Production method of high-purity 2-chloro-5-trifluoromethylpyridine

Abstract

The invention provides a production method of high-purity 2-chloro-5-trifluoromethylpyridine. The production method comprises the following steps: under the action of a silicon dioxide-aluminum oxide-chromic oxide catalyst, gasifying the raw materials acrolein and propyl aldehyde, and reacting with an ammonia gas to generate 3-methylpyridine; gasifying the 3-methylpyridine and carbon tetrachloridetogether, reacting in a chlorine atmosphere to obtain 2-chloro-5-trichloromethylpyridine, and performing fluoro-substitution to obtain a crude product of 2-chloro-5-trifluoromethylpyridine; heating to melt the crude product of 2-chloro-5-trifluoromethylpyridine; refrigerating and circulating in a low-temperature thermostat; cooling and crystallizing and separating to obtain recrystal; sweating the recrystal; repeating the processes of circulating, melting, recrystallizing and sweating to obtain high-purity 2-chloro-5-trifluoromethylpyridine. According to the production method provided by theinvention, 3-methylpyridine is adopted as a raw material, and the 2-chloro-5-trifluoromethylpyridine is molten, recrystallized and purified so that the product has high purity and stable yield.

Description

technical field [0001] The invention belongs to the field of medicinal chemistry, and in particular relates to a production method of high-purity 2-chloro-5-trifluoromethylpyridine. Background technique [0002] 2-Chloro-5-trifluoromethylpyridine, the chemical formula is C 6 h 3 CIF 3 N, is an important organic intermediate for the synthesis of pharmaceuticals, agrochemicals and biochemicals, and can be used to produce fluorine-containing pesticides such as the highly effective herbicide fluazifop-methyl, the insecticide dichranuron, and the fungicide fluazinam. Pesticides have the advantages of broad-spectrum systemic absorption, long duration, high efficiency and low toxicity, and can also develop important fine chemical intermediates such as 2-hydroxy-trifluoromethylpyridine, 2-hydroxy-3-chloro-5-trifluoroform Pyridine, 2-amino-5-trifluorotoluidine, etc. are important pharmaceutical intermediates. [0003] There are many ways to synthesize 2-chloro-5-trifluoromethylpy...

AI Technical Summary

Problems solved by technology

[0003] There are many ways to synthesize 2-chloro-5-trifluoromethylpyridine, mainly including -2-ammonia-5-methylpyridine, pyridine, 3-methylpyridine, 3-trifluoromethylpyridine, 2-chloro -5-trichloromethylpyridine, 3-pyridinecarboxylic acid or benzyl chloride as raw materials, prepared by ammoniation, condensation, acetylation, cyclization, chlorination or fluorination, etc., but currently 2-chloro-5 - The preparation process of trifluoromethylpyridine is not perfect

The method solves the problems of low yield, easy coking and high energy consumption in the separation of 2-chloro-5-picoline and 2-chloro-3-picoline

However, in the preparation process of 2-chloro-5-trifluoromethylpyridine, it is difficult to position chlorinate pyridine, and there are many by-products with similar properties and difficult purification. Therefore, it is necessary to develop a newer, better and more economical method. resolve resolution

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