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        Intermediate 2-chloro-5-chloromethylpyridine

        Release time:2019-10-09 17:03:06

           

        Product use: Imidacloprid and thiacloprid are high-efficiency new nicotine pesticides. The intermediate 2-chloro-5-chloromethylpyridine has many production methods. At present, the majority of domestic manufacturers adopt cyclopentadiene route, that is, ring Pentadiene (CP) is used as a raw material to react with acrolein (AL) to form 5-norbornene-2-aldehyde (NC), which is then reacted with acrylonitrile to form 2-cyanoethyl-5-norbornazole-2- The aldehyde (CNC) is then subjected to a chlorination step to give the intermediate.
        Existing processes and problems: At present, NC production is to add AL to CP at 5-10 ° C, then naturally heat up and keep at 25 ° C, and then heat to 40 ° C to remove unreacted raw materials. This process lasts for nearly 30 hours, and over time the polymer sticks to the walls and coils. CNC production is to add NC to acrylonitrile at 30 ° C for 5 hours. Solid KOH and a large amount of toluene and acrylonitrile are required, and nitrogen protection is required.
        The present technology and characteristics: the technology adopts a microstructured reactor, and the NC preparation is to directly mix CP and AL under high temperature and a certain pressure, and the residence time is less than 4 minutes, and the same conversion rate and yield can be obtained as the kettle reaction, only There are few polymerization products; the CNC preparation is based on the replacement of KOH with t-butoxide as a catalyst. After being dissolved in toluene, it is mixed with NC at low temperature and then mixed with acrylonitrile. After 5 minutes of reaction, it can be obtained higher than the existing industrial production. NC conversion and product yield of the process. The amount of acrylonitrile and toluene is one-half and one-third of the existing process, respectively, and nitrogen protection is not required; since the amount of acrylonitrile is greatly reduced, the polymerization problem brought about by it does not exist.

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