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Method for preparing 2,3,5-trichloropyridine

A technology of triclopyridine and tetrachloropyridine, which is applied in the field of compound preparation, can solve the problems of low yield, high cost, and non-environmental protection, and achieve the effects of high product yield, low cost, and low pollution

Inactive Publication Date: 2018-07-31
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

[0014] The purpose of the present invention is to overcome the defects of high cost, low yield and environmental protection of the method for preparing 2,3,5-trichloropyridine in the prior art, and provide a method for preparing 2,3,5-trichloropyridine

Method used

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Embodiment approach

[0043] According to a preferred embodiment of the present invention, the method further includes: pretreating the catalyst carrier before impregnating the catalyst carrier. Different catalyst supports have different pretreatment methods, which can be implemented by conventional methods in the art. For example, when the catalyst support is silica, the pretreatment method is: the catalyst support is placed at 400-600 ° C under an inert gas Roasting under the atmosphere for 4-8 hours; when the catalyst carrier is activated carbon, the pretreatment method is: at room temperature-85 ° C, the catalyst carrier is soaked in 10-30% by weight of hydrochloric acid aqueous solution or nitric acid aqueous solution for 4-9 Hours, then washed with deionized water until neutral, dried at 100-120 ° C, then placed in a muffle furnace and roasted at 300-600 ° C for 4-8 hours, cooled to room temperature under an inert gas atmosphere; when the When the catalyst carrier is a molecular sieve with a ...

Embodiment 1

[0058] (1) Preparation of supported catalyst

[0059] Clean coconut shell activated carbon with deionized water to remove impurities, put it in 10% nitric acid solution, soak it at 70°C for 5 hours, then wash it with deionized water until neutral, dry it at 120°C, and place it in a muffle furnace calcination at 350°C for 4 hours, and cooled to room temperature under an inert gas atmosphere to obtain a pretreated catalyst carrier.

[0060] Weigh 30g of SnCl 4 Dissolve in 70mL of deionized water, add 50g of pretreated catalyst carrier under stirring, after soaking for 5 hours, filter to remove excess FeCl 3 aqueous solution. Rinse the impregnated catalyst carrier with deionized water, then vacuum-dry it at 120°C for 6 hours, and then bake it at 450°C for 4 hours to obtain a catalyst carrier loaded with SnCl 4 The supported catalyst Sn-AC (loading amount based on Sn element is 9.6% by weight).

[0061] (2) Preparation of 2,3,5-trichloropyridine

[0062] Add 300g of 2-chlorop...

Embodiment 2

[0064] (1) Preparation of supported catalyst

[0065] SiO 2 Calcined at 400°C for 4 hours under an inert gas atmosphere to obtain pretreated SiO 2 Catalyst carrier.

[0066] Weigh 20g of FeCl 3 ·6H 2 O was dissolved in 100 mL of ethanol, and 50 g of SiO was added under stirring 2 Catalyst support, after impregnation for 3 hours, filtered to remove excess FeCl 3 solution. Rinse the solid material with ethanol, then dry it under vacuum at 100°C for 18 hours, and then roast it at 700°C for 2 hours to obtain FeCl-loaded 3 The supported chlorination catalyst Fe-SiO 2 (The supported amount in terms of Fe element is 9.5% by weight).

[0067] (2) Preparation of 2,3,5-trichloropyridine

[0068] Add 300 g of 2-chloropyridine, 30 g of supported catalyst Fe-SiO to a 500 mL glass reaction flask with a thermometer, a reflux condenser, and a chlorine pipe. 2 , be warmed up to 100 DEG C, pass into chlorine gas (pressure is 0.15MPa) with the flow rate of 180ml / min, react after 22 hou...

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Abstract

The invention relates to the field of compound preparation, and discloses a method for preparing 2,3,5-trichloropyridine, wherein the method comprises the following steps: a. in the presence of a chlorination catalyst, a compound A is contacted with chlorine for chlorination reaction to obtain a mixture containing the 2,3,5-trichloropyridine and 2,3,4,5-tetrachloropyridine; b. the mixture obtainedin the step a is contacted with hydrogen in the presence of a hydrogenation catalyst and a solvent to carry out catalytic hydrogenation reaction; or, the 2,3,5-trichloropyridine and the 2,3,4,5-tetrachloropyridine in the mixture obtained in the step a are separated, the separated 2,3,4,5-tetrachloropyridine is contacted with the hydrogen for catalytic hydrogenation reaction; wherein the compoundA is 2-chloropyridine and / or 2-chloropyridine hydrochloride. The raw materials in the method are simple and easy to obtain, the operating conditions are mild, the product yield is high, the cost islow, the pollution is small, and the method is suitable for large-scale application.

Description

technical field [0001] The invention relates to the field of compound preparation, in particular to a method for preparing 2,3,5-trichloropyridine. Background technique [0002] 2,3,5-Trichloropyridine is an important fine chemical intermediate, which is widely used in the fields of medicine and pesticides. 2,3,5-Trichloropyridine can be further fluorinated to synthesize 2,3-difluoro-5- Chloropyridine, the latter is the basic raw material for the synthesis of clodinafop-propargyl, and 3,5-dichloro-2-pyridinol prepared from 2,3,5-trichloropyridine is a series of synthetic herbicides and herbicides such as oxafluben An important raw material for pesticides. [0003] At present, the preparation method of 2,3,5-trichloropyridine can be divided into two types according to the difference of starting materials: [0004] 1. Ring-joining method [0005] US4245098 discloses a technology for synthesizing 2,3,5-trichloropyridine by catalytic ring closure, specifically, in the presenc...

Claims

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Application Information

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IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 宦斌李勇张小航程荣华
Owner 盐城恒盛化工有限公司
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