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Novel method for synthesizing 2-fluoro-3-chloro-5-trifluoromethylpyridine

A technology for trifluoromethylpyridine and trichloromethylpyridine, which is applied in the field of synthesizing 2-fluoro-3-chloro-5-trifluoromethylpyridine, can solve the problems of unsatisfactory yield and general effect, and achieves Environmentally friendly, enhanced molecular activity, mild reaction conditions

Inactive Publication Date: 2011-04-06
NANJING REDSUN BIOCHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] There are also reports on the use of potassium fluoride as a fluorinating agent in China, but potassium fluoride has not been dehydrated and activated by reflux with a solvent, nor has it been activated by a phase transfer catalyst, so the effect of the reaction is general and the yield is not ideal.

Method used

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  • Novel method for synthesizing 2-fluoro-3-chloro-5-trifluoromethylpyridine

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] 25g (0.43mol) of potassium fluoride, 50ml of toluene and 150ml of N, N-dimethylformamide were added to a 250ml four-necked reaction flask, and 0.66g (0.0029mol) of benzyltriethylammonium chloride was added as a phase transfer catalyst. Install the steam-water separator, heat to reflux at 115°C for reflux and dehydration for 3 hours, after the dehydration is completed, add 19.1g (0.072mol) of 2,3-dichloro-5-trichloromethylpyridine, and keep it warm at 120°C for 5 hours. After the end, filter with suction and discard the solid phase. The organic phase was decompressed and rectified to collect the effluent at 50-55°C / 11mmHg to obtain 2-fluoro-3-chloro-5-trifluoromethylpyridine with a purity of 98.5% and a yield of 94.7%.

Embodiment 2

[0024] Except that the reaction time was 6 hours, the ratio of potassium fluoride to 2,3-dichloro-5-trichloromethylpyridine added was 8:1, other reaction conditions and post-treatment methods were the same as in Example 1, and finally 2 -Fluoro-3-chloro-5-trifluoromethylpyridine, the purity reached 95.2%, and the yield was 92.1%.

Embodiment 3

[0026] Except that the reflux dehydration temperature was 90°C, other reaction conditions and post-treatment methods were the same as in Example 1, and finally 2-fluoro-3-chloro-5-trifluoromethylpyridine was obtained with a purity of 94.2% and a yield of 89% %.

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Abstract

The invention relates to a novel method for synthesizing 2-fluoro-3-chloro-5-trifluoromethylpyridine. The method comprises the following steps of: (1) taking methylbenzene as a dehydrant, heating a mixture of solvent, potassium fluoride and phase transfer catalyst up to the temperature of between 80 and 135 DEG C and refluxing for 3 hours, and removing water in the solvent and the potassium fluoride by taking the methylbenzene as the dehydrant; and (2) adding 2,3-dichloro-5-trifluoromethylpyridine in the mixture for reaction for 5 hours at a temperature of between 105 and 135 DEG C, and afterthe reaction, post-treating the reaction product to obtain the 2-fluoro-3-chloro-5-trifluoromethylpyridine in high purity. The yield of the method is 94.7 percent, and the purity of the 2-fluoro-3-chloro-5-trifluoromethylpyridine synthesized by the method is 98.5 percent.

Description

technical field [0001] The invention belongs to the field of chemical synthesis, and in particular relates to a new method for synthesizing 2-fluoro-3-chloro-5-trifluoromethylpyridine. Background technique [0002] 2-Fluoro-3-chloro-5-trifluoromethylpyridine is an important chemical intermediate raw material and a key intermediate in the synthesis of herbicides with high-efficiency grass-grass energy. Its market value and application prospects have attracted much attention. [0003] There are currently two methods to prepare 2-fluoro-3-chloro-5-trifluoromethylpyridine. One is to use 2-chloro-5-trifluoromethylpyridine as the starting material. US4490534 reports in detail the synthesis of 2- The method of chloro-5-trifluoromethylpyridine, on this basis, adopts chlorides such as tungsten, zinc, iron, etc. as a catalyst, and at a higher temperature, chlorine can be added to the 3-position of the pyridine ring to obtain 2,3- Dichloro-5-trifluoromethylpyridine, but the raw materi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D213/61B01J31/02
Inventor 杨寿海王述刚芮忠南周典海孔新福
Owner NANJING REDSUN BIOCHEM CO LTD
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