Preparation methods and examples of uses of 2,3,5-trichloropyridine_Industrial additives

Background and overview of preparation methods and uses of 2,3,5-trichloropyridine

2,3,5-Trichloropyridine is a light yellow solid and an important fine chemical intermediate, widely used in the fields of medicine and pesticide research. 2,3,5-Trichloropyridine reacts with alkali metal hydroxide to prepare 3,5-dichloro-2-pyridinol, which is an important raw material for the synthesis of pesticides such as insecticidal mites and the herbicide oxafen. 2,3,5-Trichloropyridine can also be further subjected to fluorination reaction to synthesize 2,3-difluoro-5-chloropyridine, which is the basic raw material for synthesizing the herbicide clodinafopyrpyridine.

Preparation methods and usage examples of 2,3,5-trichloropyridine

Examples of preparation methods and uses of 2,3,5-trichloropyridine 1.

Add 60g methanol into a 1000mL four-necked flask, add 100g 2,3,5,6-tetrachloropyridine and 31.7g hydrazine hydrate, raise the temperature to 60~65°C, and keep the reaction for about 2 hours. When the reaction is completed, cool down to 0~5°C, stir for 1 hour, filter, the solid is 2,3,5-trichloro6-hydrazinopyridine hydrate, and dry to obtain 101.6g of white solid, with a yield of 96% and a content of 98.5%.

Add 100g of 2,3,5-trichloro6-hydrated hydrazylpyridine and 50g of 5% sodium hydroxide aqueous solution into a 1000ml four-neck bottle, raise the temperature to 70~75°C, and add dropwise 387.6g of 10% sodium hydroxide solution Sodium hypochlorite aqueous solution is kept at 70-75°C and reacts for 1 hour. When the reaction is completed, cool down to 5-10°C and stir for 1 hour. Filter to obtain crude 2,3,5-trichloropyridine. Distill under reduced pressure to obtain the product, which is light yellow. Solid, yield: 95%, content: 98%.

Examples of preparation methods and uses of 2,3,5-trichloropyridine 2.

Add 25kg ferric chloride, 1000kg pyridine, and 0kg carbon tetrachloride into the chlorination reaction kettle, seal the reaction kettle, stir, and introduce 4500kg chlorine gas. After the reaction is completed, polychlorinated pyridine is obtained.

The polychlorinated pyridine obtained through the above process was mixed with 3kg palladium carbon, 12000kg ethanol, and 900kg pyridine, reacted at 80°C, 0.1MPa, and stirred until the reaction was completed to obtain 1840.8kg 2,3,5-trichloro Pyridine and 8kg 2,3-dichloropyridine.

Examples of preparation methods and uses of 2,3,5-trichloropyridine III.

Add 2,3,4,5-tetrachloropyridine (216.88g/mol, 50g, 0.231mol) into a 1000ml four-neck bottle, add solvent (solvent composition: 200g methanol and 200g water), and stir to mix. Then add zinc powder (65.38g/mol, 22.6g, 0.346mol) and ammonium chloride (53.49g/mol, 37.1g, 0.693mol), raise the temperature to 72°C, continue to stir the reaction for 2 hours while maintaining this temperature, and take samples. HPLC detection, detection results: 2,3,5-trichloropyridine is 82.25%, 2,5-dichloropyridine is 13.42%, and 2,3,4,5-tetrachloropyridine is 4.33%.

After the reaction is completed, the reaction solution is heated and filtered to obtain a filter cake and filtrate. The filter cake is zinc powder and zinc chloride. Post-process the filtrate. First, cool the filtrate to 0-5°C for crystallization for 2 hours. The solid obtained is a mixture of 2.3.5-trichloropyridine (182.44g/mol) and 2.5-dichloropyridine (147.99g/mol). Filter And wash with a small amount of hydrochloric acid to obtain a filter cake, namely 37.9g ​​of 2,3,5-trichloropyridine, with an HPLC purity of 98% and a molar yield of magnesium carbonate based on 2,3,4,5-tetrachloropyridine of 90%.

Examples of preparation methods and uses of 2,3,5-trichloropyridine IV.

In a 3000-liter reaction kettle, add 1200 kg of water, 434 kg of 2,3,5,6-tetrachloropyridine, 163 kg of 80% hydrazine hydrate, 43 kg of n-butanol, and 319 kg of sodium carbonate, and then react The kettle is heated to 90-95 degrees Celsius, and after stirring and refluxing for 4-5 hours, a trichloropyridine hydrazine group is generated; then, the temperature is lowered to 70-75 degrees Celsius, and then 43 kg of 30% sodium hydroxide and β-cyclopaste are added. 2.2 kg of essence, and slowly add 450 kg of 30% hydrogen peroxide dropwise for 6-8 hours. After the reaction is completed, the phases are separated to obtain an organic layer. The organic layer is washed with water and distilled to obtain 311 kilograms of 2,3,5-trichloropyridine.

Preparation methods and usage examples of 2,3,5-trichloropyridine

Preparation methods and uses of 2,3,5-trichloropyridine, application examples 1,

CN201610151939.7 discloses a method for preparing 5-chloro-2,3-difluoropyridine, using 2-aminopyridine as the starting material, and chlorinating it to generate 2-amino-3,5-dichloro Pyridine is then diazotized and undergoes Sandmeier reaction to form a mixture of 2,3,5-trichloropyridine and 3,5-dichloropyridin-2-one, which is chlorinated again and treated to obtain 2,3, 5-Trichloropyridine; Finally, use the prepared 2,3,5-trichloropyridine as the raw material, use sulfolane and dimethyl sulfoxide as the solvent, add a mixture of cesium fluoride and potassium fluoride as the fluorinating agent, the reaction temperature Control at 145°C and keep the temperature for 17 hours, then raise the temperature to 190°C and keep the temperature for 19 hours. The above preparation process and operation are highly practical, simple steps, and do not require high equipment. They are suitable for industrial production. The product yield reaches 90% and the content reaches 99.8%. .

Preparation methods and application examples of 2,3,5-trichloropyridine 2.

CN201810903026.5 provides a method using 2,3,5-trichloropyridine as a starting material, organic acid as a solvent, bromide reaction to prepare the intermediate 2-bromo-3,5-dichloropyridine, and then React with cuprous cyanide in the presence of an organic solvent and a catalyst, and then purify with an organic solvent to obtain 3,5-dichloro-2-cyanopyridine. The product purity is ≥99.0%. The raw materials of this reaction are cheap and easy to obtain, the reaction steps are few, the product purity is high, the post-processing process is greatly simplified, and organic solvents such as ethyl acetate can be recycled multiple times, with little pollution, safety, and is conducive to the realization of industrial production.

References

[1] [Invented in China] CN201811011295.7 一�Synthetic method of �2,3,5-trichloropyridine

[2] [Chinese invention] CN201710207907.9 A method for synthesizing oxafen and its intermediate 2,3,5-trichloropyridine

[3] [Chinese invention] CN202010918958.4 A preparation method of 2,3,5-trichloropyridine

[4] [Chinese invention, Chinese invention authorization] CN201810156696.5 A preparation method of 2,3,5-trichloropyridine

[5] CN201610151939.7 A method for preparing 5-chloro-2,3-difluoropyridine

[6] CN201810903026 Basic magnesium carbonate. Synthesis method of 53,5-dichloro-2-cyanopyridine