2-[2-(4-Chloro-6-nitro-2,4-cyclohexadien-1-yl)diazenyl]-4,6-bis(1,1-dimethylethyl)-phenol is an intermediate used in the synthesis of 2,4-Di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol-d20 (D428017), which is an isotope labelled form of 2,4-Di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (D428015), which is a UV absorber.