1: 77 percent / conc. HCl / H2O / 2 h / Heating 2: 62 percent / 0.5 h / 90 - 100 °C 3: 71 percent / PPA / toluene / 0.58 h / 100 °C 4: dimethylsulfoxide / 40 °C / or over the mixed anhydrides with BF3 or BBr3 (facilitate the aromatic substitution) View Scheme

hydrogenchloride in water 2 h; Heating;

1: 77 percent / conc. HCl / H2O / 2 h / Heating 2: 62 percent / 0.5 h / 90 - 100 °C 3: 71 percent / PPA / toluene / 0.58 h / 100 °C View Scheme