Sulfuric Acid → 3-Iodo-4-methylphenol
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OS(O)(=O)=O.[I:6][C:7]1[CH:8]=[C:9]([CH:11]=[CH:12][C:13]=1[CH3:14])N.N([O-])=[O:16].[Na+].C(Cl)Cl>O.CCOC(C)=O>[I:6][C:7]1[CH:8]=[C:9]([OH:16])[CH:11]=[CH:12][C:13]=1[CH3:14]OS(O)(=O)=O.[I:6][C:7]1[CH:8]=[C:9]([CH:11]=[CH:12][C:13]=1[CH3:14])N.N([O-])=[O:16].[Na+].C(Cl)Cl>O.CCOC(C)=O>[I:6][C:7]1[CH:8]=[C:9]([OH:16])[CH:11]=[CH:12][C:13]=1[CH3:14]A mixture of 8 mL of concentrated H2SO4, 12 mL of water, 3-iodo-4-methylaniline (5.00 g, 21.5 mmol) and 20 g of ice was stirred under ice-bath cooling until a paste resulted. To this paste was added slowly an ice-cold solution of NaNO2 (1.55 g, 22.4 mmol) in 3.5 mL of water and the resulting mixture stirred for 20 minutes while maintaining the temperature at <5° C. The resulting suspension was slowly added to a mixture of 26 mL of concentrated H2SO4 and 24 mL of water preheated to 80° C. This mixture was stirred at 80° C. for 15 min, then chilled in an ice-bath and poured onto 200 g of ice. The resulting mixture was extracted with 100 mL of EtOAc, and the organic extract washed with water, brine, dried (MgSO4) and evaporated to give a residue. The residue was adsorbed onto 15 g of SiO2 from CH2Cl2, loaded into a precolumn and subjected to MPLC through a 120 g column of SiO2 eluting with 5% EtOAc in hexanes (10 min) and then 10% EtOAc (20 min) to provide 3-iodo-4-methylphenol 1-1 as an oil. 1H NMR (300 MHz, DMSO-d6): δ 2.25 (s, 3H), 6.71 (dd, 1H, J=8, 2 Hz), 7.11 (d, 1H, J=8 Hz), 7.23 (d, 1H, J=2 Hz), 9.51 (s, 1H); LC-MS: calculated for C7H7IO 234.0, observed m/e 234.6 (M+H)+.
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