Preparation method of chlorophenoxycarboxamide salt

Abstract

The invention provides a preparation method of chlorophenoxycarboxamide salt, wherein the preparation method includes the following steps: S1) carrying out 2-site and / or 4-site selective chlorinationreaction of phenoxycarboxylic ester with a chlorinating agent under the action of a catalyst A and a catalyst B to obtain chlorophenoxycarboxylic ester, wherein the catalyst A is Lewis acid, and the catalyst B has the following structural formula of R1'-S-R2'; and S2) carrying out ammonolysis reaction of chlorophenoxycarboxylic ester and amine to obtain chlorophenoxycarboxamide salt. By redesigning of the process route and fine screening of the catalysts and the chlorinating agent, the method reduces energy consumption, improves chlorination selectivity and avoids loss of effective components.The yield of the obtained chlorophenoxycarboxamide salt can reach 98.5% or more. At the same time, the production of high-salt wastewater is completely eradicated, the dust hazard caused by drying and use of chlorophenoxycarboxylic acid is avoided, energy is saved and equipment investment is reduced.

Description

technical field [0001] The invention relates to the technical field of herbicide preparation, in particular to a preparation method of chlorophenoxycarboxylate amine salt. Background technique [0002] At present, the preparation method of chlorophenoxy carboxylic acid amine salt mainly comprises the following steps: [0003] 1) Using phenol as the main raw material, chlorinated phenols are obtained through chlorination. The chlorophenol produced in this step has an extremely unpleasant pungent odor, which leads to a very poor production site environment and poor chlorination selectivity. [0004] 2) Chlorophenol is condensed with chlorinated carboxylic acid under alkaline conditions, and the reaction solution is acidified and filtered to obtain chlorophenoxycarboxylic acid wet material, which is dried to obtain chlorophenoxycarboxylic acid. During the condensation process of the dichlorophenol or polychlorophenol in the chlorophenol in this step, condensation between two ...

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Problems solved by technology

In this step, the dioxins contained in the chlorophenoxycarboxylic acid will enter into the chlorophenoxycarboxylic acid amine salt, and enter the plants, air, soil and water with the use of the chlorophenoxycarboxylic acid amine salt, And with the enrichment of the food chain, it will cause more serious environmental hazards

[0006] In the above-mentioned preparation process, the chlorination selectivity is poor, and the post-treatment process will cause the loss of active ingredients, and the yield of the product is low

At the same time, when phenol is used as a raw material to synthesize chlorinated phenoxycarboxylic acid through chlorination and condensation, a large amount of waste water containing hydroxycarboxylic acid and waste salt will be produced, and a large amount of hazardous waste containing chlorophenol and chlorophenoxycarboxylic acid will be produced. Waste, three wastes treatment pressure, high treatment cost

[0007] In the process of acidifying the chlorinated phenoxy carboxylate obtained by condensation, and then ammonizing it into salt, not only will a large amount of high-salt wastewater be produced, but also the loss of active ingredients will be caused, and the long process will increase equipment investment and production costs.

[0008] The existing synthetic technology of chlorophenoxy amine salts has been very backward. With the continuous improvement of environmental protection awareness and environmental protection standards, the old and backward technology has seriously restricted the development of the synthetic industry of chlorophenoxy carboxylic acid amine salts. Benign development and sustainable development, the development of an advanced synthesis process is imminent

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