Preparation method of 3-amino-4-fluorophenol
A technology of fluorophenol and amino, which is applied in the field of preparation of 3-amino-4-fluorophenol, which can solve the problems of large amount of waste water, low yield, and separation of products, and achieves short synthetic route, high purity, and few steps Effect
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[0026] The invention provides a kind of preparation method of 3-amino-4-fluorophenol, comprising the following steps:
[0027] mixing ethyl 2-bromo-4-fluoro-5-nitrophenoxycarboxylate, an alkaline substance, a hydrogenation catalyst and an organic solvent to obtain a mixture;
[0028] Pass hydrogen into the mixture under airtight conditions to carry out hydrogenation reaction to obtain 3-amino-4-fluorophenol; before the hydrogen is introduced, the air in the airtight system is discharged.
[0029] The invention mixes ethyl 2-bromo-4-fluoro-5-nitrophenoxyformate, an alkaline substance, a hydrogenation catalyst and an organic solvent to obtain a mixture. In the present invention, the alkaline substance is preferably an inorganic base and / or an organic amine; the inorganic base is preferably a mixture of one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide, more preferably It is preferably sodium carbonate or potassium carbonate; the orga...
Embodiment 1
[0054] Add 183g (0.59mol) of ethyl 2-bromo-4-fluoro-5-nitrophenoxycarboxylate, 916g absolute ethanol, 5g palladium carbon and 244.3g (1.77mol) of potassium carbonate to a 2L autoclave. Seal the kettle, start stirring, nitrogen replacement three times, pass hydrogen until the pressure in the kettle is 1.0MPa, heat up to 45°C for reaction, when the hydrogen pressure is <0.5MPa, replenish hydrogen to the pressure of 1.0MPa, repeat the operation until the pressure does not drop, After the reaction was completed, the temperature was lowered to room temperature, and the reaction solution was replaced by nitrogen three times to remove the catalyst. The filtrate was distilled at atmospheric pressure to distill methanol to obtain a solid crude product, which was washed with 100 g of water, filtered, and then vacuum-dried at 70°C to obtain a light yellow solid 3-amino- 4-fluorophenol 68.3g;
[0055] The structure of the product was identified using nuclear magnetic resonance, and the id...
Embodiment 2
[0058] Add 183g (0.59mol) of ethyl 2-bromo-4-fluoro-5-nitrophenoxycarboxylate, 916g of methanol, 5g of Raney nickel and 174.9g (2.36mol) of 1,3-propylenediamine into a 2L autoclave After the addition, seal the kettle, start stirring, replace with nitrogen three times, pass hydrogen until the pressure in the kettle is 1.5MPa, raise the temperature to 40°C to start the reaction, when the hydrogen pressure is <1.0MPa, replenish hydrogen to the pressure of 1.5MPa, and repeat the operation until no Until the pressure is dropped, after the reaction is completed, the temperature is lowered to room temperature, and the reaction solution is replaced by nitrogen for three times to remove the catalyst. Yellow solid 3-amino-4-fluorophenol 68.3g;
[0059] The structure of the product was identified using nuclear magnetic resonance, and the identification result was consistent with Example 1, and it can be seen that the product was indeed 3-amino-4-fluorophenol;
[0060] Use GC chromatogra...
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