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Method and device for preparing 2, 6-dichloropyridine through step-by-step photochlorination of pyridine

A technology of dichloropyridine and photochlorination, applied in chemical instruments and methods, feeding devices, organic chemistry, etc., can solve the problems of less waste, low reaction speed, and high conversion rate of pyridine

Active Publication Date: 2021-01-05
ZHEJIANG AVILIVE CHEM CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Design purpose: to avoid the deficiencies in the background technology, to design a method that can not only solve the problems of insufficient light source intensity, low reaction speed, and poor reaction selectivity in the background technology in the large-scale production process, but also has a high conversion rate of pyridine. Method and device for preparing 2,6-dichloropyridine by step-by-step photochlorination of pyridine, less waste, high reaction selectivity, and easy industrial production

Method used

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  • Method and device for preparing 2, 6-dichloropyridine through step-by-step photochlorination of pyridine
  • Method and device for preparing 2, 6-dichloropyridine through step-by-step photochlorination of pyridine
  • Method and device for preparing 2, 6-dichloropyridine through step-by-step photochlorination of pyridine

Examples

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Effect test

Embodiment 1

[0012] Example 1: A method and device for preparing 2,6-dichloropyridine by step-by-step photochlorination of pyridine, using gasified pyridine and preheated chlorine as initial raw materials, and using gasified trifluoromethyl Chlorobenzene is used as a diluent, and the gas-phase pre-photochlorination reaction is continuously carried out at 180°C to 280°C under ultraviolet light irradiation. The chlorination liquid enters the bottom liquid-phase photochlorination tank after pre-cooling and gas-liquid separation. Deep chlorination is carried out at 150°C to 230°C under the irradiation of ultraviolet lamps, and pyridine chlorination solution is obtained after the chlorination is qualified.

[0013] In this embodiment, vaporized pyridine and trifluoromethylchlorobenzene and heated chlorine enter the photochlorination reactor at the same time to carry out a continuous prechlorination reaction. The feed weight ratio of pyridine, solvent and chlorine gas is 1:0.1~4:1.8~2.7. The ul...

Embodiment 2

[0016] Example 2: On the basis of Example 1, the preliminary gas-phase photochlorination material is used for liquid-phase deep chlorination at 150°C to 230°C, until the content of 2-chloropyridine is less than 0.5%. The chlorinated liquid is subjected to rough steaming to separate tar and high boilers, and the obtained distillate is pyridinium chloride containing solvent.

[0017] Preliminary gas-phase photochlorination of pyridine to prepare 2,6-dichloropyridine conditions (chlorinated material after batch) test data

[0018]

[0019] for example:

example 1

[0021] 1. Turn on the ultraviolet lamp, and after the temperature of the gas-phase photoreaction tower rises to 140°C, chlorine flow begins, with a flow rate of 490ml / min.

[0022] 2. Heat up the temperature of the solvent vaporization chamber to 220° C., start to add trifluoromethyltrichlorobenzene dropwise, and control the dropping rate to 1 ml / min.

[0023] 3. Heat up the pyridine vaporizer to 120°C, start adding pyridine dropwise at a rate of 0.7ml / min, the temperature will gradually rise as the reaction progresses, and finally control the reaction temperature at 180°C to 280°C.

[0024] 4. The material discharged from the outlet of the gas-phase light reaction tower is slightly cooled by the gas-phase cooler, the gas-liquid is separated, and the chlorinated liquid flows into the 3000ml liquid-phase photochlorination kettle. 760g of pyridine and 1656g of trifluoromethyltrichlorobenzene were added dropwise.

[0025] 5. Turn on the ultraviolet lamp in the liquid-phase photo...

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Abstract

The invention relates to a method and a device for preparing 2, 6-dichloropyridine by step-by-step photochlorination of pyridine. According to the invention, pyridine and chlorine are used as initialraw materials, trifluoromethyl chlorobenzene is used as a diluent, continuous feeding is performed in a gas-phase photoreactor at the temperature of 180-280 DEG C or under ultraviolet irradiation or under temperature and ultraviolet irradiation to perform a gas-phase pre-chlorination reaction to control the pyridine content in reactants to be less than 10%, and gas after the reaction is condensedby a condenser to obtain primary chlorinated liquid; chlorine gas is continuously introduced into a liquid phase photochlorination kettle, a deep chlorination reaction is carried out at 150-230 DEG C,the content of 2-chloropyridine in the reaction solution is controlled to be less than 0.5% as a reaction endpoint, and steps of coarse distillation, crystallization separation or rectification purification are carried out on the chlorination solution to obtain 2, 6-dichloropyridine with the purity of 99.0% or more and the yield of 90% or more. The method has the advantages that the problems of insufficient light source intensity, low reaction speed, low reaction selectivity and the like in the background art can be solved in the large-scale production process, and the method has the advantages of high pyridine conversion rate, less three wastes, high reaction selectivity and easiness in industrial production.

Description

technical field [0001] The invention relates to a method that can not only solve the problems of insufficient light source intensity, low reaction speed, and poor reaction selectivity in the background technology in the large-scale production process, but also has high pyridine conversion rate, less three wastes, high reaction selectivity, and is easy to use. A method and device for preparing 2,6-dichloropyridine by stepwise photochlorination of industrially produced pyridine. Background technique [0002] Taking pyridine as raw material to prepare 2,6-dichloropyridine existing main synthetic methods are: [0003] 1. Pyridine aqueous solution gas-phase photochlorination method, for example, CN1245801 uses water as the diluent to carry out gas-phase photochlorination at 170°C to 180°C. The main products obtained are hydrochloric acid aqueous solution of pyridine, 2-chloropyridine and 2,6-dichloropyridine. The conversion rate of pyridine is 90~95%. Chemical materials need to...

Claims

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Application Information

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IPC IPC(8): C07D213/61B01J19/12B01J4/00
CPCC07D213/61B01J19/123B01J4/001Y02P20/10
Inventor 李惠跃朱加权李兰杰
Owner ZHEJIANG AVILIVE CHEM CO LTD