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Method for synthesising 2,3-dichloropyridine

A technology of dichloropyridine and trichloropyridine, which is applied in the field of organic synthesis, can solve problems such as low yield, worrying industrialization prospects, and difficulty in obtaining 2-chloronicotinamide, and achieves the effect of simple and easy operation

Active Publication Date: 2017-03-22
JIANGSU ZHONGBANG PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Chinese patent application CN102086174A discloses a production method of 2,3-dichloropyridine, which uses 2-chloronicotinamide as a raw material to avoid the problem of many side reactions caused by 2-position chlorination, but 2 - Chloronicotinamide is not easy to obtain, so the industrialization prospect of this method is worrying
This method has no selectivity to 2-position and 6-position chlorine in the hydrogenation process, so there are many side reactions, which seriously affect the yield and purity of the final product
[0006] Chinese patent application CN103145609A discloses a preparation method of 2,3-dichloropyridine, which uses 2,3,6-trichloropyridine as a starting material and ammonium formate as a hydrogen donor, but the transformation of the method The yield is low, so the rectification method needs to be adopted in the separation process, and the yield is not high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Example 1: Synthesis of 2,3-dichloropyridine.

[0023] 2,3,6-Trichloropyridine (18.2g, 0.1mol), RhH(CO)(Ph 3 P) 3 (0.455g), triethylamine (12.1g, 0.12mol) and methanol (182g) were put into the autoclave, and the air in the autoclave was replaced after sealing the autoclave, and hydrogen gas was introduced to a pressure of 60MPa, and reacted at 60°C until no Until the phenomenon of hydrogen absorption, the control in HPLC (2,3,6-trichloropyridine)≤1%; -A mixture of dichloropyridine and water, the temperature was lowered and suction filtered to obtain 14.5 g of 2,3-dichloropyridine, the purity (HPLC) was ≥98%, and the yield was 98%.

Embodiment 2

[0024] Example 2: Synthesis of 2,3-dichloropyridine.

[0025] 2,3,6-Trichloropyridine (18.2g, 0.1mol), RhH(CO)(Ph 3 P) 3 (0.455g), triethylamine (80.9g, 0.8mol) and ethanol (182g) are put into the autoclave, after sealing the autoclave, replace the air therein, feed hydrogen to a pressure of 100MPa, and react at 80°C until no Until the phenomenon of hydrogen absorption, the control in HPLC (2,3,6-trichloropyridine)≤1%; -A mixture of dichloropyridine and water, obtained 13.5 g of 2,3-dichloropyridine by suction filtration under reduced temperature, with a purity (HPLC)≥98%, and a yield of 91.2%.

Embodiment 3

[0026] Example 3: Synthesis of 2,3-dichloropyridine.

[0027] 2,3,6-Trichloropyridine (18.2g, 0.1mol), RhH(CO)(Ph 3 P) 3 (0.182g), triethylamine (10.1g, 0.1mol) and isopropanol (91g) are put into the autoclave, after sealing the autoclave, replace the air therein, feed hydrogen until the pressure is 100MPa, react at 80°C, Until there is no hydrogen absorption phenomenon, the control (2,3,6-trichloropyridine) in HPLC≤1%; A mixture of 2,3-dichloropyridine and water was obtained, and 12.2 g of 2,3-dichloropyridine was obtained by suction filtration under reduced temperature, with a purity (HPLC)≥98% and a yield of 82.4%.

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Abstract

The invention discloses a method for synthesising 2,3-dichloropyridine. The synthesis method disclosed by the invention specifically comprises the following steps: adding 2,3,6-trichloropyridine, hydridocarbonyltris(tri-phenylphosphine)rhodium, triethylamine and a solvent into an autoclave, carrying out airtight ventilation, charging hydrogen until the pressure is 50-100MPa, reacting at 50-80 DEG C until a hydrogen absorption phenomenon disappears, removing the solvent in a manner of reduced pressure distillation, adding water and then distilling out the mixture of 2,3-dichloropyridine and water in a manner of constant-pressure water vapour distillation, and obtaining 2,3-dichloropyridine through cooling and suction filtration. A dechloridation reaction can be selectively carried out on 6-site chlorine atom because a catalyst with a large volume is adopted, and then 2,3-dichloropyridine with both ideal purity and yield is obtained; and the used raw materials are relatively easily-available, the operation process is simple, convenient and practicable, and a great industrialized application prospect is achieved.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis and relates to a method for synthesizing 2,3-dichloropyridine by utilizing 2,3,6-trichloropyridine. Background technique [0002] 2,3-Dichloropyridine is an important fine chemical intermediate, which can be used as a key intermediate in the synthesis of a new type of insecticide, sulfbendamide, and is widely used in many fields such as medicine and pesticides. [0003] Chinese patent application CN103570609A discloses a method for preparing 2,3-dichloropyridine, which uses nicotinamide as raw material to react with sodium hypochlorite to prepare 3-aminopyridine, and then reacts hydrochloric acid and hydrogen peroxide to obtain 2-chloro-3-amino Pyridine, and finally the target product was obtained by Sandmeyer reaction. This method has more side reactions and lower yield. [0004] Chinese patent application CN102086174A discloses a production method of 2,3-dichloropyridine, which uses ...

Claims

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Application Information

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IPC IPC(8): C07D213/61
CPCC07D213/61
Inventor 李维思钱勇陈涛章月唐景玉
Owner JIANGSU ZHONGBANG PHARMA
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