Method and apparatus for electrolytic synthesis of 3,6-dichloropyridine-carboxylic acid

Abstract

The invention provides an electrolytic synthesis method and equipment of 3,6-dichloropicolinic acid with high electrolytic efficiency. The electrolytic synthesis method includes: taking 3,4,5,6-tetrachloropicolinic acid as the main electrolytic raw material, placing the electrolytic solution in an electrolytic cell for electrolysis, neutralizing after the reaction, cooling and crystallizing, filtering, and drying to obtain 3 , 6-dichloropicolinic acid, in which the cathode of the electrolytic cell is automatically roughened by the voltage-stabilized and current-controlled silicon-controlled periodic commutation power supply. The electrolytic synthesis equipment includes a power supply, a batching tank, and an electrolytic tank. The power supply is a voltage-stabilizing thyristor periodic commutation power supply. The power supply is connected to a current commutator, and the current commutator is provided with a program control unit ; The positive pole of the power supply is connected to the anode of the electrolyzer, and the negative pole of the power supply is connected to the cathode of the electrolyzer. The electrolytic synthesis equipment solves many defects in the current 3,6-D electrolytic synthesis process, and has great practical value and social and economic benefits.

Description

(1) Technical field [0001] The invention relates to an electrolytic synthesis method of 3,6-dichloropicolinic acid, and also relates to an electrolytic synthesis equipment of 3,6-dichloropicolinic acid. (2) Background technology [0002] The English name of 3,6-dichloropicolinic acid is 3,6-dichloropicolinic acid, commonly known as Bikecao. 3,6-Dichloropicolinic acid (3,6-D) is a highly active plant growth regulator. Since the publication of US3317549, 3,6-D has attracted more and more attention, especially in the control of 2,4-D [0003] (2,4-Dichlorophenoxy)acetic acid and MCPA (2-methyl-4-chlorophenoxy)acetic acid are very effective on herbicide-resistant plants such as Canada thistle, Russian nettle and wild buckwheat etc. are very sensitive to 3,6-D. 3,6-D is also very active against pasture shrubs such as nettles, cat's claw acacia [0004] (A silk tree), mesquite is also very sensitive to 3,6-D. In addition, 3,6-D is not only less toxic to mammals, fish and poul...

AI Technical Summary

Problems solved by technology

The method has the following disadvantages: (1) the amount of dichloromethane is large, and 90% of the 3 in the filtrate is extracted, and the volume of 6-D needs to use dichloromethane to be about three times of the volume of the filtrate; (2) the energy consumption is high, and two Although the boiling point of methyl chloride is low, a large amount of dichloromethane needs to be heated and volatilized, and the energy consumption cannot be ignored; (3) the loss of dichloromethane is serious, because the boiling point of dichloromethane is low, so dichloromethane is easy to volatilize in use (4) Serious pollution, dichloromethane is a highly toxic solvent, and dichloromethane volatilized into the air seriously endangers the health of operating workers and residents around the factory

This method better solves the problems of high energy consumption and serious loss of dichloromethane in conventional separation methods provided by US4217185, etc., but the increase in operation steps makes the process complicated, and the use of toxic chemical dichloromethane cannot be avoided at the same time

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