toluene-4-sulfonic acid in toluene 3 h; Heating;

1: 95.6 percent / bromine / acetic acid / 2 h / Ambient temperature 2: 65.7 percent / sodium hydride, cuprous iodide / dimethylformamide / 1.) room temperature, 30 min, 2.) 80 - 85 deg C, 12 h 3: 88.1 percent / manganese dioxide / CH2Cl2 / 72 h / Ambient temperature 4: 71.9 percent / Claisen's alkali / 0.5 h / Heating View Scheme

bromine in acetic acid 2 h; Ambient temperature;

1: 95.6 percent / bromine / acetic acid / 2 h / Ambient temperature 2: 65.7 percent / sodium hydride, cuprous iodide / dimethylformamide / 1.) room temperature, 30 min, 2.) 80 - 85 deg C, 12 h View Scheme