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A kind of electrolytic synthesis method of 4-amino-3,6-dichloropicolinic acid

A technology of diclopyralid and triclopyralid, which is applied in the direction of electrolytic components, electrolytic process, electrolytic organic production, etc., can solve the problems of large alkali consumption and large amount of waste salt, so as to improve product yield and reduce alkali The effect of consumption

Active Publication Date: 2021-06-08
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The present invention aims at the problem of "large alkali consumption and large amount of waste salt" existing in the prior art, and provides a method for the electrolytic synthesis of 4-amino-3,6-dichloropicolinic acid, which adopts recycled catholyte as anolyte, so that The pH of the catholyte is more stable, reducing the consumption of alkali, reducing the discharge of acidic sodium chloride, and increasing the product yield

Method used

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  • A kind of electrolytic synthesis method of 4-amino-3,6-dichloropicolinic acid
  • A kind of electrolytic synthesis method of 4-amino-3,6-dichloropicolinic acid

Examples

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Embodiment 1

[0026] Embodiment 1: the preparation of activated silver electrode

[0027] H-type electrolyzer with Nafion 117 cationic membrane as diaphragm (such as figure 1 In shown), the silver net (purity is 99.99wt%, size is 0.1cm * 4.0cm * 6.0cm) is the working electrode; The platinum sheet of the same area is the opposite electrode; Silver / silver chloride is the reference electrode. The working electrode chamber is 300mL 0.5M NaCl+0.5M NaOH aqueous solution, and the counter electrode chamber is 300mL 1.0M sodium hydroxide aqueous solution. Control the temperature of the aqueous solution in the working electrode chamber to 20-25°C, first apply 0.3A / dm to the silver grid 2 The anodizing current until the electrode potential reaches +0.7vs.SHE (relative to the standard hydrogen electrode potential); then reverse the electrode and apply 0.3A / dm to the silver grid 2 The cathodic reduction current until the electrode potential reaches -0.4vs.SHE. Take out the silver electrode and put it...

Embodiment 2

[0028] Example 2: Electrolytic synthesis of 4-amino-3,6-dichloropicolinic acid

[0029] H-type electrolyzer with Nafion 117 cationic membrane as diaphragm ( figure 1 ), the activated silver mesh prepared by the method of Example 1 is the negative electrode (working electrode), and the titanium-based ruthenium oxide, titanium oxide and iridium oxide mixed coating electrode of the same area (geometric size is 0.1cm * 4.0cm * 6.0cm, The thickness of the coating is about 0.1mm, purchased from Hangzhou Sail Electrochemical Experimental Equipment Co., Ltd.) as the anode (counter electrode); 300mL of 1.3M NaCl aqueous solution with pH=1.5 is the anolyte, and 300mL contains 0.5M NaOH+0.4M 4-amino - The aqueous solution of 3,5,6-trichloropicolinic acid is catholyte, pH=13.1. Stir the catholyte at 40-45°C and feed it with 3.75A / dm 2 The electric current, stop electrolysis after reaction 10.5 hours, the pH=13.5 of catholyte at this moment. The concentration of NaCl in the anolyte was ...

Embodiment 3

[0032] Example 3: Synthesis of 4-amino-3,6-dichloropicolinic acid by electrolysis of recycled catholyte

[0033] H-type electrolyzer with Nafion 117 cationic membrane as diaphragm ( figure 1 ), the activated silver mesh prepared by the method of Example 1 is the cathode, and the titanium-based ruthenium oxide, titanium oxide and iridium oxide mixed coating electrode (same as Example 2) of the same area is the anode; With 300mL Example 2, reclaim the catholyte Anolyte, 300mL aqueous solution containing 0.5M NaOH+0.4M 4-amino-3,5,6-trichloropicolinic acid is catholyte, pH=13.2. Stir the catholyte at 40-45°C and feed it with 3.75A / dm 2 The electric current, stop electrolysis after reaction 10.5 hours, the pH=13.5 of catholyte at this moment. The concentration of NaCl in the anolyte was determined to be about 0.45M by ion chromatography. The conversion rate of 4-amino-3,5,6-trichloropicolinic acid in the catholyte was determined by high performance liquid chromatography to be 9...

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Abstract

The invention discloses an electrolytic synthesis method of 4-amino-3,6-diclopyridine carboxylic acid. A diaphragm electrolytic cell is used, and an aqueous solution of alkali metal chloride salt with a pH of 0.5 to 1.5 is used as an anolyte to dissolve 4-amino- The alkali metal hydroxide aqueous solution of 3,5,6-triclopyridine carboxylic acid is used as the catholyte, and the electrolysis reaction is carried out with silver as the cathode; the pH of the catholyte is adjusted to 0.5-1.5 with concentrated hydrochloric acid, crystallized, filtered, and filtered Cake obtains the organic matter containing 4-amino-3,6-diclopyridine, collects the filtrate and extracts it with an organic solvent to obtain a raffinate; after the raffinate is adsorbed by an adsorbent, it is filtered, and the filtrate is taken to recover the catholyte. Recycle the anolyte for the next batch of electrolysis. The invention adopts the recovered catholyte as the anolyte, so that the pH of the catholyte is more stable, the product yield is increased by 5-8%, the consumption of the alkali is greatly reduced, and the discharge of the acidic sodium chloride aqueous solution is greatly reduced.

Description

[0001] (1) Technical field [0002] The invention relates to an electrolytic synthesis method of 4-amino-3,6-dichloropicolinic acid. [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 6352635, 7666293, 8685222 and 0090639 disclose a method for preparing 4-amino-3,6-dichloropicolinic acid by electrochemic...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25B3/05C25B3/25C25B11/042C25B13/08
CPCC25B3/00C25B11/04C25B13/08
Inventor 徐颖华石凯储诚普丁旭芬张洋亮
Owner ZHEJIANG UNIV OF TECH