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Method for preparing 3,6-dichloropyridine-2-formic acid by catalytic electrolysis of 3,4,5,6-tetrachloropyridine-2-formic acid

A technology of tetrachloropyridine and dichloropyridine, applied in the production field of chemical products, can solve the problems of inability to meet the sustainable development of chemical industry, unfriendly environment, and high replacement cost, achieve obvious economic advantages and environmental protection advantages, reduce post-processing Difficulty and low cost

Active Publication Date: 2018-03-27
ZHEJIANG AVILIVE CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, the chemical method uses hydrazine hydrate for reduction, and the waste water containing high concentration of ammonia nitrogen is large and difficult to handle, which is very unfriendly to the environment
Second, there are defects in the electrolytic cell in the electrolysis method, and the electrode application life is short and the replacement cost is high
Therefore, the existing production process can no longer meet the needs of the sustainable development of the chemical industry, and a more advanced clean production process is urgently needed to replace it.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Embodiment 1 A method for preparing 3,6-dichloropyridine-2-carboxylic acid by catalytic electrolysis of 3,4,5,6-tetrachloropyridine-2-carboxylic acid comprises the following steps: , voltmeter, thermometer, 130-liter electrolyzer, add 100kg 4% sodium hydroxide aqueous solution, turn on the circulating pump, gradually add 13.1kg 3,4,5,6-tetrachloropyridine-2-carboxylic acid, 0.79kg 5% Pd / C; turn on the heat exchange device, raise the temperature of the feed liquid to 50°C; turn on the constant voltage DC power supply, adjust the cell voltage to 3.5V; sample the 3,4,5,6-tetrachloropyridine-2 in the electrolyte -Formic acid content, until 3,4,5,6-tetrachloropyridine-2-carboxylic acid in the electrolyte≤0.4%, turn off the DC power supply; continuously monitor the pH value of the electrolyte during electrolysis, and keep ph=13.2. If the pH value drops, 30% sodium hydroxide needs to be supplemented; after the electrolysis, filter, the filter cake (catalyst) is washed with 8%-...

Embodiment 2

[0024] Example 2 The operation was the same as that of Example 1, keeping ph = 12.5 to obtain 8.86 kg of 3,6-dichloropyridine-2-carboxylic acid with a content of 96.0% and a yield of 88.3%.

Embodiment 3

[0025] Example 3 The operation is the same as that of Example 1, but the catalyst is replaced by 5% Rh / C to obtain 9.00 kg of 3,6-dichloropyridine-2-carboxylic acid with a content of 96.9% and a yield of 90.5%.

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PUM

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Abstract

The invention discloses a method for preparing 3,6-dichloropyridine-2-carboxylic acid by catalytic electrolysis of 3,4,5,6-tetrachloropyridine-2-carboxylic acid, which belongs to the production field of chemical products. The technical problem to be solved in the present invention is to prepare 3,6-dichloropyridine-2-formic acid by electrolysis of 3,4,5,6-tetrachloropyridine-2-formic acid, which requires long electrolysis time, high energy consumption and poor selectivity. The solution of the present invention to solve the above-mentioned technical problems is to add a catalyst during the electrolysis of 3,4,5,6-tetrachloropyridine-2-carboxylic acid, and combine conditions such as specific temperature and pH value to make the 4,5-position two on the pyridine ring The chlorine is removed, and the final product is 3,6-dichloropyridine-2-carboxylic acid. The catalyst is filtered and washed in the post-treatment process, and recovered for mechanical use. On the basis of electrolysis, the present invention adds a small input, increases product content and yield, and reduces energy consumption.

Description

technical field [0001] The invention belongs to the production field of chemical products, and in particular relates to a method for preparing 3,6-dichloropyridine-2-carboxylic acid by catalytic electrolysis of 3,4,5,6-tetrachloropyridine-2-carboxylic acid. Background technique [0002] 3,6-dichloropicolinic acid, English name 3,6-dichloropicolinic acid, referred to as 3,6-DCP, commonly known as Bikecao, is a new type of green pesticide with high efficiency, low toxicity and low residue, which can be used as Insecticides and herbicides, but also as fungicides and plant growth regulators. [0003] The synthesis methods of 3,6-dichloropyridine-2-carboxylic acid currently include chemical synthesis and electrolysis. The chemical synthesis of 3,6-dichloropyridine-2-carboxylic acid is carried out using 3,4,5,6-tetrachloropyridine-2-carboxylate as a raw material, and is completed through step-by-step reduction with hydrazine hydrate, acidification, and purification. However, the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C25B3/04C25B15/00C25B3/25
CPCC25B15/00C25B3/25
Inventor 厉云阳李惠跃黄程徐庆华朱加权
Owner ZHEJIANG AVILIVE CHEM CO LTD