Preparation method of 2,3-dichloropyridine

A technology of dichloropyridine and trichloropyridine, which is applied in the field of important fine chemical intermediates 2, can solve the problems of multiple synthesis steps, complex reaction types, and high raw material prices, and achieve high-efficiency separation and recovery technology, novel and simple process routes

Active Publication Date: 2011-08-17
LIANHE CHEM TECH +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] In view of this, in order to solve the problems of high raw material price, many synthesis steps and complicated reaction types in the above-mentioned existing preparation method of 2,3-dichloropyridine, the present invention provi

Method used

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  • Preparation method of 2,3-dichloropyridine

Examples

Experimental program
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Embodiment 1

[0033] Chlorination reaction

[0034] Weigh 1480.0 g of 2,6-dichloropyridine and anhydrous FeCl 3 Mix 89.2g in a 2000ml four-neck flask and heat up. When the temperature reaches 100-120°C, introduce chlorine gas. After the reaction is complete, cool down to 100°C, rectify under reduced pressure, at -0.1MPa, top temperature 118-124°C The product fraction is collected next, and the low-concentration distillate produced during the rectification process can also be applied to the next batch of re-reaction or to the next batch of re-distillation and purification. After mechanical application, 1715.0 g of 2,3,6-trichloropyridine was finally obtained, with a total yield of 94.0% and a purity of ≥99.5%.

[0035] hydrogenation reaction

[0036] Put 557.8g of 2,3,6-trichloropyridine, 123.5g of triethylamine, 8.4g of palladium carbon, and 1673g of toluene prepared in the chlorination reaction into the reactor at one time, raise the temperature to 60-80°C, and feed Hydrogen is carried ...

Embodiment 2

[0040] Chlorination reaction

[0041] Take by weighing 2,6-dichloropyridine 299.2g and reclaimed distillate liquid 533.7g (wherein 2,6-dichloropyridine accounts for 86.1%, 2,3,6-trichloropyridine accounts for 9%), and anhydrous AlCl 3 Put 36.5g in a 1000ml four-necked flask and mix it. When the temperature rises to 120-140°C, chlorine gas is introduced. After the reaction is complete, cool down to 100°C, rectify under reduced pressure, and collect at -0.1MPa at a top temperature of 118-124°C. Product fractions, low-concentration products that are evaporated can be applied mechanically to the next batch of re-reaction or to the next batch of rectification and purification; after the mechanical application, 890.7g of 2,3,6-trichloropyridine is finally obtained, and the total yield after the mechanical application is 95.2% , purity ≥ 99.5%.

[0042] hydrogenation reaction

[0043] 1340 g of the toluene solution of 2,3,6-trichloropyridine recovered in Example 1 can be added with 4...

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Abstract

The invention discloses a preparation method of 2,3-dichloropyridine. 2,3-dichloropyridine is an intermediate in fine chemical industry, which is widely used in the fields of medicine and pesticide. The method comprises the following steps: carrying out chlorination reaction on 2,6-dichloropyridine, which is used as a raw material, to obtain 2,3,6-trichloropyridine; adding the 2,3,6-trichloropyridine, an acid binding agent, a metal catalyst and an organic solvent into a reactor, and carrying out hydrogenation reaction, wherein the mol ratio of 2,3,6-trichloropyridine to acid binding agent is 1:(0.1-0.5); and cooling the hydrogenation reaction liquid, adding water to dissolve the acid binding agent hydrochloride, filtering, standing, separating out the water layer, extracting the organic solvent layer with water-containing acid at least three times, merging the water-containing acid layers after extraction, diluting by adding water, precipitating a solid, filtering, and drying to obtain the 2,3-dichloropyridine product. The invention has the advantages of novel process route, short reaction steps, high yield, low production cost and environmental friendliness, is simple to operate, and is suitable for industrial production.

Description

technical field [0001] The invention relates to a chemical synthesis method, in particular to a preparation method of 2,3-dichloropyridine, an important fine chemical intermediate widely used in the fields of medicine and pesticides. Background technique [0002] 2,3-dichloropyridine is an important fine chemical intermediate, which is widely used in the fields of medicine and pesticides. There are reports on the synthesis methods of 2,3-dichloropyridine at home and abroad, and the chemical processes of these methods have their own characteristics. There are mainly the following types: [0003] 1. Both US4515953 and SU652177 patent documents disclose the liquid phase chlorination of pyridine or pyridine hydrochloride. However, in addition to 2,3-dichloropyridine, the product obtained by this method also includes many other chlorinated pyridine mixtures, and this method requires multiple purification steps to obtain 2,3-dichloropyridine. [0004] 2. In the US62242631 patent...

Claims

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Application Information

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IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 王萍樊小彬张俊涛叶芳胜
Owner LIANHE CHEM TECH
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