Method for synthesizing flupirtine maleate by use of one-pot process
A technology of flupirtine maleate and maleic acid, applied in the field of chemical drug preparation, can solve the problems of expensive, impossible to achieve continuous operation, high preparation cost, reduce production cost, improve product quality and yield, The effect of simplifying the operation process
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Embodiment 1
[0022] Add 2,6-dichloro-3-nitropyridine (5kg, 25.9mol) into a reaction kettle filled with 50L of methanol, stir at 50-60°C until completely dissolved, then feed ammonia gas for 10 hours, monitor by TLC The reaction was stopped when the reaction of the raw materials was complete, and a yellow suspension was generated. After the reaction was cooled to room temperature, nitrogen gas was passed into the reaction solution to discharge the remaining ammonia gas in the reaction kettle, and p-fluorobenzaldehyde (3.5kg, 28.5mol) was slowly added dropwise under the protection of nitrogen gas, and the reaction was refluxed for about 8 hours, monitored by TLC Stop the reaction when the reaction of raw materials is complete. After the reaction solution was cooled to room temperature, 400 g of 10% Pd / C was added, and hydrogen gas was introduced at 25° C. for 20 hours. TLC monitored that the reaction of the raw materials was complete, and then stopped the reaction. Under the protection of n...
Embodiment 2
[0024] Add 2,6-dichloro-3-nitropyridine (5kg, 25.9mol) into a reaction kettle filled with 40L of ethanol, stir at 50-60°C until completely dissolved, and react with ammonia gas for 8 hours, monitored by TLC The reaction was stopped when the reaction of the raw materials was complete, and a yellow suspension was generated. After the reaction was cooled to room temperature, nitrogen gas was introduced into the reaction solution to discharge the remaining ammonia gas in the reaction kettle, and p-fluorobenzaldehyde (3.8kg, 31.1mol) was added dropwise under the protection of nitrogen gas, and the reaction was refluxed for about 4 hours, and the raw materials were monitored by TLC. Stop the reaction when the reaction is complete. After the reaction solution was cooled to room temperature, 500 g of 10% Pd / C and 9.8 kg of ammonium formate were added, and the reaction was continued under nitrogen protection under reflux for about 14 hours, and the reaction was stopped after TLC monito...
Embodiment 3
[0026]Add 2,6-dichloro-3-nitropyridine (5kg, 25.9mol) into a reaction kettle filled with 60L of isopropanol, stir at 50-60°C until completely dissolved, then pass through ammonia gas for 8 hours, TLC monitors that the reaction of the raw materials is complete and the reaction is stopped, and a yellow suspension is generated. After the reaction was cooled to room temperature, nitrogen gas was passed into the reaction solution to discharge the remaining ammonia gas in the reaction kettle, and p-fluorobenzaldehyde (3.5kg, 28.5mol) was added dropwise under the protection of nitrogen gas, and the reaction was refluxed for about 5 hours, and the raw materials were monitored by TLC. Stop the reaction when the reaction is complete. After the reaction solution was cooled to room temperature, 450 g of 10% Pd / C and 9.6 kg of ammonium formate were added. Under the protection of nitrogen, the reaction was continued under reflux for about 14 hours. TLC monitored that the reaction of the raw...
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