Method for preparing 2-amino-3-chloro-5-trifluoromethylpyridine
A technology of trifluoromethylpyridine and amino group is applied in the field of preparing 2-amino-3 chloro-5-trifluoromethylpyridine, which can solve the problem of high cost of raw materials and achieve the effect of reducing synthesis cost
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Embodiment 1
[0021] Both the amination reaction and the zinc reduction reaction in this embodiment are illustrated by taking toluene, a water-insoluble solvent, as an example, and sulfuric acid is added dropwise during the reduction process.
[0022] The first step, amination reaction:
[0023] Put 200g of 2,3,6-trichloro-5-trifluoromethylpyridine (≥98%) and 400g of toluene into a 2000mL autoclave with mechanical stirring, add 120g of liquid ammonia into the autoclave, and react at 50°C for 12 hours, the reaction pressure is 0.7-2MPa, the raw material content after reaction is less than 0.3%, exhaust the pressure after the reaction is over, absorb the excess ammonia gas with water, add 200mL water to the reaction kettle and stir for 20 minutes, then discharge the material, separate the water phase, distill and strip the toluene The solid product 2-amino-3,6-dichloro-5-trifluoromethylpyridine was obtained, the content of which was 95%. The yield is 92%.
[0024] The second step, zinc redu...
Embodiment 2
[0027] Both the amination reaction and the zinc reduction reaction in this embodiment are described by taking the water-soluble solvent methanol as an example, and concentrated sulfuric acid is added dropwise during the reduction process.
[0028] The first step, amination reaction:
[0029] Put 200g of 2,3,6-trichloro-5-trifluoromethylpyridine (≥98%) and 300g of methanol into a 2000mL autoclave with mechanical stirring, add 120g of liquid ammonia to the autoclave, and react at 80°C 10 hours, the pressure is 2.5-3MPa, the raw material content after the reaction is less than 0.3%, exhaust the pressure after the reaction to absorb the excess ammonia gas with water, steam the solvent out of the material, add water 300g to wash out the salt in the material at 90°C, and obtain a solid product 2-Amino-3,6-dichloro-5-trifluoromethylpyridine, content 94%, yield 91.2%.
[0030] The second step, zinc reduction reaction:
[0031] 40g (0.165mol) of 2-amino-3,6-dichloro-5-trifluoromethyl...
Embodiment 3
[0033] In this embodiment, the amination reaction is illustrated by taking the non-water-soluble solvent toluene as an example, and the zinc reduction reaction is described by taking the non-water-soluble solvent dichloroethane as an example, and sulfuric acid is added dropwise during the reduction process.
[0034] The first step, amination reaction:
[0035] Put 2,3,6-trichloro-5-trifluoromethylpyridine (≥98%) 200g, toluene 400g into a 2000mL autoclave with mechanical stirring, add 25% ammonia water 500g into the autoclave, React for 9 hours, and the reaction pressure is 1.5-2MPa. After the reaction, the raw material content is less than 0.3%. After the reaction, exhaust the pressure to absorb the excess ammonia gas with water, remove the water phase from the output, and distill off the toluene to obtain the solid product 2-amino-3,6-dichloro-5-trifluoro Picoline, content 92.3%. The yield is 91%.
[0036] The second step, zinc reduction reaction:
[0037] 40g (0.165mol) ...
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