1917-92-6Relevant articles and documents
Preparation method for 2,4-dichlorophenoxyacetic acid
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, (2018/09/08)
The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: A) reacting C2 or above-C2 alcohol with halogenated acetic acid soas to obtain halogenated acetate; B) reacting halogenated acetic acid with 2,4-dichlorophenolate so as to obtain 2,4-dichlorophenoxyacetate; and C) hydrolyzing 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, C2 or above-C2 alcohol reacts with halogenated acetic acid to obtain a halogenated acetate intermediate, the intermediate has good stability, few reaction by-products are produced, and high yield is realized; then the intermediate further reacts with 2,4-dichlorophenolate to obtain 2,4-dichlorophenoxyacetate; and finally, 2,4-dichlorophenoxyacetate is hydrolyzed to obtain 2,4-dichlorophenoxyacetic acid. Through a specific reaction route of the invention, the finally prepared 2,4-dichlorophenoxyacetic acid has high purity and yield, few by-products are produced, the reaction route is simple, and the application of the preparation method is facilitated.
Preparation method of 2,4-dichlorophenoxyacetic acid and salt thereof
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Paragraph 0111; 0113, (2019/01/06)
The invention provides a preparation method of 2,4-dichlorophenoxyacetic acid and a salt thereof, wherein the preparation method includes the following steps: S1) carrying out a reaction of phenol andchloracetic ester under alkaline conditions to obtain phenoxyacetic ester; S2) carrying out selective chlorination reaction of the phenoxyacetic ester with a chlorinating agent under the action of acatalyst A and a catalyst B to obtain 2,4-dichlorophenoxyacetic ester, wherein the catalyst A is Lewis acid, and the catalyst B is C5-22 thioethers, thiazoles, isothiazoles and thiophenes or halogenated derivatives thereof; and S3) carrying out hydrolysis reaction of 2,4-dichlorophenoxyacetic ester under acidic conditions to obtain 2,4-dichlorophenoxyacetic acid; or after 2,4-dichlorophenoxyaceticester is obtained, carrying out an alkaline hydrolysis reaction with an alkaline compound to obtain 2,4-dichlorophenoxyacetate. The production and use of 2,4-dichlorophenol with unpleasant odor are avoided, the production of dioxins is eliminated, the yield of products is improved, and the output of three wastes is greatly reduced.