Immobilized silver nanoparticles on silica gel as an efficient catalyst in nitroarene reduction

Nanoparticles have properties that can be fine-tuned by their size as well as shape. Hence, there is significant current interest in preparing nano-materials of small size dispersity and to arrange them in close-packed aggregates. This letter describes a way of synthesising silver nanoparticles and their protection to aggregate by silica gel. The combination of catalytic quantities of immobilized silver nanoparticles with reductive ability of NaBH4 efficiently reduces aromatic nitroarenes to the corresponding amines in aqueous medium. Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogen and carboxylic acid groups. The silver particles immobilized on silica gel are stable in the presence of oxygen for several months.