Synthesis of Benzotriazole Ultraviolet Absorbers by Catalytic Hydrogenation

The catalytic performance of Pd-Pt-Cu/C catalysts for the synthesis of 2-(2'-hydroxy-5'-methylphenyl) benzotriazole (UV-P) from 2-nitro-(2'-hydroxy-5'-methylphenyl) azobenzene (HAB) was studied.The conversion of HAB reached 100% and the selectivity of UV-P was 92.2% under the optimum reaction conditions (at 323 K, 0.5 MPa hydrogen pressure and reaction time 5 h).A highly selective synthesis of benzotriazole ultraviolet absorbers via hydrogenation of azo compound was obtained.The as-prepared catalysts were characterized by XRD, TEM and XPS.The results showed that the formation of Cu-Pd and Cu-Pt alloys and the moderate electro-deficient state of noble metal species (Mδ+) on the surface of the catalyst could effectively inhibit N-N bond breakage and reduce side reactions due to excessive hydrogenation, which thereby suppressed the formation of tetrahydrofins and aromatic amines by-products. © 2018, Editorial Office of FINE CHEMICALS. All right reserved.