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Method for preparing picolinic acid through electro-catalysis selective dechloridation of chloropicolinicacid

A technology of chloropicolinic acid and chloropicolinic acid, which is applied in the field of electrocatalytic selective dechlorination of chloropicolinic acid, can solve the problems of poor dechlorination selectivity, incomplete dechlorination, toxic reducing agents and toxic electrode materials, etc. Achieve high chemical selectivity and high added value

Active Publication Date: 2015-10-21
菏泽建数智能科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The object of the invention is to provide a kind of method that electrocatalytic selective dechlorination of chloropicolinic acid prepares picolinic acid, take acidic solution as reaction medium, the conductive material modified by noble metal is negative electrode, and chemically inert conductive material is anode, to

Method used

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  • Method for preparing picolinic acid through electro-catalysis selective dechloridation of chloropicolinicacid
  • Method for preparing picolinic acid through electro-catalysis selective dechloridation of chloropicolinicacid
  • Method for preparing picolinic acid through electro-catalysis selective dechloridation of chloropicolinicacid

Examples

Experimental program
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Embodiment 1

[0035] Embodiment 1 electrolysis of 3,6-dichloropicolinic acid (3,6-D) to synthesize picolinic acid (PA)

[0036] Diaphragm plate frame tank is the electrolytic reactor, the perfluorosulfonic acid membrane is the diaphragm, and the expanded screen palladium-modified silver is the cathode (1g pd / m 2 ), the platinum-plated titanium mesh is the anode. 1000mL 1mol / L sulfuric acid + 20% methanol + 100g 3,6-D aqueous solution is catholyte; 1mol / L sulfuric acid aqueous solution is anolyte. During the electrolysis process, the temperature is controlled at 20-25°C, and the current density is controlled at 3A / dm 2 , catholyte pH=0~0.5, cathode potential is -0.3~-0.6V vs.Ag / AgCl (3.0M KCl). Stop electrolysis after feeding 4F / mol 3,6-D electricity. After the catholyte was transferred to the beaker, sodium hydroxide was added to adjust the pH=4, and then the yield of PA was analyzed by HPLC to be 95%, the selectivity was 95%, and the dechlorination current efficiency was 96%.

[0037] ...

Embodiment 2

[0040] Example 2 Electrolysis of 3,5,6-trichloropicolinic acid, 3,6-D, 3,5-dichloropicolinic acid, 3-chloropicolinic acid, 6-chloropicolinic acid mixture to synthesize PA

[0041] Diaphragm plate frame tank is the electrolytic reactor, the perfluorosulfonic acid membrane is the diaphragm, and the expanded screen palladium-modified silver is the cathode (1g pd / m 2 ), the platinum-plated titanium mesh is the anode. 1000mL 1mol / L sulfuric acid+40%methanol+2.26g 3,5,6-trichloropicolinic acid+95.0g 3,6-D+1.16g 3,5-dichloropicolinic acid+1.1g 3-chloropicolinic acid+ The aqueous solution of 0.48 gram of 6-chloropicolinic acid is catholyte; 1mol / L sulfuric acid aqueous solution is anolyte. During the electrolysis process, the temperature is controlled at 35-40°C, and the current density is controlled at 5A / dm 2 , catholyte pH=0~0.5, cathode potential is -0.3~-0.7V vs. Ag / AgCl (3.0M KCl). Stop electrolysis after feeding 5F / mol 3,6-D electricity. After the catholyte was transferred ...

Embodiment 3

[0042] Example 3 Electrolysis of 4-amino-3,5,6-trichloropicolinic acid, 4-amino-3,6-dichloropicolinic acid, 4-amino-3,5-dichloropicolinic acid, 4-amino-3 Synthesis of 4-aminopicolinic acid from a mixture of -chloropicolinic acid and 4-amino-6-chloropicolinic acid

[0043] Diaphragm plate frame tank is the electrolytic reactor, the perfluorosulfonic acid membrane is the diaphragm, and the expanded screen palladium-modified silver is the cathode (1g pd / m 2 ), the platinum-plated titanium mesh is the anode. 1000mL 1mol / L sulfuric acid + 20% methanol + 2.42 grams of 4-amino-3,5,6-trichloropicolinic acid + 95.0 grams of 4-amino-3,6-dichloropicolinic acid + 0.84 grams of 4-amino-3, The aqueous solution of 5-dichloropicolinic acid+1.5 g of 4-amino-3-chloropicolinic acid+0.24 g of 4-amino-6-chloropicolinic acid is the catholyte; the aqueous solution of 1mol / L sulfuric acid is the anolyte. During the electrolysis process, the temperature is controlled at 25-35°C, and the current dens...

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Abstract

The invention discloses a method for preparing picolinic acid through electro-catalysis selective dechloridation of chloropicolinicacid. According to the method, the chloropicolinicacid is added into a water solution for supporting an electrolyte or a mixed water solution for supporting the electrolyte and organic solvent, so that electrolytic reaction liquid is obtained, an electrolytic reaction is conducted in an electrolytic bath with a precious metal modified conducting material used as the cathode and a chemical inertness conducting material used as the anode, and accordingly the picolinic acid shown as the formula (II) is obtained. By the adoption of the method, the chloropicolinicacid or a mixture of the chloropicolinicacid can be reduced into the picolinic acid in high chemoselectivity, high efficiency and high yield modes, the problem that by-products cannot be handled easily in an existing synthetic technique of 3,6-clopyralid and 4-amino-3,6-clopyralid can be solved, and picolinic acid and 4-aminopyridine carboxylic acid products with high additional values further can be obtained.

Description

(1) Technical field [0001] The invention relates to an electrocatalytic selective dechlorination method of chloropicolinic acid, in particular to a method for selectively reducing chlorine substituents on the pyridine ring of chloropicolinic acid by electrolysis in the presence of a 2-position carboxyl group. (2) Background technology [0002] During the synthesis of 3,6-dichloropicolinic acid and 4-amino-3,6-dichloropicolinic acid, 3,5,6-trichloropicolinic acid, 3,6-dichloropicolinic acid, 3,5-dichloropicolinic acid, 3-chloropicolinic acid, 6-chloropicolinic acid and 4-amino-3,5,6-trichloropicolinic acid, 4-amino-3,6-dichloropicolinic acid, Mixed by-products of 4-amino-3,5-chloropicolinic acid, 4-amino-3-chloropicolinic acid, 4-amino-6-chloropicolinic acid. The various chloropicolinic acids in the by-products are very close in physicochemical properties, so the cost of separation is very high. Due to the high biological toxicity of these chloropicolinic acids, direct disc...

Claims

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Application Information

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IPC IPC(8): C25B3/04C25B3/25
Inventor 徐颖华王一想马红星马淳安
Owner 菏泽建数智能科技有限公司
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