(Green) Photocatalytic Synthesis Employing Nitroaromatic Compounds

Abstract

The combination of a solid photocatalyst (TiO 2 ) and a co-catalyst (p-toluenesulfonic acid) has been successfully applied for the light-induced conversion of nitroarenes in O 2 -free ethanolic suspensions yielding substituted quinolines and tetrahydroquinolines, while in the presence of TiO 2 loaded with a noble metal (Pt, Pd) N-alkylarylamines and N,N-dialkylarylamines were formed. Depending on the compounds that have been detected by GC-MS the reaction mechanism is discussed comprising the formation of anilines and ethanal by a photocatalytic reaction step and their subsequent thermal reactions to quinolines, tetrahydroquinolines, and N-alkylated anilines via a Schiff base as an intermediate product.