3,5-Difluoro-4-(2-phenyldiazenyl)phenol → 4-Amino-3,5-difluorophenol

20.4 g (0.09 mol) of 3,5-difluoro-4-(phenyldiazenyl)phenol from Example 1 and 0.5 g of Pd/C (10%) were initially charged in 120 ml of methanol. The solution was degassed and aerated with hydrogen. The mixture was stirred at room temperature under a 1 bar hydrogen atmosphere for 16 hours. On completion of hydrogen uptake, the catalyst was filtered off and the filtrate concentrated on a rotary evaporator. The residue was chromatographed on silica gel (n-hexane/ethyl acetate, 3:1). The resulting solid was stirred with n-hexane and dried. 7.6 g (60%) of 4-amino-3,5-difluorophenol were obtained as a yellow-brown solid.

1. customThe solution was degassed
2. filtrationOn completion of hydrogen uptake, the catalyst was filtered off
3. concentrationthe filtrate concentrated on a rotary evaporator
4. customThe residue was chromatographed on silica gel (n-hexane/ethyl acetate, 3:1)
5. stirringThe resulting solid was stirred with n-hexane
6. customdried

ORD record

ord-3541ad6a1a0e4a91b167c5b538f471c7

Source dataset

uspto-grants-2008_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07358397B2