Amine-Functionalized GO as an Active and Reusable Acid-Base Bifunctional Catalyst for One-Pot Cascade Reactions

The amine-functionalized graphene oxide was prepared by a facile one-step silylation approach and used as an acid base bifunctional catalyst in one-pot cascade reactions containing successive acetal hydrolysis and Knoevenagel condensation owing to the separate coexistence of original carboxylic acid on the edge of the GO sheet and the postgrafted amine groups on the GO basal surface. This catalyst exhibited much higher activity than either amine-functionalized active carbon, amine-functionalized SBA-15, or amine-functionalized Al2O3 due to the enriched surface acid sites and the diminished diffusion limitation as well as high catalyst dispersion in liquid solution due to the unique two-dimensional structure. More importantly, this catalyst could be easily recycled and used repetitively, showing potential application in industry.