2-(2H-Benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl-butyl)phenol (45.0 g, 140 mmol) is dissolved in acetic acid (200 mL) at 90° C. Zinc chloride (2.0 g, 14 mmol) and paraformaldehyde (18 g, 600 mmol) are added and HCl gas is passed through the reaction mixture for 12 hours at 90° C. The product, which precipitates after cooling to room temperature, is filtered off, washed with cold pentane and dried at 60° C. under vacuum to yield 36 g of 2-(2H-Benzotriazol-2-yl)-6-chloromethyl-4-(1,1,3,3-tetramethyl-butyl)-phenol.
