1: thionyl chloride / CHCl3 / 2 h / Heating 2: AlCl3 / CH2Cl2 / 1.) 0 deg C, 0.5 h, 2.) RT, 0.5 h 3: p-toluenesulfonic acid / benzene / 89.5 h / Heating View Scheme

1: AlCl3 / CH2Cl2 / 1.) 0 deg C, 0.5 h, 2.) RT, 0.5 h 2: p-toluenesulfonic acid / benzene / 89.5 h / Heating View Scheme

toluene-4-sulfonic acid in benzene 89.5 h; Heating; Yield given;