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 the problems of many hydrolysis by-products, incomplete reaction, low product yield and the like , to achieve the effect of less hydrolysis by-products, fast reaction speed, high conversion rate and yield

Inactive Publication Date: 2018-08-21
SHANDONG RUNBO BIOTECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] These two existing processes all include the reaction of phenate and chloroacetate, and the reaction system is an aqueous phase system, which has problems such as incomplete reaction, many hydrolysis by-products, low product yield, and low product purity.

Method used

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preparation example Construction

[0019] The invention provides a kind of preparation method of 2,4-dichlorophenoxyacetic acid, comprises the steps:

[0020] a) Reaction of haloacetate with anhydrous 2,4-dichlorophenoxylate solid to obtain 2,4-dichlorophenoxyacetate;

[0021] b) hydrolysis of the 2,4-dichlorophenoxyacetic acid ester to obtain 2,4-dichlorophenoxyacetic acid.

[0022] The preparation method provided by the invention can overcome the problems existing in the prior art such as incomplete reaction, many hydrolysis by-products, low product yield, low product purity, large consumption of raw materials, large amount of waste water generation, difficult control of waste gas discharge and the like.

[0023] In an embodiment of the present invention, the halogenated acetate is selected from one or more of chloroacetate, bromoacetate and iodoacetate, preferably chloroacetate or bromoacetate.

[0024] The embodiment of the present invention first prepares the haloacetate, which can be prepared by the foll...

Embodiment 1

[0047] 200g of ethanol, 95g (1mol) of chloroacetic acid and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated at 80°C for 5h to obtain ethyl chloroacetate.

[0048] Mix and stir 164g (1mol) of 2,4-dichlorophenol and 125g (1mol) of sodium hydroxide aqueous solution with a mass fraction of 32%, raise the temperature to 70°C, and evaporate the water for 6 hours to obtain anhydrous sodium 2,4-dichlorophenate solid.

[0049] Put the anhydrous 2,4-dichlorophenate sodium solid into the prepared ethyl chloroacetate, stir at 80°C for 0.5h, filter off the sodium chloride generated by the reaction, and dilute the obtained 2,4-dichlorobenzene Put the filtrate of the oxyacetate into a hydrolysis reactor, add 125 g (1 mol) of aqueous sodium hydroxide solution with a mass fraction of 32% and reflux and stir for 0.5 h, add 130 g of hydrochloric acid with a mass concentration of 30%, crystallize at 10°C for 1 h, filter, and dry the filter cake , to obtai...

Embodiment 2

[0051] 200g of methanol, 95g (1mol) of chloroacetic acid and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated at 100°C for 5h to obtain methyl chloroacetate.

[0052] Mix and stir 164g (1mol) of 2,4-dichlorophenol and 113g (1mol) of potassium hydroxide aqueous solution with a mass fraction of 50%, raise the temperature to 90°C, and evaporate the water for 5 hours to obtain anhydrous potassium 2,4-dichlorophenoxide solid.

[0053] Put the anhydrous 2,4-dichlorophenate potassium solid into the prepared methyl chloroacetate, stir at 90°C for 0.5h, filter off the potassium chloride generated by the reaction, put the obtained filtrate into the hydrolysis reactor, add mass 130g of hydrochloric acid with a concentration of 30% was dealcoholized under reflux for 3h, crystallized at 10°C for 1h, filtered, and the filter cake was dried to obtain 219g of 2,4-dichlorophenoxyacetic acid as a solid with a purity of 99.3% and a yield of 98.4%.

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Abstract

The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: a) reactinghalogenated acetate with an anhydrous 2,4-dichlorophenolate solid so as to obtain 2,4-dichlorophenoxyacetate; and b) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, the anhydrous 2,4-dichlorophenolate solid reacts with halogenated acetate to prepare 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid and corresponding alcohols. The mass transfer effect of a solid-liquid reaction in the invention is good; few hydrolysis by-products are produced during the reaction; fast reaction speed and high conversion rate and yield are obtained; the amount of produced waste water is low; so industrial application of the preparation method can be easily implemented.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a preparation method of 2,4-dichlorophenoxyacetic acid. Background technique [0002] 2,4-Dichlorophenoxyacetic acid compounds are a very important class of compounds. They are the longest-used organic synthetic herbicides in the world and are still widely used. Among them, 2,4-dichlorophenoxyacetic acid is a synthetic auxin, which is widely used as a herbicide and plant growth agent in agriculture. [0003] The synthesis method of 2,4-dichlorophenoxyacetic acid disclosed in the prior art 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. Among them, specifically speaking, chlorination is followed by condensation, that is, phenol is first condensed with sodium chloroacetate to obtain sodium phenoxyacetate, and then chlori...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/09C07C59/70
CPCC07C51/09C07C67/31C07C59/70C07C69/712
Inventor 孙国庆侯永生赵广理陈桂元徐延磊朱小猛
Owner SHANDONG RUNBO BIOTECH CO LTD
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