2,4-dichlorophenoxyacetic acid preparation method

A technology of dichlorophenoxyacetic acid and phenoxyacetic acid, which is applied in the preparation of carboxylate salts, organic compounds, chemical instruments and methods, etc., can solve the problems of many by-products and complicated processes, and simplify the cumbersome end point control Effect

Active Publication Date: 2016-06-01
ZHENJIANG JIANGNAN CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
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Problems solved by technology

However, the above-mentioned synthesis process is two-step chlorination to obtain 2,4-D, the process is complicated and there are many by-products

Method used

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[0035] The invention provides a kind of preparation method of 2,4-dichlorophenoxyacetic acid, comprises the following steps:

[0036] A) providing phenoxyacetic acid;

[0037] B) mixing hydrochloric acid, an oxidizing agent and the phenoxyacetic acid in the step A), and performing a chlorination reaction in the presence of a chlorination catalyst to obtain 2,4-dichlorophenoxyacetic acid;

[0038] The molar ratio of the phenoxyacetic acid, hydrochloric acid and oxidizing agent is 1:(2-200):(2-200), and the molar ratio of the hydrochloric acid and oxidizing agent is 1:(0.1-10).

[0039] The preparation method of 2,4-dichlorophenoxyacetic acid provided by the invention only needs one-step chlorination reaction to obtain 2,4-dichlorophenoxyacetic acid, and the purity and purity of 2,4-dichlorophenoxyacetic acid are guaranteed While improving the yield, the production process of 2,4-dichlorophenoxyacetic acid is simplified.

[0040] In the present invention, the phenoxyacetic aci...

Embodiment 1

[0079] In a 250ml four-necked flask, add 5g phenol, 5.1g chloroacetic acid and 10g water respectively, add liquid caustic soda to adjust the pH value to 12, add 0.5g catalyst (polyethylene glycol 400, benzyltriethylammonium chloride, cyclic The molar ratio of dextrin and tetrabutylphosphine acetate is: 10:5:2:1.5), using temperature program, the reaction solution rises from the initial 35°C to reflux in 3 minutes, and reflux reaction for 5 hours; cool down to room temperature, add hydrochloric acid Adjust the pH value to 2, cool to 10°C, crystallize for 3 hours, filter, wash, and dry at 90°C for 2 hours to obtain 7.49g of white needle-like crystals with a phenoxyacetic acid content of 98.2%; filtrate 13.1g, The phenoxyacetic acid content is 2.67%. The solid yield of phenoxyacetic acid was 91.9%, and the total yield was 97.95% (all calculated as phenol).

Embodiment 2

[0081] In a 250mL four-neck flask, add 5g phenol, 5.5g chloroacetic acid and 10g water respectively, add liquid caustic soda to adjust the pH value to 12, add 0.5kg catalyst (polyethylene glycol 800, dodecyltrimethylammonium chloride , 18 crown ethers 6, and the mol ratio of tetrabutylphosphine chloride are: 40:10:5:3), using a temperature program, rising from normal temperature to reflux within 3.5min, and reflux reaction for 3hr; cooling to room temperature, adding Adjust the pH value to 2 with hydrochloric acid, cool to 10°C, crystallize for 3 hours, filter, wash, and dry at 90°C for 2 hours to obtain 7.53g of white solid with a phenoxyacetic acid content of 99.1%; filtrate 13.4g, benzene The oxyacetic acid content is 3.50%. The solid yield of phenoxyacetic acid was 93.27%, and the total yield was 99.2% (all calculated as phenol).

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Abstract

The invention provides a 2,4-dichlorophenoxyacetic acid preparation method including the following steps: A) providing phenoxyacetic acid; B) mixing hydrochloric acid, an oxidizing agent and the phenoxyacetic acid of the step A), carrying out a chlorination reaction in the presence of a chlorination catalyst, to obtain 2,4-dichlorophenoxyacetic acid, wherein the molar ratio of the phenoxyacetic acid to the hydrochloric acid to the oxidizing agent is 1 to (2-200) to (2-200), and the molar ratio of the hydrochloric acid to the oxidizing agent is 1 to (0.1-10). The 2,4-dichlorophenoxyacetic acid preparation method provided by the invention only needs one-step chlorination reaction, and then the 2,4-dichlorophenoxyacetic acid can be obtained; while the purity and yield of the 2,4-dichlorophenoxyacetic acid are ensured, the production process of the 2,4-dichlorophenoxyacetic acid is simplified. Moreover, the preparation method provided by the invention has no 'three wastes' emissions and achieves greenization of synthesis of the product.

Description

technical field [0001] The invention belongs to the field of organic synthesis, in particular to a preparation method of 2,4-dichlorophenoxyacetic acid. Background technique [0002] 2,4-dichlorophenoxyacetic acid, referred to as 2,4-D (or 2,4-D), is the world's first industrialized selective hormone-based high-efficiency organic herbicide, and has a milestone significance in the history of pesticides . The synthesis method of this product was first discovered by American R. Coponi in 1941, and it was introduced into the market in 1945, and it is widely used as a plant growth regulator and herbicide. In 2011, the market sales of 2,4-D reached 580 million US dollars, ranking third among herbicides in the world, second only to glyphosate and paraquat. With the promotion and application of anti-2,4-D transgenic crops, the market prospect of 2,4-D products is generally optimistic, and many domestic enterprises have launched or expanded 2,4-D production facilities. However, ac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C59/70C07C51/363
Inventor 周曙光姜胜宝郑新朱建民秦龙刘春杰
Owner ZHENJIANG JIANGNAN CHEM
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