Preparation of 3-Fluorophenol

Introduction

3-Fluorophenol is an organic compound with the chemical formula C6H5F, which is a phenol derivative with the position 3 on the benzene ring replaced by a fluorine atom.3-Fluorophenol has certain applications in chemical and pharmaceutical fields, and can be used as a reagent and intermediate in organic synthesis.

Preparation method

1. Dissolve the raw material intermediate of aminophenol completely in organic solvent, and at the same time reduce the temperature to 10~15℃. Slowly add anhydrous hydrofluoric acid drop by drop under stirring until the drop is completed and then continue to stir the reaction until the raw material is completely converted to hydrofluoric acid salt. The volume ratio of aminophenol to organic solvent between raw materials was 1:3~5, and the molar ratio to anhydrous hydrofluoric acid was 1:3~35.

2. When the reaction system was completed, the system was cooled to -10 °C, then solid KNO was added uniformly and the reaction was carried out at -5 °C under control. The molar ratio of aminophenol to solid sodium nitrite between raw materials was 1:105~125.

3.Segmented temperature rise for pyrolysis reaction. The temperature was ramped up to 65 °C at a rate of 5 °C per hour, heating was stopped, and the temperature was lowered to 10 °C after the system did not continue to ramp up. Neutralise the reaction system by slowly adding 10% aqueous KOH solution dropwise, keeping the temperature of the neutralisation reaction at 30 °C until the pH of the system reaches 7, then stop stirring and allow the system to stand and stratify.

4, the separated organic phase was washed with water twice, and then the separated aqueous phase was extracted with an organic solvent, and the combined organic phase was filtered to remove solid residues, and then the aqueous phase was separated again and distilled.

5.Atmospheric pressure distillation was carried out to separate the organic solvent and recover it. Decompression distillation was then carried out to obtain the product 3-fluorophenol.

Cautions:

1, in the above method for the preparation of 3-fluorophenol, the organic solvent used is one of toluene, fluorobenzene, fluorinated toluene, pyridine or a mixture thereof, the volume ratio of m-aminophenol to the organic solvent is 1:3~5, the fluorination medium is anhydrous hydrofluoric acid, and the molar ratio of the m-aminophenol to the anhydrous hydrofluoric acid is 1:3~35.

2, the preparation method of 3-fluorophenol according to claim 1, the diazotising reagent is KNO, the molar ratio of m-aminophenol to KNO is 1:105~125.