Method for synthesizing 2-chloro-5-trifluoromethylpyridine

A technology of trifluoromethylpyridine and trichloromethylpyridine, which is applied in the field of preparation of pharmaceutical and pesticide intermediate 2-chloro-5-trifluoromethylpyridine, can solve the problem of long catalyst activity, difficulty in industrialization, and single-pass yield Low-level problems, to achieve the effect of low equipment material requirements, simplified separation procedures, and simple operation

Inactive Publication Date: 2012-05-16
NINGBO UNIV
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Problems solved by technology

There are two synthetic methods using 3-picoline as raw material, one is step-by-step chlorination and fluorination, the other is one-step chlorofluorination, the former reacts with HF under the action of catalyst after chlorination of 3-picoline , the latter directly uses 3-picoline to obtain the target product by one-step chlorofluorination. This process improves the overall yield and minimizes industrial waste because the by-products can be recycled after dechlorination in the process. It is widely favored due to its advantages, but there are many difficulties in realizing industrialization due to the disadvantages of low single-pass yield and catalyst activity that is easily deactivated due to too long time.

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Embodiment Construction

[0012] Below in conjunction with embodiment the present invention is described in further detail.

[0013] Implementation example 1

[0014] 1. Synthesis of N-oxygen-3-methylpyridine

[0015] Add 46.6g (0.5mol) of 3-methylpyridine and 120mL of glacial acetic acid into a 500mL four-neck flask equipped with a stirrer, thermometer, condenser, and constant pressure dropping funnel, stir electrically, raise the temperature to 75°C, and add dropwise After 74.0 mL (0.72 mol) of 30% (mass percent) hydrogen peroxide, the reaction was incubated for 24 hours. After the reaction, the product was distilled off excess glacial acetic acid and water under reduced pressure, neutralized to weak alkalinity (pH=7-8) with saturated sodium bicarbonate solution, extracted with chloroform, dried, and the solvent was distilled off under reduced pressure to obtain 50.2g of orange-red oily liquid, yield 86.7%.

[0016] 2. Synthesis of 2-chloro-5-picoline

[0017] Add 28.7g (0.25mol) N-oxygen-3-methy...

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Abstract

The invention relates to a method for synthesizing 2-chloro-5-trifluoromethylpyridine. In the method, the 2-chloro-5-trifluoromethylpyridine is synthesized by performing three-step reaction, namely N-oxidation, benzoyl chloride chlorination and chorine gas chlorination on 3-methylpyridine serving as an initial raw material. In the reaction process of preparing 2-chloro-5-methylpyridine from N-oxy-3-methylpyridine, an isomer 2-chloro-3-methylpyridine of which the property is similar to that of the target product is not required to be separated, and the 2-chloro-5-methylpyridine can be directly used for the next-step reaction, so that the separation process is simplified, and operation efficiency is improved; and the whole synthesis route is easy to operate, reaction conditions are mild, and the requirement on an equipment material is low.

Description

technical field [0001] The invention relates to a preparation method of 2-chloro-5-trifluoromethylpyridine, a medicine and pesticide intermediate. Background technique [0002] 2-Chloro-5-trifluoromethylpyridine is an important trifluoromethylpyridine chemical raw material, many special-purpose compounds can be synthesized from it, and it is suitable for the preparation of pharmaceuticals, agricultural chemicals and biological agents. It is an important intermediate, especially the key intermediates for the production of high-efficiency insecticide diflurane, high-efficiency herbicide fluazifop and high-efficiency fungicide fluazinam and other pesticides. The method for synthesizing 2-chloro-5-trifluoromethylpyridine includes by raw material classification: pyridine, 2-amino-5-picoline, nicotinic acid, 3-picoline, wherein 2-picoline is prepared from 3-picoline The synthesis method of -chloro-5-trifluoromethylpyridine is considered to have the most development potential. Th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D213/61
Inventor 王爽米张剑锋王明升许自扬钱雁冰
Owner NINGBO UNIV
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