Sulfuric Acid → 3,5-difluoro-2-hydroxybenzaldehyde
Reaction equation
[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[CH:4][C:3]=1[OH:9].C1N2CN3CN(C2)CN1C3.S(=O)(=O)(O)O.FC(F)(F)[C:27](O)=[O:28]>>[F:1][C:2]1[CH:7]=[C:6]([F:8])[CH:5]=[C:4]([CH:27]=[O:28])[C:3]=1[OH:9]Participants
5
Conditions
- Temperature
- 75 °C
Procedure
260 g (2.00 mol) of 2,4-difluorophenol are dissolved in 1.6 l of trifluoroacetic acid, and 560 g (4.00 mol) of hexamethylenetetramine are added in portions. After 30 min, the batch is warmed to 75° C. and stirred overnight. 2 l of 40 percent sulfuric acid are subsequently added at RT, the mixture is left to stir for 2.5 h, 1.5 l of ice-water are added, and the mixture is stirred for a further 30 min. The deposited precipitate is separated off, washed with water and taken up in dichloromethane. The resultant solution is dried over sodium sulfate and evaporated, giving 3,5-difluorosalicylaldehyde as a beige solid.