Preparation method of tetrachlorpyridine

A technology of tetrachloropyridine and chloropyridine, which is applied in the field of preparation of tetrachloropyridine, can solve problems such as residues, waste materials, and complicated product separation processes

Active Publication Date: 2014-04-23
盐城恒盛化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The object of the present invention is to overcome the product separation process complexity existing in the existing tetrachloropyridine preparation method, waste material is many, residual catalyst such as ferric chloride etc. defects in the product, provide a kind of easy to operate industrialized production, less waste material, And the preparation method of the new tetrachloropyridine that catalyst can be reused

Method used

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Examples

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preparation example Construction

[0016] The invention provides a method for preparing tetrachloropyridine, the method comprising: in the presence of a catalyst, contacting a low-chlorinated pyridine compound with chlorine gas to obtain a product after the contact reaction, wherein the catalyst is ferric chloride, One or more of zinc chloride, magnesium chloride and aluminum chloride, the inert gas is passed through the product after the contact reaction and then distilled.

[0017] According to the present invention, the catalyst is a catalyst commonly used in the art to synthesize tetrachloropyridine through the contact reaction of low-chlorinated pyridine compounds and chlorine gas. Such a catalyst is one or more of the above-mentioned ferric chloride, zinc chloride, magnesium chloride and aluminum chloride; from the aspect of cost performance, it is preferred that the catalyst is ferric chloride. The catalysts described in the present invention are all Lewis acids of metal chlorides, which can form complex...

Embodiment 1

[0035] This example is used to illustrate the preparation method of 2,3,5,6-tetrachloropyridine of the present invention.

[0036] Mix 15g of ferric chloride and 350g of 2,6-dichloropyridine, heat to 200°C under a nitrogen atmosphere, and then react with chlorine gas for 12 hours to obtain a product after the contact reaction, which contains 489g 2,3,5,6-tetrachloropyridine, 5.6g of 2,3,6-trichloropyridine and 10.2g of pentachloropyridine.

[0037] The product was bubbled with nitrogen at 200°C for 2 hours, then cooled to 160°C, and distilled under a vacuum of 0.095MPa to collect fractions at a temperature of 146-154°C to obtain 472g of fractions. The content of 2,3,5,6-tetrachloropyridine, 2,3,6-trichloropyridine and pentachloropyridine contained in is 96.7% by weight, 0.86% by weight and 1.78% by weight respectively, The distillation yield of 6-tetrachloropyridine was 93.3%.

[0038] Take 0.12g of the above fraction for digestion, and make a 25ml solution of the digestion ...

Embodiment 2

[0042] This example is used to illustrate the preparation method of 2,3,5,6-tetrachloropyridine of the present invention.

[0043] 100g of 2,6-dichloropyridine prepared by the method of Example 1 and the product material after the contact reaction with chlorine gas were bubbled with nitrogen gas for 1 hour at 200°C under the condition of a vacuum of 0.085MPa. Distillation, collecting fractions at a temperature of 185-190°C, and obtaining fractions of 92.8g, the contents of 2,3,5,6-tetrachloropyridine, 2,3,6-trichloropyridine and pentachloropyridine were respectively 97.6% by weight, 1.45% by weight, and 0.56% by weight, and the distillation yield of 2,3,5,6-tetrachloropyridine was 92.6%.

[0044] Take 0.12g of the above fraction for digestion, and make a 25ml solution of the digestion product for ICP analysis. The measured iron ion concentration is 0.0213mg / L, which is close to the iron ion concentration of the blank sample (deionized water) 0.0182mg / L.

[0045] The residue A...

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Abstract

The invention discloses a preparation method of tetrachlorpyridine. The method comprises the following steps: in the presence of a catalyst, performing a contact reaction between a low-chloropyridine compound and chlorine gas to obtain a product after the contact reaction, wherein the catalyst is one or more of iron chloride, zinc chloride, magnesium chloride and aluminum chloride; introducing inactive gas into the product after the contact reaction, and distilling. By adopting the method disclosed by the invention, the distillation yield of tetrachlorpyridine can exceed 92%, and the obtained product tetrachlorpyridine does not contain the component of the catalyst; moreover, the residue after the distillation can be further applied to a catalytic synthesis reaction of tetrachlorpyridine.

Description

technical field [0001] The invention relates to a preparation method of tetrachloropyridine, in particular to a preparation method of 2,3,5,6-tetrachloropyridine. Background technique [0002] 2,3,5,6-Tetrachloropyridine (hereinafter referred to as CP) is an important pharmaceutical and pesticide intermediate. For example, in pesticide chemistry, 2,3,5,6-tetrachloropyridine is mainly used as the precursor of 3,5,6-trichloropyridin-2-ol to synthesize the high-efficiency and low-toxic pesticide chlorpyrifos (Chlorpyrifos) Or Chlorpyrifos-Methyl. In the synthetic method of 2,3,5,6-tetrachloropyridine, currently widely used is 2,6-dichloropyridine as a raw material, and 2,6-dichloropyridine is catalyzed by chlorine gas and chlorine by Lewis acid. In order to obtain four CPs, wherein the Lewis acid of the metal chlorides commonly used is used as a catalyst, such as ferric chloride, zinc chloride, aluminum chloride, etc., preferably ferric chloride. This method has the advantag...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
CPCY02P20/584C07D213/61
Inventor 张小航李勇李季
Owner 盐城恒盛化工有限公司
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