- Preparation method for 2,4-dichlorophenoxyacetic acid
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The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: reacting phenol with a chloridizing agent under the action of a catalyst so as to obtain 2,4-dichlorophenol, wherein the catalyst is a composite catalyst composed of at least one metallic compound and at least one ether compound; reacting 2,4-dichlorophenol with analkaline compound so as to obtain 2,4-dichlorophenate; reacting haloacetic acid with an alkaline compound so as to obtain haloacetate; reacting the 2,4-dichlorophenate with the haloacetate so as to obtain 2,4-dichlorophenoxyacetate; and acidifying the 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, the specific composite catalyst is added in the chlorination process of phenol, so the prepared 2,4-dichlorophenoxyacetic acid contains few by-products, has high purity and yield, and is friendly to environment.
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- Preparation method for 2,4-dichlorophenoxyacetic acid
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The invention provides a preparation method for 2,4-dichlorophenoxyacetic acid. The preparation method comprises the following steps: a) reacting 2,4-dichlorophenol with alkali to obtain a 2,4-dichlorophenolate reaction solution, drying the 2,4-dichlorophenolate reaction solution so as to obtain a 2,4-dichlorophenolate solid, reacting haloacetic acid with an alkali so as to obtain a haloacetate reaction solution and carrying out drying so as to obtain a haloacetate solid; B) reacting the 2,4-dichlorophenolate solid with the haloacetate solid so as to obtain 2,4-dichlorophenoxyacetate; and C) acidifying the 2,4-dichlorophenoxyacetate so as to obtain 2,4-dichlorophenoxyacetic acid. According to the invention, the 2,4-dichlorophenolate reaction solution and the haloacetate reaction solution are separately dried to remove water; and the 2,4-dichlorophenolate solid and the haloacetate solid are subjected to a reaction in a non-aqueous phase, so the reaction is more thorough, and the prepared 2,4-dichlorophenoxyacetic acid has high yield and purity.
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Paragraph 0053; 0054; 0056; 0058; 0060; 0062
(2018/09/29)
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