1: aq. H2SO4 / acetic acid / 20 h / Heating 2: p-toluenesulfonic acid / benzene / 7 h / Heating 3: 28.6 g / p-toluenesulfonic acid / benzene / Heating 4: Br2, CaCO3 / CHCl3; CCl4 / 0.5 h / 5 °C 5: 72 percent / LiBr2, Li2CO3 / dimethylformamide / 0.5 h / Heating View Scheme

1: aq. H2SO4 / acetic acid / 20 h / Heating 2: p-toluenesulfonic acid / benzene / 7 h / Heating View Scheme

1: aq. H2SO4 / acetic acid / 20 h / Heating 2: p-toluenesulfonic acid / benzene / 7 h / Heating 3: 28.6 g / p-toluenesulfonic acid / benzene / Heating 4: Br2, CaCO3 / CHCl3; CCl4 / 0.5 h / 5 °C View Scheme

1: aq. H2SO4 / acetic acid / 20 h / Heating 2: p-toluenesulfonic acid / benzene / 7 h / Heating 3: 28.6 g / p-toluenesulfonic acid / benzene / Heating 4: Br2, CaCO3 / CHCl3; CCl4 / 0.5 h / 5 °C 5: 72 percent / LiBr2, Li2CO3 / dimethylformamide / 0.5 h / Heating 6: 100 percent / N-bromosuccinimide, 2,2-azadiisobutyronitrile / CCl4 / 5 h / Heating 7: 62 percent / H2O / dioxane / 2.5 h / Heating View Scheme

1: aq. H2SO4 / acetic acid / 20 h / Heating 2: p-toluenesulfonic acid / benzene / 7 h / Heating 3: 28.6 g / p-toluenesulfonic acid / benzene / Heating 4: Br2, CaCO3 / CHCl3; CCl4 / 0.5 h / 5 °C 5: 72 percent / LiBr2, Li2CO3 / dimethylformamide / 0.5 h / Heating 6: 100 percent / N-bromosuccinimide, 2,2-azadiisobutyronitrile / CCl4 / 5 h / Heating 7: 62 percent / H2O / dioxane / 2.5 h / Heating 8: 72 percent / conc. HCl / 4 h / Ambient temperature View Scheme