Method for preparing 4-amino-3,6-dichloropicolinic acid by electrochemical selective dechlorination

A diclopyralid and selectivity technology, applied in electrodes, electrolytic processes, electrolytic components, etc., can solve the problems of silver electrode dechlorination activity and selectivity that are difficult to guarantee and maintain

Active Publication Date: 2019-11-12
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The problem with this method is that the dechlorination activity and selectivity of silver electrodes are difficult to guarantee and maintain

Method used

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  • Method for preparing 4-amino-3,6-dichloropicolinic acid by electrochemical selective dechlorination
  • Method for preparing 4-amino-3,6-dichloropicolinic acid by electrochemical selective dechlorination

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Embodiment 1: the preparation of activated silver electrode

[0023] (1) Soaking: Soak the silver net (purity is 99.99wt%, size is 0.3cm * 4.0cm * 6.0cm) in static 10wt% hydrochloric acid aqueous solution (prepared with deionized water), 20 ℃ for 20min, after soaking silver network;

[0024] (2) Oxidation: in H-type electrolyzer with Nafion 117 cation membrane as diaphragm (such as figure 1 Shown), in step (1) the silver mesh is the working electrode, and the platinum sheet of the same area is the counter electrode; silver / silver chloride is the reference electrode. The working electrode chamber is 0.1M NaCl+1.0M NaOH aqueous solution (prepared with deionized water), and the counter electrode chamber is 1.0M sodium hydroxide aqueous solution (prepared with deionized water). Control the temperature of the aqueous solution in the working electrode chamber to 20-25°C, first apply 0.5A / dm to the silver electrode 2 The anodizing current until the electrode potential reach...

Embodiment 2

[0026] Embodiment 2: the preparation of activated silver electrode

[0027] (1) Soaking: the silver nets with a purity of 99.95wt% (recorded as silver mesh 1#) and 99.0wt% (recorded as silver mesh 2#) and a size of 0.3cm×4.0cm×6.0cm were soaked respectively In 15wt% hydrochloric acid aqueous solution (prepared with deionized water), stand at 25°C for 60min;

[0028] (2) Oxidation: In an H-type electrolytic cell with Nafion 117 cationic membrane as a diaphragm ( figure 1 ), respectively with step (1) silver mesh 1# and silver mesh 2# as the working electrode, the platinum sheet of the same area as the counter electrode; silver / silver chloride as the reference electrode. The working electrode chamber is 1.0M NaCl aqueous solution (prepared with deionized water), and the counter electrode chamber is 1.0M sodium hydroxide aqueous solution (prepared with deionized water). Control the temperature of the aqueous solution in the working electrode chamber to 20-25°C, first apply 2A / d...

Embodiment 3

[0030] Embodiment 3: the preparation of activated silver electrode (hydrochloric acid does not soak)

[0031] (1) Oxidation: In the H-type electrolytic cell with Nafion 117 cationic membrane as the diaphragm ( figure 1), the silver mesh (purity is 99.95wt%, size is 0.3cm * 4.0cm * 6.0cm) is the working electrode; the platinum sheet of the same area is the counter electrode; silver / silver chloride is the reference electrode. The working electrode chamber is 0.1M NaCl+1.0M NaOH aqueous solution (prepared with deionized water), and the counter electrode chamber is 1.0M sodium hydroxide aqueous solution (prepared with deionized water). Control the temperature of the aqueous solution in the working electrode chamber to 20-25°C, first apply 0.5A / dm to the silver grid 2 The anodizing current until the electrode potential reaches +0.5vs.vs.Ag / AgCl;

[0032] (2) Reduction: use the silver mesh in step (1) as the counter electrode, the platinum sheet as the working electrode, and other...

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Abstract

The invention discloses a method for preparing 4-amino-3,6-dichloropicolinic acid by electrochemical selective dechlorination. The method comprises the following steps: a diaphragm electrolytic tank is adopted, a 4-amino-3,5,6-trichloropyridine formate aqueous solution prepared from electronic-grade ultrapure water is used as a catholyte, an alkali metal hydroxide aqueous solution preparedfrom electronic-grade ultrapure water is used as an anolyte, a nickel-based material is used as an anode, and silver with purity of 99.95%-99.99% is used as a cathode; and an electrolysis reaction is carriedout under the conditions of a current density of 1-20 A / dm<2> and a reaction temperature of 0-90 DEG C, after the electrolysis reaction is completed, the catholyte is separated and purified to obtainthe 4-amino-3,6-dichloropicolinic acid. According to the method provided by the invention, the catholyte and the anolyte are prepared by adopting the electronic-grade ultrapure water, the 4-amino-3,6-dichloropicolinic acid can be prepared through highly-selective dechlorination, the product yield is improved by 4-10%, and the purity is improved by 2-5%.

Description

[0001] (1) Technical field [0002] The invention relates to a method for preparing 4-amino-3,6-dichloropicolinic acid through electrochemical selective dechlorination. [0003] (2) Background technology [0004] 4-Amino-3,6-dichloropicolinic acid, whose trade names are Amazoram, Aminopyralid, and Dichloroaminopyralid, is a pyridinecarboxylic acid herbicide, which can quickly enter the plant body, causing Plant growth interruption and rapid death are used primarily for weed control in pastures, plantations and non-crop areas. In addition, 4-amino-3,6-dichloropicolinic acid is also a key intermediate in the synthesis of halopyridine and halopyridine. Fluclopyridine and cloflupyridine are new aryl picolinate herbicides developed by Dow AgroSciences. They are new varieties of hormonal herbicides and have the characteristics of lower dosage and wider herbicidal spectrum . [0005] US patents US 7666293 and US 8685222 disclose a method for preparing 4-amino-3,6-dichloropicolinic ...

Claims

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Application Information

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IPC IPC(8): C25B3/00C25B11/03
CPCC25B3/00C25B11/031
Inventor 徐颖华韩方玉丁旭芬毛信表储诚普
Owner ZHEJIANG UNIV OF TECH
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