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Method for preparing 2,4-dichlorphenoxyacetic acid

A technology of dichlorophenoxyacetic acid and dichlorophenoxyacetic acid salt, applied in 2 fields, can solve problems such as low product yield, many hydrolysis by-products, and incomplete reaction

Inactive Publication Date: 2017-06-27
SHANDONG RUNBO BIOTECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But these two kinds of processes are the reaction of phenate and acetate, and the reaction system is an aqueous phase system, which has the problems of incomplete reaction, many hydrolysis by-products, low product yield, large consumption of raw materials, and difficult control of waste discharge.

Method used

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preparation example Construction

[0022] The invention provides a preparation method of 2,4-dichlorophenoxyacetic acid, comprising the following steps: S1) reacting haloacetic acid with alkali metal alkoxide to obtain haloacetate; Acetate is reacted with phenolate to obtain phenoxyacetate; S3) chlorinating the phenoxyacetate in an alcohol solvent to obtain 2,4-dichlorophenoxyacetate; S4) The 2,4-dichlorophenoxyacetic acid salt is acidified to obtain 2,4-dichlorophenoxyacetic acid.

[0023] Wherein, the present invention has no special limitation on the sources of all raw materials, which can be commercially available or self-made.

[0024] Reaction of haloacetic acid with an alkali metal alkoxide; the haloacetic acid is a haloacetic acid well-known to those skilled in the art, and there is no special limitation. In the present invention, it is preferably chloroacetic acid, bromoacetic acid and iodoacetic acid. One or more, more preferably chloroacetic acid and / or bromoacetic acid; the alkali metal alkoxide is...

Embodiment 1

[0034] 95g (1mol) of chloroacetic acid and 108g of 50% sodium methoxide methanol solution were mixed and stirred to obtain sodium chloroacetate methanol solution.

[0035] Mix and stir 94.3 g (1 mol) of phenol and 125 g (1 mol) of aqueous sodium hydroxide solution with a mass fraction of 32%, raise the temperature to 110° C., and remove water to obtain a solid sodium phenate.

[0036] The obtained sodium phenoxide solid was put into sodium chloroacetate methanol solution and stirred at 100°C for 5 hours, then 0.1 g of ferric chloride was added, and chlorine was passed at 70°C for 5 hours to obtain sodium 2,4-dichlorophenoxyacetate.

[0037] The 2,4-dichlorophenoxyacetic acid sodium reaction solution was transferred into the acidification reactor, 130g of 30% hydrochloric acid was added, crystallized at 10°C for 1h, filtered, and the filter cake was dried to obtain 220g of 2,4-dichlorophenoxyacetic acid solid. The purity is 99.5%, and the yield is 99.0%.

Embodiment 2

[0039] 95g (1mol) of chloroacetic acid and 245g of 90% sodium ethoxide ethanol solution were mixed and stirred to obtain sodium chloroacetate ethanol solution.

[0040] Mix and stir 94.3 g (1 mol) of phenol and 113 g (1 mol) of potassium hydroxide aqueous solution with a mass fraction of 50%, raise the temperature to 110° C., and remove water to obtain a solid potassium phenate.

[0041] Put the obtained potassium phenate solid into sodium chloroacetate ethanol solution, stir and react at 100°C for 4 hours, then add 0.1 g of aluminum chloride, and pass chlorine at 20°C for 5 hours to obtain sodium 2,4-dichlorophenoxyacetate.

[0042]The 2,4-dichlorophenoxyacetic acid sodium reaction solution was transferred to the acidification reactor, 130g of 30% hydrochloric acid was added, crystallized at 5°C for 1h, filtered, and the filter cake was dried to obtain 220g of 2,4-dichlorophenoxyacetic acid solid. The purity is 99.6%, and the yield is 99.1%.

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Abstract

The invention provides a method for preparing 2,4-dichlorphenoxyacetic acid. The method comprises the step S1 of causing haloacetic acid and alkali metal alkoxide react in an alcohol solvent toobtain halogenated acetate, the step S2 of causing the halogenated acetate and phenoxide to react in the alcohol solvent to obtain phenoxyacetic acid salt, the step S3 of causing the phenoxyacetic acid salt to undergo chlorination in the alcohol solvent, and obtaining 2,4-dichlorobenzene acetate, and the step S4 of acidizing 2,4-dichlorobenzene acetate to obtain 2,4-dichlorphenoxyacetic acid. Compared with the prior art, the method enables chlorination to be performed in an anhydrous system, reaction selectivity is good, by-products are fewer, the yield is high, the 2,4-dichlorphenoxyacetic acid can be obtained after acidification, and the 2,4-dichlorphenoxyacetic acid is simple to prepare.

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 Williamson condensation method, which can be divided into two types: first condensation and then chlorination and first chlorination and then condensation. But these two kinds of processes are the reaction of phenate and acetate, and the reaction system is an aqueous phase system, which has the problems of incomplete reaction, many hydrolysis by-products, low product yield, large consumption of raw materials, and difficult control of waste discharge. Contents of the invention [0004] In view of this, the technical problem to...

Claims

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Application Information

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IPC IPC(8): C07C51/02C07C59/70
CPCC07C51/02C07C51/41C07C51/412C07C59/70C07C53/16
Inventor 孙国庆侯永生徐延磊赵广理陈桂元
Owner SHANDONG RUNBO BIOTECH CO LTD
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