Nitric Acid → Thiomorpholine, 4-(2,6-difluoro-4-nitrophenyl)-, 1,1-dioxide

Reaction equation

[F:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([F:8])[C:3]=1[N:9]1[CH2:14][CH2:13][S:12](=[O:16])(=[O:15])[CH2:11][CH2:10]1.[N+:17]([O-])([OH:19])=[O:18].O>C(O)(=O)C>[F:8][C:4]1[CH:5]=[C:6]([N+:17]([O-:19])=[O:18])[CH:7]=[C:2]([F:1])[C:3]=1[N:9]1[CH2:10][CH2:11][S:12](=[O:16])(=[O:15])[CH2:13][CH2:14]1

Participants

Procedure

To a suspension of 4-(2,6-difluorophenyl)thiomorpholine 1,1-dioxide (Step 1, 300 g, 1.21 mol) in 3 L of acetic acid, nitric acid (255 mL, ca. 6 mol, fuming, 90%) is added over 30 minutes at ambient temperature. A yellow precipitate forms within minutes and increases over time. The reaction is kept at room temperature for 18 h and is then poured into 6 L of water. After stirring for 2 h, the yellow suspension is filtered. The precipitate is washed with water (1.5 L×3) and ethanol (0.5 L×2) and dried at 50° C. overnight to give the title compound, 1H NMR (DMSO-d6) δ 8.05 (m, 2H), 3.69 (m, 4H), 3.26 (m, 4H).