(779b) Cooperative Catalysis By Acid-Base Bifunctional Graphene

Graphene is a promising candidate to disperse or immobilize catalytically active species for heterogeneous catalysis. Despite various graphene-based nanocatalysts have been reported, the applications of graphene supported nanocatalysts limit to individual reaction. In another aspect, Acid-base bifunctional catalyst is of particularly interest, but also has great challenges in synthesis and applications. In this study, the acid-base bifunctional graphene was prepared by modifications of graphene oxide (GO) with organic amine and sulfonic acid groups through consequent silylanization and free-radical addition, and catalytic organic amine and sulfonic acid groups could be homogeneously introduced to the surfaces of graphene sheets with high densities.. The successful bifunctionalization of GO was confirmed through a series of Characterizations, including fourier transform infrared spectroscopy (FTIR), the X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) and Raman spectroscopy. It is found that the obtained acid-base bifunctional graphene show extraordinary performances in a typical one-pot acid-base reaction sequence called Deacetalization--Nitroaldol reaction sequence, which are probably due to the high densities of both acidic and basic functional groups, as well as the unique two-dimensional structure of the graphene supports. Such kind of graphene-based bifunctional catalysts used in acid-base one-pot reaction sequences can reduce cost and waste water by saving separation/purification steps and solvents/reagents, as well as increase the yield by avoiding the separation of intermediate products.