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Preparation method of 2,4-dichlorin phenoxyacetic acid

A technology of dichlorophenoxyacetic acid and sodium chloroacetate, applied in the field of herbicides, can solve the problems of increasing labor intensity of workers, unfavorable production stability, and deteriorating operating environment, so as to avoid leakage of phenol-containing waste gas and avoid human operation errors , the effect of pollution control

Active Publication Date: 2007-10-31
SHANDONG WEIFANG RAINBOW CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 3. Since the reaction is carried out under the conditions of high temperature (about 100°C), alkalinity (PH9-11) and presence of solid material (2,4-D sodium salt), there is currently no pH meter that can be used for a long time In this environment, the detection of PH value can only rely on the method of manual detection with PH test paper. Frequent opening and closing of the sampling port on the reactor not only increases the labor intensity of workers, deteriorates the operating environment, but also easily causes human errors, which is not conducive to production. The stability of this step makes it difficult to achieve self-control
Thereby 2,4-dichlorophenol cannot be fully utilized, which not only increases the cost, but also causes pollution

Method used

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Experimental program
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Effect test

Embodiment 1

[0029] Choose 90% 2,4-dichlorophenol and partly recovered phenol as raw materials, neutralize with liquid caustic soda of equimolar amount, make 50% sodium dichlorophenate solution;

[0030] Choose raw material chloroacetic acid to neutralize with equimolar liquid caustic soda, make 40% sodium chloroacetate solution;

[0031] In the condensation kettle, put sodium dichlorophenate solution into it, raise the temperature to reflux, start to add sodium chloroacetate solution dropwise, and continue the reflux reaction after dropping. During the reaction, the oil-water separator is connected, the water phase is returned to the reactor, and the oil phase is separated for reuse next time; when the separated oil phase reaches 12wt% of the total amount of dichlorophenol, the reaction ends. The molar ratio of above-mentioned sodium dichlorophenate to sodium chloroacetate is 1:1.

[0032] After the reaction is completed, adjust the pH to 10 with liquid alkali, lower the temperature to 4...

Embodiment 2

[0036] In a 500ml three-neck flask, add 56g of 90% 2,4-dichlorophenol, 42.9g of 32% NaOH, and 20ml of water, raise the temperature to reflux, and then add sodium chloroacetate solution dropwise for about half an hour. The molar ratio of dichlorophenol to chloroacetic acid is 1:0.9. At this temperature, the reaction was continued for 3.5 hours. During the reaction, an oil-water separator was connected, the water phase was returned to the reactor, and the oil phase was separated. Then use liquid alkali to adjust the pH to about 10, lower the temperature to about 40°C, filter with suction, wash with water, get wet sodium salt, add water, raise the temperature, acidify with hydrochloric acid, filter with suction, wash with water, and dry to obtain 54.3g of the product with a purity of 97.6%. The rate is 79.5%.

Embodiment 3

[0038] In a 500ml three-necked bottle, add 56g of 90% 2,4-dichlorophenol, recover 5-10g of phenol, 32% NaOH, water, heat up to reflux, then add an equimolar amount of sodium chloroacetate solution dropwise, and finish dropping in about half an hour . At this temperature, the reaction was continued for 3.5 hours. During the reaction, an oil-water separator was connected, the water phase was returned to the reactor, and the oil phase was separated. Then use liquid alkali to adjust the pH to about 10, lower the temperature to about 40°C, filter with suction, wash with water, get wet sodium salt, add water, raise the temperature, acidify with hydrochloric acid, filter with suction, wash with water, and dry to obtain 63.8g of the product with a purity of 97.3%. The rate is 93.4%.

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Abstract

The invention discloses a preparing method of weed killer 2, 4-dichlorobenzene oxide acetic acid, which comprises the following steps: (1) producing bi-chlorophenol sodium solution and sodium monochloracetate solution; (2) putting into bi-chlorophenol sodium solution in condensed still; heating to 90-110 deg. c; dropping sodium monochloracetate solution; reacting for 2-8h; connecting to oil-water separator in reacting period; refluxing; returning water phase to reactor; dividing out of oil phase; setting the mole ratio of bi-chlorophenol sodium and sodium monochloracetate at 1:0. 8-1. 2; disposing; getting the product. This invention possesses low cost, high receiving ratio and simple operation, which can realize self-control.

Description

(1) Technical field [0001] The invention relates to a preparation method of herbicide 2,4-dichlorophenoxyacetic acid. (2) Background technology [0002] 2,4-dichlorophenoxyacetic acid, referred to as 2,4-D, is one of the longest and most widely used herbicides in the world. The synthesis method can be roughly divided into water method and non-aqueous method according to the amount of water in the condensation. The non-aqueous method has become a more advanced method at present because it can greatly reduce the hydrolysis of chloroacetic acid. It mostly uses excess dichlorophenol as the medium, and the reaction is basically carried out under anhydrous conditions. After the reaction, adjust the pH with acid to make sodium phenoxide into phenol and sodium phenoxide does not react, and then separate the phenol from the product by distillation or extraction. However, the reaction temperature of this method is relatively high, and the requirements for the material of the equipm...

Claims

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Application Information

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IPC IPC(8): C07C59/13C07C51/347
Inventor 陈素红孙国庆陈琦刘卫聪李志清孙国冉杨剑锋
Owner SHANDONG WEIFANG RAINBOW CHEM
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