dichloroacetophenone; performing a Baeyer-Villiger oxidation reaction between the 2,5-dichloroacetophenone and a peroxide in the presence of a catalyst at room temperature to obtain 2,5-dichlorobenzene acetate; and performing a hydrolysis reaction between the 2,5-dichlorobenzene acetate and inorganic aqueous alkali in a reflux condition to obtain 2,5-dichlorophenol. The preparation method disclosed by the invention has the characteristics of simple synthesis process, short line, low production cost and high yield; and moreover, with less quantity of generated three wastes and high environmental protection property, the preparation method is more suitable for large-scale industrial production.

Description

Technical field: [0001] The invention relates to the technical field of pesticide intermediate synthesis, in particular to a preparation method of 2,5-dichlorophenol. Background technique: [0002] The pure product of 2,5-dichlorophenol is a white needle-like crystal with a special odor. It is an important intermediate for the synthesis of benzoin herbicide dicamba. At present, there are three main processes for preparing 2,5-dichlorophenol. The patent US4326882 proposes to use 2,5-dichloroaniline as a raw material to prepare 2,5-dichlorophenol through diazotization and hydrolysis. This process It is currently the most mature 2,5-dichlorophenol production process. Its biggest disadvantage is that the route is long, a large amount of waste water is generated, and the pollution is serious; the patent US2799714 proposes to use 1,2,4-trichlorobenzene as raw material, alkali Mixed dichlorophenols were obtained by hydrolysis under neutral conditions, and then separated to obtain ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C39/30C07C37/055
CPCC07C45/46C07C37/0555C07C67/00
Inventor 李云政万玉青张磊李龙辉
Owner ANHUI XUELANG BIOTECHNOLOGY CO LTD
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