1: 1.) aluminium amalgame; 2.) oxygen / 1.) ethanol, 95 deg C, 1 h; 2.) 8 h 2: 1.) sodium nitrite, p-sulfanilic acid, sodium acetate; 3.) sodium dithionite, 2.5 percent sodium hydroxide / 1.) acetic acid, -2 deg C, 1 h; 2.) 33 percent aq. acetic acid, 0 deg C, 15 min; 3.) 1 h 3: 1.5 M sulfuric acid, potassium dichromate / CHCl3 4: 66 percent / bromine / CHCl3 / 24 h / Ambient temperature View Scheme