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Synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid

A technology of dichlorophenoxyacetic acid and a synthesis method, which is applied in the directions of oxidative preparation of carboxylic acid, organic chemistry, etc., can solve problems such as increasing solvent loss, reducing product yield, phenol-containing wastewater, etc., and achieves easy operation, little environmental pollution, Product quality effect

Inactive Publication Date: 2010-10-13
上海力智生化科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the above synthesis process, in order to reduce the residual amount of free phenol in the product, the treatment method is recrystallization or steam distillation. The former will reduce the product yield and increase the loss of solvent, while the latter will produce phenol-containing wastewater. certain defect

Method used

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  • Synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] (1) Synthesis of 2,4-dichlorophenoxyacetone

[0027] In a 1000mL three-necked flask, add 58g (0.55mol) of sodium carbonate, 81g (0.5mol) of 2,4-dichlorophenol, 6.0g of PEG-400, 1.2g of sodium iodide and 200mL of acetonitrile, and heat up to 70°C. A mixture of 55 g (0.6 mol) of monochloroacetone and 50 mL of acetonitrile was slowly added dropwise under vigorous stirring, and the reaction was continued for 3 hours after the drop was completed. After cooling to room temperature, filter, remove the solvent from the filtrate, and collect fractions at 100-102° C. / 1 mmHg by fractional distillation to obtain 101 g of 2,4-dichlorophenoxyacetone with a purity of >99% and a yield of 92%.

[0028] (2) Synthesis of 2,4-dichlorophenoxyacetic acid

[0029] In a 500mL three-necked flask, add 150g of sodium hypochlorite solution with available chlorine ≥ 20%, 20g of sodium hydroxide, add dropwise 22g (0.1mol) of 2,4-dichlorophenoxyacetone and 40mL of 1,4-dioxyl The solution of the hex...

Embodiment 2

[0031] (1) Synthesis of 2,4-dichlorophenoxyacetone

[0032] In a 1000mL three-necked flask, add 65g (0.6mol) of sodium carbonate, 81g (0.5mol) of 2,4-dichlorophenol, 2.5g of tetrabutylammonium chloride, 1.2g of sodium iodide and 200mL of acetone, and heat up to 50°C . A mixture of 55 g (0.6 mol) of monochloroacetone and 50 mL of acetone was slowly added dropwise under vigorous stirring, and the reaction was continued for 3 hours after the drop was completed. After cooling to room temperature, filter, remove the solvent from the filtrate, and obtain 99 g of 2,4-dichlorophenoxyacetone by fractional distillation, with a yield of 90%.

[0033] (2) Synthesis of 2,4-dichlorophenoxyacetic acid

[0034]In a 500mL three-necked flask, add 150g of sodium hypochlorite solution with available chlorine ≥ 20%, 15g of sodium hydroxide, add dropwise a solution of 22g (0.1mol) 2,4-dichlorophenoxyacetone and 40mL of tetrahydrofuran at room temperature with stirring, and dropwise Then continue...

Embodiment 3

[0036] (1) Synthesis of 2,4-dichlorophenoxyacetone

[0037] In a 1000mL three-necked flask, add 300mL saturated aqueous sodium carbonate solution, 81g (0.5mol) 2,4-dichlorophenol, 2.5g tetrabutylammonium chloride, 1.2g sodium iodide and 200mL toluene, heat to 60°C, and A solution of 64 g (0.7 mol) of monochloroacetone and 80 mL of benzene was added dropwise with stirring, and the reaction was continued for 5 hours after the drop was completed. The reaction mixture was lowered to room temperature, and the water layer was separated after standing still. The organic layer was washed with 100 mL of 10% dilute hydrochloric acid solution and water (100 mL×2) respectively. After drying with anhydrous sodium sulfate to remove benzene, fractional distillation gave 95 g of 2,4-dichlorophenoxyacetone with a yield of 88%.

[0038] (2) Synthesis of 2,4-dichlorophenoxyacetic acid

[0039] In a 500mL three-necked flask, add 180g of sodium hypochlorite solution with available chlorine ≥ 20%...

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Abstract

The invention relates to a synthesis method of herbicide 2, 4-dichlorphenoxyacetic acid, which comprises the following steps that: under the existence of weak base and the effect of sodium iodide and phase transfer catalyst, 2, 4-dichlorophenol is condensed with monochloroacetone through Williamson to obtain 2, 4-dichlorophenoxy acetone; the obtained 2, 4-dichlorophenoxy acetone is reacted and acidified in sodium hypochlorite solution to finally obtain 2, 4-D. With the method, the free phenol content in the product can be effectively controlled below the national standard, the discharge of the phenol-contained waste water can be reduced, and the synthesis method is simple and convenient to operate and has good product quality and small environmental pollution.

Description

technical field [0001] The invention relates to a method for synthesizing herbicide 2,4-dichlorophenoxyacetic acid. Background technique [0002] 2,4-D is 2,4-dichlorophenoxyacetic acid, which is one of the most widely used herbicides. It can remove broad-leaved weeds such as quinoa and amaranth in crop fields such as wheat, rice, corn, and sugarcane, as well as germination period Poaceae weeds can be used as plant growth regulators at low concentrations to prevent tomato, cotton, pineapple, etc. For fungicide. [0003] The pure product of 2,4-D is white crystal with low solubility in water, easily soluble in organic solvents such as ethanol and benzene, and is usually processed into liquids, powders, emulsions, etc. of sodium salts, ammonium salts, or esters. [0004] The traditional synthesis process of 2,4-D is relatively mature and the cost is relatively low. There are two main synthesis processes: one is phenol chlorination etherification method, that is, phenol is fi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C59/70C07C51/16
Inventor 洪伟朱红刘锡玲
Owner 上海力智生化科技有限公司
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