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Preparation method for 2,4-dichlorophenoxyacetic acid

A technology of dichlorophenoxyacetic acid and dichlorophenoxyacetic acid ester is applied in the field of preparation of 2,4-dichlorophenoxyacetic acid, and can solve problems such as low conversion rate and yield, incomplete reaction, adverse effects and the like , to achieve the effect of improving the conversion rate and yield of the reaction, reducing the reaction time and completing the reaction

Inactive Publication Date: 2018-09-07
SHANDONG RUNBO BIOTECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The solvent used in the above method is toluene or xylene, which is highly toxic and has a large adverse effect on the workshop workers and the environment.
Simultaneously above method has the defect that reaction is incomplete, conversion rate and yield are lower

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] 200g of ethanol, 95g (1mol) of chloroacetic acid and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated for 5h to obtain ethyl chloroacetate. 164g (1mol) of 2,4-dichlorophenol, 125g (1mol) of aqueous sodium hydroxide solution with a mass fraction of 32%, and 300g of DMF were mixed and stirred, heated and dehydrated to obtain a DMF solution of sodium 2,4-dichlorophenolate. Add the obtained ethyl chloroacetate to the DMF solution of sodium 2,4-dichlorophenate, stir for 0.5 h, add 200 g of water, separate layers, transfer the upper oil phase to a hydrolysis reactor, and add hydrogen with a mass fraction of 32% Sodium oxide aqueous solution 125g (1mol) was refluxed and stirred for 0.5h, added 130g of 30% hydrochloric acid, crystallized at 10°C for 1h, filtered, and the filter cake was dried to obtain 220g of 2,4-dichlorophenoxyacetic acid as a solid, with a purity of 99.2%, and a yield of 98.8 %.

Embodiment 2

[0035] 200g of methanol, 95g (1mol) of chloroacetic acid and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated for 5h to obtain methyl chloroacetate. 164g (1mol) of 2,4-dichlorophenol, 113g (1mol) of potassium hydroxide aqueous solution with a mass fraction of 50%, and 300g of DMAC were mixed and stirred, heated and dehydrated to obtain a DMAC solution of sodium 2,4-dichlorophenolate. Add the obtained methyl chloroacetate to the DMAC solution of potassium 2,4-dichlorophenate, stir for 0.4 h, add 200 g of water, separate layers, transfer the upper oil phase to a hydrolysis reactor, add 130 g of 30% hydrochloric acid, and reflux Dealcoholized for 3 hours, crystallized at 10°C for 1 hour, filtered, and the filter cake was dried to obtain 219 g of 2,4-dichlorophenoxyacetic acid as a solid, with a purity of 99.5% and a yield of 98.6%.

Embodiment 3

[0037] 300g of isooctyl alcohol, 140g (1mol) of bromoacetic acid and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated for 4 hours to obtain isooctyl bromoacetate. 164g (1mol) of 2,4-dichlorophenol, 125g (1mol) of 32% sodium hydroxide aqueous solution, 100g of DMSO, and 200g of isopropanol were mixed and stirred, heated and dehydrated to obtain a sodium 2,4-dichlorophenolate solution. Add the obtained isooctyl chloroacetate to the sodium 2,4-dichlorophenolate solution, stir for 0.6h, add 200g of water, separate layers, transfer the upper oil phase to a hydrolysis reactor, add 20g of concentrated sulfuric acid, and reflux dealcoholization 3h, crystallized at 10°C for 1h, filtered, and dried the filter cake to obtain 221g of 2,4-dichlorophenoxyacetic acid as a solid, with a purity of 99.3% and a yield of 99.3%.

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PUM

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Abstract

The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: a) reacting haloacetic acid with 2,4-dichlorophenolate in a strong-polarity solvent so as to obtain 2,4-dichlorophenoxy acetate; and B) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, the strong-polarity solvent is utilized, so the mass transfer effect of the reaction is improved, reaction time is reduced, the reaction is more complete, and the conversion rate and yield of the reaction are greatly improved.

Description

technical field [0001] The invention relates to the technical field of synthesis, in particular to a preparation method of 2,4-dichlorophenoxyacetic acid. Background technique [0002] 2,4-Dichlorophenoxyacetic acid is a very important class of compounds. It is the longest-used organic synthetic herbicide in the world and is still widely used. [0003] CN106278862 discloses a preparation method of 2,4-dichlorophenoxyacetic acid. In this method, 2,4-dichlorophenol is used as a raw material to obtain 2,4-dichlorophenolate anhydrous system through the action of a water-carrying agent, and then react with methyl chloroacetate to obtain 2,4-dichlorophenoxyacetic acid methyl Esters, 2,4-dichlorophenoxyacetic acid methyl ester hydrolyzed under solid acid catalyst to prepare 2,4-dichlorophenoxyacetic acid. [0004] CN106278863 discloses a preparation method of 2,4-dichlorophenoxyacetic acid, adding methyl 2,4-dichlorophenoxyacetic acid into water, adding a solid acid catalyst, sti...

Claims

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Application Information

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IPC IPC(8): C07C67/31C07C69/712C07C27/02C07C59/70
CPCC07C67/31C07C51/09C07C69/712C07C59/70
Inventor 孙国庆侯永生赵广理陈桂元
Owner SHANDONG RUNBO BIOTECH CO LTD
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