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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 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

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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) In the presence of a phase transfer catalyst, the haloacetate is reacted with 2,4-dichlorophenoxide 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, wh...

Embodiment 1

[0048] 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.

[0049] Mix and stir 164g (1mol) of 2,4-dichlorophenol and 125g (1mol) of aqueous sodium hydroxide solution with a mass fraction of 32%, and raise the temperature to 70°C to obtain a sodium 2,4-dichlorophenate solution.

[0050] Add 0.1 g of tetrabutylammonium bromide to the 2,4-dichlorophenate sodium solution, then add the prepared ethyl chloroacetate in one go, stir at 80°C for 0.5 h, and separate layers, the 2,4- The upper oil phase of dichlorophenoxyacetate is transferred to a hydrolysis reactor, 125 g (1 mol) of aqueous sodium hydroxide solution with a mass fraction of 32% is added and stirred under reflux for 0.5 h, and 130 g of hydrochloric acid with a mass concentration of 30% is added, crystallized at 10° C. for 1 h , filtered, and the filter cake was dried to obtain 221 g of...

Embodiment 2

[0052] 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.

[0053] 164g (1mol) of 2,4-dichlorophenol and 113g (1mol) of potassium hydroxide aqueous solution with a mass fraction of 50% were mixed and stirred, and the temperature was raised to 90°C to obtain potassium 2,4-dichlorophenolate solution.

[0054] Add 0.1 g of 18 crown ether to the potassium 2,4-dichlorophenate solution, then add the prepared methyl chloroacetate at one time, stir at 90°C for 0.5 h, separate layers, and transfer the upper oil phase to the hydrolysis reactor , add 130g of hydrochloric acid with a mass concentration of 30%, dealcoholize under reflux for 3h, crystallize at 10°C for 1h, filter, and dry the filter cake to obtain 219g of 2,4-dichlorophenoxyacetic acid solid with a purity of 99.2% and a yield of 98.3%.

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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 2,4-dichlorophenolate in the presence of a phase-transfer catalyst 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, oil-phase halogenated acetate reacts with 2,4-dichlorophenolate under the action of the phase-transfer catalyst to prepare 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid and corresponding alcohols. Under the action of the phase-transfer catalyst, few hydrolysis by-products are produced during a reaction, fast reaction speed and high conversion rate and yield are obtained, and 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): C07C27/02C07C51/09C07C59/70C07C67/31C07C69/712
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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