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Preparation method and production system for 2,4-dichlorophenoxyacetic acid

A technology of dichlorophenoxyacetic acid and dichlorophenoxyacetic acid ester, which is applied in the field of preparation method and production system of 2,4-dichlorophenoxyacetic acid, can solve the problem of low product purity, low product yield, reaction Low production capacity and other problems, to achieve the effect of less hydrolysis by-products, high conversion rate and yield, and fast reaction speed

Inactive Publication Date: 2018-08-21
SHANDONG RUNBO BIOTECH CO LTD
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

[0004] These two existing processes both include the reaction of phenate and chloroacetate, and the reaction is a batch reaction, which has problems such as low reaction capacity, low product yield, and low product purity.

Method used

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  • Preparation method and production system for 2,4-dichlorophenoxyacetic acid

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[0026] The invention provides a kind of preparation method of 2,4-dichlorophenoxyacetic acid, comprises the steps:

[0027] A) Alcohol and halogenated acetic acid undergo the esterification reaction of 3-5 stages of overflow dehydration to obtain halogenated acetate;

[0028] B) After the haloacetate is mixed with 2,4-dichlorophenoxylate, 2,4-dichlorophenoxyacetate is obtained through 3-5 stages of continuous condensation reaction;

[0029] C) hydrolyzing the 2,4-dichlorophenoxyacetic ester to obtain 2,4-dichlorophenoxyacetic acid.

[0030] The preparation method provided by the invention can overcome the low reaction capacity, incomplete reaction, many hydrolysis by-products, low product yield, low product purity, large consumption of raw materials, large amount of waste water, and difficult control of waste gas discharge in the prior art. And other issues.

[0031] In the embodiment of the present invention, the haloacetate is firstly prepared by the following method: the ...

Embodiment 1

[0070] Put 2000g of butanol, 950g (10mol) of chloroacetic acid and 1g of concentrated sulfuric acid into the primary esterification tank, mix and stir, desolventize and dehydrate at 80°C for 1 hour, and then enter the secondary and tertiary esterification tanks through overflow in sequence, and the feed rate is 2000g / h, and the residence time of each stage is controlled at 1h to obtain butyl chloroacetate.

[0071] Mix and stir 1640g (10mol) of 2,4-dichlorophenol and 1250g (10mol) 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.

[0072] Put the 2,4-dichlorophenate sodium solution into the first-stage condensation kettle and mix it with the butyl chloroacetate obtained by esterification, stir at 80°C for 0.5h, and then enter the second, third, and fourth-stage condensation kettles through overflow , the feeding rate of butyl chloroacetate is 2200g / h, the residence time of each ...

Embodiment 2

[0074] Mix and stir 2000g ethanol, 1400g (10mol) bromoacetic acid and 1g concentrated sulfuric acid, desolventize and dehydrate at 100°C for 1.5h, then enter the second and third stage esterification kettles through overflow, the feed rate is 1500g / h, each stage stays The time was controlled at 1.5h to obtain ethyl bromoacetate.

[0075] 1640g (10mol) of 2,4-dichlorophenol and 1122g (10mol) of potassium hydroxide aqueous solution with a mass fraction of 50% were mixed and stirred, and the temperature was raised to 70°C to obtain potassium 2,4-dichlorophenolate solution.

[0076] Put the 2,4-dichlorophenate potassium solution into the ethyl bromoacetate obtained by esterification and mix it into the first-stage condensation kettle, stir at 90°C for 0.5h, and then enter the second, third, and fourth-stage condensation kettles in turn through overflow, The feeding rate of ethyl bromoacetate is 2000g / h, the residence time of each stage is controlled at 0.5h, then the condensation ...

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Abstract

The invention provides a preparation method and production system for 2,4-dichlorophenoxyacetic acid, belonging to the technical field of organic synthesis. The preparation method comprises the following steps: A) subjecting alcohol and halogenated acetic acid to an esterification reaction with three to five stages of overflow dehydration so as to obtain halogenated acetate; B) mixing halogenatedacetate with 2,4-dichlorophenolate, and carrying out three to five stages of continuous condensation reaction so as to obtain dichlorophenoxyacetate; and C) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. The production system mainly comprises a multistage esterification device, a multistage condensation device and a hydrolysis device. According to the invention, a specific continuous method is employed in the invention for preparation of 2,4-dichlorophenoxyacetic acid, so reaction capacity is improved, few hydrolysis by-products are produced in the reaction, a fast reaction speed and high conversion rate and yield are obtained, and 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 and a production system thereof. 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, referred to as 2,4-D or 2,4-d, 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 sodiu...

Claims

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Application Information

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IPC IPC(8): C07C51/09C07C59/70
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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