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2,4-dichlorphenoxyacetic acid preparation method

A technology of dichlorophenoxyacetic acid and phenoxyacetic acid, which is applied in the direction of carboxylate preparation, organic compound preparation, chemical instruments and methods, etc., can solve the problems of complex synthetic route process, affecting quality and yield, etc., to achieve Effects of shorter reaction time, lower cost, and less loss of chlorine gas

Inactive Publication Date: 2015-03-11
常熟市尚登新材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The existing synthetic route has a complex technological process, and the products contain impurities such as 2,6-dichlorophenoxyacetic acid, trichlorophenoxyacetic acid, and intermediate monochlorophenoxyacetic acid; the existence of these impurities directly affects the quality and yield. Rate

Method used

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  • 2,4-dichlorphenoxyacetic acid preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Preparation of phenoxyacetic acid

[0024] The mass ratio of chloroacetic acid, sodium hydroxide, and phenol is 1: 0.1: 0.8; the mass ratio of the acid and water is 3: 1; the mass ratio of the phenoxyacetic acid and chlorine is 1: 2.2

[0025] Add 1Kg of chloroacetic acid and 1Kg of 10% sodium hydroxide solution into the reactor, stir for 15-20 minutes, then add 800g of phenol 0.6mol, adjust the pH value to 11 with sodium bicarbonate; then heat at 100°C for 40 Minutes; then add hydrochloric acid to adjust the pH value to 4; finally cool in an ice-water bath, wash and dry the obtained solid to obtain phenoxyacetic acid with a content of 96%.

[0026] Preparation of Ni-Al-Mg Composite Oxide

[0027] Add 10g of nickel nitrate, 5g of magnesium nitrate, and 2g of aluminum nitrate to 50g of water respectively to obtain three aqueous solutions; mix the three aqueous solutions at 50°C; add 3g of sodium bicarbonate after half an hour; then stir at 50°C to obtain a precipitate; ...

Embodiment 2

[0028] Embodiment two: the preparation of 2,4-dichlorophenoxyacetic acid

[0029] In the reaction flask, put 10 mol of the original powder of phenoxyacetic acid in Example 1, 700 g of acetic acid and 175 g of water, and 76 g of nickel-aluminum-magnesium composite oxide; after stirring, start feeding 22 mol of chlorine gas for chlorination reaction, and stir to heat up to 75 ° C. Continue to stir for 20 minutes; then the reaction product is directly cooled to 18°C, kept for about 0.6 hours, filtered with suction, and the obtained filter cake is directly dried at 60°C to obtain 2,4-dichlorophenoxyacetic acid with a content of 98.6% and a yield (relative Phenoxyacetic acid calculation) 98.1%.

Embodiment 3

[0030] Embodiment three: the preparation of 2,4-dichlorophenoxyacetic acid

[0031] Using the mother liquor obtained in Example 2, add 50 g of 60% acetic acid aqueous solution and 9 mol of phenoxyacetic acid powder, and follow the process and operation described in Example 1 to obtain 2,4-dichlorophenoxyacetic acid with a content of 98.3% and a yield of 98.8%.

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Abstract

The invention discloses a 2,4-dichlorphenoxyacetic acid preparation method which comprises the following special steps: adding chloroacetic acid into a sodium hydroxide solution, stirring, adding into phenol, and regulating the PH value to 11 with sodium bicarbonate; then heating for 40 minutes at 100 DEG C; adding into hydrochloric acid to regulate the PH value to 4; finally cooling in an ice-water bath, and washing and drying the obtained solid to obtain phenoxyacetic acid; adding into the phenoxyacetic acid into an acetic acid and water mixed solution, adding into an Ni-Al-Mg composite oxide, stirring and mixing, wherein the mass of the Ni-Al-Mg composite oxide is 0.05% of that of phenoxyacetic acid; then introducing chlorine to carry out chlorination; reacting for 20-40 minutes, and finishing the chlorination; then cooling the reaction product, and filtering to obtain a solid; at last, drying the solid to obtain the 2,4-dichlorphenoxyacetic acid. The product prepared by the method disclosed by the invention is high in quality, yield and purity; the preparation process is simple, convenient and stable, the industrial cost is low, and the environment is protected.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a preparation method of 2,4-dichlorophenoxyacetic acid. Background technique [0002] 2,4-Dichlorophenoxyacetic acid (2,4-D) is a plant growth regulator widely used at present. It is an effective herbicide and preservative. It has the functions of preventing lodging, promoting rice production and early maturity , can also be used as an antifungal agent. After 1945, many countries put it into production and application. [0003] Phenol is first chlorinated by chlorine gas to produce 2,4-dichlorophenol, and then etherified and acidified with sodium chloroacetate under alkaline conditions to prepare 2,4-D; phenol and chloroacetic acid can be quickly Etherification, acidification, phenoxyacetic acid, and then chlorination in the aqueous phase can also synthesize 2,4-D. [0004] However, the chlorination end point of phenol is difficult to control. Dichlorophenol contai...

Claims

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Application Information

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IPC IPC(8): C07C59/70C07C51/363
CPCC07C51/363C07C51/367
Inventor 吴国民
Owner 常熟市尚登新材料有限公司
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