Preparation of some 2-(2'H-Benzotriazol-2'-yl)phenol ultraviolet absorbers: application of the transalkylation reaction

When 2-(2′H-benzotriazol-2′-yl)phenols containing t-alkyl substituents are warmed in toluene solution with an aluminium chloride/ nitromethane catalyst, the t-alkyl groups are transferred to the solvent (toluene). This transalkylation reaction has been used to prepare not readily accessible or previously inaccessible 2-(2′H-benzotriazol-2′- yl )phenols, a class of ultraviolet absorbers widely used in industry.