Hexamethylenetetramine → 3,5-Difluoro-4-hydroxybenzaldehyde

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Reaction Steps

A solution of 2,6-difluorophenol (25 g, 192 mmol), hexamethylenetetramine (26 g, 192 mmol) and trifluoroacetic acid (190 mmol) was refluxed overnight. The reaction was cooled and diluted with water (200 mL) and extracted with dichloromethane (3×100 mL). The organic layer was washed with 10% aqueous potassium carbonate (2×100 mL). The aqueous layer was acidified with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer was dried over sodium sulfate, filtered, and concentrated in vacuo to yield 3,5-difluoro-4-hydroxybenzaldehyde as a white solid. Upon sitting the desired product began to precipitate from the original aqueous layer that was extracted with dichloromethane. The layer was filtered to provide the product (6) as long white crystals.

Provenance & Evidence