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Method for synthesizing 2,3-difluoro-5-chloropyridine

A synthetic method, dichloropyridine technology, applied in the direction of organic chemistry, etc.

Inactive Publication Date: 2006-09-13
WENZHOU UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to overcome the shortcoming of existing synthetic method, provide a kind of raw material that is easy to get, easy and simple to handle and the new method of environment-friendly 2,3-difluoro-5-chloropyridine synthesis

Method used

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  • Method for synthesizing 2,3-difluoro-5-chloropyridine
  • Method for synthesizing 2,3-difluoro-5-chloropyridine
  • Method for synthesizing 2,3-difluoro-5-chloropyridine

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Embodiment 1

[0016] Put 2,3,5-trichloropyridine (10.95g, 0.06mmol), KF (6.97g, 0.12mol), CsF (3.04g, 0.02mol), 0.5g K in a 100mL reaction flask 2 CO 3 And 50mL room temperature ionic liquid 1-methyl-3-butylimidazolium tetrafluoroborate ([Bmim]BF 4 ). . The reaction mixture was reacted at 200° C. for 10 hours, and the reaction mixture was cooled and distilled under reduced pressure to collect the liquid (86-127° C. / 150 mmHg). Column chromatography was performed with 5:1 petroleum ether (60-90° C.) and ethyl acetate as The eluent obtained 2-fluoro-3,5-dichloropyridine (3.60 g, yield 36.1%) and 2-fluoro-3,5-dichloropyridine (1.89 g, yield 21.0%).

[0017] Since the boiling points of 2-fluoro-3,5-dichloropyridine and 2,3-difluoro-5-chloropyridine are quite different, they can also be separated by rectification. The following are the physical data and detection data of these two compounds .

[0018] 2-Fluoro-3,5-dichloropyridine: colorless solid with low melting point, melting point 38-39°...

Embodiment 2

[0027] 50mL room temperature ionic liquid 1-methyl-3-butylimidazolium tetrafluoroborate ([Bmim]BF 4 ). , add 18.4g (0.122mol) CsF (dried under vacuum at 200°C for 16 hours before use), 0.5gK 2 CO 3 , 13.3g (0.08mol) 2-fluoro-3,5-dichloropyridine, heated and distilled under reduced pressure (about 200mmHg) for 6 hours, the distillation temperature is 97-106°C / 200mmHg, and the oil bath temperature is 139°C to 144°C, the product was slowly evaporated during the reaction process, 6.8g of the product was collected, and the reaction was stopped. After overnight, the above method was used to react for 3 hours, and 2.1g of the product was collected. Analysis by gas chromatography contained 7.4g of 2,3- Difluoro-5-chloropyridine (62% yield), 1.0 g 2-fluoro-3,5-dichloropyridine (7.5% recovery).

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Abstract

A 2,3-bifluoro-5-chlorophridine is prepared from 2,3,5-trichloropyridine and potassium (or cesium) fluoride through catalytic reaction in ionized solution.

Description

technical field [0001] The present invention relates to a new method for synthesizing 2,3-difluoro-5-chloropyridine. The method is suitable for the occasion of synthesizing 2,3-difluoro-5-chloropyridine with 2,3,5-trichloropyridine and fluorine-containing salt as main raw materials. Background technique [0002] 2,3-Difluoro-5-chloropyridine is a chiral, high-efficiency, low-toxicity, broad-spectrum herbicide (R)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)phenoxy Base] propargyl propionate and other chemical pesticides necessary intermediates. The herbicide can effectively control weeds in cotton, rapeseed, soybean, sugar beet and wheat fields, and has broad application prospects. [0003] The references of the present invention are all related patents on the synthesis of 2,3-difluoro-5-chloropyridine. They all use 2,3,5-trichloropyridine and fluorine-containing salts as the main starting materials to synthesize 2,3-difluoro-5-chloropyridine. European patent (EP95810654) inv...

Claims

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Application Information

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IPC IPC(8): C07D213/61
Inventor 钟平张兴国袁继新
Owner WENZHOU UNIVERSITY
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