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A kind of continuous synthesis method of phenoxyacetic acid

A technology for the synthesis of phenoxyacetic acid, which is applied in chemical instruments and methods, preparation of organic compounds, organic chemistry, etc., can solve problems such as increased consumption of chloroacetic acid, reduced selectivity and yield of chemical synthesis reactions, and meets equipment requirements Low, reduce energy consumption, improve the effect of yield

Active Publication Date: 2017-04-26
邳州市润宏实业有限公司
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

The current method for preparing phenoxyacetic acid is to directly react sodium chloroacetate and sodium phenate at the reflux temperature, and then acidify to obtain the target product. For example, Chinese patents CN101062893A, CN101066915A, CN101921188A, CN102911039A, CN103058855A, etc. generally adopt kettle reaction or batch method For production, the molar ratio of chloroacetic acid to phenol is 2 to 1.4:1.0, because chloroacetic acid is prone to dechlorination and hydrolysis under alkaline conditions to obtain glycolic acid, which leads to a decrease in the selectivity and yield of the chemical synthesis reaction, and increases consumption of chloroacetic acid

Method used

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  • A kind of continuous synthesis method of phenoxyacetic acid
  • A kind of continuous synthesis method of phenoxyacetic acid

Examples

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Effect test

example 1

[0024] 1) Add 56.7g of chloroacetic acid to a clean 500mL four-necked bottle and slowly dissolve the solid Na with 100g of water under stirring 2 CO 3 26.5g was dissolved and slowly added to chloroacetic acid to obtain a colorless sodium chloroacetate solution for use;

[0025] 2) Add 47g of solid phenol and 60g of water to a clean 1000mL four-necked bottle, and slowly add 40% sodium hydroxide solution (24g of sodium hydroxide + 36g of purified water) dropwise under nitrogen protection to control the temperature below 35°C;

[0026] 3) Add sodium phenate aqueous solution and sodium chloroacetate aqueous solution at a molar ratio of 1.0: 1.0 to a constant pressure funnel with a heating sleeve at the same time, and react at about 95°C to keep the retention time at 15 minutes. The reaction solution is then Overflow into a three-necked flask filled with dilute hydrochloric acid at 15°C, adjust pH=5 with dilute hydrochloric acid, then stir at 25°C for 1 hour, and filter with sucti...

example 2

[0028] 1) Add 56.7 g of chloroacetic acid to a clean 500 mL four-necked bottle and slowly dissolve the solid Na with 100 g of water under stirring. 2 CO 3 26.5g was dissolved and slowly added to chloroacetic acid to obtain a colorless sodium chloroacetate solution for use;

[0029] 2) Add 47 g of solid phenol and 60 g of water to a clean 1000 mL four-necked bottle, and slowly add 40% sodium hydroxide solution (24 g of sodium hydroxide + 36 g of purified water) dropwise under nitrogen protection to control the temperature at 35 Below ℃;

[0030] 3) The sodium phenate aqueous solution and the sodium chloroacetate aqueous solution were added dropwise at the same time in a constant pressure funnel with a heating sleeve at a molar ratio of 1.0: 1.05, and reacted at about 95°C to keep the retention time at 12 min. Then overflowed into a three-necked flask filled with dilute sulfuric acid at 20°C, adjusted to pH=6 with dilute sulfuric acid, then stirred at 30°C for 1 h, and filter...

example 3

[0032] 1) Add 56.7 g of chloroacetic acid to a clean 500 mL four-necked bottle and slowly dissolve the solid Na with 100 g of water under stirring. 2 CO 3 26.5 g was dissolved, and it was slowly added to chloroacetic acid to obtain a colorless sodium chloroacetate solution for use;

[0033] 2) Add 47 g of solid phenol and 60 g of water to a clean 1000 mL four-necked bottle, and slowly add 40% sodium hydroxide solution (24 g of sodium hydroxide + 36 g of purified water) dropwise under nitrogen protection to control the temperature Below 35°C;

[0034] 3) Add sodium phenate aqueous solution and sodium chloroacetate aqueous solution at a molar ratio of 1.0: 1.0~1.03 to a constant pressure funnel with a heating sleeve at the same time, and react at about 95°C to keep the retention time at 10 minutes. The liquid then overflowed into a three-neck flask filled with dilute hydrochloric acid at 18°C, adjusted to pH=5.5 with dilute hydrochloric acid, then stirred at 27°C for 1 h, and ...

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Abstract

The invention provides a continuous synthetic method of phenoxy acetic acid and belongs to the technical field of preparation of a herbicide 2,4-D intermediate. The method comprises the following steps: simultaneously adding a sodium phenoxide aqueous solution and a sodium chloroacetate aqueous solution into a constant-pressure funnel provided with a heating sleeve to perform mixed reaction, and retaining the mixture in the constant-pressure funnel for 10-15min; overflowing reaction liquid into a 3-mouth flask containing dilute hydrochloric acid or dilute sulfuric acid at 15-20 DEG C; adjusting the pH value to 5-6 by using the dilute hydrochloric acid or dilute sulfuric acid; stirring for 0.8-1.2 hours at room temperature; and performing suction filtration to obtain white crystalline powder namely phenoxy acetic acid. According to the method provided by the invention, the sodium phenoxide aqueous solution and the sodium chloroacetate aqueous solution are simultaneously added into the constant-pressure funnel provided with the heating sleeve to perform reaction, so that the internal pressure can be kept unchanged, inverse suction can be prevented and the liquid in the funnel can flow downwards smoothly to improve the reaction efficiency; and moreover, during the preparation of the sodium chloroacetate solution, a Na2CO3 solution is dropwise added into chloroacetic acid slowly, and the chloroacetic acid is excessive, so that the reaction temperature can be beneficially controlled, and side reactions are reduced.

Description

technical field [0001] The invention belongs to the technical field of preparation of herbicide 2,4-D intermediates, in particular to a continuous synthesis method of phenoxyacetic acid. Background technique [0002] 2,4-D is a phenoxycarboxylic acid herbicide, which has a very broad market demand. Phenoxyacetic acid is a key intermediate in its first etherification and then chlorination process. The current method for preparing phenoxyacetic acid is to directly react sodium chloroacetate and sodium phenate at reflux temperature, and then acidify to obtain the target product. For example, Chinese patents CN101062893A, CN101066915A, CN101921188A, CN102911039A, CN103058855A, etc. generally adopt kettle reaction or batch method For production, the molar ratio of chloroacetic acid to phenol is 2 to 1.4:1.0, because chloroacetic acid is prone to dechlorination and hydrolysis under alkaline conditions to obtain glycolic acid, which leads to a decrease in the selectivity and yield...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C59/70C07C51/41C07C51/02C07C51/367
CPCC07C51/02C07C51/367C07C51/41C07C59/70
Inventor 何海琴戴志猛蓝健戴丹丹谭成侠
Owner 邳州市润宏实业有限公司
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