Method for preparing a category of compound of trifluoro methylpyridine

Abstract

This invention discloses a method for preparing trifluoromethyl pyridine. The method comprises: utilizing trichloromethyl pyridine as the raw material, and fluorinating at 100-250 deg.C in the presence of inexpensive commercialized catalyst and HF to synthesize trifluoromethyl pyridine. The catalyst is commercialized, and is inexpensive. The method has such advantages as simple process, abundant and inexpensive raw material and catalyst, and high yield, and is suitable for mass production.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to the technical field of preparation methods of trifluoromethylpyridine compounds. Background technique [0002] Fluorine-containing heterocyclic pesticides are currently an important class of pesticides with good development prospects. Compounds containing trifluoromethylpyridines have important and extensive applications in pesticides. For example, 2-chloro-5-trifluoromethylpyridine is the key intermediate of the high-efficiency herbicides fluazifop-p-p and valalofop-p-p, and the fungicide picoxystrobin. 2,3-dichloro-5-trifluoromethylpyridine compounds can be used to prepare highly efficient herbicide haloxyfop, highly efficient insecticides dichranuron, pyridoxuron, highly efficient herbicide haloxyfop and highly efficient bactericidal Fluazinam and other varieties. Some of these products have developed into key products in the international market and have good market prospec...

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Problems solved by technology

[0004] In patents such as US4680406 and US4567273, trichloromethylpyridine compounds are used as raw materials, and the gasified and boiling hydrogen fluoride is fully contacted and reacted on the reaction bed attached to the catalyst. The catalyst is a compound containing mercury and silver. The disadvantages are: Reaction conditions and equipment requirements are very high

[0005] In US007518, carboxypyridine is used as raw material to react with sulfur tetrafluoride to synthesize trifluoromethylpyridine compounds under high temperature conditions. The disadvantage is that the raw material is difficult to obtain, and sulfur tetrafluoride is highly toxic.

[0006] In patent documents such as GB1599123, trichloromethylpyridine is used as a raw material, and antimony trifluoride is used as a catalyst to obtain trifluoromethylpyridine compounds by fluorination. The disadvantage of this method is that the yield of this method is very low

[0007] In the EP110690 patent, trichloromethylpyridine compounds are used as raw materials. In the presence of catalysts containing iron or antimony compounds, anhydrous hydrogen fluoride is used as a fluorinating agent. The liquid phase reaction synthesizes trifluoromethylpyridine compounds. The disadvantage is that : This method has a high reaction temperature and a long time

[0008] In US4745193, trichloromethylpyridine is used as raw material, anhydrous hydrogen fluoride is used as fluorinating agent and solvent, and the reaction is carried out under high temperature and high pressure. The disadvantage is that this method requires very high reaction equipment and low yield

[0009] Therefore, according to the above-mentioned method, all are unfavorable for suitability for industrialized production

[0010] According to the above method, the production cost is too high and the raw material catalyst is expensive and difficult to obtain, so that there are many difficulties in industrial realization

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