General procedure for the synthesis of 3-chloro-4-methoxyphenol from 3-chloro-4-methoxyaniline: 3-chloro-4-methoxyaniline (1.0 g; 6.4 mmol) was dissolved in a 1:1 mixture of water and concentrated sulfuric acid (100 mL) at 0 °C. A solution of sodium nitrite (NaNO2, 0.5 g; 7.6 mmol) in water (10 mL) was slowly added and a thick yellow fume was produced during the reaction. Subsequently, the reaction mixture was heated and refluxed for 30 min and the color of the solution changed to black. After completion of the reaction, the mixture was extracted with ethyl acetate (EtOAc, 4 × 50 mL). The organic phases were combined and concentrated under vacuum. Finally, the residue was purified by silica gel column chromatography (SiO2; 4:1 hexane:EtOAc) to afford 3-chloro-4-methoxyphenol (300 mg; 30% yield) as a yellow oil.
