1: 1.) sodium nitrite, conc. HCl, 2.) HBF4 / 1.) water, 0 deg C, 30 min, 2.) 0 deg C, 30 min 2: 66 percent / xylene / 1 h / Heating 3: 86 percent / aq. HBr / acetic acid / 4 h / Heating View Scheme

sodium nitrite in hydrogenchloride; anhydrous xylene; water

1: 1.) sodium nitrite, conc. HCl, 2.) HBF4 / 1.) water, 0 deg C, 30 min, 2.) 0 deg C, 30 min 2: 66 percent / xylene / 1 h / Heating View Scheme

1: 1.) sodium nitrite, conc. HCl, 2.) HBF4 / 1.) water, 0 deg C, 30 min, 2.) 0 deg C, 30 min 2: 66 percent / xylene / 1 h / Heating 3: 86 percent / aq. HBr / acetic acid / 4 h / Heating 4: 1.) bromine, 2.) SnCl2, conc. HCl / 1.) glacial acetic acid, heated on a steam bath, 1 h, then RT, overnight, 2.) glacial acetic acid, heated on a steam bath, 1 h View Scheme