Diphenylmethane → 4,4'-Di-tert-butyldiphenylmethane

In a 500-ml flask, to a mixture of 16.8 g (100 mmol) of diphenylmethane and 21.3 g (230 mmol) of tert-butyl chloride, 67 mg (0.5 mmol) of anhydrous AlCl3 were added, at room temperature, under vigorous stirring, resulting in immediate HCl gas emission. The reaction mixture turned red. After 5 min, a second portion of 67 mg (0.5 mmol) of AlCl3 were added. After 5 min of vigorous stirring, the reaction mixture became hard. After about 1 h, the hard mass obtained was recrystallised from about 100 mL of hot isopropanol. The crystalline product precipitated from this solution at a temperature of −30° C. after a period of time of about 2 to 3 h. It was separated, washed with 50 ml of cold isopropanol, and dried in vacuum under a reduced pressure of 10 to 20 mm Hg. 19.6 g of product were obtained with a yield of 70%. The procedure was repeated with a yield ranging between 67 and 74%.