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A New Synthetic Process of 2,4-Dichlorophenoxyacetic Acid

A technology of dichlorophenoxyacetic acid and methyl dichlorophenoxyacetate, applied in the field of chemical synthesis, can solve the problems of large amount of three wastes, high chlorination selectivity and high condensation yield, and achieves reduced production cost, good purity, high yield effect

Active Publication Date: 2019-06-25
QINGDAO UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The advantages of this method are high condensation yield, less hydrolysis of chloroacetic acid, high chlorination selectivity, and the disadvantage is that the amount of three wastes is large and difficult to handle.
[0008] However, the wastewater produced by the existing production process has the characteristics of high COD concentration, high salinity, and chlorophenol organic pollutants. The organic pollutants are mainly 2,4-dichlorophenoxyacetic acid and chlorophenols. , the inorganic pollutants are basically NaCl
However, regardless of the first chlorination and then condensation method or the first condensation and then chlorination method, a large amount of three wastes will be generated, and it will cost a lot of money to deal with the emissions that meet the standards
[0009] Therefore, these two methods do not meet the requirements of industrial production

Method used

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  • A New Synthetic Process of 2,4-Dichlorophenoxyacetic Acid
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  • A New Synthetic Process of 2,4-Dichlorophenoxyacetic Acid

Examples

Experimental program
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Effect test

Embodiment 2

[0061] Mix and stir 83.2g (0.5mol) of 2,4-dichlorophenol, 416g toluene, and 116.7g (1mol) of KOH aqueous solution with a mass fraction of 48%, raise the temperature to 120°C, and react with water for 4 hours. After cooling to 110°C, 81.3 g (0.75 mol) of methyl chloroacetate was added dropwise, and the addition was completed in 4 hours, and the reaction was continued for 2 hours. Cool to 80°C, add 150g of water, adjust the pH of the reaction solution to 8, let it stand for stratification, add 120g of toluene to the water layer for extraction, add 10w.t.% sulfuric acid to the organic layer, wash it with rotary evaporation, and then add 300g of water for desolvation Dissolved to constant weight to obtain 105.2 g of the product with a purity of 99.5% and a yield of 89.1%.

Embodiment 3

[0063] 2,4-dichlorophenol 83.2g (0.5mol), chlorobenzene 100g, mass fraction 25% K 2 CO 3 276g (0.5mol) of aqueous solution, mixed and stirred, heated to 135°C, reacted with water for 3 hours, slightly cooled the neutralized solution to 100°C, added dropwise 43.4g (0.4mol) of methyl chloroacetate, and the dropwise addition was completed in 5 hours. The reaction was continued for 2 hours. Cool to 50°C, add 83.2g of water, adjust the pH of the reaction solution to 8, let it stand for stratification, add 16.6g of chlorobenzene to the water layer for extraction, add 30w.t.% acetic acid to the organic layer, wash it with rotary evaporation, and add 500g of water was precipitated to constant weight to obtain 108g of product with a purity of 99.3% and a yield of 91.3%.

[0064] Reference Example 4:

[0065] Mix and stir 83.2g (0.5mol) of 2,4-dichlorophenol, 416g xylene, and 75g (0.6mol) of NaOH aqueous solution with a mass fraction of 32%, raise the temperature to 145°C, and react ...

Embodiment 1

[0081] Embodiments 1 to 6 and comparative examples 1 to 3 are the preparation process of 2,4-dichlorophenoxyacetic acid, and its raw material 2,4-dichlorophenoxyacetic acid methyl ester is prepared by the method of reference example 1, and the reaction The formula is as follows:

[0082]

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Abstract

The invention discloses a novel synthesis process of 2,4-dichlorphenoxyacetic acid. The technique is characterized by comprising the following steps: (1) in the existence of a water-carrying agent, carrying out reflux water-carrying reaction on 2,4-dichlorophenol and an inorganic alkali water solution to obtain a 2,4-dichlorophenate anhydrous system; (2) after the reaction solution in the step (1) is cooled, dropwisely adding methyl chloroacetate, and carrying out reflux reaction to obtain methyl 2,4-dichlorphenoxyacetate; (3) separating, purifying and desolventizing; and (4) hydrolyzing the methyl 2,4-dichlorphenoxyacetate under the action of a solid acid catalyst to prepare the 2,4-dichlorphenoxyacetic acid. The method solves the problem of generation of waste salts and wastewater in the traditional technique for preparing 2,4-dichlorphenoxyacetic acid, does not have the problem of hydrolysis of chloroacetic acid, and has the advantages of high yield, favorable purity and low cost.

Description

technical field [0001] The invention relates to a new synthesis process, in particular to a new synthesis process of 2,4-dichlorophenoxyacetic acid. It belongs to the technical field of chemical synthesis. Background technique [0002] 2,4-Dichlorophenoxyacetic acid is the world's first industrialized selective hormone efficient organic herbicide. After its discovery in 1941, production began in the United States in the 1940s and in China in the late 1950s. Its structural formula is as follows: [0003] [0004] The synthesis of 2,4-dichlorophenoxyacetic acid mainly adopts the Williamson condensation method, and the production process can be divided into two types: first condensation followed by chlorination, and first chlorination followed by condensation. [0005] First condensation and then chlorination, that is, phenol is first condensed with sodium chloroacetate to obtain sodium phenoxyacetate, and then chlorinated to obtain 2,4-dichlorophenoxyacetic acid. The ad...

Claims

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Application Information

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IPC IPC(8): C07C51/09C07C59/70
CPCC07C37/66C07C51/09C07C67/31C07C59/70C07C69/712C07C39/44
Inventor 岳涛邢文国冯维春陈琦付永丰徐婷杨旭王达彤
Owner QINGDAO UNIV OF SCI & TECH
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