4-Bromo-3-fluorobenzoic acid (CAS# 153556-42-4)
Reference Information
| Uses | 4-bromo-3-fluorobenzoic acid is an important chemical raw material that can be used to prepare a variety of drugs (such as the anti-cancer drug benzamit). |
| Synthesis method | 4-bromo-3-fluorobenzoic acid can be obtained by oxidation of 4-bromo-3-fluorotoluene through potassium permanganate. (1) oxidation: 100kg of kg4-bromo -3-fluorotoluene, 120kg of water and 0.1kg of fatty alcohol polyether sodium sulfate (AES) are sequentially added to the K-400L glass-lined reaction kettle (manufactured by Jiangsu industrial lining chemical equipment co., ltd.) with stirring and heating and condensation reflux device, then 167kg of potassium permanganate is slowly added under stirring condition, kept in boiling state, and reacted for 9 hours, stop the reaction after the reflux solution no longer has oil beads; (2) Filtration: filter the reaction solution obtained in step (1) while hot to obtain the filtrate containing the target product 4-bromo -3-fluorobenzoic acid; (3) Remove potassium permanganate: In order to remove the remaining potassium permanganate in the filtrate, 0.1kg of sodium sulfite must be added to the filtrate obtained in step (2), the addition amount of sodium sulfite is based on the transparent liquid with the purple color of the solution. (4) acidification: in the stirring state, slowly add the substance to the solution obtained in step (3) with a concentration of 12mol/L concentrated hydrochloric acid. when the pH value of the solution is 2.2, stop adding concentrated hydrochloric acid and continue the reaction for 30min. (5) crystallization: in the stirring state, the solution obtained in step (4) is cooled to 2°C, and the crystals precipitated in the solution are 4-bromo-3-fluorobenzoic acid. During the operation, it must be stirred continuously, otherwise 4-bromo-3-fluorobenzoic acid will form a large solid, which is difficult to deal with in subsequent processes; (6) Filtration and washing: The mixed liquid containing 4-bromo-3-fluorobenzoic acid crystals obtained in step (5) is centrifuged to obtain a filter cake that is a crude 4-bromo-3-fluorobenzoic acid product, the crude product is washed with pure water and centrifuged (using a centrifuge with washing function) to obtain refined 4-bromo-3-fluorobenzoic acid; (7) Drying: The 4-bromo-3-fluorobenzoic acid solid prepared in step (6) is dried at 75°C for 12 hours to obtain 197 kg4-bromo-3-fluorobenzoic acid, the content of which is greater than 98%. |
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