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Electrolytic synthesis method for 3,6-dichloropicolinic acid

A technology of clopicolinic acid and tetraclopyridine, which is applied in the direction of electrolysis process, electrolysis components, electrolysis organic production, etc., can solve the problems that the feeding speed cannot be too fast, the feeding time is long, and the reaction time is long, etc. Effects of treatment process, improvement of solubility performance, and short reaction time

Active Publication Date: 2008-08-06
LIER CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, in order to control the generation of foam, the feeding speed of reaction raw material 3,4,5,6-tetrachloropicolinic acid can not be too fast, and the one-time amount can not be too much, so that the feeding time of reaction is long, the reaction time consumption is many, The output rate of the electrode per unit area is reduced
At the same time, due to the low temperature, the concentration of reactants cannot be effectively increased, and the amount of three wastes increases accordingly, which is not conducive to industrial production

Method used

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  • Electrolytic synthesis method for 3,6-dichloropicolinic acid
  • Electrolytic synthesis method for 3,6-dichloropicolinic acid
  • Electrolytic synthesis method for 3,6-dichloropicolinic acid

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Experimental program
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Effect test

Embodiment 1

[0019] In a 500ml beaker, dissolve 36.9g (0.128mol) and 20.5g (0.19mol) of sodium carbonate at 65°C in 270ml of distilled water with a content of 98% TCPANa (sodium tetraclopyridine), and install the electrodes under the same temperature conditions During the electrolysis reaction, 2.5ml 10mol / L NaOH (sodium hydroxide) solution was slowly added dropwise to maintain the alkaline range of the system at pH 9.5 to 11. After about 1.5 hours of reaction, the TCPANa content was lower than 1% (HPLC detection). Cool down to 25°C, and add 26.5ml of 10mol / L NaOH solution in batches to maintain the alkalinity of the reaction system to pH 13-13.5, control the cathode potential to -1.30v relative to the calomel electrode, and continue the reaction for 4 hours to complete. After cooling and filtering the electrolyte, adjust the pH of the electrolyte to 1.0 with concentrated hydrochloric acid, cool, crystallize, filter, and dry to obtain 21.6 g of white needle-like crystals of 3,6-dichloropico...

Embodiment 2

[0022] In a 500ml beaker, dissolve 98% TCPA Na (sodium tetraclopyridine) 45.3 (0.157mol) and 2.65g (0.025mol) of sodium carbonate and 270ml of distilled water at 65°C, install electrodes for electrolysis, batch 24.5g of sodium carbonate was added once, and it was finished within half an hour to maintain the system's alkaline range of pH 8.5 to 9.5. After reacting for about 2 hours, the content of TCPANa was lower than 1% (detected by HPLC). Lower the temperature to 30°C, add 33ml of 10mol / L NaOH solution in batches, maintain the alkalinity of the reaction system to pH 13-13.5, control the cathode potential to -1.30v relative to the calomel electrode, and continue the reaction for 4 hours to end. After the electrolyte is cooled and filtered, the pH of the electrolyte is adjusted to 1.0 with concentrated hydrochloric acid, then cooled, crystallized, filtered, and dried to obtain 26.5 g of white needle-like crystals of 3,6-dichloropicolinic acid. After the filtrate is concentrated...

Embodiment 3

[0024]In a 500ml beaker, dissolve 26.6g (0.1mol) and 26.5g (0.25mol) of sodium carbonate with a content of 98% TCPA (tetraclopicralic acid) in 270ml of distilled water at 65°C, and install electrodes for electrolysis. The NaOH solution of 2ml 10mol / L can be slowly dripped into the medium to maintain the alkalinity of pH 9.5~11 of the reaction system. After reacting for about 1.5 hours, the content of TCPANa is lower than 1% (HPLC detection). Cool down to 30°C, and add 20ml of 10mol / L NaOH solution in batches to maintain the alkalinity of the reaction system to pH 13-13.5, control the cathode potential to -1.30v relative to the calomel electrode, and continue the reaction for 4 hours to complete. After cooling and filtering the electrolyte, adjust the pH of the electrolyte to 1.0 with concentrated hydrochloric acid, cool, crystallize, filter, and dry to obtain 16.8 g of white needle-like crystals of 3,6-dichloropicolinic acid. After the filtrate is concentrated, extract with dic...

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Abstract

An electrolytic synthesis method of 3,6-matrigon takes alkaline aqueous solution as the reacting medium, which comprises the following step: dissolving 3,4,5,6-tetrachloropicolinic acid or the salt of the 3,4,5,6-tetrachloropicolinic acid in the alkaline aqueous solution, proceeding the electrolytic reducing reaction, obtaining target compound (II) after the electrolytic reaction and the acidification, wherein, firstly, proceeding the electrolytic reaction in the alkaline aqueous solution system with pH value 8.5-11, secondly, continuingly completing the electrolytic reaction under condition of the alkaline range is between pH value 13 and pH value 13.5 after obtaining trichloropyridine formate intermediate compound (I). The method has the advantages of easy operation, safety, friendly to the environment, the reaction temperature of the first stage can reach over 80 DEG C, the dissolvability of the reactant is efficiently improved, the reaction velocity is quickened, the batch output of the products is increased, and the spurging and the hydroxylating secondary reaction are efficiently avoided.

Description

technical field [0001] The invention relates to an electrolytic synthesis method for preparing 3,6-dichloropicolinic acid (Bikegrass). Background technique [0002] 3,6-Dichloropicolinic acid, whose trade name is Bikegrass, was reported by T.Haagsma in 1975 to have herbicidal activity, and is currently widely used in wheat cereal crops, corn, rapeseed, sugar beet, cruciferous vegetables, lawns, etc. Pastures and grasslands can effectively control annual and perennial broad-leaved weeds, especially Compositae and leguminous weeds, with high selectivity. [0003] The electrolytic reduction method is currently the most effective method for the synthesis of 3,6-dichloropicolinic acid. US Patent No. 4,217,185 first published a method for preparing 3,6-dichloropicolinic acid by electrolytic reduction of tetraclopyridine. Under the conditions of strong alkaline NaOH solution and not higher than 60°C, silver plate or silver powder is used as cathode, graphite is used as anode, lye...

Claims

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Application Information

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IPC IPC(8): C25B3/04C07D213/79C25B3/25
Inventor 范谦姚理任杰李燕飞石明珠
Owner LIER CHEM CO LTD
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