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Preparation method for 2,4-dichlorophenoxyacetic acid

A technology of dichlorophenoxyacetic acid and dichlorophenoxyacetic ester, which is applied in two fields, can solve problems such as low yield, large amount of three wastes, and poor chlorination selectivity of phenol, and achieve simple reaction route, few by-products, The effect of high purity 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

The advantage of this method is that the hydrolysis of chloroacetic acid is less, and the chlorination selectivity is high, but the disadvantage is that the amount of three wastes is large and difficult to handle; the method of first chlorination and then condensation, the chlorination selectivity of phenol is poor, and the chlorination selectivity of phenol is obtained after 2,4-Dichlorophenol At the same time, by-products such as 2,6-dichlorophenol
Difficulty separating by-products
And the above two methods yield low

Method used

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Examples

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preparation example Construction

[0018] The invention provides a kind of preparation method of 2,4-dichlorophenoxyacetic acid, comprises the steps:

[0019] A) Haloacetate reacts with 2,4-dichlorophenoxide to obtain 2,4-dichlorophenoxyacetate;

[0020] B) 2,4-dichlorophenoxyacetic ester is hydrolyzed under the action of a catalyst to obtain 2,4-dichlorophenoxyacetic acid; the catalyst is selected from polyether, crown ether, quaternary ammonium salt, tertiary amine, One or more of quaternary phosphonium salt, pyridine, titanate, inorganic acid and organic acid.

[0021] In the present invention, firstly, haloacetates are prepared.

[0022] Preferably, it is specifically: react a monohydric alcohol with C2 or higher and a haloacetic acid to obtain a haloacetate. More preferably, the specific monohydric alcohol above C2 and the haloacetic acid are mixed and stirred under the action of a catalyst, and dehydrated to obtain the haloacetic acid ester. The present invention does not limit the specific method of s...

Embodiment 1

[0039]31g of propanol, 95g (1mol) of chloroacetic acid, 50g of toluene and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated at 80°C for 7h to obtain propyl chloroacetate. Add 202g (1mol) of potassium 2,4-dichlorophenate, keep stirring at 80°C for 4 hours, filter off the solid potassium chloride formed by the reaction, and remove toluene from the filtrate to obtain propyl 2,4-dichlorophenoxyacetate, add 50g Concentrated sulfuric acid was dehydrated under reflux for 3 hours, crystallized at 10°C for 1 hour, filtered, and the filter cake was dried to obtain 221 g of 2,4-dichlorophenoxyacetic acid as a solid, with a purity of 99.6% and a yield of 99.6%.

Embodiment 2

[0041] 300g of isooctyl alcohol, 140g (1mol) of bromoacetic acid and 0.1g of concentrated sulfuric acid were mixed and stirred, and desolvated and dehydrated at 180°C for 4 hours to obtain isooctyl bromoacetate. Add 202g (1mol) of potassium 2,4-dichlorophenate, keep stirring at 180°C for 4 hours, filter off the solid potassium bromide formed in the reaction, remove isooctyl alcohol from the filtrate, and obtain isooctyl 2,4-dichlorophenoxyacetate For ester, add 100g of 30wt% hydrochloric acid, reflux dehydration and stir for 6h, crystallize at 10°C for 1h, filter, and dry the filter cake to obtain 222g of 2,4-dichlorophenoxyacetic acid solid, with a purity of 99.2% and a yield of 99.6%.

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Abstract

The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: a) reacting halogenated acetate with 2,4-dichlorophenolate so as to obtain 2,4-dichlorophenoxyacetate; and B) hydrolyzing 2,4-dichlorophenoxyacetate under the action of a catalyst so as to obtain 2,4-dichlorophenoxyacetic acid, wherein the catalyst is one or more selected from the group consisting of polyether, crown ether, quaternary ammonium salt, tertiary amine, quaternary phosphonium salt, pyridine, titanate, inorganic acid and organic acid. According to theinvention, halogenated acetate reacts with 2,4-dichlorophenolate to obtain 2,4-dichlorophenoxyacetate, and then 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid. Through usage of a specific reaction route and the specific catalyst of the invention, the finally prepared 2,4-dichlorophenoxyacetic acid has high purity and yield, few by-products are produced, the reaction route is simple, and the application of the preparation method is facilitated.

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 is a synthetic auxin that is used in agriculture as a herbicide and plant growth agent with a wide range of applications. [0003] The synthesis method of 2,4-dichlorophenoxyacetic acid disclosed in the prior art mainly adopts the condensation method, which can be divided into two types: first condensation and then chlorination and first chlorination and then condensation. Specifically, 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 advantage of this method is that the hydrolysis of chloroacetic acid is less, and the chlorination selectivity is high, but the disadvantage is that the amount of three wa...

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
Owner SHANDONG RUNBO BIOTECH CO LTD
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