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Synthesis method of 2-methyl-4-chlorophenoxyacetic acid

A technology of o-methylphenoxyacetic acid and chlorophenoxyacetic acid, applied in chemical instruments and methods, carboxylate preparation, carboxylate preparation, etc., can solve the problem of reducing product content and yield, refractory waste acid, reaction Incomplete and other problems, to achieve the effect of increasing content and yield, reducing waste acid production, and less "three wastes"

Inactive Publication Date: 2018-11-23
ANHUI HUAXING CHEM IND CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the global research on 2-methyl-4-chlorophenoxyacetic acid has not stopped so far.
[0003] The synthetic route of 2-methyl-4-chlorophenoxyacetic acid mainly adopts neutralization-condensation-chlorination. Most manufacturers use sodium hydroxide for neutralization, chlorine chlorination, and dichloroethane as solvent, but dichloro Ethane as a solvent reacts incompletely and has many by-products, which reduces the content and yield of the product; and the use of chlorine for chlorination will produce a large amount of difficult-to-handle waste acid

Method used

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  • Synthesis method of 2-methyl-4-chlorophenoxyacetic acid
  • Synthesis method of 2-methyl-4-chlorophenoxyacetic acid
  • Synthesis method of 2-methyl-4-chlorophenoxyacetic acid

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Embodiment 1

[0019] A kind of synthetic method of 2-methyl-4-chlorophenoxyacetic acid, comprises the following steps:

[0020] (1) Preparation of sodium chloroacetate: add quantitative chloroacetic acid and sodium bicarbonate to a special reactor, mix and stir for 2 hours, and simultaneously use 25°C water for circulating heating, and add water after sampling to completely dissolve as the reaction end point;

[0021] (2) Preparation of o-methylphenoxyacetic acid: add o-cresol in a special reactor, put it into the reaction kettle together with sodium chloroacetate under stirring and heat up to reflux, add dropwise 32% sodium hydroxide solution, and Make sure the pH value of the solution is 8-9. After the dropwise addition, continue to remove phenolic water until the temperature rises to 120°C, then start to cool down and add water, and then add hydrochloric acid dropwise to adjust the pH of the solution. After the acid adjustment is completed, suction filter and dry the filter cake. o-methy...

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Abstract

The invention discloses a synthesis method of 2-methyl-4-chlorophenoxyacetic acid, and relates to the technical field of organic synthesis. The synthesis method comprises the following steps that methyl phenoxyacetic acid and methyl ethyl carbonate are added into a reaction kettle, chlorine is introduced for chlorination, and after washing, cooling crystallization, suction filtration and drying are conducted, the target product is obtained. According to the synthesis method of the 2-methyl-4-chlorophenoxyacetic acid, the methyl ethyl carbonate is adopted for replacing dichloroethane, so that by-products are few, and the synthesis method of the 2-methyl-4-chlorophenoxyacetic acid is beneficial for improving the content and the yield of the product; a large amount of waste acid is avoided, and the solvent (methyl ethyl carbonate) is environmentally friendly and non-toxic, and meets the requirements of modern green pesticides; compared with an original technology, a reaction technology has the obvious advantages of high yield, little three-waste and low energy consumption.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a synthesis method of 2-methyl-4-chlorophenoxyacetic acid. Background technique [0002] There are many types of herbicides currently available on the market, and phenoxyacetic acid herbicides account for an important one. Due to the different substituents and substituent positions on the benzene ring, and the different numbers of carbon atoms of the carboxylic acid, different phenoxycarboxylic acid herbicides are formed. 2-Methyl-4-chlorophenoxyacetic acid is a hormone-type systemic phenoxycarboxylic acid herbicide developed and promoted by Imperial Chemical Industrirs in 1945. It has strong physiological activity on plants and is easy for roots and leaves. surface absorption and conduction. At low concentration, it can stimulate the growth of crops, prevent flower and fruit drop, form seedless fruit, promote fruit ripening and rooting of cuttings, etc.; at high conc...

Claims

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Application Information

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IPC IPC(8): C07C51/41C07C51/367C07C51/02C07C51/363C07C59/70
CPCC07C51/02C07C51/363C07C51/367C07C51/412C07C59/70
Inventor 李霞赵龙凯金奎尹仕兵汪志稳王玉贵
Owner ANHUI HUAXING CHEM IND CO LTD
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