Selective Photocatalytic Reduction of Nitrobenzene to Anilines, Azoxybenzene, and Azobenzene: A Solvent-Dependent and Light-Induced Process Mediated by CdS/NH2-MIL-125 Nanocomposite

Abstract

While photocatalytic selective transformations have advanced significantly, selective reduction reactions remain less developed. This study investigated the photocatalytic reduction of nitrobenzene using a previously characterized CdS/MOF photocatalyst, focusing on the selective formation of aniline, azoxybenzene, and azobenzene. Results demonstrated that various parameters strongly influence reaction selectivity. High yields and selectivity were achieved for aniline (in methanol), azoxybenzene (in tetrahydrofuran), and azobenzene (in ethanol) using hydrazine as a hydrogen source. Notably, the addition of K₂CO₃ was crucial for achieving high selectivity towards azobenzene. The scope of the reaction was checked for the production of various anilines and azobenzene derivatives using the corresponding aromatic nitro compounds. The CdS/MOF photocatalyst exhibited good reusability, maintaining a high yield and selectivity over several cycles with only a slight decrease in performance.