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Method for synthesizing 2,4-dichlorphenoxyacetic acid

A technology of dichlorophenoxyacetic acid and chlorophenoxyacetic acid is applied in chemical instruments and methods, preparation of carboxylate, preparation of organic compounds, etc., to achieve the effects of low production cost, low odor, and simple processing flow

Active Publication Date: 2015-02-04
SHANDONG WEIFANG RAINBOW CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Among them, the patent CN 101921188 R not only compares the advantages and disadvantages of these two methods, but also improves the post-chlorination method, including using a catalyst, a mixed solvent, and using phenol as a raw material to obtain 2,4-D through condensation and chlorination. Products, the technology of synthesizing 2,4-D by other processes has not been reported yet

Method used

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  • Method for synthesizing 2,4-dichlorphenoxyacetic acid
  • Method for synthesizing 2,4-dichlorphenoxyacetic acid
  • Method for synthesizing 2,4-dichlorphenoxyacetic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] First, add 40g of water and 214g of 98% chloroacetic acid into a 500ml four-necked flask, and then dropwise add 205g of 32% liquid caustic soda, during which the temperature is controlled to be less than 60°C. Preparation of sodium chloroacetate solution. stand-by.

[0029] Add 262g of 98% o-chlorophenol into a 2000ml glass four-neck flask, then add 332.5g of 32% liquid caustic soda, then heat up to 60°C, then add the above prepared sodium chloroacetate solution, and then heat up to 95°C During the period, the pH is controlled at 9-11 by dropping liquid caustic soda, and the reaction is kept for 5 hours. During this period, 22g of 32% liquid caustic soda is added, and then the temperature is lowered to 80°C, and 267.8g of 30% hydrochloric acid is added dropwise, and then the temperature is lowered to 25°C, and filtered , dry to obtain 367.5g of o-chlorophenoxyacetic acid dry material, content 98.6%, the yield of o-chlorophenol is 97.1%.

[0030] Filtration obtained 93...

Embodiment 2

[0032] Take 100g of the dry material of o-chlorophenoxyacetic acid in Example 1, add it to a 1000ml four-necked flask, and then add 100g of DMF (N,N-dimethylformamide) to the flask, 15g of water, dichloro 150 g of ethane, and then mixed to dissolve the solid completely, then the temperature was raised to 30° C., and chlorine gas was introduced. After passing 38.5g of chlorine, take a sample test, the unconversion rate is 0.4%, then turn on the vacuum pump, control the vacuum degree in the flask to 0.09Mpa, then raise the temperature to remove the solvent, the end point temperature is 95°C, after removing 260g of solvent, add water to the flask 200g, began to cool down and crystallize. Cool down to room temperature, filter and dry to obtain 116.3g of 2,4-D dry material, 2,4-D content 97.1%, 2,6-dichlorophenoxyacetic acid content 0.5%, 2,4,6-trichlorobenzene The content of oxyacetic acid is 1.1%. This step yield is 96.8%. 212.6 g of filtrate was obtained. Add 20 g of dichlor...

Embodiment 3

[0034] Add 40g of water and 250g of 98% chloroacetic acid into a 500ml four-necked flask, and then dropwise add 205g of 32% liquid caustic soda, during which the temperature is controlled to be less than 60°C. Preparation of sodium chloroacetate solution. stand-by.

[0035] Add 257g of 98% o-chlorophenol into a 2000ml glass four-necked flask, and simultaneously add 15.8g of the alkali washing solution in Example 1, then add 319g of 32% liquid caustic soda, then heat up to 60°C, and then Add the above-prepared sodium chloroacetate solution, then raise the temperature to 110°C, during which the pH is controlled at 9-11 by dropwise adding liquid caustic soda, keep the temperature for 3 hours, add 19.9g of 32% liquid caustic soda during this period, and then cool down to 80°C, Add 268.2g of 30% hydrochloric acid dropwise, then cool down to 25°C, filter and dry to obtain 368.3g of dry o-chlorophenoxyacetic acid, with a content of 98.4%, and a yield of 97.23% based on o-chloropheno...

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Abstract

The invention discloses a method for synthesizing 2,4-dichlorphenoxyacetic acid. The method comprises the following steps of: reacting o-chlorophenol which is used as a raw material with chloroacetic acid to generate o-chlorophenoxyacetic acid; and then reacting o-chlorophenoxyacetic acid with chlorine in a mixed solvent to obtain 2,4-dichlorphenoxyacetic acid, wherein the mixed solvent is a mixture of DMF (dimethyl formamide), water and dichlorethane. According to the method, o-chlorophenol is used as the raw material, so that o-chlorophenol can be used, and a new train of thought is provided for the synthesis of 2,4-D; and the raw material is easily available and low in cost, so that the production cost of a product is low. By adopting the mixed solvent, the selectivity of reaction is improved, so that a catalyst is not needed; and through the matching of other conditions, the reaction temperature and other conditions ensure that the yield of the product is improved, the generation of 2,6-dichlorphenoxyacetic acid and 2,4,6-trichlorophenoxyacetic acid is greatly reduced, and the yield of 2,4-dichlorphenoxyacetic acid in a single step can reach over 95%.

Description

Technical field [0001] The present invention involves a synthesis method of 2,4-dichlineroxyxohydrates (2,4-D), which specifically involves a synthesis method with 2,4-dichlorolytic acid that starts raw materials that starts raw materials.Essence Background technique [0002] 2,4-dichlorophenoxide referred to as 2,4-d.In 1942, P.W. Zimerman and A.E. Hichkkk first reported that 2,4-D was used as plant growth regulators. In 1944, the Ministry of Agriculture reported the 2,4-D grass-killing effect.Later, due to the small amount and low cost, it has always been one of the main herbicide varieties in the world. [0003] The current 2,4-D synthetic industrial methods reported include the following two: [0004] 1. Phenol chloride and then shrink the method to chlorine for phenols in a melting state. Subsequent dichlorolyrol and chlorolytic acid are shrunk under alkaline conditions to obtain 2,4-D. [0005] 2. The method of phenol first shrinking and then chloride is used to shrink the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C59/70C07C51/363
Inventor 孙国庆侯永生陈桂元李志清刘元强张杰刘元波王庆伟赵恒民路效磊齐宝悦李光文李英刘凤莲凌晓光韩双玲韩玲玲
Owner SHANDONG WEIFANG RAINBOW CHEM
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